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This document contains technology under
The export jurisdiction of the U.S. Department
Of Commerce, Export Administration Act of
1979, as amended, Title 50, U.S.C., App
2401 et seq and EAR 15 CFR 730
ECCN: 9E990
U.S. Schedule B: 4906-00-0000
Manual No.9449-6
April 26, 2001
Model8500C/8500C+
Operators Manual
Model 8500C/C+ Balancer/Analyzer System
Chadwick-Helmuth
Company, Inc.
Copyright Notice
Copyright
©
2001 by Chadwick-Helmuth Company, Inc.
All Rights Reserved
Sixth Edition, April 2001
Printed in the U.S.A.
This Manual is supplied to the User under license, subject to change without notice and/or recall by
Chadwick-Helmuth Company, Inc., at any time. The Manual at all times remains the property o
Chadwick-Helmuth Company, Inc. The information contained in this Manual is considered confidential. No part of this Manual is to be copied or reproduced or transmitted in any form whatever
(including orally or by electronic transmission), nor is any information in this Manual to be disclosed in any form whatever (including orally or by electronic transmission) to anyone other than an authorized representative of the User's employer who also shall agree not to disclose same, without express prior written consent of Chadwick-Helmuth Company, Inc.
Chadwick-Helmuth Company, Inc.
4601 N. Arden Drive
El Monte, CA 91731
(626) 575-6161
Fax: (626) 350-4236
BBS: (626) 350-9697
E-mail: [email protected]
ii Chadwick-Helmuth Company, Inc.
Contents
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Chapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Chapter 2. Overview and Basic Theory . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.2 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
2.2.2.2 Theory of Chart Creation and Correction . . . . . . . . . . . . . . . . . . . . . . . 2-9
Chapter 3. Unpacking and Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Chapter 4. Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Model 8 500C/8500C+ Operators Manual iii
Contents iv
Chapter 5. Balance Measurement and Solutions . . . . . . . . . . . . . . . . . . 5-1
Chadwick-Helmuth Company, Inc.
Contents
Chapter 6. Blade Track Observation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Chapter 7. Spectrum Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Model 8 500C/8500C+ Operators Manual
v
Contents
7.3.1.7 Signal Selector Velocimeter Channel(s). . . . . . . . . . . . . . . . . . . . . . . . . 7-5
Chapter 8. Using Printouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
8.1 Printouts With the 8500C/C+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Chapter 9. Status Screen Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
vi Chadwick-Helmuth Company, Inc.
Contents
Chapter 10. Printer and Disk Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
Chapter 11. Model 8520C Signal Selector . . . . . . . . . . . . . . . . . . . . . . . 11-1
Appendix A. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
Appendix B. Spectral Data File Format. . . . . . . . . . . . . . . . . . . . . . . . . . B-1
Appendix C. Balance History Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
Appendix D. Quick Reference Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1
Model 8 500C/8500C+ Operators Manual vii
Contents viii Chadwick-Helmuth Company, Inc.
List of Figures
Figure 2-1. Ideal Rotor With Weight And Supporting Springs . . . . . . . . . . . . . . . . . . . 2-2
Figure 2-4. Displacement, Velocity, and Acceleration in an Imbalanced Hub . . . . . . . 2-5
Figure 5-8. Strobex: No Balance Frequency Signal Error Screen . . . . . . . . . . . . . . . . 5-10
Figure 5-9. Magnetic Pickup/Photocell: No Synchronization Signal Error . . . . . . . . . 5-11
Figure 5-10. Magnetic Pickup/Photocell Phase Meter Display . . . . . . . . . . . . . . . . . . 5-11
Model 8 500C/8500C+ Operators Manual ix
List of Figure x
Figure 5-13. Balance Run Start-up Screen, Additional Soft Keys . . . . . . . . . . . . . . . . 5-15
Figure 5-18. Measurements Only/Strobex Balance Start-up Screen . . . . . . . . . . . . . . . 5-20
Figure 7-13. Spectral Frequency Plot With Harmonics Cursors. . . . . . . . . . . . . . . . . . 7-11
Chadwick-Helmuth Company, Inc.
List of Figures
Figure 11-3. Balance Setup Screen With Model Signal Selector Support . . . . . . . . . . 11-4
Figure 11-4. Balance Setup With Two 8520 velocimeter Channels . . . . . . . . . . . . . . . 11-4
Model 8 500C/8500C+ Operators Manual xi
List of Figure xii Chadwick-Helmuth Company, Inc.
List of Tables
Model 8 500C/8500C+ Operators Manual xiii
List of Tables xiv Chadwick-Helmuth Company, Inc.
Chapter 1
1.
Introduction
This chapter introduces you to the basic characteristics of this manual and important related documentation, as well as the Chadwick-Helmuth Mode l 8 500C/C+ Balancer/Analyzer and its system.
The chapter also contains information about contacting customer service, in case you need any help
with the product. Chapter 1 includes the following topics:
1.1 About This Manual
This manual is the guide to operating t he Model8500C/C+ Balancer/Analyzer (from now on called th
8500C/C+), that is, how to use the unit and its system, as well as how to interpret the information it gives you. This document contains procedures for installing and running the 8500C/C+, as well as instructions on how to interpret the information presented while it is in operation.
1.1.1 Organization
This manual explains the operation of the 8500C/C+ in detail. Briefly, its chapters cover the following subjects:
also tells you how to contact Customer Service.
Chapter 2. Overview and Basic Theory - Gives a general system overview and explains the basic
theory of operation for the 8500C/C+.
Chapter 3. Unpacking and Installation - Describes how to unpack and install the 8500C/C+.
Chapter 4. Getting Started - An introduction to using the 8500C/C+. It describes the display and
function keys in detail, defines terminology used throughout the rest of the manual, and introduces general operating procedures.
Chapter 5. Balance Measurement and Solutions - Explains the balance measurement and solution
features of the 8500C/C+. It explains the procedures for lateral and vertical balancing of vibrating rotor systems, including the analysis of balance data and implementation of balance solutions.
Chapter 6. Blade Track Observation - Describes the blade track observation feature of the 8500C/
C+. It explains the procedures for visual tracking of rotor blades and techniques for determining out-of-track elements.
Chapter 7. Spectrum Analysis - Describes the spectrum analysis features of the 8500C/C+. It
provides details on acquiring, displaying, and analyzing vibration spectra.
Chapter 8. Using Printouts - Describes how to read and annotate printouts that are printed by the
8500C/C+.
Mode l8500C/8500C+ Operators Manual
1-1
Chapter 1 - Introduction
Chapter 9. Status Screen Operation - Explains the 8500C/C+ Status screen, and explains procedures
for modifying the date and time, reviewing other work, formatting disks, and other 8500C/C+ status-related features.
Chapter 10 Printer and Disk Drive - Describes the 8500C/C+ printer and disk drive, and how to use
them to create printouts and to load and store data from a disk.
Signal Selector and its use with the 8500C/C+.
1.1.2 Document Conventions
This manual uses the following text and format conventions:
• Keys on the Mod el8500 are shown in boldface type. Dedicated keys are in regular type, for example, PRINT . Soft keys are in italic type, for example, ENTER . For details on the 8500C/C+
keys see Section 4 .2 “Keypa ” on pa ge4-3.
• Keys on your PC keyboard are shown in boldface and italic. For example, the “Shift” key is shown as Shift and the “Enter” (or Return) key is shown as Enter. Sometimes keys are used in combination. Ctrl+F1 means hold down the “Control” key and press the “F1” (Function one) key, both together. Ctrl~F1 means to press the two keys in succession, one at a time.
• Take care to distinguish between the number 1 and the letter I. The text tries to help you out as much as possible in this regard.
• Text on a display screen, for example, the Mo del8500 screen, is shown in monospaced type. This represents text in this guide exactly as it appears on screen. When you see the instruction, “Typ
this text,” it tells you to type the text as it appears, then press the Enter key.
• Important topics or terms are in italics. Definition lists have the first term or software menu option at the start of the list entry in boldface, for example,
Product Name - The Mode l8500C/C+ Balancer/Analyzer
• Titles of chapters or sections are in quotation marks, for example, “Document Conventions,” but
the section numbers are not, for example, see Sect ion1.1.2 “Document Conventions” on pa ge1-2.
• MS-DOS file and directory names are shown in all-capital letters. For example,
AUTOEXEC.BAT and C:\DOS\COMMAND.COM. The letters after the dot are called the file
extension. An asterisk (*) followed by a dot and a file extension means all files with that extension, for example, *.COM means all files with the COM extension.
1.1.3 Formats
In many places in the manual, special notices appear. Their headings and formats have the following meanings:
• NOTE: Here is additional useful information pertaining to the current subject.
• CAUTION: Be careful with the current procedures or items because of possible damage to equipment or loss of data.
• WARNING: Exercise extreme care with current procedures because of possible personal injury.
Special notices appear in the format you see here, with the heading in capital letters and the rest of the notice next, after a colon, with the entire paragraph set in boldface italic type.
1-2 Chadwick-Helmuth Company, Inc.
Reference Documentation
1.1.4 Inserts, Changes, and Revisions
This publication is the sixth edition of this manual. Changes and/or later editions will be issued as needed because of hardware changes and/or firmware upgrades.
NOTE: This manual is written for 8500C/C+ firmware Ver sion4.00.
1.2 Reference Documentation
Table 1-1. Reference Documentation
Document Name
Mode l 8 500C/C+ System Maintenance
Manual
Mode l 1 35M-12 Strobex Operation and
Maintenance Manual
FasTrak
TM
Operators Manua
The Smooth Propeller (Versi on2)
The Polar Coordinate Chart: Balanc
Chart Making in the Real World
Universal Balance Chart Worksheet
Application user guide for the subject aircraft
Stock No.
Publisher
10902-2 Chadwick-Helmuth
9076
13011-1
9511-2
AW8016
3659
Contact
Customer
Support
Chadwick-Helmuth
Chadwick-Helmuth
Chadwick-Helmuth
Chadwick-Helmuth
Chadwick-Helmuth
Chadwick-Helmuth
The part numbers in the previous list indicate Chadwick-Helmuth documentation. Use the numbers shown in the list for ordering purposes. Each or any Application Note has its own order number. You
example aircraft maintenance manuals, as needed.
NOTE: For part numbers of all 8500C/C+ parts and/or other order information, see the
Mode l8500C/C+ System Maintenance Manual.
Mode l8500C/8500C+ Operators Manual
1-3
Chapter 1 - Introduction
1.3 Technical Support
In the United States you may reach an 8500 techical representative for Chadwick-Helmuth’s Technical
Support by dialing the number below,
(626) 575-6161
Call this number Monday through Friday between 8:00a.m. a nd 4:30p.m. Pacific Time. If at all possible, please fax a copy of your customer support report in care 8500 support before calling.
1.3.1 Fax Service
You may send a fax detailing your questions or comments at any time, by dialing the 24-hr number below.
(626) 350-4236
1.3.2 Internet Service
Chadwick-Helmuth also has an Internet e-mail box. Make sure you send any messages to the attention of Customer Support. Our e-mail address is
Our Web site address is www.chadwick-helmuth.com
For more details on this or any of our other support services, please contact an 8500C/C+ technical representative at Chadwick-Helmuth’s Technical Support number.
1-4 Chadwick-Helmuth Company, Inc.
Chapter 2
2.
Overview and Basic Theory
The Mode l 8 500C/C+ Balancer/Analyzer contains a number of different components. This chapte
gives you summaries of what they are and how they operat e. Chapter2 provides a general system
overview and the 8500C/C+’s basic theory, under the following topics:
2.1 About the Model 8 5 00C/C+
The 8500C/C+ is a portable, microprocessor-based instrument specifically designed for the acquisition and analysis of rotor system vibration data. It is intended for use with systems such as helicopters and airplane propellers, where the identification and suppression of rotor vibrations are essential to correct performance and maintenance. The unit incorporates state-of-the-art digital technology in its design.
The result is a family of instruments that achieves a high level of performance and is at the same time both versatile and easy to use.
The 8500C/C+ supports a broad range of functions that provide for sophisticated and detailed analyses of target rotor systems. For example, the 8500C/C+ may be used as an analyzer to
• Perform on-site maintenance through vibration trend analysis
• Generate documentation both before and after maintenance
• Display and record vibration profiles of new or overhauled aircraft
You may also use the 8500C/C+ as a balancer/tracker to
• Track and balance helicopter main and tail rotors
• Balance propellers
• Balance shafts and blowers
• Balance high-bypass jet fans
• Perform all balancing and tracking on the aircraft
In addition, the 8500C/C+ provides for
• Hard-copy reproductions of graphics, text, and dat
• Floppy disk storage for software balance charts, spectral setups, and data
For a detailed functional description of the 8500C/C+ system, see t he Model8500C/C+ System
Maintenance Manual.
NOTE: For part numbers of all 8500C/C+ parts and/or other order information, see the
Mode l8500C/C+ System Maintenance Manual.
Mode l8500C/8500C+ Operators Manual
2-1
Chapter 2 - Overview and Basic Theory
2.2 Theory of Operation
This section gives an overview of the basic theory of the 8500C/C+’s operation.
2.2.1 Characteristics of Balancing
If a perfectly balanced circular disc is mounted on a rigid center spindle and rotated, the outward
centrifugal forces created are constant everywhere along the edge of the disc (see F igure2-1).
Consequently, the disc edge appears to maintain a perfectly stable circular orbit around the spindle axis with no uneven or extraneous forces being transmitted to the surrounding environment.
Figure 2-1. Ideal Rotor With Weight And Supporting Springs
Now if a weight is added to the edge of the disc, the increased centrifugal force created there when th disc is rotated perturbs its orbit, inducing a mass imbalance around the center of rotation and a wobble
maximum wobble would accordingly feel the effects of this imbalance, experiencing an up-and-down vibration once per revolution as the weighted disc edge passes through the top and bottom of its rotary trajectory. This effect is called a lateral mass imbalance because the direction of the vibration is aligned with (that is, parallel to) the rotor system's plane of rotation.
Figure 2-2. Shaft Wobble Induced By Mass Imbalance
2-2 Chadwick-Helmuth Company, Inc.
Theory of Operation
The vibrational forces created by a lateral mass imbalance are transferred with equal intensity to th opposite end of the spinning shaft and from there to any components the wobbling spindle may contact. In large, rapidly spinning rotor systems such as helicopters and propeller airplanes, this phenomenon may be felt by passengers and crew as an uncomfortable, resonating “buzz” caused by the propagation of vibrations through the air frame and cabin. A second consequence is far more serious, that is, damage to system hardware. If an excessive rotor imbalance is left untreated, components that are continually subjected to the associated vibrational energies can, over a period o time, suffer wear, abrasion, fatigue, or even breakage. Such damage is at best costly in terms of aircraft maintenance, and at worst dangerous to the ship and its occupants.
How can we locate and neutralize a lateral mass imbalance in a rapidly spinning disc? Since we know that the weighted edge of the rotating disc must be at the top of its rotary travel when the vibrating spring reaches the point of maximum expansion (positive amplitude), and at the bottom of its arc when the spring reaches the point of maximum contraction (negative amplitude), it follows that the location of the weight can be determined from the spring position alone. That is, if we could stop the spinning disc at the point of maximum vibrational amplitude, the weighted edge would appear at the top of its trajectory.
The expansion and contraction of the spring can be measured as positive and negative vibration
The position of the disc at any given moment is called its angular position (expressed in either phas angle or clock angle). Angular position is a measure of the relationship between a given point on th edge and some fixed artificial reference (also called azimuth) and is computed in terms of the central angle subtended by the two points. The angular position of the disc thus tells us exactly where th destabilizing mass is located. Moreover, the magnitude of the vibrational amplitude, that is, the amount of expansion and contraction seen in the spring, is directly related to the weight of the mass.
With this information, we can now pinpoint the source of the imbalance and either remove the appropriate amount of weight or add a counterbalancing weight to the opposite edge of the disc. Either action can correct the out-of-balance condition.
Mode l8500C/8500C+ Operators Manual
2-3
Chapter 2 - Overview and Basic Theory
0
Figure 2-3. Displacement in an Imbalanced Rotor
and frequency f, whose displacement, y, may be described mathematically by the equation d
(
y = r sin
θ )
In this equation, r is the amplitude of vibration and
θ
the phase angle.
2-4 Chadwick-Helmuth Company, Inc.
Theory of Operation
The 8500C/C+ determines the angular position and vibrational amplitude of an unbalanced rotor with the help of a device called a velocimete . The Chadwick-Helmuth Mode l 7 310 Velocimeter is a electroni transducer that measures displacement velocity, that is, the rate of change of displacement with respect to time. The velocity, v, of a simple harmonic oscillator can be expressed mathematically by v = 2
π
fr cos
θ
In this equation, f is the frequency of rotation, r the amplitude of vibration, and
θ
the phase angle. The
waveform produced by this equation can be seen in Figure2-4. No te the 90°phase shift from th
displacement waveform.
Displacement
0
Acceleration
Velocity
Figure 2-4. Displacement, Velocity, and Acceleration in an Imbalanced Hub
A velocimeter is usually attached directly to a rotor system's support structure and oriented in th direction of the vibration. It generates an electrical signal whose voltage varies from plus to minus as the support structure moves up and down during each revolution. This varying voltage is directly proportional to the amplitude of vibration and actually represents the physical motion of the point where the velocimeter is attached. The 8500C/C+ samples this signal and transforms it, using fast
Fourier transform (FFT) software techniques. Then, the 8500C/C+ extracts the frequency component of the vibration, otherwise called th balance frequency of the system.
1
1. Out-of-balance rotors are often subjected to several different kinds of vibration. The 8500C/C+ extracts a profile of these different vibration amplitudes across a broad range of frequencies and displays the values in a plot of frequency against amplitude. The largest of the peaks is usually the balance frequency of the lateral mass imbalance. This frequency must be selected by the user before the balance can continue.
Mode l8500C/8500C+ Operators Manual
2-5
Chapter 2 - Overview and Basic Theory
In one approach, the Balance Frequency is used to time a one-per-revolution triggering pulse to th
Chadwick-Helmuth Mode l 1 35-M12 Strobex Tracker (see Fi gure2-5). The Strobex flashes a
stroboscopic light with each trigger, and if it is aimed at a special retro-reflective target attached to the spinning rotor, the target appears frozen at some angular position. This angular position indicates th exact location of the mass imbalance. The 8500C/C+ can modulate the Strobex trigger so you can visually move the target toward the rotor's reference azimuth. When the two points converge, the
8500C/C+ fixes the exact angular position and amplitude of vibration then computes the balance solution.
STROBEX
MODEL 135M-12
CHADWICK HELMUTH
E L M O N T E , C A L I F O R N I A
Figure 2-5. Strobex Strobe Tracker
The Strobex is one way to locate a lateral mass imbalance. You may also use the Chadwick-Helmuth
Mode l3030 Magnetic Pickup and interrupter or Chadwick-Helmuth Photocell System and reflectiv target to generate a one-per-revolution reference signal for the spinning rotor. If the interrupter or reflective target has been secured to a known point on the spinning rotor, the 8500C/C+ can compare this signal against the velocimeter output to compute the angular position of the out-of-balance element.
2-6 Chadwick-Helmuth Company, Inc.
Theory of Operation
2.2.1.1
Track Imbalances
A rotor system's track describes the geometry of the circular path made by the blades as they rotate. A blade that is out of track may follow a slightly different path because its alignment in the plane o rotation is skewed. The result is a one-per-revolution vibration whose direction is perpendicular to the plane of rotation. We can analyze this condition either by measuring the amplitude and frequency of vibration or by visually characterizing the track to determine the extent of the imbalance. The former technique is called a track or vertical balance and employs principals and procedures nearly identical to those used to correct a lateral mass imbalance. The latter technique is called a visual track and uses the Strobex or FasTrak
Tm
Optical Tracker to illuminate the relative position of the blades as they rotate. In both cases, the goal is to match the aerodynamic qualities of all the blades and thereby eliminate the vertical vibrations caused by an out-of-track condition.
The major difference between vibrations generated by a lateral mass imbalance and those generated by a track or vertical imbalance is the direction of the vibrational forces. Otherwise, the principals governing them are nearly identical. To solve a track imbalance, we therefore have only to orient the velocimeter perpendicular to the plane of rotation. The 8500C/C+ extracts from the velocimeter signal the amplitude of vibration and balance frequency and uses a reference signal from a magnetic pickup or Photocell to determine the phase angle of the out-of-track vibration. With this information it can then compute a solution based on the adjustment of trim tabs or pitch links that physically modify the blade's track.
In a visual track the one-per-revolution signal from a magnetic pickup or Photocell is used to drive th
Strobex flash. If each rotor blade has secured to it a retro-reflective target, we can identify each target as it is illuminated by the Strobex flash. In a perfectly tracked system, the images line up precisely along the planar path of rotation established by all the blades. The extent to which any blade image deviates from the path is an indication of the relative degree of track imbalance. Adjustments to th aircraft's trim tabs and/or pitch links can usually bring the anomalous blade back into alignment.
2.2.1.2
Blade Sweep
Blade sweep or lead-lag refers to the angle of separation between individual blades within the plane of rotation. Blade spacing that is not equiangular can cause significant perturbations to the system's lateral balance. For this reason, balance solutions for some helicopters call for modification of the rotor's blade sweep rather than addition or subtraction of weights.
Visual tracking allows you to gauge the relative amount of separation between Strobex-illuminated blade images. This separation is indicative of the relative angular spacing between the actual blades.
The FasTrak
TM
Optical Tracker is able to exactly determine the Lead-Lag of the target rotor.
2.2.2 Balance Charts
We have seen how the 8500C/C+ can identify the vibrational characteristics of a rotor system by providing two essential measurements, vibration amplitude and angular position. But in order to compute an actual balance solution, that is, how much weight to add or subtract, and where to apply the changes, the operator first needs to know something about the relationship between the physical balance points of the system and values for amplitude and position. In particular, one needs to be able to predict how vibration amplitude and angular position change when one makes specific adjustments at the balance points. This information has been experimentally determined for most aircraft types and organized into a unique form called a balance chart.
Mode l8500C/8500C+ Operators Manual
2-7
Chapter 2 - Overview and Basic Theory
Each balance chart contains data that describe a single rotor element from a particular aircraft type. In the 8500C/C+, related balance charts are stored digitally in a balance chart file. They may also b represented graphically and can be found in almost any Chadwick-Helmuth paper balance chart. Paper balance charts provide a simple way to visually fix a balance measurement and calculate the weight adjustments required to balance the rotor. Although the 8500C/C+ does not require the use of paper balance charts, it does use the information they contain. It is therefore important for purposes of ou discussion to understand some of the theory behind them.
2.2.2.1
Paper Balance Charts
A paper balance chart consists of a clock face who se 12radial lines represent the clock angle of th
balance measurement (see Figur e2-6). Concentric circles drawn around the center of the clock face
delimit different values of vibration amplitude. Finally, a graph is laid over the clock face. The graph’s axes represent the geometrical relationship between the weight attachment points of the aircraft. If, for example, the attachment points are 9 0 °apart, as on a four-blade rotor, the axes of the graph are perpendicular to each other. The axes are labeled with weight amounts, and their values are inversely proportional to the length of the moment arm formed by the center of rotation and the weight attachment point (a weight has more effect the further out it is placed along a blade, so smaller amounts are needed).
16
12
Su bt ra ct
Ad d
-o rto
A
8
f ro m
C
9
10
11
12
"IPS"
1.0
.9
.8
.7
.6
.5
.4
.3
.2
.1
1
2
.1
.2
.3
.4
.5
.6
8
0
1.
S"
"IP
4
0
WE
Pi tc
IG
-G
RA h
HT
a
Li
MS
nk t
.9
7
.8
4
.7
6
8
Su bt ra ct
Ad d
-o rto
C
12
f ro m
A
16
5
4
Figure 2-6. Sample Paper Balance Chart
4
3
2 m
B o r f t c a r t b u
S
r o
-
T o t d d
A
E
G
R
A
T
1
3
0
WEIGHT AT TIP
-GRAMS-
4
3
2
1
A
T m o r f t c a r t b u
S
T
E
G
R
r o
-
B o t d d
A
2-8 Chadwick-Helmuth Company, Inc.
Theory of Operation
A balance measurement reading allows the operator to plot the intersection of vibration amplitude and phase angle on the clock face. Extrapolation of this point to the axes of the graph determines the location and magnitude of the required adjustments. In most cases, a balance point indicates two corrective moves, one for each blade whose axis encompasses the balance point. The exact procedur required to balance the rotor depends on the chart being used.
2.2.2.2
Theory of Chart Creation and Correction
Individual rotor systems of a particular type rarely exhibit identical vibrational characteristics.
Differences in manufacture and repair, as well as variations in airframe stiffness and resonant frequency often call for different balance solutions. The uniqueness of each system's mechanical response thus precludes using a single set of ideal parameters to build balance charts. As a result, charts do not exemplify abstract theoretical models of rotor performance. Instead, they are created by carefully averaging many experimental measurements of a particular rotor type. This approach means that charts may not always accord with actual rotor measurements, in some cases diverging enough to prevent proper balancing.
We can compensate for these inherent biases by using the 8500C/C+ to correct individual balanc charts, modifying them so that each chart can be tuned to the unique physical characteristics of individual systems.
Chart corrections compare the actual effects of weight on vibration amplitude and clock angle against the changes predicted by the chart. We can quantify the comparison by means of a special calculation, the move line. The move line is the vector difference between two balance measurements. On a paper balance chart it is identified by the straight line drawn between two balance points. Normally, the direction of the move line changes in a predictable manner as one makes the weight adjustments prescribed by the chart. If, for example, both corrective moves are made, the move line goes toward o through the center of the chart. If only one move is made, the move line runs parallel to the fine lines extending from the axis of the unmodified blade. In other words, the weight on this blade has not been changed. The difference between the observed direction and the expected direction indicates the amount of phase angle correction that must be applied to subsequent measurements. This correction is usually accomplished by rotating the clock face or writing new clock numbers around the paper chart.
In the 8500C/C+, a correction factor for phase is computed and added to the balance chart database.
This correction factor is thereafter applied to all calculations involving the phase angle.
The magnitude of the move line (that is, its length) also signifies a particular vibration level or amplitude. It should also change in a predictable manner as we make the weight adjustments prescribed by the chart. Making only one of the corrective moves brings the move line directly to the zero weight change axis for that blade. In other words, the weight change required by this blade has been implemented. The length of the move line is therefore directly related to the size of the weight adjustment. The ratio of the observed magnitude to the expected magnitude indicates the percentag weight correction, as well as the percentage amplitude adjustment, which must be applied to subsequent measurements. For example, if the move line is too long, too much weight has been added.
If it is too short, not enough weight has been used. In the 8500C/C+, this ratio becomes the correction factor for vibration amplitude. It is added to the balance chart database and thereafter applied to all calculations of weight adjustment.
Mode l8500C/8500C+ Operators Manual
2-9
Chapter 2 - Overview and Basic Theory
2.3 System Architecture
Figur e2-7 below shows an overall block diagram for the 8500C/C+ system. The 8500C/C+ itself can
be divided into the following major logical components:
• Digital subsystem, containing memory, microprocessor, communications controllers, and clock chips
• Data acquisition or analog subsystem, containing analog inputs, waveform generator, input multiplexor, analog-to-digital converter, programmable gain stage, antialiasing filter, and clip detector
Strobex
28 VDC
Model 8500C/C+
Balancer/Analyzer
Main Unit
28 VDC
Model 8520C
Signal Selector
Signals
Aircraft
Under Test
28 VDC
Vibration Input
Magnetic/Photocell Pickup Input
8500SYBK.DS4
Figure 2-7. 8500C/C+ System Block Diagram
2.3.1 Digital Subsyste
The 8500C/C+ digital subsystem is made up of eight major functional blocks, as depicted in the block
diagram in Figur e2-8 on pag e2-11. All components communicate over a high-speed system bus, with
each block controlling its peripherals directly through dedicated interfaces.
2-10 Chadwick-Helmuth Company, Inc.
System Architecture
The microprocessor controls the entire system by communicating with the other blocks over the system bus. Instructions and data used by the microprocessor are stored in memory. The memory block itself is divided into the following sections:
• Program memory in the form of the read-only memory (ROM) that stores the system's software
• Temporary data memory in the form of dynamic random-access memory (DRAM
• Permanent data memory in the form of nonvolatile static RAM
Sensor
Input Disk Unit
Timing
Controller Acquisition Controller
System
Bus
Micro-
Processor
Parallel
I/O
Memory Serial I/O
Display
Control
Operator
Keypad
Printer
Unit
Operator
Display
Figure 2-8. 8500C/C+ Digital Subsystem Block Diagram
The timing controller is the system timing master. It generates the timing signals used to control majo functions, such as analog-to-digital conversion, external synchronization, and strobe triggering. Th timer drives the Strobex trigger by connecting to it through an opto-isolator at the strobe interface.
Timer counters are completely under program control, and the microprocessor communicates with them over the system interface.
The serial input-output (I/O) block controls the various serial interfaces, as well as the clock interface and a portion of the analog data acquisition interface. The clock interface communicates with dedicated real-time clock that maintains the system date, day, and time. The disk controller block mediates data flow between the rest of the system and the 8500C/C+’s 3.5-in. floppy disk drive. The keyboard controller block reads keyboard input through the keyboard interface, and the display controller block directs the liquid-crystal display (LCD) output through the display interface.
Mode l8500C/8500C+ Operators Manual
2-11
Chapter 2 - Overview and Basic Theory
2.3.2 Analog Subsyste
The analog subsystem reads analog input signals directly from the velocimeter or waveform generator, filters them, samples them, and converts them to digital form through the analog-to-digital converter
(see Figur e 2 -9 below). The timing controller provides programmable clock signals that synchronize
this process. The digitized data are output to the microprocessor over the system bus where they are stored in memory for analysis and display by the executive software.
A uto-calib ration
Te st W aveform
G enerato r
M ux
A n ti-
A lias
F ilter
Stag e 1
V ibra tio n
S en so r In put
P rogram m ed
G ain
A nti-
A lias
F ilte r
Stag es 2-5
A /D
Con ve rte r
C lip
D etecto r
Ana log Bo ard
B us
Interface/
T im in g
Con tro ller
D ig ita l Bo ard
Figure 2-9. 8500C/C+ Analog Subsystem Block Diagram
The analog subsystem includes a high-performance antialiasing filter to reduce spurious signals introduced by the sampling process. A variable gain stage in the analog input signal path amplifies the analog signal so that a high signal-to-noise ratio can be maintained over a wide dynamic range of signal amplitudes. The gain is under program control and is set by the microprocessor through a digital-to-analog converter. The on-board waveform generator provides known reference signals fo calibration verification and test of the analog subsystem. A multiplexer selects either the velocimeter input or the internal waveform generator as the input to the analog signal path. Finally, a clip detector circuit ensures that no input signal amplitudes exceed a fixed reference voltage level.
For a detailed functional description of the 8500C/C+’s system architecture, see t he Model8500C/C+
System Maintenance Manual.
2-12 Chadwick-Helmuth Company, Inc.
Chapter 3
3.
Unpacking and Installation
The Mode l 8 500C/C+ Balancer/Analyzer is a self-contained kit packed in a rugged case. All the accessories needed for operation are included in the kit. Complete unpacking instructions for the kit are included in the Mod el8500C/C+ System Maintenance Manual. The information in this chapter is a
brief summary. Chapter 3 gives you unpacking and installation information, under the following
topics:
3.1 Model 8 5 00C/C+ and Installation
Figur e3-1 on page3-2 shows a top and front view of the 8500C/C+ . The Model135M-12 Strobex and
28-Vdc power/signal connectors are on the right side. The liquid-crystal display (LCD) contrast adjustment is on the left. The disk drive door is on the front of the unit.
CAUTION: The 8500C/C+ can only operate from a 28-Vdc power supply. Plugging the
8500C/C+ into a power source other t han 28Vdc may cause severe damage to the instrument.
Mode l8500C/8500C+ Operators Manual
3-1
Chapter 3 - Unpacking and Installation
M
O
DE
L 8
50
0C
POWER INDICATOR
(ABOVE KNOBS)
LCD CONTRAST ADJ.
BACKLIGHT ADJ.
F I L
E : I
S O
8 5
C D
K . D
R W
DISK EJECT
Figure 3-1. Model8500C/C+ Balancer/Analyzer
3.2 Signal Selector and Installation
The Mode l 8 520C Signal Selector (see Figure3- 2 on page 3-3) multiplexes vibration and pickup
signals from several sources and allows a host processor (8500C/C+) to select any pair of signals fo analysis. Up to twenty Mode l7310 Velocimeter inputs and 4 Syn ch or Model11800 FasTrak Optical
Tracker, Mode l3030 Magnetic Pickup, and/or Photocell inputs may be connected at a time. The
8500C/C+ has the ability to automatically determine the presence of a Signal Selector, and to read the
input channels selected by the operator. See C hapter11 Mode l8520C Signal Selecto ” for a more
detailed description of the Signal Selector and its use with the 8500C/C+.
3-2 Chadwick-Helmuth Company, Inc.
Signal Selector and Installation
The Signal Selector is part of the 8500C/C+ kit. Although it is not required in order to make full use o the 8500C/C+, it may be required for those applications that read input signals from more than on velocimeter or magnetic pickup at a time.
SIGNAL
SELECTOR
MODEL 8520C
1
2
4 7 10
5 8 11
VIBRATION
CHANNELS
CHADWICK-HELMUTH
3
E L M O N T E , C A L I F O R N I A
POWER
VELO
SHORT
A
6 9 12
VELOCIMETER CHANNELS
MAGNETIC PICKUP/PHOTOCELL CHANNELS
B C D
AZIMUTH
CHANNELS
CN_8520..DRW
Figure 3-2. Model 8520C Signal Selector
Signal Selector signal channels are labeled on the front panel of the unit. Cha nnels N o.1 through12 accept velocimeter inputs, and channe lsA thr oughD accept FasTrak, magnetic pickup or Photocell inputs. Also on the right of the front panel are the power conn ector (28Vdc) and a power/output connector for attachment to an 8500C/C+. Note that when used together with the 8500C/C+, the Signal
Selector supplies all power and communications signals to the 8500C/C+. It is therefore essential that only a 2 8Vdc power supply be used to operate the Signal Selector. Plugging the Signal Selector into a power source other than 2 8Vdc may cause severe damage to the instrument.
Mode l8500C/8500C+ Operators Manual
3-3
Chapter 3 - Unpacking and Installation
Show
Hide
More
Keys
BALANCER/ANALYZER
CURRENT BALANCE MEASUREMENT FOR
BAe ATP (RIGHT) #123ABCXA
RUN NUMBER: 1 FREQUENCY: 480 RPM
PHASE ANGLE: 2:42 VIB LEVEL: 0.870 IPS
PRESS START TO BEGIN NEXT RUN
REDO MEAS SEL CHART < RIGHT > SOLUTION
* *
Balance
:
Help
Spectrum
Load Setup
Track Store Annotate
1
4
7 8
0
2
5
3
6
9
Start
Stop
M O D E L 8 5 0 0
""""
####
%%%%
&&&&
$$$$ ''''
,,,,
++++
((((
))))
****
NOTE: Information in this manual pertains to all version of 8500 Balancer/Analyzer
(8500-6, 8500C/C+), as applicable, dependent of firmware version.
3-4 Chadwick-Helmuth Company, Inc.
Chapter 4
4.
Getting Started
This chapter introduces you to the major functional aspects of the Model8500C/C+ Balancer/
Analyzer. It also introduces you to some general operating procedures, as well as the relevant terms
under the following topics:
4.1 Display
The 8500C/C+ liquid-crystal display (LCD) is located on the front panel of the instrument. The LCD has a resolution of 256 horizontal by 64 vertical pixels and is used to display graphical information, as well as text. The 8500C/C+ LCD is back-lighted to provide a superior display under adverse viewing conditions.
Figur e4-1 on pag e4-2 shows the LCD and keypad on the 8500C/C+ unit.
Mode l8500C/8500C+ Operators Manual
4-1
Chapter 4 - Getting Started
M
O
DE
L 8
50
0C
POWER INDICATOR
(ABOVE KNOBS)
LCD CONTRAST ADJ.
BACKLIGHT ADJ.
F I L
E : I
S O
8 5
C D
K . D
R W
DISK EJECT
Figure 4-1. Model 8500C/C+ Balancer/Analyzer
There is a display contrast adjustment knob located inside the disk drive access door. It is used to adjust the viewing angle of the LCD. If turned completely in the clockwise direction, the display appears blank. If it is turned completely counter-clockwise, the display becomes completely dark. You may adjust LCD contrast for optimum viewing, though adjustment is most often required when power is first applied to the instrument. See the Mod el8500C/C+ System Maintenance Manual for complete operating temperature range specifications.
In the 8500C/C+ the LCD contrast adjustment is the topmost control knob inside the disk drive door.
An adjustment knob to control backlight brightness is located just below it.
The 8500C/C+ should never be exposed to excessive heat or sunlight. Overheating may cause the LC to turn completely dark. It usually recovers when cooled, but permanent damage may result. Similarly, the 8500C/C+ must never be exposed to excessive cold. Otherwise, screen changes and transitions become noticeably slower. If conditions are severe enough, the LCD may shut down completely.
Information displayed on the LCD is called a screen. A screen may consist of a list or menu, a collection of data fields, a plot or drawing, or some combination thereof. A single screen may contain more data than can fit on the LCD, and the portion that can been seen is called a window. In most cases, the data within a window may be scrolled up or down with the Arrowkeys to reveal different areas of the screen.
In this manual, fields on the LCD screen are shown in the text as monospaced type, for example,
FREQUENCY
4-2 Chadwick-Helmuth Company, Inc.
Keypad
4.2 Keypad
The 8500C/C+ accepts commands and data through the keypad on the unit's front panel. There ar
32 keys, and most of them support more than one function or character depending on the state of the
instrument or the combination of keys pressed in concert (see Figure4- 1 on page4-2).
Throughout this manual, 8500C/C+ function keys are indicated with special typefaces in this manual and in user guides, in order to help you better distinguish them, as follows:
• START - Dedicated keys, that is, those keys whose functions are printed on the key.
• ENTER - Soft keys, whose functions are bound to the four grey keys beneath the LCD.
The basic features of the keypad are explained in the rest of this section. For the most part, individual keys are described in detail in the appropriate chapters of this manual.
each function.
Table 4-1. Model8500C/C+ Function Keys (Sheet 1 of 2)
Key
1
4
7
Start
Stop
←
↑
↓
→
Balance
Spectrum
Track
Help
Load
Store
Status
Setup
Annotat
Function/Value
1
4
7
Start data acquisition
Terminate data acquisition
Move cursor left
Move cursor up
Move cursor down
Move cursor right
Select Balance mode
Select Spectrum mode
Select Track mode
Display on-line help
Load data from disk
Store data to disk/memory
Display/change system status
Enable parameter entry
Annotate printer output
Character
X or *
Z or *
W
Y
L or -
R or /
G
M
S
D or :
J or #
P or %
E
K or <
Q or >
F or .
Mode l8500C/8500C+ Operators Manual
4-3
Chapter 4 - Getting Started
Table 4-1. Model8500C/C+ Function Keys (Sheet 2 of 2)
Key
6
9
0
8
3
2
5
Show/hid
More keys
Soft key
Soft key
Soft key
Soft key
Function/Value
8
3
2
5
6
9
0
Print display
Display/hide soft keys
Display more soft keys
Soft function key 1
Soft function key 2
Soft function key 3
Soft function key 4
Character
V
A
O
U
B
C
I
T
H
N
4.2.1 Auto-Repeat
Some keys, such as the Arrow keys, support an auto-repeat feature, that is, pressing the key for more than half a second causes the function to be repeated for as long as the key is held down.
4.2.2 Arrow Keys and Cursor
The four Arr owkeys allow the display cursor to be moved in the desired direction. When text is displayed, the cursor appears as a black, highlighting rectangle. It may be moved around the screen to select an item from a list or menu, or to select a data field whose contents are to be modified. Moving the cursor above or below the current window scrolls the window in the appropriate direction. If th beginning or end of the screen has been reached, the cursor wraps around to the window containing the bottom or top portion of the screen.
When a spectral plot is displayed, the cursor appears as a special cross-hair that highlights th intersection of the X-coordinate (frequency) and Y-coordinate (amplitude) o n the X-and Y-axes. Th spectrum cursor may be moved with the Ar rowkeys, but does not wrap around when the beginning or end of the axes has been reached.
4-4 Chadwick-Helmuth Company, Inc.
Keypad
4.2.3 Soft Keys
differ from the other keys in that their functions vary according to the state of the 8500C/C+. This feature provides easy access to any special functions to be used while the instrument is in a particular state or mode. If a soft key is operational, its function is defined in a label at the bottom of the display, directly above the key. Note that if a soft key label is hidden from view its function may still be invoked by pressing the key. In other words, labels do not have to be visible in order to execute a soft key function. See the explanation of th SHOW/HIDE
key in Section 4.2.3.2 “SHOW/HIDE Key” on page 4-7.
There are two types of soft function keys, as follows:
• Action
• Mode
Action soft keys typically change the display and initiate a major transition or action. Action soft key
labels appear with solid black rectangles. In Figure4- 5 on page4-10 th
RED OMEAS , SEL CHART , and SOLUTION soft keys are action soft keys.
The second type of soft key is the Mode soft key. A mode soft key defines a number of user-selectable operating modes. They are enabled by toggling the soft key, which then selects a new mode and displays the new setting in the soft key label. Mode soft keys have a diamond-shaped label contained in a thin black border.
Mode l8500C/8500C+ Operators Manual
4-5
Chapter 4 - Getting Started
<RIGHT> / <LEFT> soft key is a mode soft key. Toggling the <RIGHT> / <LEFT> key changes the engine for the selected balance chart. If the soft key is <RIGHT> , the data for the right engine is displayed. If the soft key is <LEFT> , data for the left engine is displayed.
MORE KEYS
CURRENT BALANCE MEASUREMENT FOR
BAe ATP (RIGHT) #123ABCXA
RUN NUMBER: 1 FREQUENCY: 480 RPM
PHASE ANGLE: 2:42 VIB LEVEL: 0.870 IPS
PRESS START TO BEGIN NEXT RUN
REDO MEAS SEL CHART < RIGHT > SOLUTION
SOFT KEY LABELS
SHOWS/HIDES SOFT KEY LABELS
CURRENT BALANCE MEASUREMENT FOR
BAe ATP (RIGHT) #123ABCXA
RUN NUMBER: 1 FREQUENCY: 480 RPM
PHASE ANGLE: 2:42 VIB LEVEL: 0.870 IPS
PRESS START TO BEGIN NEXT RUN
REDO MEAS SEL CHART < RIGHT > SOLUTION
* *
+
SOFT KEYS
ASTERISK INDICATES
MORE LABELS ARE
AVAILABLE WHEN MORE
KEYS IS PRESSED
Figure 4-2. Model 8500C/C+ With Display and Soft Keys
4.2.3.1
HELP Key
The HELP key enables the on-line help facility, which provides operator assistance for the 8500C/C+.
See the section on the Help facility below for a complete description. For help on an individual chart, press the CHAR TINFO soft key.
4-6 Chadwick-Helmuth Company, Inc.
Keypad
4.2.3.2
SHOW/HIDE Key
Soft key labels can sometimes hide or obscure portions of the LCD that contain text, graphics, or a plot. To view this information, press the SHOW/HIDE key. It removes all soft key labels and displays the hidden sections. Pressing SHOW/HIDE a second time restores the soft key labels to their previous positions. Soft keys can be pressed whether the label is visible or not, that is, using
SHOW/HIDE to hide soft key labels does not affect the actual soft key or its function.
4.2.3.3
MORE KEYS Key
In some modes, the 8500C/C+ provides more soft functions than there are soft function keys. Th presence of an asterisk (*) in the bottom right corner of the LCD indicates there are soft keys available, which are not currently displayed. To enable the additional soft keys, press MORE KEYS . It removes the current set of soft key labels and displays the next group. The soft keys themselves now take on the functions indicated by the new labels. Pressing MORE KEYS again enables the next group, and so on, until the original set of soft keys is restored.
4.2.3.4
SETUP Key
The SETUP key allows you to modify basic parameters governing the Balance, Spectrum, Track, and
Status modes of operation. Pressing SETUP while in one of these modes accesses a Setup screen, showing current values for the appropriate parameters. These values appear as part of data fields that contain the instrument settings to be selected or changed. The Ar rowkeys can then be used to position the cursor over the desired parameter. Once selected in this manner, a parameter may be modified,
below).
Figure 4-3. Sample Setup Screen
Setup screens allow for two types of display fields. Those that are enclosed by angle brackets are called mode fields. Their contents are changed by pressing the <CHANGE> soft key. Numeric fields have no brackets and accept only numeric input from the keypad. Digits are shifted to the left as they are entered and decimal points automatically inserted where necessary. Most numeric fields impose a range of acceptable values. Entering an improper value causes an error message screen display, and the original value to be restored to the field.
Changes to the display fields of the entire Setup screen can be removed and the original contents restored by pressing the RESTORE soft key. Only those values changed since the last ENTER operation are lost.
After making all desired changes to the display fields, press the ENTER soft key to enable the changes, quit the Setup screen, and resume operations. Alternatively, any key that quits the Setup screen executes an implicit ENTER before performing its intended function. Setup screen data fields are stored in nonvolatile memory. Consequently, they are always preserved, even if the 8500C/C+ has been turned off.
Mode l8500C/8500C+ Operators Manual
4-7
Chapter 4 - Getting Started
4.2.3.5
STATUS Key
Pressing the STATUS key displays general information about the state of the 8500C/C+, such as the current date and time, software version number, and pickup pulse rate. Some of these items can be modified by pressing SETUP to access the Status Setup screen.
Status information is not available while error messages are being displayed, or while the 8500C/C+ is performing certain time-critical actions, such as data acquisition or flashin g the Model135M-12
Strobex Tracker.
See Chapte r9 “Status Screen Operation” for a complete explanation of the
STATUS function.
4.2.3.6
BALANCE Key
Pressing the BALANCE key puts the 8500C/C+ into its Balance mode of operation. The 8500C/C+ has the following basic operational modes:
• Balance - For balancing systems
• Spectrum - For using the spectrum analysis feature
• Track - For using the Strobex or M odel11800 FasTrak Optical Tracker for track operations
Once in the Balance mode, you can initiate a lateral or track balance for the target rotor system. See
Chapter 5 “Balance Measurement and Solutions” for a complete explanation of balance measurement
and solutions. These primary operating modes are set in first-letter-cap in the manual and user guides, for example, Balance mode, to distinguish them from other 8500C/C+ modes.
4.2.3.7
SPECTRUM Key
Pressing the SPECTRUM key puts the 8500C/C+ into its Spectrum mode of operation. Once in
Spectrum mode, you can acquire, display, and analyze vibration signals from the target rotor system,
that is, use the 8500C/C+’s spectrum analysis feature. See Chapte r7 Spectrum Analysis” for a
complete explanation of this feature.
4.2.3.8
TRACK Key
Pressing the TRAC key puts the 8500C/C+ into its Track mode of operation. Once in Track mode, you can initiate visual tracking for the target rotor system. Pressing the Track key while running a
Smart Chart that supports the FasTrak will allow you to initiate either visual or FasTrak tracking. Se
Chapter 6 “Blade Track Observation” for a complete explanation of visual tracking.
4.2.3.9
START Key
The START key is used to initiate data acquisition in Balance, Spectrum, and Track modes. In some modes, such as self-test, START may be used to select or begin a particular function. When editing the
printout annotation (see Chap ter8 “Using Printouts”), the
START key is used to move the cursor to th beginning of the previous data field.
4.2.3.10 STOP Key
The STOP key is used to terminate data acquisition in Balance, Spectrum, and Track modes. In some modes such as self-test, STOP may be used to abort a particular operation. When editing the printout
annotation (see Chapt er8 “Using Printouts”), the
STOP key is used to move the cursor to th beginning of the next data field.
4-8 Chadwick-Helmuth Company, Inc.
On-line Help
4.2.3.11 PRINT Key
Pressing the PRINT key sends a hard-copy reproduction of the current LCD window to the 8500C/C+ thermal dot matrix printer. Printing in the 8500C/C+ proceeds as a background task, which means you may continue to operate the instrument while the printer is working. Successive use of the PRINT key saves the additional printouts and queues them so they are printed in the order they were requested. Up to 2 0printouts may be queued at one time. Each printout ta kes about 30sec to complete.
4.2.3.12 ANNOTATE Key
Printouts are always appended with annotation information that aids in describing and documenting the printout contents. The annotation data and their labels may be edited by pressing the ANNOTATE
key, which puts the 8500C/C+ into its edit mode of operation. See Chapt er8 “Using Printouts” for a
complete discussion of annotation editing.
4.2.3.13 LOAD Key
The LOAD key is used to load balance charts from the 8500C/C+ disk drive to nonvolatile memory.
See Chapte r5 “Balance Measurement and Solutions” for a complete discussion of the
LOAD key.
4.2.3.14 STORE Key
The STORE key is used to store spectral data sets, balance charts, and balance measurements and
solutions to 8500C/C+ static memory or the 8500C/C+ disk drive. See Chapter10 Printer and Disk
Drive” for a detailed discussion of the
STORE key.
4.2.3.15 Numeric Keys
There are ten numeric keys, labeled 0 through 9 . They are typically used to enter numeric data, in particular when modifying Setup screens or editing the printout annotation.
4.3 On-line Help
Pressing the HELP key enables the on-line help facility, which provides valuable assistance while
running the 8500C/C+ (see Fig ure4-4). The help facility is context sensitive, that is, it knows the
current state of the instrument and displays the appropriate text when HELP is pressed. HELP is not available during certain time-critical operations such as data acquisition or blade tracking. Otherwise,
HELP may be pressed at any time.
Press the HELP key twice to get help on instrument basics.
Figure 4-4. Help Screen
Mode l8500C/8500C+ Operators Manual
4-9
Chapter 4 - Getting Started
4.3.1 Scrolling Help Topics and Text
Press the PRE VTOPIC or NEX TTOPIC soft keys to scroll the Help screen window up or down, respectively, to a new subtopic. Alternately, you may use the Up a nd Dow nArrowkeys to scroll th help text a line at a time in the desired direction.
4.3.2 Help Menu
The HELP MENU
soft key displays the menu of available help topics (see F igure4-5). Use th
Arrow keys to select a topic; press SHOW HELP to display help text about that topic.
Figure 4-5. Help Menu Screen
4.3.3 Exiting the On-line Help
Press the EXIT HELP soft key to quit the help facility and resume operations.
4.4 Printer and Disk Drive
4.4.1 Printer
The printer is a thermal dot-matrix printer capable of creating hard-copy reproductions of the current
LCD window. Printing can be initiated by pressing the PRINT
key (see Section 4.2.3.11 “PRINT Key” on pa ge4-9).
4.4.2 Disk Drive
The 8500C/C+ disk drive uses double-sided, double-de nsity (720KB) 3.5-in. diskettes. The 8500C/
C++ disk drive accepts, in addition to 720 KB diskettes, High-Density 1.44 MB diskettes. It can read and write any diskettes that have been formatted on a personal computer (PC) running PC- or
MS-DOS, Versio n3.2 or later or the MicroSoft Windows
TM
Operating System . Diskettes are used to store aircraft chart information as well as spectral and balance data acquired by the instrument.
Diskettes may be freely interchanged between the 8500C/C+ and appropriately configured PCs. This
4-10 Chadwick-Helmuth Company, Inc.
Printer and Disk Drive compatibility provides the user with the ability to subject the acquired data to more rigorous post-
processing and analysis. See Chap ter10 “Printer and Disk Drive” for more information on using the
8500C/C+ disk drive.
Mode l8500C/8500C+ Operators Manual
4-11
Chapter 4 - Getting Started
4.5 Booting Up the 8500C/C+
This section explains how to boot up the 8500C/C+, either as from a cold start or a soft reset situation.
4.5.1 Starting the 8500C/C+
The 8500C/C+ automatically starts up when power is applied to the instrument. During this period, a suite of diagnostic programs run to verify the operational integrity of the hardware and software. These diagnostics include tests of the machine's memory and an automatic verification of the analog circuitry calibration. The entire set of tests may take up to 45sec to complete. You may use this time to adjust the LCD display contrast so that the power-up message screen is clearly visible.
diagnostics do not complete successfully, the instrument must be considered unreliable and unusable.
Further use may produce erroneous results and is therefore strongly discouraged.
NOTE: If you receive the Power Up Self-test Failure 3.X or 4.X message, try a second attempt by pressing TRY AGAIN. In this case, a retry may be successful.
If the 8500C/C+ does report a failure (other than the Power Up Self-test), replace the unit with a spare and return the 8500C/C+ to Chadwick-Helmuth for assistance.
Figure 4-6. Power-up Message Screen
CAUTION: The 8500C/C+ only operates from a 28-Vdc power supply. Plugging the 8500C/
C+ into a power source other than 28 Vdc may cause severe damage to the instrument.
Upon successful completion of the power-up sequence, an introductory Start-up screen displays
(Figur e 4 -7). The 8500C/C+ is now fully operational and ready to use.
Figure 4-7. Start-up Message Screen
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Booting Up the 8500C/C+
4.5.2 Restarting the 8500C/C+
In the event of an instrument malfunction or lock-up, a manual reset can be performed by temporarily removing power to the 8500C/C+. This action resets the machine without clearing the memory.
If this procedure fails, you must clear the memory by doing a cold start (hard reboot). To do this procedure, remove the power, hold down th START key, and reconnect the power. Wait approximately 5se c before releasing the START key.
NOTE: Disconnecting the power supply while the 8500C/C+ is in status mode may disrupt the time-of-day clock’s normal functioning.
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Chapter 4 - Getting Started
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Chapter 5
5.
Balance Measurement and Solutions
This chapter describes the methods and procedures for acquiring balance measurements and
computing/using balance solutions with the Model85 00C/C+ Balancer/Analyzer. Chapter 5 explains
how to take balance measurements and get solutions, under the following topics:
5.1 Getting Balance Solutions: Introduction
Balance measurement is similar to spectral data acquisition in that both operations collect spectral frequency data from the rotor system being tested. Balance measurement, however, focuses on data from a particular vibration signal, with the goal of providing a solution to the vibration problem. Two types of out-of-balance conditions may be analyzed here, lateral mass imbalances and vertical track imbalances. Lateral imbalances create vibrations that are oriented parallel to the plane of rotation.
Vertical imbalances stem from track misalignments in the rotor blades and produce vibrations that ar perpendicular to the plane of rotation. The correct solution to both problems only requires that the appropriate balance chart be used and that the Mode l7310 Velocimeter's cylindrical axis be oriented in the same direction as the vibrational forces.
The solution is based on the unique characteristics of the rotor system being balanced and is presented in terms of prescribed adjustments to the rotor hardware. These adjustments include
• Incremental addition or removal of weights at the balance points of the aircraft
• Adjustments to the sweep of the blades
• Adjustments to the trim tabs
• Adjustments to the pitch links
WARNNG: Due to the complex interaction between vertical and lateral vibrations, it is essential that an aircraft's track be adjusted and verified before performing a lateral
balance (for more information, see Chapte r6 “Blade Track Observation”).
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Chapter 5 - Balance Measurement and Solutions
Selecting the Balance Mode
To put the 8500C/C+ into its Balance mode of operation, press th BALANCE key. A Balance Mode
Start-up screen displays along with two soft keys, SEL CHART and CHAR TINFO
Figure 5-1. Balance Start-up Screen
NOTE: If the 8500C/C+ is currently performing other time-critical functions, it may b necessary to press STOP to terminate the function before the Balance mode can be entered.
5.2 Balance Charts
Aircraft balance characteristics are maintained in discrete data sets called balance charts. A balance chart contains data that describes a single rotor element from a particular aircraft type. Charts for the constituent rotor elements that comprise an aircraft are typically grouped together in one or more balance chart files. Balance chart files are stored on PC compatible diskettes for safekeeping, and loaded into 8500C/C+ memory as required. The distribution disk chart files provided by Chadwick
Helmuth are write-protected and must be copied to another disk before they may be modified o
overwritten. See Chapt er10 Printer and Disk Drive” for more information on disk usage.
5.2.1 Measurements Only Chart
Without the appropriate balance chart, the 8500C/C+ cannot present balance solutions for an out-of balance rotor system. A special chart, th Measurements Only chart, allows you to see only the balanc measurements of vibration amplitude and phase angle. No balance solutions are ever presented.
However, solutions can easily be determined by hand with the Measurements Only chart and the appropriate paper chart from Chadwick-Helmuth. In addition, the Measurements Only chart can be used to collect the data needed to create new paper balance charts for individual systems. Se
Secti on5.6.3 “Using Measurements Only” on pa ge5-19 for more details.
The Measurements Only chart is permanently stored in the 8500C/C+. It is always available for use and always presented as the first chart in the balance chart menu of the Select Chart screen.
5.2.2 Smart Charts
Chadwick-Helmuth has developed a unique chart software technology for smoothing rotors. The 8500 runs the following types of chart programs:
• Standard - Single-type adjustment charts
• Smart - Multi-type adjustment charts
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Balance Charts
A Smart Chart represents a special class of balance chart designed to work with rotor systems having unique balance characteristics and requirements. As the name implies, a Smart Chart is intelligent. It is, in fact, a stand-alone software program that runs on a host 8500C/C+, using it as a platform to work the target aircraft.
You may treat a Smart Chart just like any other (standard) balance chart. However, when a Smart
Chart is run, it typically demands that a special set of procedures and flight regimes be followed. Th exact program sequence varies from one Smart Chart to another and so is beyond the scope of this manual. For detailed descriptions of specific Smart Charts, see the appropriate 8500C/C+ application user guide for your subject aircraft.
5.2.3 Working With Balance Charts
Pressing the SEL CHART soft key shown on the Balance Mode Start-up screen displays a menu of
Measurements Only chart, which is listed first. Use the Arr owkeys to select a chart by moving the cursor to the desired entry. Should there be more charts than the screen can hold, continued cursor movements automatically scroll the window to display them. When you have selected the desired chart, press RUN CHART to run it. Chart data is automatically read and the appropriate balance parameters filled in. Alternately, pressing any key that exits the balance chart menu screen then reads the selected chart before continuing. Pressing START , for example, reads the chart and begins data acquisition.
Figure 5-2. Balance Chart Menu
5.2.3.1
Scanning Charts on Disks
Balance charts may be loaded into memory through the 8500C/C+ disk drive. Call up the balance chart selection menu with the SEL CHART soft key and insert the appropriate balance chart disk in the disk drive. Press SCA NDISK
to view the charts on the disk (see Fig ure5-3). When
SCA NDISK finishes checking the disk, it presents a menu of the balance chart files found there. Note that some balance
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Chapter 5 - Balance Measurement and Solutions chart files may contain more than one chart. For such files, SCA NDISK lists the first chart contained in the file and appends an asterisk to the end of the chart name to indicate the presence of additional charts within that file.
Figure 5-3. Balance Chart Disk Scan
To bypass the disk scan and immediately load all the charts found on the disk, press LOAD .
5.2.3.2
Loading Charts From Disk
After SCA NDISK presents the menu of charts on disk, press LOAD ALL to load all the charts into the
LOAD FILE to load the selected chart to memory.
When the load operation is complete, the chart selection menu displays along with the new chart(s).
Note that the loading of duplicate charts does not overwrite existing copies already in memory. They are simply added to the menu and sorted accordingly.
See Sectio n10.2.1 “Loading Disk Files” on page 10-3 for a complete description of loading balance
charts from a disk.
5.2.3.3
Renaming Charts
Balance charts can be renamed and stored to disk or kept in memory. Charts that are specific to a particular aircraft may be renamed in order to better identify them. This is especially important for corrected balance charts, since the correction factors that have been added to the chart are applied to all
subsequent balance measurements (see Sect ion5.6.2 “Chart Corrections” on page 5-17).
To rename a chart, press the RENAME CHT soft key. The 8500C/C+ enters its edit mode of operation
and displays the Balance Chart Edit screen (see Figu re5-4). The soft keys and procedures used here
are nearly identical to those used to edit the printout annotation. The only exceptions are the use of th
START and STOP
keys that tab five spaces to the left and right, respectively. See Section8.3
“Annotating Printouts” on pa ge8-5 for a complete description of the edit mode. When you have
finished renaming the chart, press th ENTER soft key to enter the new name and exit edit mode. The name of the chart is then updated accordingly on the menu of available charts.
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Balance Charts
Note that for the RENAM ECHT soft key, ENTER does not store the renamed chart to disk (see the next
Secti on5.2.3.4 Storing Charts to Disk”).
Figure 5-4. Balance Chart Edit Screen
5.2.3.4
Storing Charts to Disk
Balance charts may be stored from memory to disk through the 8500C/C+ disk drive. Call up the balance chart selection menu with th SEL CHART soft key and insert the appropriate disk in the disk drive. Select the desired chart with the Arr owkeys and press STORE . Note that there are two kinds of charts that cannot be stored to disk: The Measurements Only chart and Smart Charts. Since most charts are specific to a particular aircraft, you are first asked to give the chart a new name before it is actually written to disk. Make sure the name you supply provides a unique identification for the chart, for example, the rotor type and the tail number of the aircraft. When a chart is stored to disk, a balance chart file is created containing the renamed chart plus the other charts associated with the file. The new chart file then replaces an existing chart file with the same name.
NOTE: Balance histories are never written to disk during a chart store operation. This
To store all the charts listed on the balance chart selection menu, press MORE KEYS and th
STORE ALL soft key. STORE ALL stores all the charts currently in 8500C/C+ memory to the appropriate chart file(s) on disk. Charts are written as is without renaming, so you are not asked to create new names.
When you press STORE (but not STORE ALL ), the 8500C/C+ enters its edit mode of operation and
ENTER soft key to store the chart to disk and exit edit mode. Press MORE KEYS and CANCEL to undo any editing changes and cancel the store operation. When the store operation is complete, the menu is redisplayed, and the name of the stored chart updated accordingly.
See Sectio n10.2.3 “Storing Balance Charts to Disk” on pa ge10-5 for a complete explanation o
storing balance charts to disk.
5.2.3.5
Clearing Chart Memory
Balance charts that have been loaded into the 8500C/C+ are stored in the machine's static memory. Th use of static memory ensures that balance charts (and any other data stored there) do not have to b reloaded. They are always available, even if power to the instrument is turned off. Data associated with each chart, such as chart corrections and balance histories, are also stored in static memory. These
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Chapter 5 - Balance Measurement and Solutions items continue to be added to static memory until the available space is exhausted. Thus, it may become necessary from time to time to clear out some items from static memory and purge the data accumulated there.
To clear out the portion of static memory containing balance charts and histories, press CLR CHARTS .
Balance charts, chart corrections, and balance histories are then deleted from static memory, and all chart names removed from the menu in the Select Chart screen. Since the Measurements Only chart is permanent, it cannot be deleted.
5.2.3.6
Displaying Chart Information
The CHAR TINFO soft key displays important information about the currently selected rotor system, such as the location of system balance points, the installation of vibration transducers and retro reflective targets, and the orientation of the reference azimuth for determining phase angle (se
CAUTION: This information is essential to the correct setup of the system prior to balancing. Be sure to read it thoroughly and follow any given instructions.
The PRE VNFO and NEX TINFO soft keys scroll up and down, respectively, to the previous information screen or the one that follows. Similarly, the Upand Dow nArro wkeys can be used to scroll information screens as well. The last information screen displays the corresponding paper chart number (if one exists) and the balance chart version number. Press EXIT to quit the display.
To print the complete text with illustrations, press the PRINT ALL soft key.
Figure 5-5. Chart Information Screen
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Parameter Setup
5.3 Parameter Setup
The 8500C/C+ supports the modification of several important parameters used to control data acquisition and display during the balance measurement process. In general, these parameters are automatically set when a balance chart is selected. They may, however, be overridden by pressing
SETUP
, which in turn displays the Balance Setup screen (Fi gure5-6). See Se ction4.2.3.4 “SETUP
Key” on pag e4-7 for more information on Setup screens.
Figure 5-6. Balance Setup Screen
Use the Arro wkeys to select the field whose contents are to be modified, and th <CHANGE> soft key or the numeric keypad to effect the desired changes. Th ENTER soft key saves the changes and resumes operation in Balance mode. Th RESTORE soft key restores to all fields the values that were set by the most recent ENTER .
Once the Balance Setup screen parameters have been modified, you may alternately press BALANCE to save the changes and return to Balance mode, or START to save the changes and begin a balanc measurement. In effect, both of these keys execute an implicit ENTER before performing their respective functions.
The following sections describe in greater detail the various Balance Setup screen fields.
5.3.1 Balance Frequency
The balance frequency is the frequency at which a rotor balance is to be performed. On a spectral plot of a vibration signal, it usually appears as a well defined peak whose vibration amplitude and frequency characteristics were generated by an out-of-balance rotating element. During balanc measurement acquisition, the 8500C/C+ attempts to lock onto a vibration signal at the balance frequency and analyze it.
Set the balance frequency by entering the desired value from the numeric keypad. Balance frequency can also be set in Spectrum mode with the BAL FREQ soft key. Note that when a balance chart is selected, the current balance frequency value is automatically overridden with a default value from the chart. This value must be within range of the rotor system's actual vibration signal ±6 .25percent of the designated value. Otherwise, the 8500C/C+ is not able to locate the vibrational peak during balance measurement. If a balance acquisition fails, take a spectral plot before a new balance measurement is
begun in order to set the balance frequency to a known actual value. S ee Section7.4.4 Setting th
Balance Frequency” on pa ge7-9 for details on acquiring spectral frequency plots and setting the
balance frequency with th BA LFREQ soft key.
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Chapter 5 - Balance Measurement and Solutions
5.3.2 Frequency Units
The balance frequency may be displayed in either revolutions per minute (RPM) or cycles per second
(Hertz). Use the <CHANGE> soft key to convert the frequency from one form to the other. Once this parameter is set, all other displays of frequency data are made in these units. The default is RPM. This parameter is not overridden when a balance chart is selected.
5.3.3 Balance Multiplier
The balance multiplier factor is an integer value by which the balance frequency is multiplied before a balance measurement is taken. It is typically used to analyze n-per-revolution vibration signals that may be present in the spectrum. The default value i s1 (one per revolution). For example, a balanc frequency of 300RPM and a balance multipl ier of2 causes the 8500C/C+ to acquire a balanc measurement at the two-per-revolution frequency (600RPM). Set the balance multiplier by entering the desired value from the numeric keypad.
5.3.4 Balance Type
Balance type describes the particular system used to measure the phase of the vibration signal. Th
8500C/C+ currently supports the following balance type settings:
• Photocell (Photocell System)
• Mag pickup (Mode l3030 Magnetic Pickup)
• Strobex (Model 135M-12 Strobex Tracker)
The Photocell and the Strobex are optional with the 8500C/C+ kit. The magnetic pickup can be purchased separately. Use the <CHANGE> soft key to toggle between them. Note that when a balance chart is selected, the current balance type is automatically overridden with the type stored in the chart.
5.3.5 Auto/Manual Stop
If a Photocell or magnetic pickup balance is being performed, the 8500C/C+ can be directed to automatically terminate balance data acquisition when a satisfactory measurement has been obtained
(auto-stop mode). Manual stop mode, on the other hand, requires you to press the STOP key to end th measurement. Note that if you use the manual stop mode, the 8500C/C+ must have a satisfactory average of balance data points before it can accept the measurement as valid. Use the <CHANGE> soft key to toggle between the two modes. The default mode is auto-stop.
5.3.6 Angle Units
The phase angle is a measure of the phase of the velocimeter signal relative to a fixed reference point on the rotor system. It corresponds to the central angle subtended by the two vectors, and is given either by the position of a reflective target illuminated with the Strobex, or through the phase meter display on the 8500C/C+ liquid-crystal display (LCD).
Phase angle units may be displayed in either degrees or clock angle units. Use the <CHANGE> soft key to convert the units from one form to the other. Once this parameter is set, all other displays of phase measurement data are made in these units. This parameter is not overridden when a balance chart is selected.
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Balance Measurement
5.3.7 Vibration Units
Vibrations may be displayed in units of velocity (inches per second or IPS, 0-pk) acceleration (g’s or in./sec
2
), or displacement (mils, DA). Use th <CHANGE> soft key to convert the units from one form to the other. Once this parameter is set, all other displays of vibration data are made in these units. This parameter is not overridden when a balance chart is selected. One mil equals 0.001in.
5.3.8 Signal Selector Pickup Input Channel
If a Mode l8520C Signal Selector is attached to the 8500C/C+, this field allows you to select the Signal
Selector magnetic pickup or Photocell (azimuth) channel to be analyzed. Use th <CHANGE> soft key description of this instrument.
NOTE: If a Signal Selector is not attached to the 8500C/C+, this field does not appear.
5.3.9 Signal Selector Velocimeter Channels
If a Signal Selector is attached to the 8500C/C+, this field allows you to choose the Signal Selector velocimeter channel(s) to be analyzed. Use th <CHANGE> soft key to select an operator symbol, selected by positioning the screen cursor over the channel number to be changed and entering a ne
value from the numeric keypad. See Chapt er11 “Mode l8520C Signal Selector” for a complete
description of this instrument.
NOTE: If a Signal Selector is not attached to the 8500C/C+, this field does not appear.
5.4 Balance Measurement
The manner in which a balance measurement is made greatly depends on the rotor system and balanc type selected. Before attempting any of the balance procedures explained in this section, be sure that the selected chart is the correct chart for the target rotor system and that all parameters have been set to appropriate values. Be sure that all information available through th CHAR TINFO soft key has been read. Follow any directions given there. Also make sure to check the hardware. The power/signal input cable must be properly secured to its connector at the rear of the 8500C/C+, all cables neatly tied and dressed, and the appropriate signal input devices (velocimeter, Photocell, and/or magnetic pickup) correctly mounted and in good working order.
5.4.1 Initiating Strobex Measurement
Strobex balance requires that the Strobex be connected to the 8500C/C+ through the dedicated adapter at the rear of the unit. A retro-reflective target must also be attached to the target blade grip. Put the
8500C/C+ into Balance mode and make sure the balance type is set to Strobex. With the rotor system running at the appropriate speed, press START . The 8500C/C+ then attempts to acquire a vibration
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Chapter 5 - Balance Measurement and Solutions signal by locking onto the velocimeter pulse at the designated balance frequency. If a vibration signal is acquired, the 8500C/C+ then indicates that the Strobex has been activated and that the balance
measurement may continue (see Figure 5-7).
Figure 5-7. Strobex Activation Screen
If a vibration signal is not present, the measurement terminates, and an error message is displayed
key to display the acquired spectral balance data to help determine the cause of the failure. Usually, the problem is a preset balance frequency that is not within range of the actual vibration signal. The 8500C/C+ can only analyze those frequencies that are within
±6.25 percent of this designated value.
Figure 5-8. Strobex: No Balance Frequency Signal Error Screen
If the 8500C/C+ indicates that a vibration signal has been found, press the Strobex trigger and aim it at the rotor disc. The retro-reflective target then appears frozen at some angular position or clock angle, relative to the rotor's reference azimuth. The azimuth is usu ally at12:00, and the actual position is usually indicated on the balance chart. Use the Leftand Rig htArr owkeys to modulate the Strobex pulse rate so that the target appears to rotate toward the azimuth. A single keystroke changes the target position by one degree. Holding the key down changes it more quickly. The target may be rotated in either the clockwise or counter-clockwise direction. When the target stabilizes at the designated position, press the STOP key to complete the balance measurement and display the solution. Onc
STOP has been pressed, the SPECTRUM key can be used to display the spectral data acquired during the balance measurement. The plot is automatically centered about the balance frequency.
NOTE: When the retro-reflective target has been visually moved to its designated position, it may appear to fluctuate or “jitter” without ever becoming completely stable. This fluctuation does not affect the balance solution. If the mean position of the target can be judged to be stable, the computed solution does not suffer any appreciable loss of accuracy.
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Balance Measurement
5.4.2 Magnetic Pickup/Photocell Measurement
The procedures for magnetic pickup or Photocell balance measurement are nearly identical, except fo the input devices employed. The Photocell kit requires the installation of a retro-reflective target on the root of the target blade, whereas the magnetic pickup requires the installation of a magnetic interrupter on the target rotor. Put the 8500C/C+ into the Balance mode and make sure the balance type is set to
Photocell or Mag Pickup, whichever applies. With the rotor system running at the appropriate speed, press START . As in a Strobex balance, the 8500C/C+ attempts to acquire a vibration signal by locking onto the pickup pulse at the designated balance frequency.
If no azimuth pulse is found at the balance frequency, the measurement terminates and an error
correctly connected, and that the devices themselves are correctly installed and in good working order.
You may also wish to verify that the designated balance frequency is within range of the actual vibration signal. To do this action, take a spectral frequency plot via the SPECTRU key. The current magnetic pickup rate is always displayed on the Status screen. Display this screen by pressing the
STATUS
key (see Chapter 9 “Status Screen Operation”).
Figure 5-9. Magnetic Pickup/Photocell: No Synchronization Signal Error
If a vibration signal is acquired, the 8500C/C+ displays a graphic representation of an analog phas
continuously updated. Its magnitude represents the current vibration amplitude, and the central angle subtended by it and the azimuth represents the current phase angle. Numerical values for the current frequency, vibration amplitude, and phase are continuously displayed and updated.
If the auto-stop mode has been selected (see Se ction5.3.5 “Auto/Manual Stop” on pag e5-8), th
8500C/C+ automatically completes the measurement itself and displays the computed balanc solution. If manual stop mode has been selected, wait for the vector to stabilize, then press STOP to terminate the measurement and generate the balance solution. Again, the vector need not b completely stationary to obtain an accurate solution.
Figure 5-10. Magnetic Pickup/Photocell Phase Meter Display
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Chapter 5 - Balance Measurement and Solutions
Occasionally, the vibration amplitude on the phase meter display may appear as five asterisks (*****), which indicates that the amplitude value is out of range. This is usually due to the action of the analog clip detector and programmable gain stage, which may have been set too high when the measurement began. If the 8500C/C+ encounters these amplitude values, it automatically begins to adjust the gain until a correct amplitude signal is seen.
CAUTION: If the 8500C/C+ is in manual stop mode, do not press STOP while the asterisks are displayed, since this causes the 8500C/C+ to display an error message when th measurement ends. Instead, wait for the 8500C/C+ to stabilize the internal gain and produce a readable vibration amplitude before terminating the measurement.
5.5 Solution Presentation
After a balance measurement has been terminated with the STOP key, a solution to the vibration
problem is computed and displayed on the LCD (see Figur e5-11). The left side of the screen shows
schematic drawing of the rotor system (if one is available), with its balance points, targets, and azimuth labeled for clarity. The balance solution appears to the right and consists of two instructions or corrective moves, one of which is highlighted by a block cursor. Both moves must be applied to th aircraft if a full rotor balance is being performed.
Figure 5-11. Solution Screen for Balance
Note that the first balance solution always consists of two add moves. For systems with an odd number of blades, such a solution cannot be the most efficient or optimal one, that is, requiring the smallest adjustments to the balance points. It may, however, prove optimal for systems with an even number of blades. You may wish to examine alternate moves to determine the most efficient set of balance
adjustments (seeSecti on5.5.2 “Alternate Solutions” on pa ge5-13).
Three soft keys, labeled <NORML MV> / <TEST MOV> , ALTERNATE , and SHOW MEAS are also available. The rest of this section explains these keys.
CAUTION: In order to correctly implement a full balance solution, both corrective actions must be carried out. Performing one action without the other adds significantly to the number of runs required to achieve a successful balance.
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Solution Presentation
5.5.1 Initiating a Test Move (Chart Correction)
The <NORM LMV> / <TEST MOV> soft key is used to toggle between the two-move balance solution screen and the single-move balance chart correction screen. If <NORM LMV> is displayed, the twomove solution is presented. Toggling the key to <TEST MOV> displays the correction screen, in which
“Chart Corrections” on pa ge5-17 for a complete description of the chart correction procedure.
Once the test move is performed, the chart has been corrected for that particular aircraft. At any time before the 8500C/C+ memory is cleared, this corrected chart may be saved to disk for the next time
( CLR CHARTS ) and start fresh with an uncorrected chart.
5.5.2 Alternate Solutions
The first solution that is presented may not always be optimal, requiring larger adjustments to the balance points than theoretically possible. You may, however, view alternate balance solutions by using the Arrow k eys to position the block cursor over any of the solution moves. Pressing the
ALTERNATE soft key causes one of several alternative, yet equivalent, balance instructions to be substituted for the selected text. Pick the optimal solution or the one that best suits your particular situation. Note that some solutions may prove impractical, such as requiring the removal of weights where there are none to remove.
5.5.3 Exiting the Solution Screen
When you are satisfied with the balance solution presentation and have carried out the required corrective moves, press START to initiate the next balance run. If you would like to review the current balance data, including balance history, charts and c hartinformation, corrections, and so on, or repeat the measurement before starting the next run, press SHOW MEAS .
SHOW MEAS displays a Balance Run Start-up screen, containing the latest balance measurements (see
Figur e5-12). To view the Solution screen again, press th
SOLUTION soft key. SHOW MEAS always returns you to the Balance Run Start-up screen.
Figure 5-12. Balance Run Start-up Screen
At this point, you may wish to repeat the balance measurement to verify that your actions were correct.
With the Balance Run Start-up screen displayed, press th RED OMEAS soft key to initiate a new measurement. Note, however, that the current balance data is overwritten in the process.
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Chapter 5 - Balance Measurement and Solutions
You may often find that additional balance runs are needed to fine-tune the results of a single balanc measurement. Together, these runs may be viewed as a set of logically connected steps required to reach a full balance solution. The 8500C/C+ supports the ability to store and analyze this set of balance runs, called a balance histor . A balance history is created by pressing START instead of the
RED OMEAS soft key. START initiates a new balance measurement and generates a new solution, then
Histories” below for a complete explanation of this feature.
5.6 Additional Features
This section explains additional features associated with balance charts and the Balance mode. These features are helpful in doing basic balance operations with the 8500C/C+. The following topics explain these features:
•
Secti on5.6.1 “Balance Histories” on pag e5-14
•
Secti on5.6.2 “Chart Corrections” on pa ge5-17
•
Secti on5.6.3 “Using Measurements Only” on pa ge5-19
•
Secti on5.6.4 “Balancing Fixed-wing Aircraft” on page 5 -21
5.6.1 Balance Histories
Applying the corrective moves prescribed in the 8500C/C+'s Solution screen may not always bring the subject rotor system into full balance. Adjustments to the system can affect other vibrational and aerodynamic characteristics of the aircraft, resulting in smaller but pronounced vibration levels at the balance frequency. In addition, individual rotor systems may exhibit vibrational characteristics that do not agree precisely with the balance chart's predictions of system behavior (the result being slightly inaccurate solutions). For these reasons, it may be necessary to execute several successive balance runs before a satisfactory balance can be achieved. In the 8500C/C+, this iterative series of runs is called a
balance histor . Balance histories are supported by several features that allow you to store, document, and display all the moves and measurements required to reach full balance.
There is no maximum limit to the number of balance runs that can be kept in a balance history, and there may be as few as one. History data are stored in 8500C/C+ static memory. As a result, histories are always available, even if power to the instrument is turned off. Each history is associated with the balance chart that was in use when the history was created. Selecting that chart always invokes its history (if one exists) and begins the balance from the last recorded run. Histories may be saved to
5.6.1.1
Initiating a Balance History
To begin a balance history, take a Strobex or magnetic pickup/Photocell measurement, as explained in
Secti on5.4 “Balance Measurement” on pa ge5-9, and implement the two-part balance solution (use
alternate moves if desired). Press the SHOW MEAS soft key to display the Balance Run Start-up screen
(see Figur e 5 -12 on page 5 -13). This screen shows the current run number plus the phase angle,
balance acquisition frequency, and vibration level from the latest balance measurement, as well as additional soft keys. The run number identifies the latest balance run taken in this history.
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Additional Features
The SOLUTION soft key redisplays the Solution screen. SEL CHART shows the list of available balance charts, and CHAR TINFO
displays information about the current chart. See Se ction5.2.3
“Working With Balance Charts” on pa ge5-3 for a description o
SEL CHART
“Displaying Chart Information” on page 5-6 for a description of
CHAR TINFO .
The START key initiates a new balance run in the current balance history. START first ensures that the balance and solution data from the last run are preserved. The run number is then incremented and new balance and solution data generated. These data are added to the balance history and are saved ther unless the REDO MEAS soft key is used to overwrite them. Note that a balance history is an iterativ record, that is, each new run builds upon the results of previous runs. As a result, successive runs bring you closer and closer to full balance. A successful history, however, depends upon the careful implementation, after every run, of each new balance solution.
Pressing the RED OMEAS soft key instead of START initiates a new balance measurement without increasing the run number or adding to the balance history. RED OMEAS simply causes the latest balance and solution data in the balance history to be overwritten with data from the new measurement. RED OMEAS may be pressed instead of START at any point in the balance history. It is usually used to repeat a measurement or verify a solution implementation.
5.6.1.2
Displaying Histories
The balance history can be displayed and reviewed at the end of each balance run. The runs that comprise the history are presented in chronological order, with the data for each run displayed on two separate screens, one showing the vibration measurements from the run and another showing mov line data and the effects of the balance solution. It is recommended that the balance history be regularly examined throughout the balance process. Stepping through the collected set of history screens can provide a clear, concise picture of how each run has contributed to the progress of the balance as whole.
Viewing a balance history requires the implementation of at least one balance solution. As a result, a minimum of two runs must be made before a balance history screen can be displayed.
To display the balance history, first press MORE KEYS from the Balance Run Start-up screen; thre additional soft keys, HISTORY , CLEAR HIST , and SHOW CORR
CLEA RHIST
is used to clear a balance history. This key is described in detail in S ection5.6.1.4
“Clearing Histories” on pa ge5-17.
SHOW CORR is used to display and optionally clear chart
Figure 5-13. Balance Run Start-up Screen, Additional Soft Keys
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Chapter 5 - Balance Measurement and Solutions
The HISTORY soft key displays the first screen of the first run of the current balance history. The phase
Figure 5-14. Balance History Measurements Screen
The left side of the screen plots all the runs in the history on a graphic representation of a balance chart clock face. The radius of the circle delimits a maximum vibration amplitude. Each run is identified by number and plotted as a function of its phase angle (clock position) and vibration amplitude (distance from the center of the circle). The run number whose measurements are being displayed is highlighted.
The NEX TMOVE soft key displays a new screen showing the balance solution for this run and the
changes that occurred after the corrective moves were implemented (see Fi gure5-15). The move line
data shows the vector difference between consecutive runs, that is, the direction of the change and its magnitude ( inIPS). The move line vector is drawn on the clock face at the left of the screen.
Figure 5-15. Balance History Move Line Screen
The PRE VMOVE soft key displays the Move Line screen for the previous balance run. PRE VMOVE is not available when viewing the Balance History screen for the first run.
The NEX TMEAS soft key displays the measurements screen for the next balance run. NEXT MEAS is not available when viewing the Move Line screen for the last balance run. PREV MEAS displays the measurements screen for the previous balance run.
When you have finished examining the balance history, press QUIT to return to the Balance Run
Start-up screen.
5.6.1.3
Storing Histories to Disk
A balance history may be saved as a file and stored to disk. First, make sure the Store To field in the
Status screen is set to DISK (see Sectio n9.2.6 “Output Storage Device” on pag e9-2). Otherwise, the
balance history is saved to memory only. With the Balance Run Start-up screen displayed, insert formatted, writable 3.5-in. double-sided, double-density disk in the 8500C/C+ disk drive and press
STORE . The data is written to disk and given a unique file name based on the current date and time, plus the extension *.BHI. Since this file also contains the current balance chart name, you may wish to
5-16 Chadwick-Helmuth Company, Inc.
Additional Features
first rename the chart in order to better identify the history data (see Sec tion5.2.3.3 “Renaming
Charts” on page 5-4). See Secti on10.2.2 “ Storing Data to Disk or Memory” on pa ge10-4 for more
information on storing balance histories, as well as Appe ndixC Balance History Files” for a
description of the balance history file format.
NOTE: It is best that 8500C/C+ distribution chart disks not be used to store balance measurement and solution data files. Instead, use a backup copy of the chart disk and store the original chart disk in a safe place. Instructions for making a backup disk are located in
Secti on10.2.4 “Copying Balance Charts” on p age10-6.
5.6.1.4
Clearing Histories
Balance histories are stored in 8500C/C+ static memory. As a result, they are always available, even i power to the instrument is turned off. Only one balance history can be associated with a particular balance chart. Selecting that chart always invokes its history and begins the balance procedure from the last run in the series. It may become necessary, therefore, to discard histories, either to begin a new
History or to free up static memory for other balance data.
To clear a balance history, first select the balance chart whose history you wish to delete. Call up th
Balance Run Start-up screen and press MORE KEYS . Press CLEAR HIST to clear the history for the
current chart (see Figur e 5 -13 on page 5 -15).
Since multiple balance charts can be stored in static memory, it is also possible to store multipl balance histories there as well. Histories can be deleted one at a time by selecting a chart and pressing the CLEAR HIST soft key. They can also be deleted all at once by using the CLR CHARTS soft key (see
Secti on5.2.3.5 Clearing Chart Memory” on pa ge5-5). Since a balance history is always associated
with a particular chart, removing that chart always removes the history.
NOTE: The CLR CHART soft key clears all charts and all histories from static memory.
5.6.2 Chart Corrections
As explained in Sectio n2.2.2 Balance Charts” on pa ge2-7, balance charts represent an experimental
averaging of vibrational characteristics for a particular type of rotor system. Actual rotors within the group, however, often vary from individual to individual. Consequently, some systems may exhibit characteristics that deviate from the balance chart predictions for that rotor type. The 8500C/C+ has the ability to detect these differences, and through the technique of chart correction, modify th balance chart to more accurately reflect the state of the individual rotor system.
Chart correction compares the expected behavior of a vibrating rotor system, as predicted by its balance chart, with its observed behavior, as measured by the 8500C/C+. You can simplify this comparison by making a single adjustment at a single test point then analyzing the differences between the expected and observed behaviors. Using one of the adjustments that appear in the Solution screen, for example, provides a (theoretical) solution for that particular blade, that is, balancing it so that no more adjustments are required. Consequently, the next run produces a move line whose direction
(phase angle) and magnitude (vibration amplitude) accord with the solution. For an uncorrected chart, however, the move line values for direction and magnitude that are actually measured very likely differ from the values that were predicted. The 8500C/C+ uses these differences to calculate correction factors for phase angle and vibration amplitude. The correction is added to the balance chart and used to adjust all further measurements of phase angle and vibration amplitude.
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Chapter 5 - Balance Measurement and Solutions
5.6.2.1
Performing Chart Corrections
To correct a balance chart, take a Strobex or magnetic pickup/Photocell measurement as explained in
<TEST MOV> soft key. <TEST MOV> selects one of the corrective moves at
produces the longest move line, regardless of direction. The predicted move line is then compared against the actual measured move line to determine the amount of correction required. If the prescribed test move cannot be implemented, for example, removing weights where there are none to remove, press the <NORMA LMV> soft key to return to the Solution screen. Then, select an alternate move
(using the ALTERNATE
soft key) that results in a practical test move (see Secti on5.5.2 Alternate
Solutions” on pa ge5-13). When you are satisfied with the test move presentation, press
SHOW MEAS to return to the Balance Run Start-up screen. Implement the test move and begin the next run, as
described in Secti on5.6.1 “Balance Histories” on pa ge5-14. The next run computes corrections fo
phase angle and vibration amplitude and adds them to the balance chart. Afterward, all balance measurements made with this chart is corrected, according to the values stored there.
Figure 5-16. Correction Solution Screen
NOTE: Corrected Charts may be corrected as often as required.
Balance histories are kept for chart correction runs, just as they are for full balance runs. You may wish to display the balance history in order to see exactly how the test move affected the move line.
After the chart correction has been calculated, more (corrected) balance runs may be taken if you desire to bring the system to full balance. In this case, subsequent runs require the application of both corrective moves.
A corrected balance chart significantly reduces the number of runs required to balance the rotor.
Moreover, you can achieve a greater reduction of the overall vibration level as well. For these reasons, it is best that the chart for a new or overhauled aircraft first be corrected and that the corrected chart be used thereafter to balance that particular aircraft.
5.6.2.2
Storing Corrected Charts to Disk
Once a balance chart has been corrected, it may be stored to disk for future use. First, make sure the
press SEL CHART to display the list of available balance charts. The corrected chart (the one currently in use) is highlighted. Press the STORE
key and follow the procedures in Section 5 .2.3.4 “Storing
Charts to Disk” on page 5-5” and be sure to rename the chart before writing it to disk. Include th
aircraft number in the chart name. This action provides the chart with a unique name and helps you to better identify it.
5-18 Chadwick-Helmuth Company, Inc.
Additional Features
5.6.2.3
Clearing Chart Corrections
Pressing MORE KEYS and SHOW CORR from the Balance Run Start-up screen displays the correction
amplitude. It is multiplied by the measured or raw vibration amplitude to obtain the corrected amplitude. The correction angle corrects for phase angle. It is added to the measured phase angle to obtain the corrected phase angle. A cleared or uncorrected chart has a sensitivi ty factor of1 and a correction angle of 12:00, which effectively leaves the raw measurements unchanged. CLR CORRT clears the correction. CLR CORRTN is a good method for clearing a chart whose status is unknown or no longer valid. You can then perform a new chart correction to bring the chart up to date.
Figure 5-17. Balance Chart Correction Screen
Press CANCEL to quit the Correction screen without clearing the correction.
5.6.3 Using Measurements Only
The Measurements Only chart allows you to see only the balance measurements of vibration amplitud and phase angle. No balance solutions are ever presented. However, you can easily determine solutions by hand with the Measurements Only chart and the appropriate paper balance chart from Chadwick-
Helmuth. In addition, the Measurements Only chart can be used to collect data for creating new paper balance charts for individual systems.
5.6.3.1
Balance Solutions
With the 8500C/C+ in Balance mode, select the Measurements Only chart and begin a Strobex, magnetic pickup, or Photocell balance operation. If you choose to perform a Strobex balance, an additional soft key, <TURNS [clockwise arrow] > , appears on the Balance Mode Start-up screen.
Toggling the <TURNS [counterclockwi searrow] > soft key indicates the direction of the spinning rotor, either clockwise or counter-clockwise. Be sure to select the appropriate direction before starting the
balance (see Figu re5-18 on page5-20). When you press the
STOP key, the 8500C/C+ displays th
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5-19
Chapter 5 - Balance Measurement and Solutions balance frequency, the vibration amplitude, and the clock angle. Plot the amplitude and clock angle on the appropriate paper chart from Chadwick-Helmuth and follow any instructions given there for determining the correct solution.
Figure 5-18. Measurements Only/Strobex Balance Start-up Screen
5.6.3.2
Paper Chart Creation
To create a new balance chart, use the Measurements Only chart to plot the vibration amplitude and clock angle of the system on the clock face of a Universal Balance Chart Worksheet. Repeat th measurement with a precise amount of weight added to one of the system's balance points. As you move the weight around to each of the balance points and repeat the procedure using different weight amounts, you can extrapolate the orientation and calibration of the superimposed graph. The geometry of the graph has already been determined by the number of blades and the relative position of the balance points.
5.6.3.3
Paper Chart Correction
The accuracy of a new chart is biased by any inherent out-of-balance conditions that might have existed before the chart was created. The technique of chart correction removes these biases, as well as
“Chart Corrections” on pa ge5-17 for more details on chart corrections.
Chart corrections compare the actual effects of weight on vibration amplitude and clock angle against the changes predicted by the chart. We can quantify the comparison by means of a move line calculation. The difference between the observed direction and the expected direction indicates the amount of phase angle correction that must be applied to subsequent measurements. This action is usually accomplished by rotating the clock face or writing new clock numbers around the chart.
The magnitude (length) of the move line signifies a particular vibration level or amplitude. The length of the move line is directly related to the size of the weight adjustment, and the ratio of the observed magnitude to the expected magnitude indicates the percentage weight correction that must be applied to subsequent measurements. For example, if the move line is too long, too much weight has been added, but if it is too short, not enough weight has been used.
For more information about paper charts, the Chadwick-Helmuth publication “The Polar Coordinat
Chart: Balance Chart Making in the Real World” contains an overview of balancing with paper charts.
5-20 Chadwick-Helmuth Company, Inc.
Additional Features
5.6.4 Balancing Fixed-wing Aircraft
If a fixed-wing aircraft chart has been selected, the CHAR TINFO soft key is replaced with the HSGI
Balance Setup screen (th SETUP key). Two additional soft keys, SHOW CORR and CHAR TINFO , are available on the second and third row of soft keys, respectively.
Figure 5-19. HSGI Start-up Screen
The HSGI soft key is used prior to balancing in order to provide some preliminary analysis for fixedwing propeller systems. Pressing HSGI initiates two balance runs, one while the engine is running at low power and one while it is at high power. After the first run the 8500C/C+ displays the current
HSGI measurements. After this run, advance the engine to the next power setting (see Figure5-20).
Press CONTINUE to begin the second balance run.
Figure 5-20. HSGI First Run Measurements
After the HSGI balance runs have been analyzed, a move line calculation is presented instead of a
balance solution (see Fig ure5-2 1 on page5-22). The direction and magnitude (length) of the move
line indicates whether the system's vibration characteristics can submit to a full balance, or are due to more significant hardware problems and not correctable through further balancing. If the move line
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5-21
Chapter 5 - Balance Measurement and Solutions length is below 0. 4IPS, a full balance can be justified, and the 8500C/C+ presents the move line calculation. For values greater than 0. 4IPS, the 8500C/C+ presents a different screen, indicating that a full balance is not warranted. Press OK to display the Balance Run Start-up screen.
Figure 5-21. HSGI Move Line Calculation
If the move line length is below 0 .4IPS, proceed with the balance according to the directions for th particular aircraft and balance type. Note that the Balance Run Start-up screen substitutes the HSGI soft key for CHART INFO and provides a third row of soft keys containing CHART INFO and
MOVE LINE . Use MOVE LINE to view the move line calculation.
Balance histories are recorded for fixed-wing aircraft just as they are for other rotor systems. Note that the second (high-power) HSGI balance run is saved as the first balance run in the aircraft's balanc history.
5-22 Chadwick-Helmuth Company, Inc.
Chapter 6
6.
Blade Track Observation
You can use the Model 8500C/C+ Balancer/Analyzer to correct both lateral mass and vertical track
describes how the 8500C/C+ can be used to correct them using an alternative method, visual tracking, under the following topics:
6.1 Blade Track: Introduction
A rotor system's track describes the geometry of the circular path made by the blades as they rotate. A blade that is out of track may follow a slightly different path because its alignment in the plane of rotation is skewed. The result is a one-per-revolution vibration whose direction is perpendicular to the plane of rotation. We can analyze this condition either by measuring the amplitude and frequency of vibration or by visually characterizing the track to determine the extent of the imbalance. The former technique is called vertical balance and employs principals and procedures nearly identical to those used to correct a lateral mass imbalance. The latter technique is called a visual or optical track and uses the Mode l135M-12 Strobex Tracker to illuminate the relative position of the blades as they rotate. In essence, the goal in both cases is to match the aerodynamic qualities of each blade in the system.
WARNING: Due to the complex interaction between vertical and lateral vibrations, it is essential that an aircraft's track be adjusted and verified before a lateral balance is
attempted (see Chapt er5 “Balance Measurement and Solutions”).
Selecting the Track Mode
A visual track may be started by putting the 8500C/C+ into its Track mode of operation. This is done by pressing the TRACK
Figure 6-1. Track Startup Screen
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Chapter 6 - Blade Track Observation
NOTE: If the 8500C/C+ is currently performing other time-critical functions, it may be necessary to press STOP to terminate the function before Track mode can be entered.
6.2 Vertical Balancing
A vertical balance attempts to analyze the vertical (that is, perpendicular to the plane of rotation) vibration amplitude caused by an out-of-track rotor blade. Essentially, the only difference between these vibration signals and those generated by a lateral mass imbalance are their orientation to the plane of rotation. Analysis of the problem otherwise involves very similar principles. The technique used to solve a vertical imbalance is therefore nearly identical to the technique of solving a lateral mass
imbalance (see Secti on5.4 Balance Measurement” on page 5 -9). The only differences to note are
• Orientation of the Mo del7310 Velocimeter. Its cylindrical axis must be aligned in the direction of the out-of-track vibration
• Type of balance chart selected
Chadwick-Helmuth supplies charts for vertical or track balancing of many helicopter rotor systems.
Otherwise, you must closely adhere to the procedure for deriving balance solutions, as explained in
Chapter 5 “Balance Measurement and Solutions” in this manual.
In general, the refined electronic measurements taken during a vertical balance provide a mor sophisticated balance solution than visual tracking. However, in those situations where a vertical balance has been performed, visual tracking can be used to independently verify the balance solution.
Moreover, performing a visual track before a vertical balance provides important information about the track characteristics of each blade. This information can then be used during vertical balance to help select the best alternate balance solution.
6.3 Visual Track Parameter Setup
The 8500C/C+ supports the modification of several important parameters used to control data acquisition and display during a visual track. One of these parameters, the number of blades to track, is automatically set when a balance chart is selected from balance mode.
All pertinent Track mode parameters can be modified by using the soft keys at the bottom of the Track
Start-up screen (see Fig ure6-1 on page6-1).
MORE and FEWER increase and decrease the number of
blades to track, respectively (see Secti on6.3.1 “Number of Blades” on pag e6-3).
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Visual Track Parameter Setup
Track parameters may also be modified by pressing SETUP , which in turn displays the Track Setup
screen (Figu re6-2). See the explanation of th
SETUP
key in Section 4.2.3.4 “SETUP Key” on page 4-7 for more information on Setup screens.
Figure 6-2. Track Setup Screen
Use the Arro wkeys to select the field whose contents are to be modified, and the <CHANGE soft key or the numeric keypad to effect the desired changes. The ENTER soft key saves the changes and resumes operation in the Track mode. The RESTORE soft key restores to all fields the values that were set by the most recent ENTER .
Once the Track Setup screen parameters have been modified, you may alternately press TRAC to save the changes and return to the Track mode, or START to save the changes and begin the track procedure. In effect, both of these keys execute an implicit ENTER before performing their respective functions.
The rest of this section explains in greater detail the various Track Setup screen fields.
6.3.1 Number of Blades
The number of blades on the target rotor system is automatically set in the Balance mode when a chart is selected. Use the numeric keypad to change this value, if required.
The number of blades may be changed through the Track Mode Start-up screen. Use the MORE soft key to increase the displayed value, and th FEWER soft key to decrease it.
The number of blades that can be entered ranges from two to sixteen.
6.3.2 Track Type
Visual tracking may be performed in either normal or surround modes. Normal mode tracking causes the Strobex to illuminate each tip target once per revolution. You can then ascertain which blades are out of track by observing the relative alignment of the images. Surround mode tracking modulates the
Strobex trigger so that the trailing target, that is, the one farthest away from the master blade in th order of rotation, appears twice, once at either end of the group of images. Illuminating the trailing target in this way provides a line of reference so that the exact blade tip path plane may be mor accurately gauged.
The track type may be changed by selecting the type in the Track Setup screen and pressing th
<CHANGE> soft key.
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Chapter 6 - Blade Track Observation
6.4 Performing a Visual Track
A visual track illuminates targets on the rotating blade tips and fixes their relative positions. The lead blade in this configuration is called the master or target blade. This is a blade whose orientation to the source of the Strobex trigger (Mode l3030 Magnetic Pickup or Photocell System) is always known.
Typically, it is designated as that blade which is located at the front of the aircraft when the interrupter trips the magnetic pickup or when the retro-reflective target passes in front of the Photocell (see
The master blade can usually be found on the schematic drawing that is displayed when the
CH ARTINFO
soft key is pressed in Balance mode (see Sect ion5.2.3.6 “Displaying Chart
M
2
In te rru p te r
M a g n e tic P ic ku p
4
3
Figure 6-3. Sample Rotor With Four Blades
6.4.1 Initiating a Visual Track
Visual tracking requires the installation of either a magnetic pickup and interrupter or Photocell and reflective target. The Strobex must also be connected to the 8500C/C+ through the dedicated adapter.
In addition, special reflective targets must be installed on the blade tips according to the aircraft manufacturer's directions. Connect the Strobex and power/signal input cables to the 8500C/C+ and check that they are correctly secured to their connectors at the rear of the 8500C/C+. All cables must be neatly tied and dressed, and the appropriate signal input device, Photocell or magnetic pickup, correctly mounted and in good working order. Finally, bring the aircraft up to speed in the desired
6-4 Chadwick-Helmuth Company, Inc.
Performing a Visual Track flight regime. With the rotor system running at the appropriate speed and the 8500C/C+ in Track mode, press START . The 8500C/C+ then activates the Strobex and displays one soft key, th (NO) SPREAD
Figure 6-4. Visual Track Screen
Flash the Strobex at the master blade tip and observe the relative positions of the illuminated targets.
At first the images may be superimposed and difficult to distinguish visually. Their positions can b adjusted by pressing the L eftArrow key, which modulates the Strobex trigger and spreads the target images. Pressing the Rig htArrow key moves them closer together. Alternately, you may use th
(NO) SPREAD soft key (see later in this section). A spread image gives a clearer picture of the system's track. Blade images are oriented with the master blade at the most advanced position in the direction of rotation. The other blade images follow in the order of rotation. The extent to which any blade image deviates from the mean planar path established by the other blades is an indication of the
relative degree of aerodynamic imbalance (see Figure 6-5). You can verify your observations by using
the Righ tArrow key (or (NO) SPREAD soft key) to superimpose or stack the target images. Blad stacking reveals the relative vertical alignment of the images. In a correctly tracked system all blades should stack perfectly. Out-of-track blades, however, do not stack correctly, and must be adjusted until aligned.
4 3 M
2
Figure 6-5. Visual Track, Normal mode
When you are satisfied with the observation, press STOP to terminate visual track. Alternately, you may press SPECTRUM or BALANCE to terminate the Track mode and enter that particular operating mode.
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Chapter 6 - Blade Track Observation
6.4.2 The
(NO)SPREAD
Soft Key
The (NO) SPREAD soft key allows you to effect maximum and minimum blade spread with a single key stroke. This feature also provides a means by which the 8500C/C+ can save and restore blade spread amounts across different tracking operations. The ability to restore a blade spread eliminates th need to recreate the spread with the Arro wkeys when repeated track observations are performed.
Pressing the (NO) SPREA soft key during a track observation restores the most recent blade spread recorded by the 8500C/C+. If no blade spread has been performed, (NO) SPREAD effects the maximum possible spread and records it. Pressing (NO) SPREAD a second time stacks the blades, that is, reduces the blade spread to zero, but does not affect the previously recorded spread. Pressing
(NO) SPREAD again restores the recorded blade spread. Each subsequent press of the (NO )SPREAD soft key toggles the spread/stack or spread/no spread modes until the track is terminated. For each new track observation, (NO) SPREAD is initialized to restore the most recently recorded blade spread.
Alternately, the U pand Do wnArrow keys may be used to spread and stack the blades, respectively.
6.4.3 Normal and Surround Mode Observations
It is best that you always repeat your track observations in the surround mode. The surround mod displays the trailing blade twice, thereby providing a line of reference for the true blade tip path. This is
Figur e6-6 illustrate the difference between normal and surround mode observa tions. Figure6-5 shows
the visual track in Surround mode. The position of the second trailing bla de (blade No.4) establishes the true blade tip path. As you can see, blade N o.2 is in fact correctly aligned, but both the maste blade and blade No.3 are not.
4 3 M
2
4
Figure 6-6. Visual Track, Surround Mode
If a track imbalance can be identified, adjust the aircraft's trim tabs or pitch links according to the aircraft manufacturer's directions and repeat the procedure until all blades are properly aligned.
Visual tracking must be performed at several different forward air speeds before making adjustments to the aircraft's blades. By taking into account the track characteristics over the range of observations, you can often determine whether the imbalance is caused by misaligned trim tabs or pitch links. In general, a track profile that remains constant at all air speeds indicates adjustments to the pitch links are
6-6 Chadwick-Helmuth Company, Inc.
Performing a Visual Track necessary, but a variable or changing profile suggests trim tab adjustments. Having determined the typ of adjustment that is necessary, pitch link or trim tab, a vertical balance can be performed using the appropriate balance chart.
6.4.4 Blade Sweep
Blade sweep or lead-lag refers to the angle of separation between individual blades. Blades that are not equiangular can cause subtle perturbations to the system's lateral balance. Visual tracking allows you to view the blade spacing and gauge the relative separation between them. Balance solutions for some aircraft require modifications to the rotors' blade sweep, which in turn alters spacing in an attempt to redress lateral imbalance.
By stacking the blade images during a visual track it is possible to determine the amount of separation between adjacent pairs of blades. The extent to which these distances vary from blade to blade is an indication of the relative angular separation between them. Follow the aircraft manufacturer's directions to align rotor blades that are not equiangular.
6.4.5 Tail Rotor Tracking
Tail rotor track can be performed with the Strobex and the Measurements Only chart. First, following the instructions for a tail rotor balance, mount an velocimeter and apply reflective blade tip targets to the ends of the blades. Put the 8500C/C+ into the Balance mode and select the Measurements Only chart. Set the balance type to Strobex and set the balance frequency to the tail rotor's balance frequency multiplied by the number of blades. For example, a two-bladed tail rotor with a frequency of
33 00revolutions per minute (RPM) requires a balance freque ncy of 2times 33 0 0, or 6600RPM.
Operate the aircraft at the setting used for tail rotor balance and press START to acquire balance data
(see Section 5.4.1 “Initiating Strobex Measurement” on pa ge5-9). When the Strobex is activated (see
pressing the Lef tand Righ tArrow keys. Press STOP to terminate the track operation.
See Sectio n5.2.1 “Measurements Only Chart” on pa ge5-2 for more information on this chart.
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Chapter 6 - Blade Track Observation
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Chapter 7
7.
Spectrum Analysis
The Mode l 8 500C/C+ Balancer/Analyzer has the ability to capture, display, and analyze vibration signals generated by a rotor system. For some balance operations, it may first be necessary to perform
a spectrum analysis before the actual balance can be started. Cha pter7 explains the 8500C/C+’s
spectrum analysis feature, under the following topics:
7.1 Spectrum Analysis: Introduction
Spectral data acquisition requires that a Model7310 Velocimeter be installed on the target rotor system. Its cylindrical axis must be oriented in the direction of the vibrations you wish to analyze. For example, if you anticipate performing a main rotor lateral balance, the velocimeter must be aligned parallel to the rotor's plane of rotation. For a vertical balance, the velocimeter must be aligned perpendicular to the plane of rotation.
Spectral data can be collected and displayed by pressing the START key. Note that the time required for collecting the data varies inversely with the maximum frequency selected through SETUP (that is, the lower the maximum frequency, the greater the acquisition time). A high maximum frequency may also produce unreliable amplitude values at the low end of the range. As a result, be sure to select a maximum frequency that is near the spectral area of interest.
Selecting the Spectrum Mode
The analysis of vibration spectra requires that the 8500C/C+ be put into Spectrum mode. This is accomplished by pressing th SPECTRUM key. If spectral data have been captured during previous operations, they are plotted on the liquid-crystal display (LCD). To collect and display new data at any time in Spectrum mode, press START .
NOTE: If the 8500C/C+ is currently performing other time-critical functions, it may be necessary to press STOP to terminate the function before Spectrum mode can be entered.
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Chapter 7 - Spectrum Analysis
7.2 Data Acquisition and Storage
This section explains how to operate the 8500C/C+ in Spectrum mode for the purpose of collecting and storing spectral data.
7.2.1 Spectral Frequency Plots
Once the spectral data set has been collected, it is immediately displayed as a fast Fourier transform
(FFT) spectral-frequency plot, with frequency displayed along the horizontal X-axis in revolutions per minute (RPM) or Hertz (depending on the units selected), and vibration amplitude displayed along th vertical Y-axis in inches per second (IPS). A special cross-hair cursor, highlighting the intersection of frequency and amplitude on the spectral plot, may be moved left or right with th e Arrowkeys (se
Figur e7-1). If the seek peak function has been enabled (using
SE EKON ), the cursor jumps from one spectral peak to another, subject to the value of the seek amplitude threshold. Note that in seek peak mode, the cursor cannot be moved if no peaks exceed the seek amplitude level. Otherwise, if seek peak has been disabled, the cursor has an unrestricted range across the frequency axis. In both cases, th current cursor position is always shown in numerical form at the top left of the graph.
Figure 7-1. Spectral Frequency Plot
7.2.2 Aborting Data Acquisition
A data acquisition in progress may be aborted by pressing the START key. If STOP is pressed while the 8500C/C+ is in single mode, all existing spectral data becomes lost. In this case, a spectral frequency plot cannot be generated. Instead, a special Start-up screen is displayed with two soft
function keys, the repetition mode and seek mode keys (see Sec tion7.3.1.5 “Repetition Mode” on
page 7-4 and Sect ion7.4.3 “List Peaks Function” on pa ge7-8). The
SEL SETUP key is available if you wish to modify any of the spectrum parameters before initiating a new data acquisition (see
Figure 7-2. Spectrum Start-up Screen
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Spectrum Setup Operations
If STOP is pressed while the 8500C/C+ is in multiple mode, data acquisition is terminated and the last whole data set displayed. The spectral plot cursor is added, and th MULTIPLE label at the top o screen replaced with the current cursor position in vibration amplitude (in IPS) and frequency (in RPM or Hertz). The display is essentially the same as if a single mode spectral data acquisition had been
allowed to run to completion (see the next Section 7.4 “Data Analysis”).
7.2.3 Storing Spectral Data
The current spectral data set may be saved and stored in 8500C/C+ memory or as a data file on disk.
First, press the STATUS key to be sure that th Write To field is set to the desired target device, either MEMORY or DISK . If the field is set to MEMORY, subsequent store operations write data to memory. To change the field, press SETUP , use the Arrow keys to highlight the field, and press th
<CHANGE> soft key, followed by ENTER . If DISK has been selected, insert a formatted, writable
3.5-in. double-sided, double-density disk in the 8500C/C+ disk drive. In either case, press STORE to write the data. If the data is written to disk it is given a unique file name based on the current date and
time, plus the extension *.SPC. See Sectio n10.2.2 “Storing Data to Disk or Memory” on pa ge10-4 for
more information on storing spectral data and A ppendixB Spectral Data File Format” for a
description of the spectral data file format.
It is strongly recommended that 8500C/C+ distribution chart disks not be used to store spectral data files. Instead, use a backup copy of the chart disk and store the original chart disk in a safe place.
7.3 Spectrum Setup Operations
The 8500C/C+ supports the modification of several important parameters that are used to control the acquisition and analysis of spectral data. These parameters may be accessed by pressing SETUP ,
which in turn displays the Spectrum Setup screen (Figu re7-3). See the description of the
SETUP key
in Secti on4.2.3.4 SETUP Key” on pa ge4-7 for more information on Setup screens.
Figure 7-3. Spectrum Setup Screen
Use the Arrow keys to select the field whose contents are to be modified, and use the <CHANGE> soft key or the numeric keypad to effect the desired changes. The ENTER soft key saves the changes and resumes operation in Spectrum mode. Th RESTORE soft key restores to all fields the values that were set by the most recent ENTER .
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Chapter 7 - Spectrum Analysis
7.3.1 Using the Spectrum Setup Screen
Once the Spectrum Setup screen parameters have been modified, you may alternately press
SPECTRUM to save the changes and return to the Spectrum mode, or START to save the changes and begin spectral data acquisition. In effect, both of these keys execute an implicit ENTER before performing their respective functions.
The rest of this section explains in greater detail the various Spectrum Setup screen fields.
7.3.1.1 Maximum Frequency
The maximum frequency is the highest frequency for which spectral data can be acquired. Use the numeric keypad to enter an appropriate value, which may range from 200 RPM (3.3 Hz) to
600, 000RPM (10KHz). The default i s 10,000R PM (166.7Hz).
Note that, as the maximum frequency increases, amplitude values at the low end of the spectrum suffer a loss of resolution. Low-frequency resolution can fall off dramatically when there is a large amount of activity at low frequencies and the maximum range has been set high (above 1 0 0,000RPM). In general, the upper three-fourths of the range contain the most valid data. You must therefore select maximum frequency that is as close as possible to the area of spectral activity you wish to examine.
7.3.1.2 Frequency Units
The acquisition frequency may be displayed in either RPM or cycles per second (Hertz). Use the
<CHANGE> soft key to convert the frequency from one form to the other. Once this parameter is set, all other displays of frequency data are made in the selected units. The default is RPM.
7.3.1.3 Seek Amplitude
If the seek peak function is enabled, the seek amplitude becomes the minimum vibration signal amplitude that can be recognized by the spectral plot cursor. The allowable range is from 0.010IPS to
10.0 0IPS. The default is 0. 010IPS.
7.3.1.4 Vibration Units
Vibrations may be displayed in units of velocity (IPS, 0-pk) acceleration (g’s or in./sec
2
), or displacement (mils, DA). Use the <CHANGE> soft key to convert the units from one form to the other.
Once this parameter is set, all other displays of vibration data are made in these units. A mil equals
0.001 i n.
7.3.1.5 Repetition Mode
The repetition mode parameter indicates whether single or multiple spectral data frames are to be acquired. In single mode only one set of data is collected and displayed. The data are retained and can be scaled and manipulated, as described below. In multiple mode, data sets are continuously collected and displayed, purging the current set during each pass. This process continues indefinitely until the
STOP key is used to abort data acquisition. The multiple mode displays are always labeled with th word MULTIPLE at the top of the screen. The default repetition mode parameter is SINGLE .
7.3.1.6 Seek Peak Function
Enabling the seek peak function confines the spectral plot cursor to those points that exceed th specified vibration amplitude level. Otherwise, the cursor has free movement across the range of the plot. Use the <CHANGE> soft key to turn the seek peak function on or off. The default is seek on.
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Spectrum Setup Operations
7.3.1.7 Signal Selector Velocimeter Channel(s)
If a Mode l 8 520C Signal Selector is attached to the 8500C/C+, the velocimeter channel field(s) allow you to select the Signal Selector velocimeter channel(s) to be analyzed. Use the <CHANGE soft key to select an operator symbol, ei ther+ (to add signa ls), or- (to subtract signals), or ONLY (to select one channel only). Channels are selected by positioning the screen cursor over the channel number to be
changed and entering a new value from the numeric keypad. See Chapt er11 “Mode l8520C Signal
Selector” for a complete description of this instrument.
NOTE: If the Signal Selector is not attached to the 8500C/C+, these fields do not appear.
7.3.2 Using Spectrum Setups
The Spectrum mode parameters displayed in the Spectrum Setup screen may be saved and recalled, as desired. This feature allows you to restore commonly used parameters without having to manually re-enter the information. spectrum setup thus consists of all the setup parameters explained in this
chapter plus the current printout annotation (see S ection8.3 Annotating Printouts” on pa ge8-5 for
more details on printout annotations).
7.3.2.1 Saving Setups
To save a spectrum setup, call up the Spectrum Setup screen and press the STORE key. The current setup information is then saved to memory. If the STORE TO field in the Status screen has been set to
DISK , the setup information is saved to disk, as well as memory.
NOTE: It is strongly recommended that 8500C/C+ distribution chart disks not be used to store spectral data files; instead, use a backup copy of the chart disk and store the original chart disk in a safe place. Instructions for making a backup disk are located in
Secti on10.2.4 “Copying Balance Charts” on p age10-6.
of a spectrum setup is the same as the name of a previously saved setup, the 8500C/C+ asks you to
rename the current setup before writing it (se e Section7.3.2.3 Renaming Setups” on pa ge7-6).
Saved spectrum setups are stored in 8500C/C+ battery-backed memory. Since the contents of batterybacked memory are preserved when power to the instrument is turned off, it is not necessary to reload or recreate the same setups each time a restart occurs. These setups are always available when the setup selection menu is displayed. The only limit to the number of setups that may be kept on-line in this manner is the amount of available battery-backed memory. To clear spectrum setups from batterybacked memory, use the CLEAR ONE or CLEAR ALL
soft keys explained in Sect ion7.3.2.4 “Deleting
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Chapter 7 - Spectrum Analysis
7.3.2.2 Recalling Setups
To recall a spectrum setup, press the SE LSETUP soft key in the Spectrum Start-up screen or Spectrum
Setup screen (see Figure 7-3 on pa ge7-3 and Fi gure7-2 o n page7-2).
SEL SETUP displays a list of
press ENTER . The setup is restored and the spectrum parameters and printout annotation associated with it become the current spectrum setup.
Figure 7-4. Spectrum Setup Selection Menu
Additional setups can be loaded from disk by pressing SE LSETUP and inserting the appropriate disk in the 8500C/C+ disk drive. Press SCA NDISK to view the setups on the disk. When SCAN DISK
Press LOAD ALL to load all the setups to 8500C/C+ memory, or use the Arro wkeys to select a singl setup file. Then press LOAD FILE to load the selected setup to memory. When the 8500C/C+ finishes loading the desired setup file(s) it adds them to the SEL SETUP menu.
Figure 7-5. Spectrum Setup Selection Menu
7.3.2.3 Renaming Setups
To rename a saved spectrum setup, select a setup in th SE LSETUP menu and press RENAM ESE .
The 8500C/C+ enters its edit mode of operation and displays the Setup Edit screen (se e Figure7-6).
The soft keys and procedures used here are identical to those used to edit the printout annotation. Se
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Data Analysis
Secti on8.3.8 “Editing Annotation Templates” on pa ge8-8 for a complete description of edit mode.
When you have finished renaming the setup, press the ENTER soft key to enter the new name and exit the edit mode. The name of the setup is updated accordingly on the menu of available setups.
Figure 7-6. Setup Edit Screen
7.3.2.4 Deleting Setups
Spectrum setups may be deleted one at a time or all together. To delete a single setup, first use the
Arrow keys to select a setup in th SE LSETUP menu, then press the CLEAR ONE soft key. To delete all the setups stored in memory, press th CLEAR ALL soft key.
7.3.2.5 Loading Setups From Disk
Spectrum setups that have been stored to disk may be loaded into 8500C/C+ memory then restored. To load a Spectrum setup, invoke the SEL SETUP selection menu and insert the appropriate disk in th disk drive. Press LOAD to load the setup files from disk. When the load operation is complete, th menu redisplays along with the new setups. Note that the loading of duplicate setups does not overwrite existing copies. Duplicate setups are simply added to the menu and sorted accordingly.
7.3.2.6 Storing Setups to Disk
Spectrum setups stored in memory may be stored all at once to disk with the STORE ALL soft key.
First invoke the SEL SETUP selection menu and insert the appropriate disk in the disk drive. Press
MORE KEYS , followed by STORE ALL . The 8500C/C+ copies all spectrum setups from memory to disk, regardless of the state of the STORE TO field in the Status screen.
7.4 Data Analysis
The spectral data analysis features of the 8500C/C+ allow you to analyze collected vibration data by manipulating the ways in which the data are displayed. This action is done through the soft keys that
hidden. To view them, you must press SHOW/HIDE
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Chapter 7 - Spectrum Analysis
NOTE: A portion of the LCD becomes obscured by the labels until SHOW/HIDE is pressed again.
The last two soft keys, SCALE and <HA RMON> / <HA RMOFF> are also hidden and can only b enabled by pressing MORE KEYS . The rest of this section explains the functions of these spectral data analysis soft keys.
Figure 7-7. Spectral Frequency Plot Soft Keys
7.4.1
SEEK ON/SEEK OFF
Soft Key
Pressing the <SEE KON> / <SEEK OFF> soft key turns the seek peak function on and off. It is functionally identical to the seek peak parameter in the Spectrum Setup screen.
7.4.2 Select Setup Function
The SEL SETUP soft key displays a list of saved spectrum setups which may be recalled, as desired.
See Sectio n7.3.2.2 “Recalling Setups” on pa ge7-6 for a complete explanation of
SE LSETU .
7.4.3 List Peaks Function
The LIST PEAKS soft key displays a list of the spectral peaks at or above the seek amplitude threshold
frequency values for a single spectral peak. The list cursor initially highlights the entry whose position on the spectral plot is nearest that of the spectral plot cursor. Use the Arrowkeys to scroll through the list.
Figure 7-8. List of Spectral Peaks Sorted by Amplitude
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Data Analysis
Entries can be sorted with the <FRQ SORT> / <AMP SORT> soft key. Selecting <FRQ SORT> causes
the entries to be sorted by frequency, in ascending order (see Figure7-9).
<AMP SORT> sorts them by amplitude, in descending order. In both cases the sort order proceeds from left to right, and top to bottom. Peaks of equal amplitude appear in the order of increasing frequency. Pressing OK returns to the spectral plot and positions the spectral cursor on the peak last selected in the table.
Figure 7-9. List of Spectral Peaks Sorted by Frequency
7.4.4 Setting the Balance Frequency
The BAL FREQ soft key allows you to display the frequency at which a rotor balance is to be performed. Move the spectral plot cursor to the desired balance acquisition frequency (usually at a spectral peak generated by an out-of-balance rotor) and press BAL FREQ . Press OK to return to the spectral plot, or START to begin balance data acquisition at the selected frequency.
7.4.5
SINGLE/MULTIPLE
Soft Key
Pressing the <SINGLE> / <MULTIPLE> soft key alternates the repetition mode parameter between single and multiple. It is functionally identical to the repetition mode parameter in the Spectrum Setup screen.
7.4.6 Scaling Spectral Plots
Selected portions of a spectral plot can be enlarged or reduced with the spectrum scaling feature.
Scaling is initiated by pressing MORE KEYS , followed by the SCALE soft key, which in turn puts the
instrument into scaling mode and enables a new set of soft keys (see F igure7-10). Some of the new
soft key labels are initially hidden. They can be enabled by pressing MORE KEYS .
Figure 7-10. Spectral Plot With Scaling Mode Soft Keys
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Chapter 7 - Spectrum Analysis
To enlarge a region of the spectral plot, use the L eftand Righ tArrowkeys to move the cursor along the
X-axis to the minimum frequency where the target region begins. Note that moving the cursor automatically hides the soft key labels. Press SHOW/HIDE to recreate them. Press the MIN FREQ soft key. The area between the cursor and the Y-axis darkens to indicate it has been deselected. Move th cursor along the X-axis to the maximum frequency where the target region ends. The position of the cursor for the maximum frequency must be greater than the minimum frequency. Press th MAX FREQ soft key to deselect the area to the right. Now use t he Upan d Down Arrowkeys to move the curso along the Y-axis to the maximum vibration amplitude. Press MAX AMP to deselect the area above it.
Once these limits have been set, the area to be scaled becomes clearly defined by the darkened regions
that bound it. See F igure7-11 below.
Figure 7-11. Spectral Plot With Scaling Bounds
Press the ENTER soft key to display the scaled region and re-enable the spectrum soft keys (see
Figur e7-12). Note that the X-and Y-axes are automatically reannotated to reflect the new scaling
parameters.
Figure 7-12. Scaled Spectral Frequency Plot
If you press SCALE again you see the original full-sized plot with its darkened bounding regions (se
Figur e7-11 on pa ge7-10). This is a simple indication that scaling is currently in effect. Now the
Arrow keys may be used again to enlarge the plot still further or reduce it to a smaller scale.
Pressing SCALE followed by MORE KEYS enables an additional soft key, FULL SCALE , which removes all scaling and selects the entire spectral plot for viewing. Pressing FULL SCALE exits scaling mode and restores the spectral analysis soft keys.
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Data Analysis
7.4.7 Harmonics Mode
The harmonics mode allows you to view spectral frequencies that are an integer multiple of the cursor’s current frequency value. The identification of harmonic frequencies is important to vibration analysis because many of these frequencies turn out to be artifacts, that is, secondary vibrations generated by a primary vibration source. Thus, correcting a primary vibration usually eliminates th harmonic artifacts as well.
Pressing MORE KEYS followed by the <HA RMON soft key displays additional vertical cursors
identifying all harmonic frequencies in the given frequency-amplitude range (see Figure7-13). Th
annotated frequency and amplitude values at the top of the plot are always those of the primary (leftmost) cursor. The <HAR MOFF soft key disables the harmonics mode and removes any secondary cursors.
Figure 7-13. Spectral Frequency Plot With Harmonics Cursors
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Chapter 7 - Spectrum Analysis
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Chapter 8
8.
Using Printouts
The Mode l 8 500C/C+ Balancer/Analyzer gives you printouts with balance solutions and other important measurement information. This chapter explains how to read, annotate, and use these printouts to gain maximum benefits, under the following topics:
8.1 Printouts With the 8500C/C+
Along with showing you track-and-balance solutions on its liquid-crystal display (LCD), the 8500C/
C+ provides you with printouts that contain important solution and measurement information. An
8500C/C+ printout consists of a copy of the current display window, plus some annotated data fields that can provide additional information about the printout contents. By default, these data fields include the following elements: time and date of the printout, air speed, pickup number, altitude, run number, manufacturer/model number, identification number, and a comment field.
If you are using the M odel11800 FasTrak Optical Tracker with a Smart Chart that supports it the
8500C/C+ also generates track printouts with FasTrak information. For detailed information on thes printouts, see the FasTrak Operators Manual.
Use the 8500C/C+ solution printout as a hard-copy guide to implementing your current balance solution. If you are not in the auto-print mode, you must press PRINT to create a solution printout.
Normally, in auto-print mode, the 8500C/C+ automatically creates a solution printout at the end of the last flight regime. At the end of any regime, you may press the SOLVE NOW soft key to generate an interim solution. At the same time, the 8500C/C+ also displays a Solution screen, as reproduced on the printout.
See Sectio n10.1 Using the Printe ” on pa ge10-1 for additional information on the 8500C/C+ printer
and printouts. The rest of this chapter explains how to read and use an 8500C/C+ solution printout.
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Chapter 8 - Using Printout
8.2 Reading 8500C/C+ Printouts
Figur e8-1 below and Fi gure8-2 o n page8-3 show a sample 8500C/C+ solution printout. Refer to this
printout example with the additional explanations given later in this section.
SOLUTION
SCREEN
DIRECTIONS
TO THE USER
BASIC CHART
INFORMATIO
N
TAIL AND RUN
NO., DATE, AND
AZIMUTH
VIBRATION
BALANCE
READINGS
FOR EACH
REGIME
Continued on the next page.
Figure 8-1. Solution Printout (Part1)
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Reading 8500C/C+ Printouts
Continued from the last page.
SOLUTION
OPTIONS
ITERATIONS
AND GOALS
SWEEP,
WEIGHT, AND
TAB
SETTINGS
FASTRAK
TREND SCREEN
PRINTOUT
FASTRAK
MEASUREMENT
READINGS FOR
EACH BLADE
BASIC 8500C/C+
INFORMATION
Figure 8-2. Solution Printout (Part2)
Your current main rotor solution printout may differ from this example in minor respects. Data varies, depending on which chart settings, options, and/or chart version you are using.
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Chapter 8 - Using Printout
Printout Explanation List
greater detail:
Solution Screen
Directions to the User
Printout illustration reproduces for you a copy of the Solution screen displayed on the 8500C/C+ at the time the solution is generated.
Gives you brief directions on how to read the printout solution information, including symbols, terms, and how to make changes.
Basic Chart Information Gives you the name, part number, and revision date of the current balance chart.
Tail and Run No.
Tells you the following information:
• Subject aircraft tail number
• Current run number
The date and time the current data was collected.
Date
Azimuth Shows the azimuth frequency as measured by the magnetic pickup or
Photocell.
Vibration Balance ReadingsGives you all the balance measurements acquired by the 8500C/C+ up to the point when the current solution was generated. These measurements are broken down by each channel (as acquired b y each Model7310
Velocimeter) and each regime.
Solution Options Tells you which solution parameters the 8500C/C+ is taking into account in calculating your solution. YES means the 8500C/C+ is assuming in its calculations, that you can change the item listed, for example trim tab or pitch link, in implementing your solution. You may change the solution options by accessing the Solution Option screen (press SOLN OPTS ). The
8500C/C+ default is all options set to YES.
Iterations and Goals Establishes the confidence level of the current set of solutions. Iterations refer to internal calculations within the 8500C/C+. If the Flight Goal figure is less than the highest in-flight vibration balance reading (see above), then your current solution is likely to achieve optimum balance for the aircraft.
Lists the current weight and trim tab settings for each blade.
Settings
FasTrak Trend Screen Gives you FasTrak trend information. See the FasTrak Operators Manual for details.
FasTrak Measurements Gives you track height and lead-lag information, as acquired by th
FasTrak.
8500C/C+ Information Shows basic 8500C/C+ information, including the current 8500C/C+ and
Mode l8520C Signal Selector firmware version numbers.
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Annotating Printouts
8.3 Annotating Printouts
In addition to balance solution and measurement data, some 8500C/C+ printouts are further amended to include specific information pertinent to the screen being printed. Be sure to read this information.
See the printout annotation example in Fi gure8-3 below.
13:30:18 7 Aug 97
AIRSPEED: 0 KTS PICKUP #: 3
ALTITUDE: 0 FT RUN #: 1
MFR/MODEL: WHIRLIGIG MAIN ID #: 1273
COMMENTS: THIS IS AN EXAMPLE OF A PRINT-
OUT ANNOTATION FOR THE C-H 8500C/C+
Figure 8-3. Sample Printout With Annotation
Adding the appropriate information to the annotation can be extremely helpful in identifying and documenting the work performed on a particular aircraft. You may wish to modify the existing annotation fields or substitute one or more new data fields of your own.
8.3.1 Printout Annotation Screen
To edit the printout annotation, press the ANNOTATE key. The 8500C/C+ enters its edit mode and
displays the Printout Annotation screen (see F igure8-4 below and Figure8- 5 on page8-6). The
Printout Annotation screen shows the annotation data fields and labels, as they appear on each printout. You may edit any of the fields and labels, as you wish.
Figure 8-4. Printout Annotation Screen
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Chapter 8 - Using Printout
Figure 8-5. Additional Printout Annotation Screen Soft Keys
The rest of this section explains basic procedures for editing 8500C/C+ printout annotations.
8.3.2 Alpha and Numeric Editing Modes
The annotation editor can operate in one of two modes, each of which assigns different functions to the
8500C/C+ keypad keys. In alpha mode each key is mapped to the value of the character printed on the upper left corner of the key. Pressing the key displays the appropriate character at the current curso position.
In the numeric mode the numeric keypad keys assume the values of the printed numbers. Pressing the key thus displays the appropriate number at the current cursor position. The SHOW/HIDE , HELP ,
PRINT , and MORE KEYS keys revert back to their primary functions. Other keys are mapped to th
special characters printed on the lower right corner of the key (see Table8-1).
Table 8-1. Special Character Keys
Key
BALANCE
SPECTRUM
TRAC
LOAD
STORE
STATUS
SETUP
ANNOTATE
START
STOP
Special
Character
-
.
<
>
:
#
%
/
*
*
Toggle the <ALPHA> / <NUMERIC> soft key to switch between the alpha and numeric editing modes.
Note that in numeric mode there are several additional soft keys that may be accessed through the
MORE KEYS key.
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Annotating Printouts
8.3.3 Moving the Cursor
The cursor may be positioned within a data field or moved to a new one. In the alpha mode only the
Left and Rig htAr rowkeys can move the cursor. If the cursor is moved beyond the range of th selected field, it automatically goes to the beginning of the nearest field in the direction indicated by the Arro wkey.
In the numeric mode, the START , STOP , and U pand Do wnArr owkeys can be used in addition to the
Left and Rig htArr owkeys. The STOP key advances the cursor to the beginning of the next data field.
The START key moves it to the beginning of the previous field. The Upand D ownAr rowkeys move the cursor up or down one line of the display.
8.3.4 Modifying Annotations
Characters may be entered as described above. In addition, th INSERT soft key inserts a space between characters. Data field characters to the right of the space are moved in that direction. If the entire template is being edited, the rest of the line moves to the right.
The DELETE soft key deletes the character at the current cursor position. Data field characters to the right move to the left one space. If the entire template is being edited, the rest of the line moves left.
8.3.5 Saving Annotations
After making all the desired changes to the annotation fields, press the ENTER soft key to enable the changes, quit the Setup screen, and resume operations. The saved annotation appears on all subsequent printouts.
8.3.6 Restoring Annotations
Changes to the display fields of the entire annotation screen can be removed and the last entered contents restored by pressing MORE KEYS and the RESTORE soft key from numeric mode. Those values that have been modified since the last ENTER operation are lost.
If the entire annotation template is being edited, the RESTORE soft key restores the last entered template.
8.3.7 Clearing Annotations
Changes to the display fields of the entire annotation screen can be cleared by pressing MORE KEYS and the CLEAR soft key from the numeric mode. The field labels are preserved.
If the entire annotation template is being edited, the CLEAR soft key clears the entire screen. You may enter a new template or press RESTORE to restore the last entered template.
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Chapter 8 - Using Printout
8.3.8 Editing Annotation Templates
The TEMPLATE soft key allows you to modify the entire annotation screen, including the labels that
display line, and the ENTER , CLEAR , and RESTORE soft keys on both the data fields and their labels.
In the numeric mode, the START and STOP keys move the cursor to the beginning and end of the line, respectively.
Figure 8-6. Annotation Template Screen
NOTE: Labels and their data fields are separated by a colon (:). All new labels must be similarly terminated.
Pressing TEMPLATE enables a new soft key, the ORIGINAL soft key. Pressing ORIGINAL causes th permanent default template to be restored. Any modifications to the display fields and their labels ar lost, as are all previously entered templates.
8.4 Renaming Balance Charts
Since balance charts may be stored to disk, you also have the option of renaming the chart before it is actually written. This option is especially important in the case of a corrected balance chart, where the correction factors for phase angle and vibration amplitude now contained in the chart are specific to an individual rotor system. To edit a balance chart name, press SEL CHART to display the list of available charts. Highlight the chart to be renamed and press th RENAM ECHT soft key to invoke the Edit
screen and put the 8500C/C+ into the edit mode (see Figure8-7). The soft keys and procedures used
here are nearly identical to those used to edit the printout annotation. The only exceptions are the use of the START and STOP keys, which tab five spaces to the left and right, respectively.
Figure 8-7. Balance Chart Edit Screen
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Renaming Balance Charts
The Balance Chart Edit screen displays the selected chart name, along with the INSER , DELETE , and
<ALPHA> / <NUMERIC> editing soft keys. Pressing MORE KEYS displays the CLEAR , RESTORE , and
CANCEL soft keys. Use CLEAR and RESTORE, as described earlier, to clear and restore the balance chart name. The CANCEL soft key undoes any modifications made during this editing session and exits the edit mode.
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Chapter 8 - Using Printout
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Chapter 9
9.
Status Screen Operation
The Mode l 8 500C/C+ Balancer/Analyzer gives you a Status screen that displays important information about the unit’s operation, as well as general data, such as the time and date. This chapte explains how to read and operate this screen, under the following topics:
9.1 Status Screen: Introduction
time and date, pickup pulse or azimuth rate (from a magnetic pickup or Photocell System), printer, disk, and memory status, and firmware version number. The pickup pulse rate and time ar continuously updated. Status information is always available, except while error messages are being displayed or while the 8500C/C+ is performing a time-critical function such as visual tracking or a balance data acquisition. To view the 8500C/C+ Status screen, press the STATUS key.
Figure 9-1. Status Screen
Press the EXIT soft key to exit the Status screen and return the 8500C/C+ to its previous mode of operation.
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Chapter 9 - Status Screen Operation
9.2 Screen Data Fields and Functions
There are a number of data items listed in the Status screen. Each item is a separate field. The rest of this section explains each of these fields, as well as functions accessed through this screen.
9.2.1 Time and Date
The time and date indicate the current values as reported by the 8500C/C+ real-time clock. The time is displayed in a 24-hr format. Time and date are primarily used to time-stamp 8500C/C+ printouts and may be modified through the Status Setup screen.
NOTE: The real-time clock operates even if power to the 8500C/C+ has been turned off. As a result, you do not have to reset the time and date.
9.2.2 Pickup Pulse Rate
P/U Rate represents the current frequency reading from a signal source (azimuth), such as a magnetic pickup or Photocell, and is a good way to check its current state without initiating a spectral data acquisition. Frequency units may be displayed in either revolutions per minute (RPM) or cycles per second (Hertz) and may be selected through the Status Setup screen.
9.2.3 Firmware Version Number
8500C /C+Version displays the instrument's firmware version number. This field cannot be modified.
9.2.4 Prints Waiting
Prints Waiting displays the number of print jobs waiting to be printed on the 8500C/C+ printer. This field cannot be modified.
9.2.5 Paper Status
Paper indicates whether the 8500C/C+ printer has paper or not. This field cannot be modified.
9.2.6 Output Storage Device
Store To indicates the device to which the STORE command writes data files, either 8500C/C+ memory or the 8500C/C+ disk drive. The device may be selected through the Status Setup screen. This field must be set to DISK if subsequent STORE operations are to write balance charts, spectral data, or balance histories to the 8500C/C+ disk drive, or to MEMORY if the data are to be written to memory.
9.2.7 Memory Free
Memory Fre indicates the percentage amount of 8500C/C+ static memory still available for storage.
This field cannot be modified.
9-2 Chadwick-Helmuth Company, Inc.
Review Feature
9.2.8 Disk Unit Status
Disk Unit reports the status of the 8500C/C+ disk drive. This field cannot be modified. A status o
EMPTY indicates that the drive does not contain a disk. A status of NOT READY indicates that the disk in the drive is not properly formatted. A status of READY indicates the presence of a valid, DOSformatted disk.
9.2.9 Disk Status
Disk reports the status of the disk in the 8500C/C+ disk drive. This field cannot be modified and does not display if there is no disk in the drive. A status of READ ONLY indicates that the disk is writ protected. A status of WRITABLE indicates a writable disk.
9.2.10 Screen Functions
In addition, the Status screen allows for the following 8500C/C+ functions:
• Review featur
• Disk formatting
• Self-test
• About 8500
• 8520C Reset
• Test 8520 Vibration Channels
See the next Sectio n9.3 “Review Featur ” for a complete explanation of this feature.
Formatting a Disk
The FORMAT DSK soft key allows you to format a 3.5-in. diskette in the 8500C/C+ disk drive. Note
Self-test
The SELF-TES soft key invokes the 8500C/C+ self-test facility, which contains a set of on-lin diagnostic programs used to test various components of the 8500C/C+ hardware. You do not need to use this key for any ordinary 8500C/C+ operations. The SELF-TEST key is provided for use by
Chadwick-Helmuth when repairing a malfunctioning unit.
9.3 Review Feature
The review feature allows you to examine and optionally restore spectral data sets and balanc histories that currently reside in 8500C/C+ memory. With it, an operator can continually collect spectral and balance data from many different systems, store it in memory, then examine the desired data for further analysis and processing.
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9-3
Chapter 9 - Status Screen Operation
The review feature is accessed through the Status screen REVIEW soft key. The 8500C/C+ displays
below). Two rows of soft keys provide the means to select, analyze, and delete any particular set or sets of data.
Figure 9-2. Status Review With Balance History
To exit the Review screen, press QUIT .
9.3.1 Selecting the Data Type
Toggle the <SPECTRA> / <BAL HIST> / <ANY> soft key to select the data type, either spectral data o balance histories. The <ANY> soft key allows any object type to be reviewed. Once the type has been chosen, the 8500C/C+ displays the data for the first item (if one exists). For a screen example, see
Figure 9-3. Status Review With Spectral Frequency Plot
9.3.2 Selecting a New Review Item
The NEXT and PREVIOUS soft keys select new items for a particular data type, then update the display appropriately. Use NEXT and PREVIOUS to find a particular spectral plot or balance history. If the data type is <ANY> , NEXT and PREVIOU select items in the order they were stored to memory, no matter their type.
9.3.3 Storing Review Items to Disk
Press the STORE ALL: soft key to store all the items of the selected data type to disk. Pressing th
STORE key also writes the items of the selected data type to disk.
9-4 Chadwick-Helmuth Company, Inc.
Status Parameter Setup
9.3.4 Clearing Review Item
The CLEAR ITEM soft key deletes the currently displayed item and removes it from memory. An item next stored in memory is displayed in its place. Note that if the deleted item is also the current item in
Balance mode, that balance history is also deleted, and is not available when you return to the Balanc mode.
To delete all the items of the selected data type, press CLEA RALL . If the data type is <ANY> , all spectral and balance history items are deleted.
9.3.5 Analyzing the Selected Item
The ANALYZE soft key restores the selected item and makes it the current plot or history in the
Balance or Spectrum mode. Use ANALYZE , for instance, to restore an old balance history so that new runs can be taken and added to it. Note that the history that was in use befor ANALYZE was pressed is superseded by the restored item, and that the balance chart associated with the restored item is also made the current chart.
9.4 Status Parameter Setup
The 8500C/C+ supports the modification of several Status screen parameters. These parameters may be accessed by pressing SETUP
, which in turn displays the Status Setup screen (Fig ure9-4). See th
description of th SETUP
key in Secti on4.2.3.4 “SETUP Key” on page4-7 for more information on
Setup screens.
Figure 9-4. Status Setup Screen
Use the Arro wkeys to select the field whose contents are to be modified, and th <CHANGE> soft key or the numeric keypad to effect the desired changes. Th ENTER soft key saves the changes, quits status mode, and returns the 8500C/C+ to its previous mode of operation. Pressing the START key has the same effect. The RESTORE soft key restores to all fields the values that were set by the most recent
ENTER . Pressing STATUS performs an implicit ENTER and returns to the Status screen.
The following sections describe in greater detail the various Status Setup screen fields.
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Chapter 9 - Status Screen Operation
9.4.1 Setting the Time and Date
Time and date may be changed by using t he Arrowkeys to move the cursor to the appropriate Status
Setup screen data field. The current time is displayed in a 24-hr format. The hours, minutes, day of th month, or year may be changed with the numeric keys. The day of the week and the month may be selected with the <CHANGE> soft key. The seconds may not be modified and are automatically set to zero whenever the time or date is changed.
9.4.2 Setting Pickup Pulse Rate Units
Frequency units for the pickup pulse rate may be displayed in either RPM or Hertz by moving th cursor to the P/U Rate data field and pressing the <CHANGE> soft key.
9.4.3 Setting the Output Storage Device
The output storage device for subsequent STORE operations may be set by moving the cursor to th
Store To data field and pressing <CHANGE> .
9-6 Chadwick-Helmuth Company, Inc.
Chapter 10
10.
Printer and Disk Drive
The Mode l 8 500C/C+ Balancer/Analyzer contains a full-featured printer and a 3.5-in. double-sided,
topics:
NOTE: For part numbers on printer and disk drive parts and other parts and/or order information, see the Mode l8500C/C+ System Maintenance Manual.
10.1 Using the Printer
The printer is a thermal dot-matrix printer capable of creating hard-copy reproductions of the current liquid-crystal display (LCD) window. Printing is initiated by pressing the PRINT key.
NOTE: Printing is disabled during time-critical functions such as track observation and
Balance or Spectrum mode data acquisition, as well as when the 8500C/C+ is in its alpha
editing mode (see Sec tion8.3.2 “Alpha and Numeric Editing Modes” on p age8-6).
10.1.1 General Operation
Printing in the 8500C/C+ proceeds as a background task, which means you may continue to operate the instrument while the printer is working. Successive use of th PRINT key saves the additional printouts and queues them so that they are printed in the order they were requested. Up to twenty printouts may be queued at one time. Each printout takes ab o ut 30sec to complete and is amended to
specific information pertinent to the screen being printed.
10.1.2 Paper Roll Replacement
Turn the 8500C/C+ upside down and depress the stainless steel catch button next to the disk drive
door. Lift the bottom to expose the printer assembly (see F igure10- 1 on page10-2).
If there is still paper in the printer, use scissors to cut the paper from the roll. At the back of the printer assembly on the left-hand side are several black plastic gears. Rotate the left-most gear in a counterclockwise direction until the paper is ejected from the printer. Do not pull the paper out of the printer.
The spindle release bar is located immediately in front of the paper roll. It has a large spring underneath it. Depress the spindle release bar and remove the spindle and used paper roll.
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Chapter 10 - Printer and Disk Drive
Remove the used paper roll from the spindle and replace it with a new roll. Open the spindle holder by depressing the spindle release bar and insert the spindle and new paper roll. Orient the roll so that th paper feeds from the back of the roll (the side nearest the rear of the assembly) into the printer. Th paper guide should face the side of the paper with the thermal coating.
PAPER ADVANCE
GEAR
(WITHOUT POWER)
PAPER IN
PAPER OUT
PAPER ADVANCE
BUTTON
(WITH POWER)
PUSH TO
RELEASE
PAPER
Figure 10-1. 8500C/C+ Printer Mechanism
Cut the end of the paper square and feed it over the curved paper guide at the back of the unit and into the groove in the top of the printer. When the paper stops, rotate the left-most black plastic gear in a counterclockwise direction until the paper clears the back of the 8500C/C+. Be sure that the paper is feeding smoothly.
When you are finished, close the bottom of the 8500C/C+ and place the unit upright.
10-2 Chadwick-Helmuth Company, Inc.
Using the Disk Drive
10.2 Using the Disk Drive
To insert a 3.5-in. floppy disk in the 8500C/C+ disk drive, open the disk drive door on the front panel by pushing the metal plate upward. Hold the floppy disk with the front side facing up and the arrow
pointing away from you (see Fig ure10-2). Slide the disk into the disk drive slot. When the disk is
inserted, the drive locks the disk into place and the eject button on the lower right side of the driv panel pops out.
Write-protect switc
(write-enabled)
Front Rear
Figure 10-2. Front and Rear View of a 3.5-in. Floppy Disk
To remove the disk, push the eject button. When you do this, the drive then ejects the disk for easy removal by the operator.
10.2.1 Loading Disk Files
The 8500C/C+ disk drive may be used to load balance charts into memory, where they may then be used to acquire balance measurement data for the selected chart's rotor system. The disk drive may also be used to load spectrum setups, which can be used to automatically restore Spectrum mode setup parameters. To load a balance chart, first press BALANCE to put the 8500C/C+ into the Balance mode.
Call up the balance chart selection menu with the SEL CHART soft key and insert the appropriate balance chart disk in the disk drive. Press LOAD to load the charts from disk. When the load operation is complete, the menu is redisplayed along with the new charts. Note that loading duplicate charts does not overwrite existing copies. They are simply added to the menu and sorted accordingly.
To load a Spectrum Setup, first press SPECTRUM to put the 8500C/C+ into Spectrum mode. Call up the setup selection menu with the SEL SETUP soft key and insert the appropriate disk in the disk drive.
Press LOAD to load the setup files from disk. When the load operation is complete, the menu is redisplayed along with the new setups. Note that the loading of duplicate spectrum setups does not overwrite existing copies. They are simply added to the menu and sorted accordingly.
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Chapter 10 - Printer and Disk Drive
Balance charts and spectrum setups that have been loaded from disk or saved to memory are stored in the 8500C/C+’s static memory. Since the contents of static memory are preserved when power to th instrument is turned off, it is not necessary to reload the same files each time a restart occurs. The files are always available when the appropriate selection menu is displayed. The only limit to the number of charts or setups that may be kept on-line in this manner is the amount of available static memory. To clear all balance charts from static memory, use the Balance mode CLR CHARTS soft key described in
Secti on5.2.3.5 Clearing Chart Memor ” on pa ge5-5. To delete all spectrum setups from stati
memory, press the CLEA RALL soft key. You may use the CLEAR ONE soft key to delete the currently selected setup.
If an error occurs during a load operation, the 8500C/C+ informs you of it and attempts to explain th problem. In most cases, errors are caused by one or more of the following conditions:
• There is no disk in the disk drive.
• The disk is unreadable or not properly formatted.
• The disk contains no balance chart or spectrum setup files, or existing files have been corrupted.
After attempting to remedy the problem, you can do one of several responses. Pressing the RETRY soft key performs the load again from the beginning. Pressing CONTINUE skips over the chart that caused the error and continues loading the remaining charts or setups, if possible. Pressing QUIT terminates the load operation and keeps only those charts or setups that have been successfully loaded. Pressing the STOP key terminates the load and deletes those charts or setups that may have already been loaded during this operation.
10.2.2 Storing Data to Disk or Memory
Spectral data, spectrum setups, balance histories, and balance charts may be saved as files and stored on disk. First, press STATUS to be sure that the Store To field is set to DISK. If it is set to
MEMORY, subsequent store operations write data to memory instead of to disk. To change the field, press SETUP , use the Arro wkeys to highlight the field, and press the <CHANGE> soft key, followed by ENTER .
With the 8500C/C+ in either Balance or Spectrum mode, insert a formatted, writable 3.5-in. doublesided, double-density disk in the 8500C/C+ disk drive and press STORE . The data is written to disk and given a unique file name based on the current date and time, plus the extension *.BHI (for a balance history file), *.SPT (for a spectral data file), or *.SET (for a spectrum setup file). See
Append ixC Balance History Files” for a description of the balance history file format, and
Append ixB Spectral Data File Format” for a description of the spectral data file format. If you are
saving a balance chart or spectrum setup, you are first asked to rename the chart or setup before writing
it to disk (see Se ction10.2.3 “Storing Balance Charts to Disk” on page 10-5). If you are saving a
balance history, the chart name is stored along with the other history data. You may wish to first rename the chart in order to better identify the history file. Spectrum setups are written to memory, as well as to disk.
If an error occurs during a store operation, the 8500C/C+ displays an error message screen and attempts to explain the problem. In most cases, errors are caused by one or more of the following conditions:
• There is no disk in the disk drive.
• The disk is not properly formatted.
• The disk is write-protected or otherwise not writable.
10-4 Chadwick-Helmuth Company, Inc.
Using the Disk Drive
First, attempt to correct the problem before retrying the store operation. See Section10.2.5
“Formatting Disks” on page 10-6 for an explanation of disk formatting procedures.
A write-protected disk can be made writable by moving the write-protect tab on the rear of the disk so that the hole at the top of the switch is completely covered. Exposing the hole makes the disk read-only
and prevents any further writing (see Fig ure10- 2 on page10-3).
10.2.3 Storing Balance Charts to Disk
Storing balance charts to disk provides a means to copy charts from one disk to another. It also provides a means to rename charts, which is important if a chart has been corrected. Corrected charts are always unique to a specific rotor. To store a particular chart, first put the 8500C/C+ in Balance mode. Press SEL CHART to display the list of available charts, and use the Arrowkeys to highlight the desired chart. Press STORE to store the chart to disk. You are then asked to give the chart a new name before it is actually written to disk. Make sure the name you supply provides a unique identification for the chart, the rotor type and tail number of the aircraft, for example, although it is not necessary to rename the file before storing it. When a chart is stored to disk, a balance chart file is created containing the renamed chart plus other related charts associated with the file. The new chart file replaces an existing chart file with the same name. Note that balance histories are never written to disk
“Storing Histories to Disk” on pa ge5-16).
To store all the charts listed on the balance chart selection menu, press MORE KEYS and th
STORE ALL soft key. STORE ALL stores all the charts currently in static memory to the appropriate chart file(s) on disk. Charts are written as is without renaming, so you are not asked to create new names.
When you press STORE (but not STORE ALL ), the 8500C/C+ enters its edit mode of operation and
displays the Balance Chart Edit screen (see Figure 10-3). The soft keys and procedures used here are
ENTER soft key to write it out to disk. Note that when a chart is stored to disk, a new balance chart file is created containing the renamed chart plus the other charts associated with the file. If the chart has the sam name as a chart already on disk, the latter is overwritten (unless it is a distribution chart on a distribution disk, in which case an error results). When the chart has been stored, the list of available balance charts displays again, and the name of the stored chart is updated accordingly.
Figure 10-3. Balance Chart Edit Screen
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Chapter 10 - Printer and Disk Drive
10.2.4 Copying Balance Charts
Chadwick-Helmuth provides balance chart disks for many different kinds of aircraft rotor systems.
These distribution disks are write-protected and the charts may not be deleted or overwritten when in use with the 8500C/C+. Any attempt to do so results in an error. Distribution charts may, however, b copied to other disks by using the 8500C/C+’s LOAD and STORE ALL commands. Chart copies made in this way are not write-protected, and may be modified, renamed, deleted or overwritten as required.
To copy a balance chart to another disk, use the LOAD and STORE ALL commands as explained above. Once a chart has been loaded into static memory it loses any write-protection it may have had on disk. It may then be modified or renamed, then stored to another disk for future use.
10.2.5 Formatting Disks
All 3.5-in. double-sided, double-density (720-KB) diskettes used in the 8500C/C+ disk drive must b compatible with the PC-DOS, MS-DOS or Windows operating systems. Disks may be formatted on appropriately equipped personal computers (PCs) running MS/PC-DOS Versio n3.2 or greater, or
Windows 95 or greater. (The 8500C/C+ accepts HD 1.44 mb disk, as well as 720-KB disk).They may also be formatted on the 8500C/C+ by pressing the STATUS key, followed by FORMAT DSK .
NOTE: Do not use high-density 3.5-in. diskettes in the 8500C/C+. The disk drive cannot read or format these disks. High-density diskettes are marked with “HD” on the front of th diskettes.
FORMAT DSK first warns you that execution of the format destroys any resident disk data (see
CANCEL to return to the Status screen. Otherwise, make sure that the disk to b formatted is write-enabled and insert it into the 8500C/C+ disk drive. Press FORMAT and wait for th format to complete. If an error occurs, the 8500C/C+ stops the format operation and attempts to diagnose the problem. When the format process is complete, press OK to return to the Status screen.
Figure 10-4. Format Disk Warning Screen
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Using the Disk Drive
10.2.6 Disk Drive Care
The 8500C/C+ disk drive does not require preventive maintenance. If you are experiencing frequent disk read-and-write errors, the problem may be due to poor disk quality or dirty read/write heads.
Poor disk quality is easily remedied by trying a different brand of 3.5-in. floppy disks. You may order blank disks from Chadwick-Helmuth. You can use any vendor’s diskettes, as long as they are doublesided, double-density (720 K B) for 8500C/C+. 144 mb high density diskettes maybe used in the
8500C/C+.
Disk drive heads can become dirty from extended use. Symptoms usually include an increased number of disk read-and-write errors. Commercially available 3.5-in. disk drive cleaning kits provide special diskettes that are designed to clean dirty heads. These may be inserted in the 8500C/C+ disk drive and run with the disk format routine available through STATUS and th FORMAT DSK soft key. The format routine fails almost immediately due to the special cleaning medium inside the diskette, so it may be necessary to repeat the process two or three times. After the third time, the heads have made enough contact with the cleaning disk to effectively remove any dirt that may be deposited there.
If changing floppy disk brands or cleaning the disk drive heads does not alleviate a problem, contact
Chadwick-Helmuth.
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Chapter 10 - Printer and Disk Drive
10-8 Chadwick-Helmuth Company, Inc.
Chapter 11
11.
Model 8520C Signal Selector
The Mode l 8 500C/C+ Balancer/Analyzer’s companion unit is the M odel8520C Signal Selector. The
Signal Selector receives the incoming signals from the sensors and relays them to the 8500C/C+ in
way the 8500C/C+ can understand. C hapter11 explains the Signal Selector and its operation, under th
following topics:
11.1 Signal Selector: Introduction
The Signal Selector is an intelligent, microprocessor-based multiplexer that simultaneously collects incoming vibration and pickup signals from multiple sources, then sends the 8500C/C+ the selected signals for analysis. Up to six velocimeter and two magnetic pickup or Photocell System inputs may be connected to the Signal Selector, which in turn outputs to the host any pair of vibration and pickup signals chosen by the user. Velocimeter signals may be read directly from a single channel, or optionally combined with the velocimeter signal from a second channel.
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Chapter 11 - Model 8 520C Signal Selector
11.2 Signal Selector Operation
The diagram below (Figur e11-1) shows an illustration of the Signal Selector.
DC POWER
CONNECTOR
8500C/C+
INTERFACE
CONNECTOR
SIGNAL
SELECTOR
MODEL 8520C
1
2
4 7 10
5 8 11
VIBRATION
SIGNAL INPUTS
CHADWICK-HELMUTH
3
E L M O N T E , C A L I F O R N I A
POWER
VELO
SHORT
A
6 9 12
VELOCIMETER CHANNELS
MAGNETIC PICKUP/PHOTOCELL CHANNELS
B C D
AZIMUTH
SINGAL INPUTS
CN_8520..DRW
Figure 11-1. Signal Selector
Signal Selector signal channels are labeled on the front panel of the unit. Channels No.1 t hrough 12 accept velocimeter inputs, and cha nnelsA t hroughD accept magnetic pi ckup, Model11800 FasTrak
Optical Tracker, or Photocell inputs. Magnetic pickup inputs can come from the Model303 Magnetic
Pickup or any compatible single-interrupter magnetic pickup equipment. Communication with the
11-2 Chadwick-Helmuth Company, Inc.
Signal Selector Operation
8500C/C+ is by a three-wire RS-232 connection (receive data, transmit data, and ground), and employs an asynchronous serial interface with the following specificat ions: 96 00baud, 8data bits,
1 stop bit, no parity. See Fi gure11-2 below for details.
Rotor System
Under Test
Velocimeter
(up to 12)
Mag Pickup/Photocell
(up to 4)
28 VDC
Model 8520C
Signal Selector
Communications
28 VDC
Vibration signal
Pickup signal
Model 8500C/C+
Balancer/Analyzer
Figure 11-2. Model 8520 System Block Diagram
CAUTION: The Signal Selector only operates from a 2 8Vdc power supply. Plugging th unit into a power source other than 2 8Vdc may cause severe damage.
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11-3
Chapter 11 - Model 8 520C Signal Selector
11.3 Channel Selection
The 8500C/C+ automatically determines the presence of the Signal Selector at power-up. Signal sources are selected through the Balance and Spectrum Setup screens. If a Signal Selector is attached
To modify the contents of a field, move the screen cursor to the appropriate field and use the
<CHANGE> soft key or numeric keys as required. Note that the Balance Setup screen allows you to change the pickup input (azimuth) channel, whereas the Spectrum Setup screen does not.
Figure 11-3. Balance Setup Screen With Model Signal Selector Support
By default, the 8500C/C+ selects one velocimeter channel for direct input. However, pairs of velocimeter signals may also be combined, during which the 8500C/C+ optionally adds or subtracts the amplitudes of each component signal. Combining channels in this manner can be used to help determine the phase relationship between related signals (for example, the relative amount of lateral versus vertical vibration), and may in fact be required procedure for balancing certain kinds of rotor systems.
To combine velocimeter channels, move the screen cursor to the ONLY field next to the first channel specification field. Press the <CHANGE> soft key to display an operator symbol, ei ther+ (to add signals) o r- (to subtract signals), and the second channel specification field. Each channel may be changed by moving the screen cursor to the appropriate field and entering the desired channel number
from the numeric keypad (see Figur e11-4). Pressing
<CHANGE> with the operator symbol selected changes the operator and combination mode until ONLY appears again and only a single channel is selected.
Figure 11-4. Balance Setup With Two 8520 velocimeter Channels
Note that velocimeter channel selections are saved as part of a spectrum setup and may be changed
11-4 Chadwick-Helmuth Company, Inc.
Appendix A. Specifications
Model 8500/8500C/C+
General Specifications
Power Supply:
Operating Temperature Range:
Microprocessor (8500/8500c):
Microprocessor (8500C+):
Memory (8500/8500C):
Memory (8500C+):
Display:
Input:
Printer:
Mass storage:
28 volts DC
0° to 40° Celsius
8 MHz Motorola 68008
25 MHz Motorola 68332
256 KB Dynamic RAM
128 KB Static RAM up to 256 KB ROM
256 KB Dynamic Ram
1 MB Static Ram
1 MB EPROM (Flash)
Liquid crystal display. 64 vertical by
256 horizontal pixels.
Intergrated keyboard with 32 function keys.
Dot-matrix thermal printer.
PC/MS-DOS version 3.X compatible, 3.5-inch double-sided, double-density disk drive.
8500C+ can also use 1.44 MB HD disk
Dimensions:
Model 8500:
Model 8510:
Weight::
Model 8500:
Model 8510
7x10.5x1.5 in. (18x25x4 cm)
8.25x10.5x2.75 in. (21x25x7 cm)
3.25 lbs. (1.5 kg)
5.5 lbs. (2.5 kg)
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A-1
Appendix A - Specifications
Signal Input Specifications
Sensitivity:
Automatically Selected Grain
Ranges:
Input Impedance:
Coupling:
Minimum Detectable Signal:
Filtering:
19 mV/IPS fixed (velocimeter).
0.5 IPS to 256 IPS full scale
(instrument).
4080 gain settings
2000 ohms
AC, -0.1 dB at Hz
60 dB below full scale (typical).
Two fixed corner frequency analog anti-aliasing filters, 104 dB per octave initial rolloff.
Variable corner frequency digital anti-aliasing filters, 685 dB per octave initial rolloff.
66 dB minimum stop band attenuation.
Overall flatness:
+0.1 dB from 1 - 500 Hz;
+0.5 dB from .5 - 10 KHz.
Spectrum Analysis Specifications
Frequency Ranges:
FFT Frequency Resolution:
FFT Time Domain Weighting:
Frequency Accuracy:
Speed:
200 RPM to 600,000 RPM in arbitrary, user-selected steps.
461 lines
Kaiser window
Better than 0.1% without warm-up.
1 spectrum per second with 30,000
RPM maximum analysis frequency selected.
A-2 Chadwick-Helmuth Company, Inc.
Balance Measurement Specification
Averaging:
Phase Accuracy:
Phase Measurement Method:
Corrective Action Presentation:
16 most recent measurements averaged excluding measurements outside 1 standard deviation.
+1.0 degree.
Synchronizing input (magnetic pickup or photocell pickup).
Strobex.
Arbitrary vibration reduction action, e.g. blade sweep, weight additional/ subtraction, pitch-link shortening/ lengthening, etc.
System undergoing vibration reduction is displayed for reference.
Multi-plane balance capabilities with
Smart Chart software
Track Observation Specifications
Timing Resolution:
Blade Spread:
+200 nanoseconds
Continuous adjustment from initial value of 0° to ~ 5° spread.
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A-3
A-4 Chadwick-Helmuth Company, Inc.
Appendix A - Specifications
Appendix B. Spectral Data File Format
The Mode l 8 500C/C+ Balancer/Analyzer stores spectral data on disk when you press the STORE key while in the Spectrum mode. Data files consist of ASCII text and are created with a unique file nam based on the time and date, plus the file name extension *.SPC.
The annotation text last entered with the ANNOTATE key is written to the beginning of the file. This
describes the format and contents of a typical spectral data file.
Table B-1. Spectral Data File Format and Contents (Sheet 1 of 2)
Data from .SPC file
0
0
0
0
0
SPC Revision: 1.01
05/20/97
10:42:05
AIRSPEED: KTS
PICKUP NO.:
ALTITUDE: FT
RUN NO.:
MFR/MODEL:
ID NO.:
:
COMMENTS:
8520 Signal Input: 1 Only
5000000
13508
1024
Description
SPC file revision acquisition dat acquisition tim annotation text, 1
...
annotation text, 2
...
annotation text, 3
...
annotation text, 4 annotation text, 5
8520 signal source
9513 base frequency (Hz sample period (base cycles points in FFT frame pickup period (base cycles) bin 0 amplitude (mIPS) bin 1 amplitude (mIPS) bin 2 amplitude (mIPS) bin 3 amplitude (mIPS)
Mode l8500C/8500C+ Operators Manual
B-1
Appendix B - Spectral Data File Format
Table B-1. Spectral Data File Format and Contents (Sheet 2 of 2)
Data from .SPC file
:
95
108
76
90
387
377
289
73
Description
...
...
...
...
etc.
...
...
...
...
To calculate the frequency in Hertz of a specific bin, use the following formula:
bin_# x 9513_base_frequency (Hertz sample_period_ x points_in_FFT_frame
NOTE: FFT stands for fast Fourier transform.
B-2 Chadwick-Helmuth Company, Inc.
Appendix C. Balance History Files
The Mode l 8 500C/C+ Balancer/Analyzer stores balance histories on disk when you press the key while in the Balance mode. Data files consist of ASCII text and are created with a unique file name based on the time and date, plus the file name extension *.BHI. The annotation text last entered with the ANNOTATE key is written to the beginning of the file. This information is identical to the annotation text appended to printouts.
The averaged phase angle is stored in internal angle units, in which 20 48internal units equals one full circle. Thus, 2 048inter nalu n i ts = 36 0°=2ãradians. The entries for average vibration amplitude, average phase angle, and the solution are repeated for each run in the balance history. The following
table (Table C-1) describes the format and contents of a typical balance data file:
Table C-1. Balance Data File Format and Contents (Sheet 1 of 2)
Data from .BHI file
08/30/97
10:42:05
AIRSPEED: KTS
PICKUP NO.:
ALTITUDE: FT
RUN NO.:
MFR/MODEL:
ID NO.:
:
COMMENTS:
Grumman E-2C (Strobex
3600
515
0
Description
acquisition date acquisition time annotation text, 1
...
annotation text, 2
...
annotation text, 3
...
annotation text, 4 annotation text, 5 chart title acquisition frequency (RPM) averaged measurement (mIPS) averaged phase (internal units)
Mode l8500C/8500C+ Operators Manual
C-1
Appendix C - Balance History Files
Table C-1. Balance Data File Format and Contents (Sheet 2 of 2)
Data from .BHI file
Add 77.0 grams
to D.
Remove 240.0 grams
from A.
Description
solution, line 1 solution, line 2 solution, line 3 solution, line 4 solution, line 5
C-2 Chadwick-Helmuth Company, Inc.
Appendix D. Quick Reference Guide
Spectrum Analysis
To Modify Spectrum Mode Parameters
Press
SPECTRUM
Press
SETUP
Use arrow, numeric or soft keys to edit fields
Press
ENTER
Modify Spectrum Setup screen parameters
Accept current parameters
To Select Signal Selector Channels (Model 8520C):
Press
SPECTRUM
Press
SETUP
Use arrow, numeric, soft keys to edit
INPUT
and
PICKUP
fields
Press [Key: ENTER] Accept current parameters
Mode l8500C/8500C+ Operators Manual
D-1
Appendix D - Quick Reference Guide
To Save a Spectrum Setup
Press [Key: Spectrum]
Press [Key: Setup]
Insert disk in disk drive, if required
Press [Key: Store]
Edit Setup name
Press [Key: ENTER]
To Load Spectrum Setups from Disk
Press [Key: Spectrum]
Rename Setup before saving it
]
Write data to disk/memory
Press [Key: SEL SETUP]
Insert Spectrum Setup disk in disk drive
Press [Key: Load]
D-2 Chadwick-Helmuth Company, Inc.
To Store All Spectrum Setups to Disk
Press [Key: Spectrum]
Press [Key: SEL SETUP]
Press [Key: More Keys]
Insert disk in disk drive
Press [Key: STORE ALL]
To Recall a Spectrum Setup
All Setups are written to disk
Press [Key: Spectrum]
Press [Key: SEL SETUP]
Load Spectrum Setups from disk, if required
Press arrow keys
Press [Key: ENTER]
Select desired Spectrum Setup
Read Spectrum Setup parameters
To Rename a Spectrum Setup
Press [Key: Spectrum]
Mode l8500C/8500C+ Operators Manual
D-3
Appendix D - Quick Reference Guide
Press [Key: SEL SETUP]
Press arrow keys
Press [Key: RENAME SET]
Edit Setup name
Select desired Spectrum Setup
Press [Key: ENTER]
To Delete Spectrum Setup
Press [Key: Spectrum]
Press [Key: SEL SETUP]
Press [Key: CLEAR ALL]
OR
Press arrow keys
Press [Key: CLEAR ONE]
Delete all Spectrum Setups
Select desired Spectrum Setup
Delete the selected Spectrum
Setup
D-4 Chadwick-Helmuth Company, Inc.
To Acquire Spectral Setup
Press [Key: Spectrum]
Press [Key: START]
To Abort Spectral Data Acquisition
Press [Key: Stop]
To List Spectral Peaks
Press [Key: Spectrum]
Press [Key: LIST PEAKS]
To View Spectral Harmonics
Press [Key: Spectrum]
Press [Key: More Keys]
Press [Key: <HARM ON> /
[Key: <HARM OFF>]
Collect & display spectral data
Abort spectral data acquisition
Mode l8500C/8500C+ Operators Manual
D-5
To Set the Balance Frequency
Press [Key: Spectrum]
Press <- and/or ->
Press [Key: BAL FREQ]
To Scale a Spectral Plot
Press [Key: Spectrum]
Appendix D - Quick Reference Guide
Move cursor to desired frequency
Press [Key: More Keys]
Press [Key: SCALE]
Press <- and/or ->
Press [Key: MIN FREQ]
Press <- and/or ->
Press [Key: MAX FREQ]
Move cursor to desired frequency
Move cursor to desired frequency
D-6 Chadwick-Helmuth Company, Inc.
Press [up arrow] and/or [down arrow]
Move cursor to desired frequency
Press [Key: MAX AMP]
Press [Key: ENTER]
To Remove Scaling
Press [Key: Spectrum]
Press [Key: More Keys]
Press [Key: SCALE]
Press [Key: More Keys]
Press [Key: FULL SCALE]
Mode l8500C/8500C+ Operators Manual
D-7
Appendix D - Quick Reference Guide
To Store Spectral Data to Disk or Memory
Select destination in [Key:
Status]
Press [Key: Spectrum]
Insert disk in disk drive, if required
Press [Key: Store]
Select disk or memory
Write data to disk/memory
D-8 Chadwick-Helmuth Company, Inc.
Balance Measurement and Solution
To Load Balance Charts from Disk
Press [Key: Balance]
Press [Key: SEL CHART]
Insert Balance Chart in disk drive
Press [Key: Load]
To Select Balance Chart
Press [Key: Balance]
Press [Key: SEL CHART]
Load Balance Charts from disk, if required
Press arrow keys
Press [Key: Enter]
Select desired Balance Chart
Read the Balance Chart parameters
To Get Balance Chart Information
Press [Key: Balance]
Mode l8500C/8500C+ Operators Manual
D-9
Appendix D - Quick Reference Guide
Press [Key: SEL CHART]
Load Balance Charts from disk, if required
Press arrow keys Select desired Balance Chart
Press [Key: CHART INFO]
To Clear Balance Chart from Memory
Press [Key: Balance]
Press [Key: SEL CHART]
Press [Key: CLR CHARTS]
Press [Key: CLR CHARTS] Delete Charts from memory
D-10 Chadwick-Helmuth Company, Inc.
To Rename a Balance Chart
Press [Key: Balance]
Press [Key: SEL CHART]
Load Balance Charts from disk, if required
Press arrrow keys Select desired Balance Chart
Press [Key: RENAME CHT]
Edit Chart name
Press [Key: ENTER]
Mode l8500C/8500C+ Operators Manual D-11
To Modify Balance Mode Parameters
Press [Key: Balance]
Appendix D - Quick Reference Guide
Press [Key: Setup]
Use arrow, numeric, soft keys to edit fields
Press [Key: ENTER]
Modify Balance Setup screen soft keys to edit parameters fields
Accept current parameters
To Select Signal Selector Channels (if model 8520 Attached
Press [Key: Balance]
Press [Key: Setup]
Use arrow, numeric, soft keys to edit *INPUT and *PICKUP fields
Press [Key: ENTER] Accept current parameters
D-12 Chadwick-Helmuth Company, Inc.
To Perform a Strobex Balance
Press [Key: Balance]
Load/Select Balance Chart
Set Balance Type to Strobex
Press [Key: START]
Flash Strobex at target
Begin data acquisition
Press <- and/or ->
Press [Key: STOP]
Rotate target towards azimuth
Terminate data acquisition
To Perform a Magnetic Pickup or Photocell Balance
Press [Key: Balance]
Load/Select Balance Chart
Set Balance Type to Mag Pickup or Photocell
Press [Key: START] Begin data acquisition
Measurement will automatically stop when display vector stabilizes
To Select Alternate Balance Solutions
Perform Strobex/Mag Pickup/
Photocell balance measurement
Press [Key: STOP] Terminate data acquisition
Mode l8500C/8500C+ Operators Manual D-13
Appendix D - Quick Reference Guide
Press arrow keys
Press [Key: ALTERNATE]
If solution is satisfactory, press
[Key: START]
OR
Press [Key: SHOW MEAS]
Display alternate solutions
Accept solution and begin next run
Accept solution and go to
Balance Run Startup screen
To Begin the Next Run
Press [Key: Balance]
Press [Key: START] Begin the next balance run
To Repeat the Balance Measurement
Press [Key: Balance]
Press [Key: REDO MEAS]
Redo the balance measurement
D-14 Chadwick-Helmuth Company, Inc.
To View the Balance History
Press [Key: Balance]
Press [Key: More Keys]
Press [Key: HISTOR ]
Press [Key: NEXT MOVE] or
[Key: PREV MOVE]
Display 1st Balance History measurements screen
Press [Key: NEXT MEAS] or
[Key: PREV MEAS]
Press [Key: QUIT] Quit Balance History display
To Store Balance Histories
Select destination [Key: Status] Select disk or memory
Press [Key: Balance]
Press [Key: More Keys]
Press [Key: HISTOR ]
Insert disk in disk drive
Press [Key: Store]
Display 1st Balance History measurements screen
Write data to disk
Mode l8500C/8500C+ Operators Manual D-15
Appendix D - Quick Reference Guide
To Clear the Balance History
Select destination [Key: Status] Select disk or memory
Press [Key: Balance]
Press [Key: More Keys]
Press [Key: CLEAR HIST]
Press [Key: CLEAR HIST]
To Store a Correct a Balance Chart to Disk
Correct the Balance Chart
Press [Key: SEL CHART]
Press [Key: Store]
Display clear History warning
Clear History for current
Balance Chart
To Correct a Balance Chart
Perform Strobex/Mag Pickup/
Photocell balance measurement
Select alternate Test Move, if required
Press [Key: <NORML MV>] /
[Key: <TEST MOV>]
Implement Test Move
Press [Key: Start]
OR
Press [Key: SHOW MEAS]
Accept move and begin next run
Accept move and go to Balance
Run Startup screen
Display Chart selection menu
Store Chart to disk
Edit Chart Name
D-16 Chadwick-Helmuth Company, Inc.
Press [Key: ENTER]
To Clear Balance Chart Corrections
Press [Key: Balance]
Write Chart to disk
Press [Key: More Keys]
Press [Key: SHOW CORR]
Edit Chart Name
Press [Key: CLR CORRTN] Clear Chart correction
Mode l8500C/8500C+ Operators Manual D-17
Appendix D - Quick Reference Guide
Blade Track observation
To Modify Track Mode Parameters
Press [Key: Track]
Press [Key: MORE]
OR
[Key: FEWER]
Press [Key: Track]
Change number of blades
Press [Key: Setup]
User arrow, numeric, soft keys to edit fields
Press [Key: ENTER]
Modify Track Setup screen parameters
Accept current parameters
To Begin Visual Tracking
Press [Key: Track]
Press [Key: Start]
Flash Strobex at tip targets
Use <- and -> or toggle [Key (No)
SPREAD]
Press [Key: Stop]
Spread/stack blade images
Terminate visual tracking
D-18 Chadwick-Helmuth Company, Inc.
Printer and Disk Drive Operations
To Print
Press [Key: Print]
To Copy a Balance Chart Disk
Press [Key: Balance]
Print display contents
Press [Key: SEL CHART]
Insert source Balance Chart disk in disk drive
Press [Key: Load]
Insert target disk in disk drive
Format disk, if required
Press [Key: More Keys]
Press [STORE ALL]
To Format a Disk
Store all Charts to disk
Press [Key: Status]
Press [Key: FORMAT DSK ]
Mode l8500C/8500C+ Operators Manual D-19
Insert disk in disk drive
Press [Key: FORMA ]
Appendix D - Quick Reference Guide
Execute disk format
D-20 Chadwick-Helmuth Company, Inc.
Annotating Printouts
To Edit the Printout Annotation
Press [Key: Annotate]
Toggle [Key: <ALPHA>] /
[Key: <NUMERIC>]
Press arrow keys, [Key: Start], or
[Key: STOP]
Enter character, or press [Key:
INSERT], [Key: DELETE]
Press [Key: ENTER]
Select Alpha or Numeric editing mode
Move cursor to desired position
Add/delete characters, insert spaces
Accept editing changes and quit
To Restore the Previous Annotation
Toggle [Key: <ALPHA>] /
[Key: <NUMERIC>]
Select Numeric editing mode
Press [Key: More Keys]
Press [Key: RESTORE]
To Clear the Annotation
Toggle [Key: <ALPHA>] /
[Key: <NUMERIC>]
Press [Key: More Keys]
Select Numeric editing mode
Press [Key: CLEAR]
Mode l8500C/8500C+ Operators Manual D-21
Appendix D - Quick Reference Guide
To Edit the Annotation Template
Toggle [Key: <ALPHA>] /
[Key: <NUMERIC>]
Press [Key: More Keys]
Select Numeric editing mode
Press [Key: TEMPLATE]
Edit labels and fields
To Restore the Default Template
Edit the annotation template
Press [Key: More Keys]
Press [Key: ORIGINAL]
D-22 Chadwick-Helmuth Company, Inc.
The 8500C/C+ Status Screen
To Modify Status Parameters
Press [Key: Status]
Press [Key: Setup]
Use arrow, numeric, soft keys to edit fields
Press [Key: ENTER]
Modify Status Setup screen parameters
Accept current parameter settings
To Review Balance Histories or Spectral Data Plots
Press [Key: Status]
Press [Key: REVIEW]
Press [Key: More Keys]
Toggle [Key: <SPECTRA>] /
[Key: <BAL HIST>] / [Key:
<ANY>]
Press [Key: NEXT] and [Key:
PREVIOUS]
Select and display an item
Mode l8500C/8500C+ Operators Manual D-23
Appendix D - Quick Reference Guide
To Store Individual Review Items to Disk
Press [Key: Status]
Press [Key: REVIEW]
Press [Key: Store]
To Store All Review of a Type to Disk
Press [Key: Status]
Press [Key: REVIEW]
Store the item to disk
Press [Key: More Keys]
Toggle [Key: <SPECTRA>] /
[Key: <BAL HIST>] / [Key
<ANY>]
Press [Key: STORE ALL]
To Restore an Item
Select the data type
Store type items to disk
Press [Key: Status]
Press [Key: REVIEW]
D-24 Chadwick-Helmuth Company, Inc.
Press [Key: More Keys]
Press [Key: ANALYZE]
Press [Key: ANALYZE]
To Delete an Item from Memory
Press [Key: Status]
Restore the item
Press [Key: REVIEW]
Press [Key: NEXT] and/or [Key:
Previous]
Press [Key: CLEAR ITEM]
Display the item to delete
Delete the item from memory
Mode l8500C/8500C+ Operators Manual D-25
Appendix D - Quick Reference Guide
To Delete All Spectra and Balance Histories from Memory
Press [Key: Status]
Press [Key: REVIEW]
Press [Key: More Keys]
Press [Key: CLEAR ALL]
Press [Key: CLEAR ALL]
Delete all spectra and Histories memory
D-26 Chadwick-Helmuth Company, Inc.
Miscellaneous
To Restart the 8500C/C+
Press [Key: Stop], [Key: Help] and [Key: More Keys] simulaneously
Restart the 8500C/C+
To Restart the 8500C/C+ and Clear Memory
Hold down [Key: Start], [Key:
Help], and [Key: More Keys] simultaneously
Release [Key: Help] and [Key:
More Key], wait 2 seconds, then release [Key: Start]
Restart the 8500C/C+
To Restart the 8500C/C+
Press [Key: Print], [up arrow], and [Key: Start] simultaneously
To Restart the 8500C/C+ and Clear Memory
Hold down [Key: Print], [up arrow], and [Key: Start] simultaneously
Release [Key: Print] and [up arrow], wait 2 seconds, the release [Key: Start]
Restart the 8500C/C+
Restart the 8500C/C+
Mode l8500C/8500C+ Operators Manual D-27
D-28 Chadwick-Helmuth Company, Inc.
Appendix D - Quick Reference Guide
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