Section 22 GTR 20 (VHF Communications Radio) Installation. Garmin G3X Touch for Experimental Aircraft, GDU 465, GDU 455, G3X, GDU 460, GDU 450

modes even if all GDU displays in the aircraft are unavailable.

GSA 28 autopilot servos can be used to control the trim system in an aircraft. When the autopilot is disengaged, the servos can adjust the trim speed based on the current aircraft airspeed. This allows the trim to run slower at high airspeeds and faster at low airspeeds. When the autopilot is engaged in the air, the servos can adjust the trim control to minimize the force on the primary controls. This helps ensure the aircraft will be properly trimmed when the autopilot is later disengaged. This feature works the same whether using a 3rd party trim motor or a GSA 28 as the trim actuator. When using a GSA 28 as the trim actuator, the following must be considered:

• The GSA 28 cannot hold a fixed position when disengaged, as the shaft will turn freely. It can only be used in installations where the trim actuator does not need to hold a fixed position when powered off. An acceptable application is the GSA 28 driving a manual pitch trim system via capstan and bridle cables.

• When used as the trim servo, the GSA 28 communicates via the CAN bus (same as the other servos communicate), no RS-232 or other data connection is required. The GSA 28 needs to be ID

strapped appropriately for the pitch trim location (see Section 26.13.5

and Figure 27-1.9

).

• The GSA 28 should be connected to the CWS/DISCONNECT input. For manual electric trim, trim inputs from the stick or relay should be wired directly to the GSA 28 being used as the trim actuator, as well as the main autopilot servo for that axis.

During the flight test phase, the trim system is configured and set up after the primary autopilot performance has been properly configured. This is done so the pilot can focus on properly adjusting the performance of the primary autopilot system without having the auto-trim functionality interfere.

NOTE

Ensure basic autopilot functionality is properly adjusted before enabling trim control for any servo.

18.1.1 Status LED

The GSA 28 has an LED on its outer case that indicates its current status. See Section 36.1.1

for details.

18.2 Equipment Available

Table 18-1 GSA 28 Part Numbers

Model

GSA 28 Servo Actuator, Unit Only

Assembly Part Number

010-01068-00

Unit Only Part Number

011-02927-00

18.3 General Specifications

Table 18-2 General Specifications

Characteristic

Height

Width

Depth

Weight

*Harness connector not included

**Accessories not included

Specification

4.0 inches (10.16 cm)

2.5 inches (6.35 cm)

2.8* inches (7.11 cm)

1.40** lbs, (0.635 kg)

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Page 18-2

18.3.1 Power Specifications

The GSA 28 trim outputs are capable of sourcing a maximum of 1A of current to drive a DC trim motor at

12V, or a maximum of 500 mA of current to drive a DC trim motor at 24V.

To use the GSA 28 to drive DC trim motors requiring higher current, a third-party interface may be used

(see

Figure 27-1.10

).

CAUTION

The DC trim motor connected to the GSA 28 should be rated for the full power supply voltage being used to power the GSA 28. If the GSA 28 is connected by a 24-28V power input, the trim motor must also be rated for 28V.

NOTE

The GSA 28 does not provide a voltage step-up service. To drive a 24V trim motor, the

GSA 28 must be to be supplied with 24V or higher.

Table 18-3 GSA 28 Power Specifications

Supply Voltage

14 Vdc without Auto-trim

28 Vdc without Auto-trim

14 Vdc with Auto-trim

Current Draw

0.36 Amp (typical), 1.80 Amp (max)



18.3.2 Torque Specifications

Table 18-4 GSA 28 Torque Specifications

Characteristic

Maximum Rated Torque

Specification

60 in-lbs

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18.4 Required Equipment

Table 18-5 lists the kits available for the GSA 28.

Table 18-5 GSA 28 Available Equipment w/Weights

Item

GSA 28 Connector Kit

GSA 28 Connector Kit, 90°

GSA 28 Stop Bracket Kit

GSA 28 Mounting Kit, Generic, Push-Pull

GSA 28 Mounting Kit, Generic, W/Bracket

GSA 28 Mounting Kit, Generic, Capstan

GSA 28 Mounting Kit, RV-6 Roll

GSA 28 Mounting Kit, RV-4/8 Pitch

GSA 28 Mounting Kit, RV-7/8/10 Roll

GSA 28 Mounting Kit, RV-9 Roll

GSA 28 Mounting Kit, RV-6/7/9 Pitch

GSA 28 Mounting Kit, RV-10 Pitch

GSA 28 Mounting Kit, RV-10 Yaw

GSA 28 Removal Adapter

Garmin P/N

011-02950-00

011-02950-01

011-02951-00

011-02952-00

011-02952-01

011-02952-02

011-02952-10

011-02952-11

011-02952-12

011-02952-13

011-02952-14

011-02952-15

011-02952-16

011-03158-00

Weight

0.12 lb (0.054 kg)

0.13 lb (0.059 kg)

0.03 lb (0.014 kg)

0.26 lb (0.118 kg)

0.50 lb (0.227 kg)

0.14 lb (0.064 kg)

0.55 lb (0.250 kg)

0.51 lb (0.231 kg)

0.42 lb (0.191 kg)

0.42 lb (0.191 kg)

0.37 lb (0.168 kg)

0.48 lb (0.218 kg)

0.60 lb (0.272 kg)

0.03 lb (0.014 kg)

Table 18-6 Contents of Connector Kit (011-02950-00)

Item

Sub-Assy, Bkshl w/Hdw, Jackscrew, 15/26 Pin


Connector, Rcpt, D-SUB, Crimp Socket,Commercial,15 Ckt

Cont,Sckt,Mil Crp,Size 20,20-24 AWG,RoHS

Garmin P/N

011-01855-01

011-03158-00

330-00625-15

336-00022-02

Quantity

1

1

1

16

Table 18-7 Contents of Connector Kit, 90 ° (011-02950-01)

Item

Sub-Assy, Bkshl w/Hdw, Jackscrew, 90°,15/26 Pin


Connector, Rcpt, D-SUB, Crimp Socket,Commercial,15 Ckt

Cont,Sckt,Mil Crp,Size 20,20-24 AWG,RoHS

Garmin P/N

011-01959-01

011-03158-00

330-00625-15

336-00022-02

Quantity

1

1

1

16

18.4.1 Additional Equipment Required

• Cables: The installer will fabricate and supply all system cables.

• Mounting hardware is included in the available mounting kits.

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Page 18-4

18.5 Unit Installation

Fabrication of a wiring harness is required. Sound mechanical and electrical methods and practices should

be used for installation of the GSA 28. Refer to Section 2.3

for wiring considerations, and to Section 26.12

for pinouts.

Connector kits include backshell assemblies. Garmin’s backshell connectors give the installer the ability to quickly and easily terminate shield grounds at the backshell housing. The instructions needed to install the

Jackscrew Backshell are located in

Section 25 .

18.5.1 Pinouts

See

Section 26.12

for pinout information.

18.5.2 Mounting Requirements

WARNING

It is vital to ensure the autopilot servo and aircraft control linkage is free to move throughout its entire range of travel without binding or interference. Failure to ensure adequate clearance between the moving parts of the control system linkage and nearby structure could result in serious injury or death. If any control system binding or interference is detected during installation or preflight inspection, it must be corrected before flight.

CAUTION

Do not mount the GSA 28 on the ‘hot’ side (engine side) of the firewall, or in any location where it would be exposed to radiated heat from the engine.

18.5.2.1 Optional Attachments

The GSA 28 is supplied from the factory with a standard crank arm attachment (

Figure 18-2

,

Figure 18-8.1

,

Figure 18-8.2

, and

Figure 18-8.3

). Also available are a long crank arm supplied in the

011-02952-10 RV-6 roll kit and a capstan attachment available in the 011-02952-02 Capstan Kit. If one of these optional attachments will be used, it is up to the installer to remove the standard crank arm and replace it with the optional attachment. When removing the standard arm, keep the castle nut, lock washer, and flat washer as these items will need to be re-used with the optional attachment. Discard cotter pin that was removed from the GSA 28 and replace with pin provided with optional attachment. Refer to

Figure 18-8.3

and

Figure 18-8.4

for more details and instructions for tightening the castle nut.

WARNING

Cotter pins supplied with GSA 28 are only intended for one time use. If removed from GSA

28 discard and use new cotter pin.

WARNING

Do not use crank arm attachments to actuate cable driven controls. A Capstan attachment should be used for this purpose.

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Page 18-5

CRANK ARM

Figure 18-2 Crank Arm Assembly

18.5.2.2 Stop Bracket Kit

Every GSA 28 is supplied with a 011-02951-00 stop bracket kit. The intention of this stop bracket is to create redundant stops for the servo control arm that prevents the servo’s arm from going over-center relative to the push rod connected to the servo’s arm. It is highly recommended this part gets installed with every push-pull application. The stops created by installing this bracket are redundant in the sense that the aircraft’s built-in stops should always be used as the primary means of limiting travel of the servo’s control arm. This stop bracket limits the motion of the standard control arm to 100° total travel. This bracket should be positioned such that the stop bracket flanges are as close as practical to being equal distance from the servo’s control arm while at the center of travel. Also, to prevent an over-center condition, the servo’s push rod should be as close as practical to perpendicular with the servo’s control arm while positioned at the center of travel. The position of this bracket can be adjusted in increments of 15°. If necessary, further adjustments can be made by changing the length of the push rod connected to the servo.

See

Figure 18-8.2

, and

Figure 18-8.3

for more details.

After installation of the servo is complete, verify that the stop bracket does NOT impede the full movement of the associated control.

WARNING

An over-center position of the servo control arm relative to the attached push rod can cause the flight controls to jam. This could result in serious injury or death. Please be sure this is well understood prior to flying with the GSA 28 servo.

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Page 18-6

The 011-02951-00 stop bracket kit is supplied with four #4-40 screws used to attach the bracket to the front face of the servo. The screws provided are 0.25” long. This length of screw is appropriate if there is no bracket or spacers in-between the stop bracket and servo. If a mounting bracket or spacers of thickness

.040” or greater will be place in-between the stop bracket and servo, longer screws should be used to mount the stop bracket. It is recommended the thread engagement into the GSA 28, as measured from the front face of the servo shall be 0.112” – 0.25”. If screws other than what is provided will be used, be sure to use thread locking compound or a proper thread locking patch combined with the lock washers provided.

Also be sure to follow the recommended tightening torque specified in

Figure 18-8.2

.

CAUTION

If screws are being used to mount the stop bracket to the front face of the GSA 28 are different than the screws provided with the stop bracket kit, care must be taken to ensure these screws are not long enough to contact moving parts inside the GSA 28. Maximum screw insertion, as measured from the front of the

GSA 28, must be less than 0.25” to avoid contact with parts inside the GSA 28.

CAUTION

To avoid the possibility of contaminating the internal rotating mechanisms of the GSA 28, do not apply thread locking compound directly to the stop bracket attachment holes in the front face of the servo. Instead, apply a small amount of thread locking compound to the threads of the stop bracket screws before the screws are inserted. Thread locking compound is not required upon initial installation of the included stop bracket screws, which are supplied with thread locking compound already applied.

18.5.2.3 Trim Motor Interface to a 3rd Party Motor

The GSA 28 provides an optional interface between the pilot's electric trim switch and a 14 Vdc trim motor. This interface shall be used only when interfacing to a 3rd party trim motor. This interface is not to be used when a GSA 28 is being used as the trim actuator.When the GSA 28 servo is engaged (i.e. autopilot on) in the air, it automatically drives the connected trim motor as required to relieve control forces for the associated pitch, roll, or yaw axis. When the GSA 28 servo is not engaged (i.e. autopilot off), it provides manual electric trim (MET) functionality by running the trim motor in response to pilot input.

The GSA 28 can be configured to automatically reduce the speed of the trim motor at higher airspeeds, in order to provide finer control of trim tab position. In the event that power to the GSA 28 is removed, a failsafe system connects the trim input switch directly to the trim motor. In this condition, the trim switch powers the trim motor directly and the motor runs at its full speed when the switch is pressed. The same condition also occurs if a trim switch and motor are connected to the GSA 28, but the trim control function is disabled.

CAUTION

The GSA 28 can supply a maximum of 1 Amp of current to the trim motor. Do not connect a trim motor that requires higher current.

NOTE

The GSA 28 supports a single trim switch input only. For use with multiple trim switches

(e.g. pilot and co-pilot), a GAD 27 or other third-party device capable of mixing multiple

trim switches into one is required. See Figure 27-1.10

for additional details.

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Page 18-7

18.5.2.4 CWS/DISCONNECT

The CWS/DISCONNECT button is used to disengage the autopilot system. It can also optionally be used for autopilot engagement and control wheel steering (see section 9.14.1). The CWS/DISCONNECT input to all servos should be tied together and connected to a normally open momentary push button that

connects to ground when pressed (see Figure 27-1.7

).

NOTE

The CWS/DISCONNECT button must be mounted where it is easily accessible to the pilot during all phases of flight. The pilot must have ability to quickly disconnect the autopilot under all circumstances.

18.5.2.5 GSA 28 Removal Adapter

The GSA 28 connector kit is shipped with a GSA 28 removal adapter (011-03158-00). This part is not intended to be installed with the GSA 28, but is used to replace the GSA 28 when the harness connector is un-plugged. The removal adapter contains an internal 120 Ω resistor between pins 2 and 3 for CAN termination. It also contains shorts between pins 11 & 13 and 12 & 14 to pass through power for trim motors. The intention of this component is to allow operation of the CAN bus and trim motors when the servos are not plugged into the harness. It is recommended that a removal adapter is kept with each servo installation, in case the GSA 28 needs to be removed without losing functionality of the CAN bus and trim motors.

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Figure 18-3 Wiring Diagram For GSA 28 Removal Adapter


Page 18-8

18.5.2.6 GSA 28 Mounting Kits

Garmin currently provides the mounting kits listed in Table 18-8 for the GSA 28 Servo:

Table 18-8 Mounting Kits

Garmin P/N Description

011-02952-00 Sub-Assy, GSA 28 Mounting Kit, Generic, Push-Pull

011-02952-01 Sub-Assy, GSA 28 Mounting Kit, Generic, W/Bracket

011-02952-02 Sub-Assy, GSA 28 Mounting Kit, Generic, Capstan

Mounting

Bracket

Included

No

Yes

No

011-02952-10 Sub-Assy, GSA 28 Mounting Kit, RV-6 Roll

011-02952-11 Sub-Assy, GSA 28 Mounting Kit, RV-4/8 Pitch

011-02952-12 Sub-Assy, GSA 28 Mounting Kit, RV-7/8/10 Roll

011-02952-13 Sub-Assy, GSA 28 Mounting Kit, RV-9 Roll

011-02952-14 Sub-Assy, GSA 28 Mounting Kit, RV-6/7/9 Pitch

011-02952-15 Sub-Assy, GSA 28 Mounting Kit, RV-10 Pitch

011-02952-16 Sub-Assy, GSA 28 Mounting Kit, RV-10 Yaw

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Install Manual

Figures

18-8.7

18-8.8

18-8.4

18-9.1

, 18-9.1

,

18-9.1

18-10.1

,

18-10.1

,

18-10.1

,

18-10.1

18-11.1

,

18-11.1

18-12.1

,

18-12.1

18-13.1

,

18-13.1

18-14.1

,

18-14.1

18-15.1

,

18-15.1

18-15.1

The “generic” kits listed in Table 18-8 (011-02952-00, -01, & -02) are not specific to any airframe. The

airframe specific kits (GPN 011-02952-10 through -16) are for use with the specified experimental aircraft.

The contents of each kit as well as specific instructions for their use are detailed in the figures listed in

Table 18-8.

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18.5.2.7 Generic Push/Pull Kits

The 011-02952-00 and -01 kits are generic kits for push/pull applications. This kit is supplied with a 3/8”

diameter x 8” long solid rod (Figure 18-4). This rod is intended to be used as the attachment link between

the GSA 28 and the flight control system. It is the installer’s responsibility to cut this rod to the correct length and tap the ends for the male rod end bearings. It is recommended these push rods are tapped to a depth of at least 0.61” to accommodate the entire thread of the rod end bearing (minus the jam nut). The length of the push rod is adjustable by changing the thread engagement between the male rod end bearings and push rod. The acceptable range of thread engagement is 0.492” +/-0.117”. It is highly recommended the AN315-3R jam nuts are used and properly tightened. A push rod without a tightened jam nut will create backlash that can diminish autopilot performance.

WARNING

Thread engagement between the male rod end bearings supplied with GSA 28 mounting kits and push rod must not be less than 0.375”. This minimum engagement length is recommended to prevent push rod from coming apart.

.141

1.25

.75

USABLE

THREAD

.492±.117

THREAD

ENGAMENT

10-32 UNF-3A AN315-3R

JAM NUT

Figure 18-4 General Dimensions For Servo Push Rod And Rod End Bearings

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18.5.2.8 Capstan Kit

The capstan kit is part number 011-02952-02. This kit contains a capstan, a cable guard, and fasteners used to attach these items.

The capstan is designed to accept a MS20663C2 double shank ball with a 1/16” diameter cable. This kit does not currently include a bridle cable or cable clamps necessary to link the capstan to the flight control

cables as these items are generally specific to each aircraft type. The required bridle cable (Figure 18-5) is

a 1/16” cable with a MS20663C2 ball and double shank fitting swaged onto the cable where it engages with the capstan drive wheel. The MS20664C2 ball and shank fittings on the ends keep the cable from fraying.

Several companies sell custom made cable assemblies suitable for this application, a few of these are:

McFarlane Aviation

Phone: 866-920-2741 www.mcfarlane-aviation.com

Aircraft Spruce

Customer Service: 1-800-861-3192 www.aircraftspruce.com/catalog/appages/cableassy.php

NOTE

When determining the length of the bridle cable to be ordered, be sure to allow for enough cable to make the required number of wraps around the capstan (see

Figure 18-6

).

Figure 18-5 Bridle Cable

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Page 18-11

Garmin recommends using the cable arrangement (ball centered in capstan) shown in Figure 18-6 to avoid

side-loading the servo center shaft.

BOTH CABLES EXITING CAPSTAN IN SAME DIRECTION

CABLE EXITING IN OPPOSITE DIRECTION

SHOULD BE IN CENTER OF CABLE WRAP WHEN

IN EITHER

ROTATE A MAXIMUM OF 150 EITHER DIRECTION FROM

BALL

BALL

Figure 18-6 Cable in Capstan

WARNING

The ball must be located in the center of travel on the capstan when the flight control is in the neutral position. When the flight control is moved to the limits of its travel, the ball must not have any possibility of exiting the capstan groove.

The bridle cable must wrap around the capstan either 1 or 1.5 full turns, as shown in Figure

18-6, and must be routed in a way that avoids the possibility of binding.

If the installation would require more than +/- 150° of capstan rotation or more than +/- 2.6 inches of cable travel, the GSA 28 servo and capstan cannot be used.

Failure to closely follow the capstan installation guidance in this section could cause the aircraft flight controls to jam, resulting in serious injury or death

The 011-02952-02 capstan kit is provided with four #4-40 screws and lock washers for attaching the cable guard. The screws provided are 0.25” long. This length of screw is appropriate if there is no bracket or spacers in-between the cable guard and servo. If a mounting bracket or spacers of thickness .056” or greater will be place in-between the stop bracket and servo, longer screws should be used to attach the cable guard. It is recommended the thread engagement into the GSA 28, as measured from the front face of the servo shall be 0.112” – 0.25”. If screws other than what is provided will be used, be sure to use thread locking compound or a proper thread locking patch combined with the lock washers provided. Also be sure

to follow the recommended tightening torque specified in Figure 18-8.4

.

CAUTION

If screws are being used to mount the cable guard to the front face of the GSA 28 are different than the screws provided with the stop bracket kit, care must be taken to ensure these screws are not long enough to contact moving parts inside the GSA 28. Maximum screw insertion, as measured from the front of the GSA 28, must be less than 0.25” to avoid contact with parts inside the GSA 28.

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Page 18-12

18.5.2.9 Aircraft Specific Mounting Kits

GSA 28 mounting kits are available for several experimental airframes. These mounting kits are listed in

Table 18-8

. All of these kits contain sheet metal mounting brackets that have been designed for the specific application and some contain push rods that have been designed for the specific application. The push rods are supplied cut to the appropriate length and tapped for the male rod end bearings provided. Overall push rod length as well as rod end bearing thread engagement length is provided on the drawings for each kit.

The lengths specified are considered nominal. This length should be adjusted to fit the specific application.

Ideal push rod length results in the push rod being perpendicular to the servo arm when it is at the center of travel.

It is recommended the stop bracket is installed with all push/pull applications. The drawings for each of these mounting kits shows the recommended orientation of this bracket. It is acceptable to deviate from these drawings if a better orientation has been determined by the installer. The best orientation results in the stop bracket flanges being equal distance from the servo arm when at the center of travel. See

Section 18.5.2.2

on stop bracket kit for more details on mounting the stop bracket.

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Page 18-13

18.5.2.10 GSA 28 Installation Into a Non-Garmin Bracket

For installers who intend to fabricate their own brackets or use an existing bracket designed for a non-

Garmin servo, consider the following:

The geometry of the GSA 28 varies from other popular servo models.

While the GSA 28 has the same 2.5” x 4.0” footprint, the same mounting hole locations, and uses the same mounting bolts as several other popular brands of autopilot servo, it does not fit into all mounting brackets designed for other servos. Some of the key differences to consider are:

• The GSA 28 servo has a larger bushing protrusion on the front plane of the servo.

• The harness connector is larger and in a different location relative to the output shaft.

• The GSA 28 does not contain tapped holes for mounting, instead it uses through holes and a thinner mounting flange.

Brackets fabricated for other manufacturer’s servos may or may not have enough clearance for the large bushing protrusion. Modification to the bracket may be necessary to avoid interference with bushing protrusion. See

Figure 18-7

for details.

CAUTION

Damage may occur to the GSA 28 if the mounting bracket overlaps the bushing protrusion when tightening down the mounting bolts. The damage can occur when the bushing is displaced into the unit. To prevent damage, ensure there is clearance for the bushing protrusion and be sure the GSA 28 mounting plate is flush with the bracket when the mounting bolts are being tightened.

For RV-7/8/9/10 roll installations, the rear support bracket used with other popular servos is not compatible with the GSA 28. This is because of the difference in thickness of the GSA 28 mounting flange relative the other servos.

Refer to Figure 18-8.1

for GSA 28 outline dimensions. See Figure 18-8.5

for recommended bracket cutout

dimensions.

NOTE

Garmin cannot validate the structural integrity of non-Garmin brackets.

Mounting brackets provided in the Garmin GSA 28 mounting kits have been designed to withstand (and have been tested to) repetitive stress cycles endured during loads generated by the GSA 28 and aircraft vibrations. If using a non-Garmin mounting bracket, it is the installer’s responsibility to ensure the bracket is structurally adequate for the application. It is important to consider the detrimental effects of bracket displacement and potential for fatigue failures due to reaction forces created by the GSA 28 loading and aircraft vibration.

WARNING

If using a non-Garmin mounting bracket, it is the installer’s responsibility to ensure the bracket is structurally adequate for the application.

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Page 18-14

Figure 18-7 Non-Garmin GSA 28 Bracket

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Page 18-15

18.5.3 Unit Mounting

For final installation and assembly, refer to the outline and installation drawings Figure 18-8.1

through

Figure 18-14.1

.

WARNING

Unless otherwise specified, tighten all threaded fasteners in accordance with FAA advisory circular AC 43-13-1B section 7.40, including adjustment for friction drag torque.

18.6 Unit Wiring

Refer to the

Section 27-1.7

interconnect drawing for connecting GSA 28 wiring.

18.7 Outline and Installation Drawings

Refer to the following figures for GSA 28 installation guidance.

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Figure 18-8.1 GSA 28 Outline/Installation Drawing 011-02927-00


Page 18-17

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Figure 18-8.2 GSA 28 Accessory Installation Drawing


Page 18-18

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Figure 18-8.3 GSA 28 Crank Arm Attachments Drawing


Page 18-19

Figure 18-8.4 GSA 28 with Capstan Kit and Cable Instructions (011-02952-02)

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Page 18-20

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Figure 18-8.5 GSA 28 Recommended Bracket Cutout Dimensions


Page 18-21

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Figure 18-8.6 GSA 28 Recommended Mounting Hardware


Page 18-22

Figure 18-8.7 GSA 28 Generic, Push-Pull Mounting Kit (No Bracket) 011-02952-00

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Page 18-23

Figure 18-8.8 GSA 28 Generic, Push-Pull Mounting Kit w/Bracket 011-02952-01

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Page 18-24

Figure 18-9.1 GSA 28 RV-6 Roll Mounting Kit 011-02952-10 (page 1 of 3)

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Page 18-26


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Page 18-27

Figure 18-10.1 GSA 28 RV-4/8 Pitch Mounting Kit 011-02952-11 (page 1 of 4)

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Page 18-28


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Page 18-29

D

AR

RW

FO


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Page 18-30


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Page 18-31

Figure 18-11.1 GSA 28 RV-7/8/10 Roll Mounting Kit 011-02952-12 (page 1 of 2)

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Page 18-32

INBOARD

Figure 18-11.1 GSA 28 RV-7/8/10 Roll Mounting Kit 011-02952-12 (page 2 of 2)

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Page 18-34

INBOARD


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Page 18-35

RD

A

RW

FO

Figure 18-13.1 GSA 28 RV-6/7/9 Mounting Kit 011-02952-14 (page 1 of 2)

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Figure 18-13.1 GSA 28 RV-6/7/9 Pitch Mounting Kit 011-02952-14 (page 2 of 2)

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Figure 18-14.1 GSA 28 RV-10 Pitch Mounting Kit 011-02952-15 (page 1 of 2)

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Page 18-38

Figure 18-14.1 GSA 28 RV-10 Pitch Mounting Kit 011-02952-15 (page 2 of 2)

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Page 18-39

Figure 18-15.1 GSA 28 RV-10 Yaw Mounting Kit 011-02952-16 (page 1 of 3)

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Page 18-42

19 GSU 25/25B/25C/25D (AHRS/AIR DATA SENSOR UNIT)

INSTALLATION

NOTE

References to the GSU 25 throughout this manual apply equally to the GSU 25B,

GSU 25C, and GSU 25D except where specifically noted.

The GSU 25 can be installed as part of the G3X system. This section contains general information as well as installation information for the GSU 25. Use this section to mount the GSU 25 unit.

NOTE

The GSU 25 was a prior version of the GSU 25C, all form, fit, and functions are identical for the two models.

NOTE

The GSU 25B was a prior version of the GSU 25D, all form, fit, and functions are identical for the two models.

19.1 Equipment Description

NOTE

There is no TSO/ETSO applicable to the GSU 25.

The GSU 25 is not supported for installations in type certificated aircraft using the guidance in this installation manual.

The GSU 25 is an LRU that provides AHRS and Air Data information in a single mechanical package. The

GSU 25 interfaces to a remote mounted GMU magnetometer for heading information and also computes

OAT and TAS from inputs provided by the GTP 59. Up to three GSU 25 units may be installed to provide redundancy and cross-checking of attitude, heading, and air data.

The GSU 25 provides the functions in Table 19-1.

Air Data

Table 19-1 GSU 25 Functions

Interfaces

Pressure Altitude

Density Altitude

Vertical speed

Mach Number

CAN (1)

RS-232 (2 TX/2 RX)

OAT Probe (GTP 59)

Magnetometer (GMU 22)

(1 RS-232 TX/ 1 RS-485 RX)

AHRS

Magnetic Heading (with input from GMU magnetometer )

Pitch Angle

Roll Angle

Linear Accelerations

Indicated Airspeed

True Airspeed

Angle of attack

Pitch, Roll, Yaw Rotation Rates

3 axis angular rates

3 axis accelerations

190-01115-01

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G3X/G3X Touch Installation Manual - GSU 25/25B/25C/25D Installation

Page 19-1

Air Data

Outside and total air temperature (via GTP 59)

Table 19-1 GSU 25 Functions

Interfaces AHRS

Figure 19-1 GSU 25 Unit View


The GSU 25 has an LED on the outer case that indicates current status. See

Section 36.1.1

for details.

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Page 19-2


See

Section 2.2

for power/current specifications, and Section 2.4.1

for dimension/weight specifications.

GSU 25D (011-02929-51 only) HARDWARE MOD LEVEL HISTORY

The following table identifies hardware modification (Mod) Levels for the GSU 25D LRU. Mod Levels are listed with the associated service bulletin number, service bulletin date, and the purpose of the modification. The table is current at the time of publication of this manual (see date on front cover) and is subject to change without notice.

MOD

LEVEL

1

SERVICE

BULLETIN

NUMBER

N/A

SERVICE

BULLETIN

DATE

N/A

PURPOSE OF MODIFICATION

Changed Maximum Pressure Altitude from 30,000 feet to 55,000 feet

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Page 19-3


Table 19-2 lists the kits available for the GSU 25.

Table 19-2 GSU 25 Available Equipment

Item

GSU 25C Unit Assembly

GSU 25D Unit Assembly

GSU 25 Connector Kit (contains all items in Table 19-3 and Table 19-4)

Garmin P/N

011-02929-50

011-02929-51

K10-00181-00

Quantity

1

1

1

Table 19-3 Contents of 9 Pin Connector Kit (011-03002-00)

Item

Backshell w/Hdw, Jackscrew, 9/15 pin

CAN Termination Kit

D-Sub, Crimp Socket Connector, 09 CKT

Contact Socket, Mil Crimp, Size 20, 20-24 AWG

Garmin P/N

011-01855-00

011-02887-00

330-00625-09

336-00022-02

Quantity

1

1

1

9

Table 19-4 Contents of 15 Pin Connector Kit (011-03002-01) contains mounting hardware

Item

Backshell w/Hdw, Jackscrew, 15/26 pin

AN3-7A, Bolt

AN960, Cad Plate, #10 Washer

Washer, Int Star, MS35334, #10

D-Sub, Crimp Socket Connector, 15 CKT

Contact Socket, Mil Crimp, Size 20, 20-24 AWG

Garmin P/N

011-01855-01

211-00090-05

212-00035-10

212-00081-03

330-00625-15

336-00022-02

Quantity

1

4

1

15

4

4


• Wiring: The installer will fabricate cables and supply all wire for system connector kits

011-03002-00 and 011-03002-01.

• Air hoses and fittings to connect pitot air, static air, and AOA air to the GSU 25. The GSU 25 uses a female 1/8 27 ANPT fitting for each of these ports. Use appropriate aircraft fittings to connect to pitot, static, and AOA system lines (per

Section 19.4.4

).

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Page 19-4



be used for installation of the GSU 25. Refer to Section 2.3


for pinouts.

The GSU 25 connects to other LRUs in the G3X system using the CAN bus. To provide an optional redundant path for attitude and air data, a secondary RS-232 connection to a single GDU display (typically

PFD1) is also supported. See

Figure 27-1.11

for wiring and configuration information.

Connector kits include backshell assemblies. Garmin’s backshell connectors give the installer the ability to quickly and easily terminate shield grounds at the backshell housing. The instructions needed to install the

jackscrew backshell are located in Section 25

.

NOTE

Connection to a GMU magnetometer and GTP 59 is required for ADAHRS 1 but optional for ADAHRS 2 & 3.

NOTE

Ensure that backshell connectors are fully tightened. Loose connectors may cause vibration-related performance issues that are difficult to troubleshoot.

19.4.1 Mounting/Calibration Overview

It is critical that the GSU 25 is mounted in alignment with the centerline of the aircraft. The GSU 25 must be mounted with the connectors aligned within 1.0 degree of either the longitudinal or lateral axis of the

aircraft. (see Section 19.4.1 for complete requirements)

The specification for mounting the GSU 25 such that it is level with respect to pitch/roll of the aircraft is not nearly as restrictive, and must only be within 30.0 degrees in each axis. In most installations, the

GSU 25 is mounted relatively level with respect to the zero waterlines of the aircraft (e.g. longerons), even

though it is not required (again, must only be within 30.0 degrees). (see Section 19.4.2 for complete

requirements

Calibrating the pitch/roll offsets is also a crucial part of the installation (see Section 35.4.7

). During

calibration, while on the ground, the aircraft must be level in both pitch/roll such that it accurately represents the in-cruise attitude of the aircraft. This part of the calibration determines that the displayed measured attitude of the GSU 25 is zero degrees in pitch/roll when the aircraft is in level, coordinated cruise flight. (Note that the PFD allows +/- 5 degrees of pitch offset adjustment in flight. This allows the pilot to adjust the pitch offset while in flight to show a correct attitude indication on the PFD, even if the pitch attitude was slightly off when the on the ground pitch/roll offset calibration was performed.)

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Page 19-5


The GSU 25 contains an extremely sensitive strap-down inertial measurement unit, consider the following when selecting a mounting location:

• The GSU 25 can be oriented remotely in any of 24 orientations ( Figure 19-6

and Figure 19-6

), but must satisfy the mounting alignment requirements along the longitudinal/lateral axes of the aircraft. The unit can be mounted in any of the 4 cardinal directions with the connectors pointing up or down can also be mounted on a vertical surface, with the connectors facing up, down, forward, aft, left, or right.

NOTE

The “Tubes Up” mounting orientations are not recommended as any moisture in the pitot/static/AOA line could drain into the GSU 25 and damage the pressure sensors.

NOTE

Select the “Tubes Forward/Connectors Down” orientation when the GSU 25 is mounted to the back of the GDU 4XX unit.

• Although mounting the GSU 25 to the threaded holes on the back of the GDU 4XX display is not generally recommended due to instrument panel flexing, the “Tubes Forward/Connectors Down” configuration should be selected when this location is used.

• Mount the GSU 25 with the connectors aligned within 1.0 degree of either the longitudinal or lateral axis of the aircraft. The direction of the unit will be accounted for during the calibration procedure as shown in Figure 19-2 .

• The GSU 25 must be mounted rigidly to the aircraft primary structure through strong structural

members capable of supporting substantial loads, see torque specification listed on Figure 19-5 .

• The supporting plate must be rigidly connected.

• The GSU 25 should be mounted within 13 feet (4.0 meters) longitudinally and 6.5 feet (2.0 meters) laterally of the aircraft CG (center of gravity). In cases where the longitudinal distance from the

CG is planned to be greater than 6.5 feet (2.0 meters), it is preferable to mount the GSU 25 forward of the aircraft CG if possible, to enable better acceleration outputs for autopilot use.

• Avoid placing the GSU 25 near sources of vibration or audible noise. Example locations to be avoided include the engine firewall, near large motors or fans, and audible buzzers and speakers.

• Do not mount the GSU 25 in an enclosed area, it should be mounted in a location that provides adequate airflow.

• Avoid areas that are prone to severe vibration. Excessive vibration may result in degraded accuracy.

• Do not use shock mounting to mount the GSU 25. Shock mounts used for other types of inertial systems are not acceptable for the GSU 25 AHRS. The mounting system must have no resonance with the unit installed. The unit and mounting structure must not have any resonance with respect to the aircraft primary structure.

• The wing is not an ideal location to install the GSU 25. Installing a GSU 25 in the wing may exceed the lateral CG boundary for the unit, exposes the unit to potential wing flex (of which any amount is a problem), and may expose the unit to unacceptable levels of acoustic noise resulting from precipitation impacting the leading edge of the wing. These are potential sources of error in the determination of attitude and should be avoided.

190-01115-01

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Page 19-6

• The GSU 25 must be leveled to within 30.0° of the in-flight level cruise attitude and an aircraft leveling and offset calibration procedure carried out prior to flight. (This procedure is described in

Section 34.4.3.2

for GDU 37X systems and Section 35.4.7.2

for GDU 4XX systems.)

• The mounting location for the GSU 25 should be protected from rapid thermal transients, in particular, large heat loads from nearby high-power equipment.

• Avoid placing the GSU 25 within 1 inch of magnetically mounted antennas, speaker magnets, or other strongly magnetic items.

Figure 19-2 AHRS Orientation Selection


For final installation and assembly, refer to the outline and installation drawing

Figure 19-4

and

Figure 19-5

of this manual.

1. Mount the unit to a suitable mounting location using the hardware in the connector kit (

Table 19-4)

per the requirements in

Section 19.4.2

.

2. Assemble the wiring harness and backshell connectors

3. Assemble the pneumatic hoses and connectors.

4. Connect backshell connector and hoses.

5. Connect CAN terminator to unit if required (see Section 2.3.1.3.3

).

NOTE

When mounting the GSU 25 to the airframe, it is important to ensure that fastening hardware is tight for proper unit operation.

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Page 19-7

19.4.4 Pneumatic Plumbing

The GSU 25 has three ports that are connected to the aircraft’s pitot pressure source, static pressure source,

and AOA (Angle Of Attack). The ports are labeled on the unit (Figure 19-3). The pressure ports have 1/8-

27 ANPT female threads. The mating fitting must have 1/8-27 ANPT male threads.

NOTE

The temporary port plugs attached to the pressure ports on a new GSU 25 are not suitable for flight, remove prior to installation of GSU 25 into aircraft.

Figure 19-3 GSU 25 Air Hose Fitting Locations

Use appropriate air hoses and fittings to connect the pitot and static lines to the unit. Use colored (or well marked) tubing to avoid confusing pitot, static, and AOA plumbing per

Figure 27-1.6

. Avoid sharp bends and routing near aircraft control cables. The GSU 25 should not be at the low point of the pneumatic plumbing lines, to avoid moisture or debris collecting at or near the unit. Ensure that no deformations of the airframe surface have been made that would affect the relationship between static air pressure and true ambient static air pressure for any flight condition. Refer to part 43, Appendix E for approved practices while installing hoses and connections.

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Page 19-8

19.4.5 Pneumatic Connections

The following steps should be used to aid in the fabrication of pneumatic hose connections and in attaching the aircraft pitot pressure source and aircraft static pressure source to the GSU 25.

CAUTION

If the AOA port is unused, connect it to the static port to avoid overpressuring (and causing damage to) the internal AOA sensor.

CAUTION

When the GSU 25 is used in conjunction with the GAP 26 pitot/AOA probe to perform Part 43 Appendix E altimeter tests, the probe adapter from the pitot-static tester must completely cover the pitot and AOA ports and drain holes on the GAP

26 to avoid overpressuring (and causing damage to) the internal AOA sensor of the GSU 25. If the GAP 26 is installed but AOA is unused (i.e., the AOA port of the

GAP 26 is not connected to the AOA port of the GSU 25) then the GAP 26 AOA port must be connected to the same pressure port as the pitot port during pitotstatic testing.

*Note: If the AOA is unused and connected to the static port (as described in the preceding Caution statement) it can remain connected to the static port for the pitot-static test.

CAUTION

Use of different colored tubing is recommended for static, pitot, and AOA plumbing to avoid plumbing connection errors. Incorrect plumbing connections will result in erroneous air data information calculated by the GSU 25.

Observe the following cautions when connecting pneumatic lines:

1. Make sure the aircraft static pressure port is plumbed directly to the unit static pressure input port and the aircraft pitot pressure port is plumbed directly to the unit pitot pressure input port. The

AOA port must be plumbed directly to the AOA pressure port or, if unused, directly to the aircraft static port.

2. Seal the threads of pneumatic fittings at the connector ports. Use caution to ensure there are no pneumatic leaks.

3. Use care to avoid getting fluids or particles anywhere within the pneumatic lines connected to the

GSU 25.

The installer must fabricate any additional mounting equipment needed. Use outline and installation

drawings Figure 19-4 and

Figure 19-5

for reference.

190-01115-01

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Page 19-9


190-01115-01

Rev. AN

Figure 19-4 GSU 25 Outline Drawing


Page 19-10

190-01115-01

Rev. AN

Figure 19-5 GSU 25 Installation Drawing


Page 19-11

>

D

AR

>>>

RW

FO

D

>>

>>

AR

RW

FO

>

AR

>>>

D

RW

FO

>

D

AR

>>>

RW

FO

>

AR

>>>

D

RW

FO

>

D

AR

>>>

RW

FO

>

D

AR

>>>

RW

FO

>

D

AR

>>>

RW

FO

190-01115-01

Rev. AN

Figure 19-6 GSU 25 Orientation Drawings (page 1 of 3)


Page 19-12

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

190-01115-01

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Page 19-13

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

>

AR

>>>

D

RW

FO

190-01115-01

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Page 19-14

20 GSU 73 (SENSOR UNIT) INSTALLATION

The GSU 73 can be installed as part of the G3X system. This section contains general information as well as installation information for the GSU 73. Use this section to mount the GSU 73 unit.


NOTE

There is no TSO/ETSO applicable to the GSU 73.

The GSU 73 is intended for the experimental aircraft and LSA (light sport aircraft) markets. The Garmin

GSU 73 Sensor Unit is not a TSO-certified product and has received no FAA approval or endorsement.

The GSU 73 is intended to be used as a part of the G3X system and it is not suitable for installation in typecertificated aircraft.

The GSU 73 is an LRU that provides AHRS and Air Data information as well as an interface to Engine/

Airframe sensors in a single mechanical package. The GSU 73 interfaces to a remote mounted GMU 22 for heading information and also computes OAT and TAS from inputs provided by the GTP 59.

NOTE

The GSU 73 is not compatible with the GMU 11 magnetometer. Installations with a

GSU 73 must also include a GMU 22 connected to the GSU 73.

NOTE

In installations using more than one ADAHRS, the GSU 73 will always be designated as

ADAHRS 1 and the GSU 25 units will be designated as ADAHRS 2, ADAHRS 3, etc.

190-01115-01

Rev. AN

Figure 20-1 GSU 73 Unit View

G3X/G3X Touch Installation Manual - GSU 73 Installation

Page 20-1

20.1.1 Features Summary

Air Data

Pressure Altitude

Density Altitude

Vertical Speed

Mach Number

Indicated Airspeed

True Airspeed

Interfaces

CAN (1)

RS-232 (2 TX/2 RX)

ARINC 429 (4 RX/2 TX)

OAT Probe (GTP 59)

Magnetometer (GMU 22) (1 RS-232 TX/ 1 RS-485 RX)

AHRS

Magnetic Heading

Pitch Angle

Roll Angle

Linear Accelerations

Pitch, Roll, Yaw Rotation Rates

Engine/Airframe

27 Analog Inputs

4 Digital Inputs

4 Discrete Inputs

2 Discrete Outputs


See Section 2.2

for power/current specifications, and

Section 2.4.1

for dimension/weight specifications.

GSU 73 HARDWARE MOD LEVEL HISTORY

The following table identifies hardware modification (Mod) Levels for the GSU 73 LRU. Mod Levels are listed with the associated service bulletin number, service bulletin date, and the purpose of the modification. The table is current at the time of publication of this manual (see date on front cover) and is subject to change without notice.

MOD

LEVEL

1

2

SERVICE

BULLETIN

NUMBER

N/A

N/A

SERVICE

BULLETIN

DATE

N/A

N/A

PURPOSE OF MODIFICATION

Improved HSCM accuracy when using +28 V supply

Improved backup capacitor circuit to increase backup time in certain under-voltage conditions

190-01115-01

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Page 20-2


Table 20-1 lists the kits available for the GSU 73.

Table 20-1 GSU 73 Available Equipment

Item

Configuration Module w/EEPROM and Jackscrew, Kit

Thermocouple Kit

Unit Assembly, GSU 73

P731 Connector Kit, GSU 73

P732 Connector Kit, GSU 73

*Included in G3X w/GSU 73 LRU Kit (K10-00016-00)

**Included in G3X w/GSU 73 Installation Kit (K10-00017-00)

Garmin P/N

011-00979-20**

011-00981-00**

011-01817-00*

011-01818-00**

011-01818-01**

Quantity

1

1

1

1

1

Table 20-2 Contents of P731 Connector Kit (011-01818-00)**

Item

Sub-Assy,Backshell w/Hdw,Jackscrew

Connector ,Hi Dens, D-Sub, Mil Crimp 62ck

Contact Pin, Mil Crimp, Size 22D


Garmin P/N

011-01855-03

330-00185-62

336-00021-00

Quantity

1

1

20

Table 20-3 Contents of P732 Connector Kit (011-01818-01)**

Item

Sub-Assy,Backshell w/Hdw,Jackscrew

Garmin P/N

011-01855-04

Connector ,Hi Dens, D-Sub, Mil Crimp 78ck

Contact Pin, Mil Crimp, Size 22D


330-00185-78

336-00021-00

Quantity

1

1

30

20.3.1 GSU 73 Configuration Module

The GSU 73 configuration module stores a duplicate copy of the AHRS/Magnetometer calibration values which are recorded upon completion of post-installation calibration procedures. The GSU configuration module also provides a reference temperature measurement which is used for calculating thermocouple

temperatures. All thermocouple temperature readouts will be Red-x’d ( Section 36

) if the GSU configuration module is not present.

190-01115-01

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Page 20-3


• Cables: The installer will fabricate and supply all system cables.

• An example of mounting hardware is: #10-32 pan or hex head screw (4 ea.) and #10-32 selflocking nut (4 ea)

• Air hoses and fittings to connect pitot and static air to the GSU 73. The GSU 73 has a female

1/8 27 ANPT fitting for each pitot and static port. Use appropriate aircraft fittings to connect to pitot and static system lines.



be used for installation of the GSU 73. Refer to Section 2.3


for pinouts.

Connector kits include backshell assemblies. The backshell assembly houses the configuration module

(P732 only) and a thermocouple reference junction (if applicable). Garmin’s backshell connectors give the installer the ability to quickly and easily terminate shield grounds at the backshell housing. The instructions needed to install the Jackscrew Backshell, Configuration Module, and Thermocouple are located in

Section 25 .

190-01115-01

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Page 20-4

20.4.1 Pneumatic Plumbing

The GSU 73 has two ports that are connected to the aircraft’s pitot pressure source and static pressure

source. The two ports are labeled on the unit (Figure 20-2). The pressure ports have 1/8-27 ANPT female

threads. The mating fitting must have 1/8-27 ANPT male threads.

Figure 20-2 GSU 73 Air Hose Fitting Locations

Use appropriate air hoses and fittings to connect the pitot and static lines to the unit. Avoid sharp bends and routing near aircraft control cables. The GSU 73 should not be at the low point of the pitot or static plumbing lines, to avoid moisture or debris collecting at or near the unit. Ensure that no deformations of the airframe surface have been made that would affect the relationship between static air pressure and true ambient static air pressure for any flight condition. Refer to part 43, Appendix E for approved practices while installing hoses and connections.

20.4.2 Pneumatic Connections

The following steps should be used to aid in the fabrication of pneumatic hose connections and in attaching the aircraft pitot pressure source and aircraft static pressure source to the GSU 73.

NOTE

Check pneumatic connections for errors before operating the GSU 73. Incorrect plumbing could cause internal component damage. Observe the following cautions when connecting pneumatic lines.

1. Make sure the aircraft static pressure port is plumbed directly to the unit static pressure input port and the aircraft pitot pressure port is plumbed directly to the unit pitot pressure input port.

2. Seal the threads of pneumatic fittings at the connector ports. Use caution to ensure there are no pneumatic leaks.

3. Use care to avoid getting fluids or particles anywhere within the pitot and static lines connected to the GSU 73.

The installer must fabricate any additional mounting equipment needed. Use outline and installation

drawing Figure 20-4

for reference.

190-01115-01

Rev. AN


Page 20-5


Mount the GSU 73 with the connectors aligned within 1.0 deg of either the longitudinal or lateral axis of the aircraft. The direction of the unit will be accounted for during the calibration procedure as shown in

Figure 20-3.

Figure 20-3 AHRS Orientation Selection

The GSU 73 includes an extremely sensitive strap-down inertial measurement unit. It must be mounted rigidly to the aircraft primary structure, preferably to a metallic structure to conduct heat away from the unit. Do not mount the GSU 73 in an enclosed area, it should be mounted in a location that provides

adequate airflow to comply with the maximum outer case temperature listed in Appendix D.12.1

.

Do not use shock mounting to mount the GSU 73. Shock mounts used for other types of inertial systems are not acceptable for the GSU 73 AHRS. The mounting system must have no resonance with the unit installed. Excessive vibration may result in degraded accuracy.

The supporting plate must be rigidly connected to the aircraft primary structure through strong structural members capable of supporting substantial loads. Avoid areas that are prone to severe vibration.

The GSU 73 should be mounted within 13 feet (4.0 meters) longitudinally and 6.5 feet (2.0 meters) laterally of the aircraft center of gravity. In cases where the longitudinal distance from the CG is planned to be greater than 6.5 feet (2.0 meters), it is preferable to mount the GSU 73 forward of the aircraft center of gravity if possible, to enable better acceleration outputs for autopilot use. The mounting location for the

GSU 73 should be protected from rapid thermal transients, in particular, large heat loads from nearby highpower equipment.

The GSU 73 must be leveled to within 3.0° of the in-flight level cruise altitude and an aircraft leveling and offset calibration procedure carried out prior to flight. (This procedure is described in

Section 34.4.3.2

for

GDU 37X systems and

Section 35.4.7.2

for GDU 4XX systems.)

Avoid placing the GSU 73 within 1 inch of magnetically mounted antennas, speaker magnets, or other strongly magnetic items.


For final installation and assembly, refer to the outline and installation drawing Figure 20-4

of this manual.

1. Assemble the wiring harness and backshell connectors.

2. Assemble the pneumatic hoses and connectors.

3. Mount the unit to a suitable mounting location using (4 ea) #10-32 pan or hex head screws

(example) per the requirements in

Section 20.4.3

.

4. Connect backshell connector and hoses.

NOTE

When mounting the GSU 73 to the airframe, it is important to ensure that fastening hardware is tight for proper unit operation.

190-01115-01

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Page 20-6


190-01115-01

Rev. AN

Figure 20-4 GSU 73 Outline Drawing


Page 20-7

190-01115-01

Rev. AN

Figure 20-5 GSU 73 Orientation Drawings


Page 20-8

21 GTP 59 (TEMPERATURE PROBE) INSTALLATION

This section contains general information as well as installation information for the GTP 59. Use this section to mount the GTP 59.

NOTE

For installations using more than one ADAHRS, ADAHRS 1 must be connected to a

GTP 59, but installing additional GTP 59’s for other GSU 25 ADAHRS units is optional.

An ADAHRS not connected to a GTP 59 will use temperature data supplied by other

ADAHRS as long as both ADAHRS are communicating via the CAN bus.

Figure 21-1. GTP 59


The Garmin GTP 59 is an outside mounted temperature probe that provides raw air temperature data. The temperature input device is a three-wire temperature probe interface. OAT Power Out and OAT High are connected internally at the OAT probe.

The GTP 59 is available per the following part number.

Table 21-1 GTP 59 Part Number

Item

GTP 59 OAT Probe Kit

*Included in G3X w/GSU 73 LRU (K10-00016-00)

Garmin Part Number

011-00978-00*

190-01115-01

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G3X/G3X Touch Installation Manual - GTP 59 Installation

Page 21-1

Table 21-2 contains a list of items found in the GTP 59 Outside Air Temperature (OAT) Probe kit

(011-00978-00). The GTP 59 probe has an attached pigtail.

Table 21-2 GTP 59 Outside Air Temperature Kit*

Item

Nut, 5/16”, Hex, Skirt

Screw, 4-40 x .250, PHP, SS/P, w/NYL

Garmin Part Number

210-00055-00

211-60234-08

Washer, Lock, Self-Sealing, 5/16

Contact, Pin, Mil Crimp, Size 22D

GTP 59 OAT Probe

*Included in G3X w/GSU 73 LRU Kit (K10-00016-00)

212-00026-00

336-00021-00

494-00022-XX

Quantity

1

2

1

5

1


• Cables - The installer will supply all system cables.


See

Section 21-2 for mounting dimensions.


NOTE

The following instructions are general guidance.

NOTE

The GTP 59 is a Resistive Temperature Device (RTD) that detects changing temperature by monitoring small changes in resistance. For optimum accuracy, take care to avoid introducing extra resistance, such as loose, dirty, or corroded connections in the wiring path between the ADAHRS and GTP 59.

Consider the following recommendations when determining the mounting location for the GTP 59:

• Do not mount the GTP 59 where aircraft exhaust gases will flow over it.

• Do not mount the GTP 59 where it would be affected by heated air from the engine or exhaust. On most aircraft this includes any location downstream of the engine compartment.

• The GTP 59 must be exposed to the outside airflow. Do not mount the GTP 59 in a sheltered location where it is not exposed to outside airflow (for example, inside a wing or landing gear bay).

• For best results, do not mount the GTP 59 where it will be directly heated by the sun when the aircraft is parked.

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Page 21-2

Table 21-3 contains a list of parts needed for the GTP 59 installation and interconnect harness. Refer to

Figure 21-2

GTP 59 O.A.T. Probe Installation Drawing for wiring and mounting instructions.

Table 21-3 Parts Needed for GTP 59 Installation

Description

Nut

Screw

Washer

Qty. Included

1

2

1

GPN

210-00055-00

211-60234-08

212-00026-00

5 336-00021-00 Contact, Pin, Mil Crimp, Size 22D

Ring Terminal

3-Conductor Cable

OAT Sensor

1 494-00022-XX

1. Prepare the surface. The metal body of the OAT probe should be grounded to the aircraft. The installation requirements vary depending on the airframe material composition.

a) Aluminum airframe: When a mounting location has been found, prepare the inside surface of the aircraft. Remove all paint from the contacting area and clean with a degreaser.

b) Composite airframe: If possible, mount the OAT probe through a grounded metal strap or band. Otherwise, mount the OAT probe in an area of the airframe that has a significant amount of underlying metal foil or mesh. To ensure adequate conductivity, it may be necessary to mount the OAT probe through a metal doubler. Use fasteners that allow a conductive path to the airframe.

2. Mount the OAT probe on the prepared surface. Place the ring terminal (1) over the end of the OAT probe (3). Insert the probe and ring terminal into the hole in the skin of the aircraft. Place the washer (5) over the end of the OAT probe on the outside skin of the aircraft. Thread the nut (4) onto the OAT probe. Holding the OAT probe on the inside, tighten the nut (4) to 100 inch-lbs.  20 inch-lbs.

3. Route the OAT probe cable (2) to the GSU 25/GSU 73.

4. Cut the OAT Probe cable (2) to the required length. Strip back 2.0” to 3.5” of jacket while retaining the shield on the OAT Probe cable (2). Trim away enough to leave 0.5” of shield exposed.

5. Strip back 1/8” (0.125”) of insulation and crimp pins to each of the conductors in the shielded cable.

6. Cut an AWG #16 wire to 3” long. Strip back 0.5” of insulation from this cable. Connect the shield of the OAT Probe cable (2) to the AWG #16 wire.

7. Attach the ring terminal to the backshell, using the screw provided in the OAT Probe Kit and one of the tapped holes on the backshell termination area.

8. Insert newly crimped pins into the D-Sub connector and wires into the appropriate connector housing location as specified by the installation wiring diagrams.

9. Verify that all necessary pins for the GSU 25/GSU 73 have been attached to the cables and snapped into the proper slots of the 78 pin D-Sub connector.

10. Wrap the cable bundle with Silicone Fusion Tape (GPN: 249 00114 00 or similar) at the point where the backshell strain relief and cast housing contact the cable bundle. The smooth side of the backshell strain relief should contact the tape.

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21.4 GTP 59 Icing

The GTP 59 OAT probe has no icing protection. If ice accumulates on the GTP 59 OAT probe, its accuracy is unknown. Consequently, air temperature measurements may be incorrect if ice accumulates on the probe. Furthermore, computations dependent upon air temperature measurements may be affected (e.g. true airspeed and delta-ISA).

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Figure 21-2. GTP 59 O.A. T. Probe Installation Drawing


Page 21-5

22 GTR 20 (VHF COMMUNICATIONS RADIO) INSTALLATION

This section contains general information as well as installation information for the GTR 20. Use this section to mount the GTR 20 unit. Careful planning and consideration of the suggestions in this section are required to achieve the desired performance and reliability from the GTR 20. The guidance of FAA advisory circulars AC 43.13-1B and AC 43.13-2B, where applicable, may be found useful for making retro-fit installations that comply with FAA regulations.

NOTE

A GTR 20 cannot be installed in a system that also includes a GDU 37X. The GTR 20 will only work with the G3X system that uses the new GDU 4XX displays. The GTR 20 is not supported with G3X installations using GDU 37X displays.

Figure 22-1 GTR 20 Unit View (shown with mounting brackets on ends)


The GTR 20 is a transceiver that operates in the 118.000 to 136.975 MHz frequency range. The receiver sensitivity SINAD is greater than 6dB when the RF level is -107 dBm with 30% modulation. The transmitter power is 10 W carrier minimum.

Table 22-1 Available Units

Model

GTR 20

GTR 20

Part Number

011-03007-00

011-03007-10

TX Power (Watt) 8.33 KHz Spacing

10 N/A

10 N/A

25 KHz Spacing

Yes

Yes

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CAUTION

The use of ground-based cellular telephones while aircraft are airborne is prohibited by

FCC rules. Due to potential interference with onboard systems, the use of ground-based cell phones while the aircraft is on the ground is subject to FAA regulation 14 CFR §91.21.

FCC regulation 47 CFR §22.925 prohibits airborne operation of ground-based cellular telephones installed in or carried aboard aircraft. Ground-based cellular telephones must not be operated while aircraft are off the ground. When any aircraft leaves the ground, all ground-based cellular telephones on board that aircraft must be turned off. Ground-based cell phones that are on, even in a monitoring state, can disrupt GPS/SBAS performance.


The GTR 20 has an LED located in the hole to the right of the D-sub connector (J2001) that indicates its current status. See

Section 36.1.1

for details.

22.2 Equipment Available

22.2.1 Unit Configurations

Model

Table 22-2 GTR 20 Part Numbers

Assembly Part

Number

010-01076-00 GTR 20 unit only

GTR 20 Standard (includes

items in Table 22-3)*

GTR 20 (New) unit only

GTR 20 (New) Standard

(includes items in Table 22-3)*

*Includes 011-03241-00 connector kit

010-01076-01

010-01076-10

010-01076-11

Unit Only Part

Number

011-03007-00

011-03007-00

011-03007-10

011-03007-10


The connector kit in Table 22-3 is required to install the unit, it is not provided with the GTR 20 unit only

(010-01076-00, 010-01076-10).

Table 22-3 Contents of GTR 20 Connector Kit (011-03241-00)

Item

Backshell w/Hdw, Jackscrew,37 Pin

Screw, 8-32 x .312, PHP, SS/P

Washer, Split Lock, Size 8

Washer, Flat, Non-Std, SS, ID .195, OD .354

Conn, Rcpt, D-Sub, Crimp Socket, Commercial, 37 CKT

Contact, Socket, Military Crimp, Size 20

Garmin P/N

011-01855-03

211-60209-09

212-00018-04

212-20065-00

330-00625-37

336-00022-02

Quantity

1

5

5

5

1

37

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See

Table 2-2

for power/current specifications, and Table 2-4 for dimension/weight specifications.

22.3.1 COM Specifications

The GTR 20 transmitter meets the requirements of RTCA DO-186B section 2.3 for a class 4 transmitter.

Characteristic

Microphone Input

Modulation Capability

Modulation

Frequency Range

Frequency Tolerance

Output Power

Duty Cycle

Carrier Noise Level

Stuck Mic Time-Out

Demodulated Audio Distortion

Table 22-4 Transmitter Specifications

Specification

Two inputs, standard carbon or dynamic mic with integrated preamp.

The GTR 20 provides a 150 Ω AC input impedance and supplies the microphone with an 11 V bias through 470 Ω +/- 5%.

85% with 150 to 1500 mVRMS microphone input at 1000 Hz. Range can be extended from 20 mVrms to 2500 mVrms with mic gain adjustment.

AM Double sided Emission Designator: 6K00A3E (118 - 136.975 MHz)

118.000 to 136.975 MHz, 25 kHz channel spacing

+/-5 ppm from -20°C to +55°C

10 Watts carrier minimum

20%

At least 35 dB (SNR)

35 seconds time-out, reverts to receive

Less than 25% distortion when the transmitter is at 85% modulation at

350 to 2500 Hz

The GTR 20 receiver meets the requirements of RTCA DO-186B section 2.2 for a class C receiver.

Table 22-5 Receiver Specifications

Characteristic

Frequency Range

Specification

118.000 to 136.975 MHz, 25 kHz channel spacing

Headset Audio Output 60 mW minimum into a 150 Ω load

Audio Response

Audio Distortion

Sensitivity

Squelch

Less than 6 dB of variation between 350 and 2500 Hz

Less than 25% at rated output power

SINAD greater than 6 dB when the RF level is -107 dBm with 30% modulation

Automatic squelch with manual override

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22.4 Installation Considerations

22.4.1 COM Antenna

A COM Antenna that meets TSO-C37( ) and C38( ) or TSO-C169( ), 50W, vertically polarized with coaxial cable is recommended but not provided.

CAUTION

To avoid damage to the GTR 20, take precautions to avoid transmitting when no antenna is connected.

22.4.2 Installation Materials

The GTR 20 is intended for use with the standard aviation accessories. The following items are recommended for installation, but not supplied:

• Wire (MIL-W-22759/16 or equivalent)

• Shielded Wire (MIL-C-27500 or equivalent)

• Mounting Hardware - #10 hardware recommended

• Push/Pull (that can be manually reset) Circuit Breaker

• Tie Wraps or Lacing Cord

• Ring Terminals (for grounding)

• Coaxial Cable (RG-400, RG-142B or coaxial cable with 50 Ω impedance meeting applicable aviation regulations should be used.

22.4.3 Cabling and Wiring

Refer to the interconnect examples in

Section 29 for wire gauge guidance.

Use wire and cable meeting the applicable aviation regulation. When routing wire and cable, observe the following precautions:

• Keep as short and as direct as possible

• Avoid sharp bends

• Avoid routing near power sources (e.g. 400 Hz generators, trim motors, etc.) or near power for fluorescent lighting

• Do not route cable near high voltage sources

CAUTION

To avoid damage to the GTR 20, take precautions to prevent Electro-Static Discharge

(ESD) when handling the GTR 20, connectors, and associated wiring. ESD damage can be prevented by touching an object that is of the same electrical potential as the GTR 20 before handling the GTR 20 itself.

NOTE

The GTR 20 connects to the G3X system using the CAN bus. If communication is lost or no

GDU displays are present, the GTR 20 will automatically tune the emergency frequency

(121.500 MHz) and set the COM radio volume to a pre-determined level. See Section

35.4.27.1

for information on configuring the emergency volume level.

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22.5 Antenna Considerations

This section contains mounting location considerations for the antennas required for the GTR 20. For mounting the COM antenna, refer to the aircraft manufacturer’s data.

22.5.1 COM Antenna Location

The GTR 20 COM antenna should be well removed from all projections, engines and propellers. The ground plane surface directly below the antenna should be a flat plane over as large an area as possible (18 inch square, minimum). The antenna should be mounted a minimum of six feet from any DME or other

COM antennas, and four feet from any ADF sense antennas. The COM antenna should also be mounted as far as practical from the ELT antenna. Some ELTs have exhibited re-radiation problems that cause interference with other radios, including GPS. This can happen when the COM (GTR 20 or any other

COM) is transmitting on certain frequencies such as 121.15 or 121.175 MHz, which may cause the ELT output circuit to oscillate from the signal coming in on the ELT antenna coax.

If simultaneous use of two COM transceivers is desired (split-COM or simul-comm), the COM antennas should be spaced for maximum isolation. A configuration of one topside antenna and one bottom side antenna is recommended. The GTR 20 requires a transmit interlock.

Simultaneous COM performance varies significantly across installations and is affected by both the isolation between the COM antennas and the separation of the tuned frequencies. Each installation should be individually examined to determine the expected performance of simultaneous COM.

CAUTION

Garmin recommends the COM antenna be mounted a minimum of six feet from any other

COM antennas. For aircraft which cannot comply with the recommended separation,

COM antenna spacing should never be less than three feet to reduce the chance of damage to the COM receiver. All dual COM installations must use the GTR 20 interlock. An example of direct line of sight is both antennas mounted on the bottom or top surface of the aircraft. For metallic aircraft, it is recommended that one antenna is mounted on the bottom close to the front and the other on the top of the aircraft close to the tail such that the aircraft structure is between the two antennas. For composite aircraft, additional shielding may be needed between top and bottom mounted COM antennas.

NOTE

Canadian installations are required to meet Industry Canada specifications for maximum radiation as documented in Radio Specifications Standard 102 (RSS-102). For more information about RF exposure and related Canadian regulatory compliance, contact:

Manager, Radio Equipment Standards

Industry Canada

365 Laurier Avenue

Ottawa, Ontario

K1A 0C8

In accordance with Canadian Radio Specifications Standard 102 (RSS 102), an RF safety separation distance of 26 cm from the antenna should be maintained for an RF field strength exposure to persons of less than the 10W/m 2 occupational safety limit.

Under Industry Canada regulations, this radio transmitter may only operate using an antenna of a type and maximum (or lesser) gain approved for the transmitter by Industry

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Canada. To reduce potential radio interference to other users, the antenna type and its gain should be so chosen that the equivalent isotropically radiated power (e.i.r.p.) is not more than that necessary for successful communication.

The GTR 20 has been approved by Industry Canada to operate with the antenna types listed below. Antenna types not included in this list, having a gain greater than the maximum gain indicated for that type, are strictly prohibited for use with this device.

A COM Antenna that meets TSO-C37( ) and C38( ) or TSO-C169( ), 50W, vertically polarized. Maximum gain of 1 dBi with an impedance of 50 Ω.

22.5.2 Interference of GPS

On some installations, VHF COM transceivers, Emergency Locator Transmitter (ELT) antennas, and

Direction Finder (DF) receiver antennas can re-radiate to the GPS antenna. Placement of the GPS antenna relative to a COM transceiver and COM antenna (including the GTR/ COM antenna), ELT antenna, and

DF receiver antenna is critical.

Use the following guidelines, in addition to others in this document, when locating the GTR 20 and its antenna.

• Locate the GTR 20 as far as possible from all GPS antennas.

• Locate the COM antenna as far as possible from all GPS antennas.

If a COM is found to be radiating, the following can be done:

• Replace or clean VHF COM rack connector to ensure good coax ground.

• Place a grounding brace between the GTR 20 and ground.

• Shield the GTR 20 wiring harness.

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22.6 Mounting Considerations

The GTR 20 is designed to mount remotely.

22.6.1 Bracket Installation

The GTR 20 is shipped with the brackets positioned on the ends of the unit. The brackets can be removed from the bottom of the GTR 20 and repositioned by the installer. The GTR 20 mounting brackets can be positioned on the sides or the ends of the GTR 20. The installer determines the orientation and position of the brackets that best suits the installation. See

Figure 22-2

and Figure 22-3 for bracket positions.


Secure the GTR 20 to the airframe in a suitable mounting location using a minimum of four #10 fasteners

(not provided). Hardware is intended to be located in the 4 outermost mounting locations. The center locations in each bracket are additional locations provided for the installer’s convenience.

Do not mount the GTR 20 on the “hot” side (engine side) of the firewall. To reduce interference, route the

GTR 20 wiring harness separately from any COM radio or transponder antenna coax.

No cooling air is required for the GTR 20/200, however, as with all electronic equipment, lower operating temperatures extends equipment life. Reducing the operating temperature by 15° to 20°C (27° to 36°F) reduces the mean time between failures (MTBF).

For final installation and assembly, see Figure 22-2 ,

Figure 22-3

, and Figure 22-4 .

22.6.3 Antenna Installation and Connections

The GTR 20 requires a standard 50  vertically polarized antenna. Follow the antenna manufacturer’s installation instructions for mounting the antenna.

The antenna should be mounted on a metal surface or a ground plane with a minimum area of 18 inches x

18 inches. Refer to

Section 22.5.1

for installation location considerations.

22.6.4 Antenna Coaxial Cable Installation

The antenna coax cable should be made of RG-142B, RG-400 or a comparable quality 50  coax. See

Section 2.4

or follow the BNC connector manufacturer’s instructions for cable preparation/connector installation.

Check that there is ample space for the cabling and mating connectors. Avoid sharp bends in the antenna cable, and routing near aircraft control cables. Route the COM antenna cable as far as possible away from any GPS antenna cables.

Check for insertion loss and Voltage Standing Wave Ratio (VSWR). VSWR should be checked with an inline type VSWR/wattmeter inserted in the coaxial transmission line between the transceiver and the antenna. The VSWR meter should be inserted as close to the transceiver as possible. When rack and harness buildup is performed in the shop, the coax termination may be provisioned by using a 6-inch inline BNC connection. This would be an acceptable place to insert the VSWR meter. Any problem with the antenna installation is most likely seen as high reflected power. A VSWR of 3:1 may result in up to a 50% loss in transmit power. VSWR at the low, mid and high end of the tuning range should be less than 3:1, for best performance VSWR should be less than 2:1. A high VSWR decreases the amount of power radiated by the antenna and increases power supply current and heat dissipated by the radio when the radio is transmitting.

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22.7 Mounting, Wiring, and Power Checks

Fabrication of a wiring harness is required. Sound mechanical and electrical methods and practices are

recommended for installation of the GTR 20. Refer to Section 2.3

for wiring considerations, and to Section

26.17

for pinouts.

Verify that all cables are properly secured and shields are connected to the shield block of the connectors.

Check the movement of the flight and engine controls to verify there is no interference between the cabling and control systems. Ensure that all wiring is installed as described in

Section 2.3

.

Prior to powering up the unit, the wiring harness must be checked for proper connections to the aircraft systems and other avionics equipment. Point to point continuity must be checked to expose any faults such as shorting to ground. Any faults or discrepancies must be corrected before proceeding.

After accomplishing a continuity check, perform power and ground checks to verify proper power distribution to the GTR 20. Any faults or discrepancies should be corrected at this time. Remove power from the aircraft upon completion of the harness checkout.

The GTR 20 can be installed after completion of the continuity and power checks. The GTR 20 should be secured appropriately, as described in

Section 22.6

. The GTR 20 must be connected to the wiring harness

and antenna.

22.7.1 Unit Ground Checks (Normal Mode)

22.7.1.1 TX Interlock Checkout

Connect pins 4 and 5 per Section 29

.

Table 22-6 TX Interlock Connections

Pin Pin Name

4 TX INTERLOCK OUT

5 TX INTERLOCK IN

Description

Active low output that indicates the GTR 20 is transmitting.

This output is normally connected to the TX INTERLOCK IN of other COM radios installed in the aircraft.

Active Low Input that ‘desenses’ (protects) the GTR 20 receiver when another communications radio is transmitting. This input comes from another communication radio's interlock output or MIC KEY line.

22.7.1.2 Antenna Check

If desired, the antenna VSWR can be checked using an inline wattmeter in the antenna coaxial using frequencies near both ends of the band. The VSWR should be less than 2:1. A VSWR of 2:1 will cause a drop in output power of approximately 12%.

22.7.1.3 Receiver/Transmitter Check

Tune the unit to a local VHF frequency and verify the receiver output produces a clear and understandable audio output. Verify the transmitter functions properly by contacting another station and getting a report of reliable communications.

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22.7.2 Flight Checks

22.7.2.1 COM Flight Check

After the installation is complete, perform the following required flight checks to ensure satisfactory transceiver performance.

Check the communications transceiver at a range of at least 50 nautical miles: (This check verifies unit receiver sensitivity test and transmitter range)

1. Maintain an altitude of 5000 ft AGL.

2. Select the frequency of a ground station facility at a range of at least 50 nautical miles.

3. Verify that communication (RX and TX) can be established with that facility.

Check the communications receiver by receiving transmission from a ground station in close proximity

(range of less than 10 nautical miles): (This check verifies that the receiver has a high signal to noise ratio when receiving a strong signal.)

1. Select the frequency of a ground station facility at a range of less than 10 nautical miles.

2. Make sure the received audio from that station is clear (no background electrical noise).

3. If possible, perform the preceding steps 1 and 2 for frequencies in the high (~136.XXX MHz), mid

(~127.XXX MHz), and low (~118.XXX MHz) range of the GTR 20.

22.7.3 Noise

As audio signals are routed to and from the GTR 20 (Headset, Microphone, Music, AUX), care must be taken to minimize effects from coupled interference and ground loops.

Interference can be coupled into interconnecting cables when they are routed near large AC electric fields,

AC voltage sources, and pulse equipment (strobes, spark plugs, magnetos, EL displays, CRTs, etc).

Interference can also couple into interconnecting cables by magnetic induction when they are routed near large AC current-carrying conductors or switched DC equipment (heaters, solenoids, fans, autopilot servos, etc).

Ground loops are created when there is more than one path in which return currents can flow, or when signal returns share the same path as large currents from other equipment. These large currents create differences in ground potential between various equipment operating in the aircraft. These differences in potential can produce an additive effect at audio signal inputs.

The GTR 20 audio inputs may detect the desired input signal plus an unwanted component injected by ground differentials, a common cause of alternator-related noise. This can be minimized by isolating all audio jacks from ground.

Terminating shields at just one end (single-point grounding) eliminates another potential ground loop injection point. The single-point grounding method is critical for the installation of various avionics that produce and process audio signals. Single-point, in this context, means that the various pieces of equipment share a single common ground connection back to the airframe.

Good aircraft electrical/charging system ground bonding is important.

The wiring diagrams and accompanying notes in this manual should be followed closely to minimize noise effects.

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Figure 22-2 GTR 20 Outline Drawing (Mounting Brackets on Ends)

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Figure 22-3 GTR 20 Outline Drawing (Mounting Brackets on Sides)

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Figure 22-4 GTR 20 Installation Drawing


Page 22-12

23 GPS/XM ANTENNA INSTALLATION

This section contains general information as well as installation information for GPS, GPS/WAAS, and

XM antennas. Use this section to mount the antenna(s).

In an installation with multiple GDU 37X/4XX units, each GDU can be configured to use its own internal

GPS receiver, or to receive GPS data transmitted by another GDU. A minimum of one GPS antenna is required for installations using more than one GDU 37X/4XX unit, as the GDU will “share” the GPS information with all GDU units. Additional GPS antennas may be used for redundancy, but are not required. See

Section 34.4.15

(for GDU 37X systems) or

Section 35.4.24

(for GDU 4XX systems) for further information.

NOTE

The GPS 20A can only be used with GA 35, GA 36, or GA 37 antennas.

NOTE

GA 35, GA 36 and GA 37 antennas cannot be used with GDU 37X/4XX units.

NOTE

When a GPS 20A (and connected GPS/WAAS antenna) is installed, it can be used as the sole GPS for the system, however it is recommended to install a GPS antenna on at least one of the GDU 37X/4XX units for redundancy.

23.1 Non-Garmin Materials Required

BNC/TNC Coaxial Connectors May be required to terminate the antenna cable, depending upon which antenna is used. Check the antenna installation instructions for detailed information. Example below:

• Connector, BNC/TNC Coaxial, male, crimp (MIL-PRF-39012)

Coaxial Cable, 50Ω - MIL-DTL-17 (i.e. RG-400)

23.2 Non-Garmin Antennas

Table 23-1 lists non-Garmin antennas currently supported by the GDU 37X/4XX. For non-Garmin

antennas, follow the manufacturer’s installation instructions. It is the installer’s responsibility to ensure that their choice of antenna meets FAA standards according to the specific installation.

NOTE

The GPS antenna should provide a gain of 16 to 25 dB. The GDU 37X/4XX supplies power to the antenna at 4.5 V–5V with a maximum current of 50 mA.

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Page 23-1

Table 23-1 Supported Non-Garmin Antennas

Model

Comant

2480-201

VHF/GPS*

Comant

420-10 XM only Antenna

Mount Style

Screw Mount,

Teardrop

Footprint

Screw Mount,

ARINC 743

Footprint

Conn

Type

BNC

TNC

TNC

Antenna

Type

VHF

COM,

GPS

XM

Mfr

Comant

Comant

Antenna Part

Number

CI 2480-201

CI 420-10

Garmin Order

*The GPS antenna connector is TNC type. The VHF COM antenna connector is BNC type.

Number

N/A

N/A

23.3 Garmin Antennas

If using a Garmin GA 26C or GA 26XM, refer to the accompanying installation instructions

(190-00082-00 or 190-00522-03). For GA 35, GA 55/55A, or GA 56 or GA 57X antennas, refer to this

section and the outline and installation drawings in Section 23.8

.

Garmin recommends the antennas shown in Table 23-2. However, any equivalent GPS, GPS/WAAS, or

XM antenna that meets the specifications listed in Table 23-3 and Table 23-4 should work with the G3X.

Table 23-2 Supported Garmin Antennas

Model

GA 26C

Part Number

011-00149-04

Description

GPS Antenna

Weight

NA

Mounting Configuration

Flange, Magnetic, or Suction Cup

Mount (for in-cabin mounting)

GA 35*

(used with

GPS 20A only)

GA 36*

(used with

GPS 20A only)

013-00235-00

013-00244-00

GPS/WAAS

Antenna

GPS/WAAS

Antenna

0.47 lbs

(0.21 kg)

0.47 lbs

(0.21 kg)

Thru-mount (Tear-drop form factor)

Thru-mount (ARINC 743 style mount)

GA 37*

(used with

GPS 20A only)

013-00245-00

GPS/WAAS

+ SiriusXM

Antenna

0.50 lbs

(0.23 kg)


GA 55

GA 55A

GA 56

011-01033-00

011-01153-00

011-00134-00

XM Antenna

XM Antenna

GPS Antenna

0.25 lbs

(0.11 kg)

0.43 lbs

(0.20 kg)

0.24 lbs

(0.11 kg)

Stud mount (Tear-drop form factor)


Stud mount (Tear-drop form factor)

GA 57X 011-01032-10

GPS/XM

Antenna

0.47 lbs

(0.21 kg)


*For use with GPS 20A only, cannot be used with GDU 37X/4XX units

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Page 23-2

Table 23-3 GPS or GPS/WAAS Antenna Minimum Requirements

Characteristics

Frequency Range

Gain

Noise Figure

Nominal Output Impedance

Supply Voltage

Supply Current

Output Connector

Specifications

1565 to 1585 MHz

16 to 25 dB typical, 40 dB max.

<4.00 dB

50 Ω

4.5 to 5.5 VDC up to 50 mA

BNC or TNC

Table 23-4 XM Satellite Radio Antenna Minimum Requirements

Frequency Range

Gain (Typical)

Noise Figure

Characteristics Specifications

2332.5 to 2345 MHz

24 dB*

<1.2 dB

Nominal Output Impedance

Supply Voltage

Supply Current (maximum)

Operating Temperature Gain

50 Ω

3.6 to 5.5 VDC

55 mA

-50 to +85° C

*For each 1 dB gain over 24 dB, add 1 dB of attenuation into the antenna cable path between the antenna and the GDU.

It is the installer’s responsibility to ensure that their choice of antenna meets FAA standards according to

the specific installation. This installation manual discusses only the antennas listed in Table 23-2

. Other antennas may be acceptable but their installation is not covered by this manual.

There are several critical factors to take into consideration before installing an antenna for a satellite communications system. These factors are addressed in the following sections.

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23.4 Antenna Mounting Considerations

The information in this section does not pertain to in-cabin (internal) mounted antennas such as the

GA 26C, refer to the accompanying installation instructions (190-00082-00).

No special precautions need be taken to provide an electrical bonding path between the GPS Antenna and the aircraft structure.

23.4.1 VHF COM/GPS Interference

On some installation VHF COM transceivers, Emergency Locator Transmitter (ELT) antennas, and

Direction Finder (DF) receiver antennas can re-radiate through the GPS antenna. The GDU does not interfere with its own GPS receiver. However, placement of the GPS antenna relative to a COM transceiver and COM antenna, ELT antenna, and DF receiver antenna is critical.

Use the following guidelines, in addition to others in this document, when locating the GDU and its antennas.

• GPS Antenna—Locate as far as possible from all COM antennas and all COM transceivers, ELT antennas, and DF antennas. The GPS antenna is less susceptible to harmonic interference if a

1.57542 GHz notch filter is installed on the COM transceiver antenna output.

• Locate the GDU as far as possible from all COM antennas.

If a COM antenna is found to be the problem, a 1.57542 GHz notch filter (Garmin P/N 330-00067-00) may be installed in the VHF COM coax, as close to the COM as possible.

If a COM is found to be radiating, the following can be done:

1. Replace or clean the VHF COM rack connector to ensure good coax ground.

2. Place grounding straps between the GDU unit, VHF COM, and a good ground.

3. Shield the VHF COM wiring harness.

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23.4.2 GPS/XM Antenna Mounting Location

The GPS antenna is a key element in the overall system performance and integrity for a GPS navigation system. The mounting location, geometry, and surroundings of the antenna can affect the system performance and/or availability. The following guidance provides information to aid the installer in ensuring that the optimum location is selected for the installation of the GPS antenna. The installation guidelines presented here meet the intent of AC 20-138A section 16. The greater the variance from these guidelines, the greater the chance of decreased availability. Because meeting all of these installations guidelines may not be possible on all aircraft, these guidelines are listed in order of importance to achieve optimum performance. Items 4a - 4c below are of equal importance, and their significance may depend on the aircraft installation. The installer should use their best judgment to balance the installation guidelines.

1. Mount the antenna on top of the aircraft in a location with an unobstructed view of the sky, as close to level as possible with respect to the normal cruise flight attitude of the aircraft. If the normal flight attitude is not known, substitute the waterline, which is typically referenced as level while performing a weight and balance check.

2. The GPS antenna should be mounted in a location to minimize the effects of airframe shadowing during typical maneuvers. Typically mounting farther away from the tail section reduces signal blockage seen by the GPS antenna.

3. The GPS antenna should ideally be located at the opposite end of the aircraft from the COM unit in order to make the GPS less vulnerable to harmonics radiated from the COM itself.

4a. The GPS antenna should be mounted no closer than two feet (edge to edge) and ideally three feet from any VHF COM antenna or any other antenna which may emit harmonic (or other) interference at the L1 frequency of 1575.42 MHz. An aircraft EMC (Electromagnetic

Compatibility) check ( Section 34.4.15.1

for GDU 37X systems or Section 35.4.24.1

for

GDU 4XX systems) can verify the degradation of GPS in the presence of interference signals. If an EMC check reveals unacceptable interference, insert a GPS notch filter in line with the offending VHF COM or the (re-radiating) ELT transmitter.

NOTE

The separation requirement does not apply to GPS and COM combination antennas, provided the antenna has been tested to meet Garmin’s minimum performance standards.

The separating requirement includes the combination with an XM antenna element as well.

4b. The GPS antenna should be mounted no closer than two feet (edge to edge) and ideally three feet from any antennas emitting more than 25 watts of power. An aircraft EMC check can verify the degradation of GPS in the presence of interference signals.

4c. To minimize the effects of shadowing at 5° elevation angles, the GPS antenna should be mounted no closer than 6 inches (edge to edge) from other antennas, including passive antennas such as another GPS antenna or XM antenna.

5. To maintain a constant gain pattern and limit degradation by the windscreen, avoid mounting the antenna closer than 3 inches from the windscreen.

6. For multiple GPS installations, the antennas should not be mounted in a straight line from the front to the rear of the fuselage. Also varying the mounting location will help minimize any aircraft shading by the wings or tail section (in a particular azimuth, when one antenna is blocked the other antenna may have a clear view).

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Figure 23-1 shows the recommended placement of antennas.

4

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Figure 23-1 Recommended Antenna Placement


Page 23-6

23.4.3 Buried Antenna (below the skin covering or glareshield) Mounting

There are potential performance issues related to buried antennas that the kit builder/installer should be aware of prior to electing to install a buried antenna. See also

Section 23.7.2

, Non-structural Installation to

Glareshield.

• Some gain of the antenna may be lost as the signal needs to penetrate through the skin of the aircraft. The loss may not be apparent, but under the some of the worst case signal scenarios signal availability may be affected.

• The materials in some aircraft are not suitable for GPS signals to penetrate, care should be taken to properly modify the aircraft structure to accommodate this. Modifications of this sort are not recommended or inferred by Garmin or the installation of the GDU, and the installer should seek the guidance of the kit manufacture for such modifications.

• XM – FIS antennas may typically be buried without performance impact if the overlying material is fairly transparent to the satellite signal.

Figure 23-2 shows example areas of some mounting locations which have been used. Low satellite

reception and tracking are compromised in these installations due to fuselage and tail blockage. It is not possible to determine the full impact of these locations, however initial flight testing has not shown any significant impact to availability, your results may vary.

Figure 23-2 Carbon/Glass Buried Antenna Area

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Mounting the antenna under the glare shield (Figure 23-3) is a good option for XM – FIS antennas,

although it is not typically the best option for a GPS antenna. This location results in the aft fuselage shading the antenna.

Figure 23-3 Glare Shield Buried Antenna Area

NOTE

Due to the excessive temperature environment and large areas of signal blockage caused by the fuselage, mounting the antenna under the engine cowling (forward of the firewall) is not recommended and likely will not provide adequate GPS reception.

23.4.4 Antenna Doubler/Backing Plate

The antenna installation must provide adequate support for the antenna considering a maximum drag load of 5 lbs. (at subsonic speed). When penetrating the skin with a large hole (i.e. for the coax connector) a doubler plate is required to re-instate the integrity of the aircraft skin. Never weaken the aircraft structure when choosing a mounting area. Make use of any available reinforcements where appropriate.

23.4.5 Antenna Grounding Plane

Although no ground plane is required, the antennas typically perform better when a ground plane is used.

The ground plane should be a conductive surface as large as practical, with a minimum diameter of 8 inches. To use an antenna in aircraft with fabric or composite skin, a ground plane is recommended. It is usually installed under the skin of the aircraft, below the antenna, and is made of either aluminum sheet or of wire mesh.

23.4.6 Antenna Grounding

The antenna is grounded through the mounting hardware and the coax connection. The mounting hardware

(washers and nuts) and doubler plate should make contact with an unpainted grounded surface ensuring proper antenna grounding. It is important to have good conductivity between the coaxial shield and the ground plane. The bottom of the antenna does not need to make contact with the ground plane (i.e. the surface may be painted). The antenna will capacitively couple to the ground plane beneath the paint or aircraft cover.

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Page 23-8

23.5 Teardrop Footprint Antenna Installation (GA 35, GA 55, and GA 56)

This section describes the structural mounting of the teardrop footprint antenna installation.

An acceptable installation method is to use Garmin P/N: 115-00846-10 doubler plate with the GA 35 through-hole, or GA 55/GA 56 stud mount antennas. Another acceptable method is to fabricate and install

one of three doublers ( Figure 23-4

,

Figure 23-5

, and Figure 23-6 ), depending on the thickness of the skin.

The three doubler designs vary only by number of rivets and hole preparation for installation with flush

rivets. Table 23-5 provides a summary of design and installation details for selecting the appropriate

antenna doubler/backplate.

Figure 23-7

shows an example of the doubler installed between stringers on the top fuselage skin, just off centerline. The location should be flat, with no gaps between the skin and doubler, to keep from deforming the skin during installation.

Table 23-5 Teardrop Footprint Antenna Doubler Design and Installation

Aircraft Skin Thickness

Doubler Design (Figure)

Number of Rivets Required

0.032” to 0.049”

Figure 23-4

12

0.049” to 0.051”

Figure 23-5

16

0.051” to 0.063”

Figure 23-6

16

Type of Rivets Required 1

Skin Preparation for Rivets

Doubler Preparation for Rivets

Skin Cutout Detail (Figure)

Doubler Installation (Figure)

MS20426AD4-x

Dimple

Countersink

Figure 23-8

Figure 23-11

MS20426AD4-x

Dimple

Countersink

Figure 23-9

Figure 23-12

MS20426AD4-x

Countersink

None

Figure 23-10

Figure 23-13

1 Rivet length determined at installation, dependent on thickness of material (rivet length = grip length +

1.5 * rivet diameter)

Refer to the drawings in Section 23.8

for Garmin Antenna installation drawings.

23.5.1 Preparation of Doubler

1. Use Garmin P/N: 115-00846-10, or refer to Table 23-5 for guidance on selecting the appropriate

doubler drawing based on the thickness of skin at the antenna location. Make the doubler from

2024-T3 Aluminum (AMS-QQ-A-250/5), 0.063” sheet thickness.

2. For installation in aircraft skins of thickness less than 0.051”, countersink the rivet holes in the doubler for use with flush head rivets (MS20426AD4-x).

3. When using Garmin P/N: 115-00846-10 doubler, sixteen rivet holes exist in the part. For installation of Garmin P/N: 115-00846-10 in skins of thickness between 0.032” and 0.049”, only

the rivets identified for use through the skin cutout detail ( Figure 23-8 ) and doubler installation

( Figure 23-11

) are required.

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23.5.2 Teardrop Antenna Installation Instructions

1. Refer to

Table 23-5

and the outline and installation drawings in Section 23.8

for installation

guidance and selecting the appropriate mounting cutout. Drill or punch the holes to match the mating part (doubler).

2. Install a doubler plate to reinforce the aircraft skin, as required. Refer to Section 23.5.1

for doubler

preparation and Table 23-5 for additional guidance on the doubler installation. Dimple aircraft skin

when the skin thickness is less than 0.051” for installation of flush head rivets. Countersink aircraft skin when the skin thickness is between 0.051” and 0.063” for installation of flush head rivets.

3. For the GA 35, secure the O-ring in the O-ring groove on the underside of the antenna. Place the antenna over the mounting holes, using the four screw holes to align the antenna and insert the supplied four screws ( Figure 23-32 ).

CAUTION

GA 35 serial numbers below 110000 required screws with 80 degree countersink angle and most aviation fasteners (AN509) are NOT compatible. Serial numbers

110000 and higher, AN509 hardware is compatible. Antennas installed with incompatible hardware or screws that have been over tightened will void antenna warranty.

4. For a stud mount teardrop footprint antenna, place the install gasket on top of aircraft skin using

the four screw holes to align the gasket ( Figure 23-35 ,

Figure 23-37 ).

5. Washers and locking nuts (not provided) are required to secure the antenna. Torque the four #8-32 stainless steel locking nuts 12-15 in-lbs. Torque should be applied evenly across all mounting studs or screws to avoid deformation of the mounting area.

6. Ensure that the antenna base and aircraft skin are in continuous contact with the gasket or o-ring, as appropriate to the antenna model.

7. Seal the antenna and gasket to the fuselage using Dow Corning 738 Electrical Sealant or equivalent. Run a bead of the sealant along the edge of the antenna where it meets the exterior aircraft skin. Use caution to ensure that the antenna connectors are not contaminated with sealant.

CAUTION

Do not use construction grade RTV sealant or sealants containing acetic acid.

These sealants may damage the electrical connections to the antenna. Use of these type sealants may void the antenna warranty.

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23.5.3 Reference Figures

Figure 23-4 Doubler Design, Teardrop Footprint Antenna, Skin Thickness 0.032" to 0.049"


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Page 23-11


Figure 23-7 Sample Doubler Location, Teardrop Footprint Antenna, Metal Skin Aircraft

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Page 23-12

Figure 23-8 Skin Cutout Detail, Teardrop Footprint Antenna, Skin Thickness 0.032" to 0.049"


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Page 23-13


Figure 23-11 Doubler Installation, Teardrop Footprint Antenna, Skin Thickness 0.032" to 0.049"

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Page 23-15

23.6 ARINC 743 Footprint Antenna Installation (GA 36, GA 37, GA 55A, GA 57X)

This section describes the structural mounting of the ARINC 743 footprint antenna (GA 36, GA 37, GA

55A, GA 57X) installation. One acceptable method is to use Garmin P/N: 115-00846-00 doubler plate.

Another acceptable method is to fabricate and install one of three doublers, Figure 23-14 ,

Figure 23-15

, or

Figure 23-16 , depending on the thickness of the skin. The three doubler designs vary only by number of

rivets and hole preparation for installation with flush rivets.

Figure 23-24

shows installation of the ARINC

743 footprint antenna.

Table 23-6 provides a summary of design and installation details for the antenna doubler.

Figure 23-17

shows an example of the doubler installed between stringers on the top fuselage skin, just off centerline.

The location should be flat, with no gaps between the skin and doubler, to keep from deforming the skin during installation.

Table 23-6 ARINC 743 Footprint Antenna Doubler Design and Installation

Skin Thickness

Doubler Design (Figure)

Number of Rivets Required

0.032” to 0.049”

Figure 23-14

12

0.049” to 0.051”

Figure 23-15

16

0.051” to 0.063”

Figure 23-16

16

Type of Rivets Required 1

Skin Preparation for Rivets

Doubler Preparation for Rivets

Skin Cutout Detail (GA 55A)

Doubler Installation (Figure)

MS20426AD4-x

Dimple

Countersink

Figure 23-18

Figure 23-21

MS20426AD4-x

Dimple

Countersink

Figure 23-19

Figure 23-22

MS20426AD4-x

Countersink

None

Figure 23-20

Figure 23-23

1 Rivet length determined at installation, dependent on thickness of material (rivet length = grip length +

1.5 * rivet diameter)

23.6.1 Preparation of Doubler

1. Use Garmin P/N: 115-00846-00, or refer to Table 23-6 for guidance on selecting the appropriate

doubler drawing based on the thickness of skin at the antenna location. Make the doubler from

2024-T3 Aluminum (AMS-QQ-A-250/5), 0.063” sheet thickness.

2. For installation in aircraft skins of thickness less than 0.051”, countersink the rivet holes in the doubler for use with flush head rivets (MS20426AD4-x).

3. When using Garmin P/N: 115-00846-00 doubler, sixteen rivet holes exist in the part. For installation of Garmin P/N: 115-00846-00 in skins of thickness between 0.032” and 0.049”, only

the rivets identified for use through the skin cutout detail ( Figure 23-18

) and doubler installation

( Figure 23-21

) are required.

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23.6.2 ARINC 743 Antenna Installation Instructions

1. Refer to

Table 23-6

and the outline and installation drawings in Section 23.8

for installation

guidance and selecting the appropriate mounting cutout. Drill or punch the holes to match the mating part (doubler).

2. Install a doubler plate to reinforce the aircraft skin, as required. Refer to Section 23.6.1

for doubler

preparation and Table 23-6 for additional guidance on the doubler installation. Dimple aircraft skin

when the skin thickness is less than 0.051” for installation of flush head rivets. Countersink aircraft skin when the skin thickness is between 0.051” and 0.063” for installation of flush head rivets.

3. Secure the O-ring in the O-ring groove (if applicable, per Figure 23-33 ,

Figure 23-34 ) on the

underside of the antenna.

4. Place the install gasket (if applicable, per Figure 23-36

or

Figure 23-38 ) on top of aircraft skin

using the four screw holes to align the gasket.

5. Locking nuts and washers (not provided) are required to secure the GA 36 and GA 37 per

Figure 23-33 ,

Figure 23-34

(or may use locking nuts installed on doubler plate, if applicable).

GA 55A ( Figure 23-36 ) and GA 57X (

Figure 23-38 ) use locking nuts installed on doubler plate.

Torque the four supplied #10-32 stainless steel screws (Garmin P/N: 211-60212-20, MS51958-67, or equivalent) 20-25 in-lbs. Torque should be applied evenly across all mounting studs to avoid deformation of the mounting area.

6. Ensure that the antenna base and aircraft skin are in continuous contact with the gasket (if applicable).

7. Seal the antenna and gasket to the fuselage using Dow Corning 738 Electrical Sealant or equivalent. Run a bead of the sealant along the edge of the antenna where it meets the exterior aircraft skin. Use caution to ensure that the antenna connectors are not contaminated with sealant.

CAUTION

Do not use construction grade RTV sealant or sealants containing acetic acid.

These sealants may damage the electrical connections to the antenna. Use of these type sealants may void the antenna warranty.

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Page 23-17

23.6.3 Reference Figures

Figure 23-14 Doubler Design, ARINC 743 Footprint Antenna, Skin Thickness 0.032" to 0.049"

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Page 23-18

Figure 23-15 Doubler Design, ARINC 743 Footprint Antenna, Skin Thickness 0.049" to 0.051"

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Page 23-19

Figure 23-16 Doubler Design, ARINC 743 Footprint Antenna, Skin Thickness 0.051" to 0.063”

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Page 23-20

Figure 23-17 Sample Doubler Location, ARINC 743 Antenna, Metal Skin Aircraft

Figure 23-18 Skin Cutout Detail, ARINC 743 Footprint Antenna, Skin Thickness 0.032" to

0.049"

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Page 23-21

Figure 23-19 Skin Cutout Detail, ARINC 743 Footprint Antenna, Skin Thickness 0.049" to 0.051"

Figure 23-20 Skin Cutout Detail, ARINC 743 Footprint Antenna, Skin Thickness 0.051" to 0.063"

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Page 23-22

Figure 23-21 Doubler Installation, ARINC 743 Footprint Antenna, SkinThickness 0.032" to 0.049"

Figure 23-22 Doubler Installation, ARINC 743 Footprint Antenna, SkinThickness 0.049" to 0.051"

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Page 23-23

Figure 23-23 Doubler Installation, ARINC 743 Footprint, Skin Thickness 0.051" to 0.063"

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Figure 23-24 Installation of ARINC 743 Footprint Antenna


Page 23-24

23.7 Non-Structural Mount Installation

This section provides installation examples and considerations for non-structural mounting of teardrop and

ARINC 743 footprint antennas. Typical installations may be below a non-metallic glareshield, under the composite or fabric skin, or on an external, non-structural surface. Other non-structural installations may exist, but are not presented in this manual.

External mounting of the antenna is preferred, although the antenna can be mounted inside the aircraft.

When mounted internally, the antenna does not have to be aligned with the aircraft forward direction, but should be equal to the aircraft typical cruise attitude.

There should be a solid mechanical base in the mounting area for the antenna, and existing surfaces or brackets may be used with the doubler plate. Alternately, non-structural brackets may be fabricated in the field as necessary to mount the antenna. Brackets should be made of minimum 0.032” thickness aluminum and should span as short a distance as possible.

Some fabric aircraft include aluminum paste in the fabric finishing process, often referred to as “silver coats”. Presence of thick fabric and/or heavy “silver coats” may degrade the signal strength of the antenna.

23.7.1 Generic Non-structural Antenna Installation

Figure 23-25 shows the generic non-structural installation for the ARINC 743 footprint (GA 36, GA 37,

GA 55A/GA 57X) antenna. The teardrop footprint antennas (GA 35, GA 55, GA 56 stud mount) can also be installed in this manner.

For mounting the teardrop style antenna (GA 35, GA 55, or GA 56), a doubler plate similar to

Figure 23-4

or P/N 115-00846-10 can be used with the mounting surface to support the antenna. Rivets used to secure the doubler plate to the mounting surface are optional in a non-structural installation. Screws, washers, and locking nuts as shown in the outline and installation drawings in

Section 23.8

are required to secure the

Teardrop style antenna to the mounting surface. Torque the locking nuts to 12-15 in-lbs, torque should be applied evenly across all mounting studs.

A doubler plate similar to

Figure 23-11

, or P/N 115-00846-00 (ARINC 743 style) can be used with the mounting surface to support the antenna. Rivets used to secure the doubler plate to the mounting surface are optional in a non-structural installation. Locking nuts are required to secure the ARINC 743 antenna

(locking nuts installed on doubler). Torque the four supplied #10-32 stainless steel screws (Garmin P/N:

211-60212-20, MS51958-67, or equivalent) evenly across all mounting screws.

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Page 23-25

Figure 23-25 Generic Non-structural ARINC 743 Footprint Antenna Installation

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Page 23-26

23.7.2 Non-Structural Installation to Glareshield

Figure 23-26 shows an example of a bracket created to support an antenna mounted on the underside of the glare shield. Figure 23-27 shows the non-structural mounting of the antenna under the glareshield, with the bracket assembly shown in Figure 23-26.

Figure 23-26 Example Bracket Antenna Mounting Under Glareshield

Figure 23-27 Example Non-structural Antenna Mounting Under Glareshield

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Page 23-27

23.7.3 Non-structural Installation to Airframe

Internal Non-structural Installation

Figure 23-28 and Figure 23-29 show examples of under the fabric skin non-structural mounting of the

antenna to the airframe of a tube-and-fabric aircraft.

In Figure 23-28, a bracket is made to attach to the airframe, just under the fabric for a teardrop antenna

installation. The doubler plate and mounting hardware described in the generic installation (

Section 23.7.1

)

are used with the bracket as the antenna mounting surface. In Figure 23-29, a similar case is shown using

the generic installation of the ARINC 743 footprint antenna. The doubler plate is optional for this type of installation with either the Teardrop or the ARINC 743 antenna.

Figure 23-28 Example Teardrop Antenna Installation In Airframe Under Fabric Skin

Figure 23-29 Example ARINC 743 Footprint In Airframe Under Fabric Skin

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Page 23-28

External Non-structural Installation

Figure 23-30 is an example of an external, non-structural mounting of the antenna in a tube-and-fabric

aircraft. The antenna support bracket shown should be made of 2024-T3 Aluminum with a minimum material thickness 0.032” and maximum distance between airframe tubes of 36”. The bracket is installed to the airframe under the fabric, and the antenna is mounted externally to the bracket. The generic installation of the (

Section 23.7.1

) antenna is used, with the antenna support bracket as the mounting surface. Follow the applicable gasketing and sealant instructions in

Section 23.5.2

(Teardrop style) or

Section 23.6.2

(ARINC 743 style).

Figure 23-30 Example Non-structural Antenna Mounting On Airframe

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Page 23-29

Minimum Distance from Metal Tube Structure Requirements

Figure 23-31 shows minimum distance from metal tube structure requirements for internal, non-structural mounting of the antenna. Table 23-7 presents minimum distance requirements between the tube structure

and the antenna for cases where the antenna sits underneath the fabric in a metal-tube structure aircraft.

Figure 23-31 illustrates the tube diameter (d) and minimum distance (l) references in the Table 23-7.

Figure 23-31 Example Teardrop Footprint Antenna Mounting Under Fabric Skin

.

Table 23-7 Minimum Distance Required Between Tube Structure and Antenna

Illustrated Case

Top of antenna at or above the center of the tube structure

(Figure 23-31, top)

Top of antenna between the center and bottom of the tube

structure (Figure 23-31, bottom)

Tube Diameter d (in)

0.625

0.75

1.00

1.25

0.625

0.75

1.00

1.25

Minimum

Distance l (in)

3.6

4.3

5.7

7.2

7.2

8.6

11.5

14.3

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Page 23-30


190-01115-01

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Figure 23-32 GA 35 Installation Drawing


Page 23-31

R

A

D

W

R

O

F

S) 0] (2 HOLE

17.8] 0.70 [

0 [0.

0.80 [20.3]

[58.4] 2.30

2X 1.60 [40.6]

RD WA FOR

DO NOT PAINT

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Page 23-32

R

A

D

W

R

O

F

] [58.4

2.30

2X 1.60 [40.6]

HOLES)

80 [20.3] 2X 0.

0 [0.0] (2

0.70 [17.8]

ARD FORW

DO NOT PAINT

190-01115-01

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Page 23-33

GA 55 STUD MOUNT

011-00134-00

ANTENNA, AVIATION,

GA 55

FORWARD

253-00002-00

GASKET, NEOPRENE

AIRCRAFT SKIN

ON TOP OF FUSELAGE

115-00031-00

BACKING PLATE

4X 210-10004-09

#8-32 SELF LOCKING NUT

1.91 48.5

.22 5.6

4X #8-32 STUD

FORWARD

4.23 107.4

SIDE VIEW

.50 12.7

2.59 65.8

FRONT VIEW

BNC CONNECTOR

3.00 76.2

2X 1.625 41.28

.813 20.64

4X .188 4.78

190-01115-01

Rev. AN

.625 15.88

2.59 [65.8]

BACKING PLATE

OUTLINE

MOUNTING CUTOUT

(ANTENNA OUTLINE)



Page 23-34

GA 55A FLANGE MOUNT

FORWAR

D

4X 211-60212-20

#10-32 PHP x 1.00[25.4]

TORQUE 20 TO 25 in-lbs

011-01153-00

GA 55A XM ANTENNA

253-00138-00

MOLDED GASKET

AIRCRAFT SKIN

.49 12.3

2.90 73.7

.60 15.2

.80

20.2

FABRICATE AND INSTALL DOUBLER PLATE

AS REQUIRED TO COMPLY WITH APPLICABLE

AIRWORTHINESS REGULATIONS

FORWARD

2.37 60.2

4.70 119.4

.25 6.4

XM

TNC CONNECTOR

190-01115-01

Rev. AN

.70 17.8

2X 0

011-01153-00

ANTENNA OUTLINE

.750

.625

19.05

15.88

2.350 59.69

2X 3.300 83.82

4X .220

5.59

MOUNTING CUTOUT

NOTES:

1. DIMENSIONS: INCHES[mm]

Figure 23-36 GA 55A Installation Drawing


Page 23-35

GA 56 STUD MOUNT

011-00134-00

ANTENNA, AVIATION,

GA 56

FORWARD

AIRCRAFT SKIN

ON TOP OF FUSELAGE

115-00031-00

BACKING PLATE

4X 210-10004-09

#8-32 SELF LOCKING NUT

1.91 48.5

.22 5.6

4X #8-32 STUD

FORWARD

4.23 107.4

SIDE VIEW

.50 12.7

2.59 65.8

FRONT VIEW

BNC CONNECTOR

190-01115-01

Rev. AN

3.00 76.2

2X 1.625 41.28

.813 20.64

4X .188 4.78

.625 15.88

2.59 [65.8]

MOUNTING CUTOUT

(ANTENNA OUTLINE)



Page 23-36

FORWARD

4X 211-60212-20 #10-32 PHP x 1.00[25.4]

011-01032-10 GA 57X GPS/XM ANTENNA

FABRICATE AND INSTALL DOUBLER PLATE AS REQUIRED TO COMPLY WITH APPLICABLE AIRWORTHINESS REGULATIONS

011-01032-00 ANTENNA OUTLINE

19.05 15.88

.750 .625

20.3

40.64

2X.800

2X1.600

.6516.5

2X0

190-01115-01

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FORWARD

Figure 23-38 GA 57X Installation Drawing


Page 23-37

24 ENGINE/AIRFRAME SENSOR INSTALLATION

24.1 Engine/Airframe Sensor Options

Table 24-1 lists the types of engine/airframe sensors that may be used for the various engine/airframe

inputs. Many of these sensors are included in the Garmin G3X Sensor Kits ( Section 24.2

). Each of the sensors must be correctly installed and configured (

Section 34.4.19

for GDU 37X systems and

Section 35.4.32

for GDU 4XX systems) prior to use.

NOTE

In addition to the engine sensors listed in Table 24-1, the G3X system can also work with

many other sensors (not listed) that output a compatible signal, refer to the sensor specifications to determine compatibility.

Table 24-1 Compatible Engine/Airframe Input Sensors

SENSOR TYPE

COMPATIBLE

SENSORS

10-29 Vdc input

Amploc KEY100 Hall effect sensor

UMA 1C4 shunt

GARMIN PART

N/A

N/A

NUMBER*

+/- 100 A

NOTES

Bus Current

Other ammeter shunt or

Hall effect sensor types

Rotax 965531

Rotax 966385

50-150C Thermistor (e.g.

VDO 320-XXX series)

909-D0000-00

N/A

N/A

N/A

N/A

+/- 100 A

Uses custom user-defined calibration (millivolts to amps)

Carburetor

Temperature

Type K Thermocouple

MS28034/

MIL-T-7990 RTD

N/A

N/A

UMA 1B10R RTD 494-70005-00

UMA temperature sensors without the "R" designation are not compatible

0-75 psiG

Coolant Pressure

Custom Analog

Parameter

Kavlico P4055-5020-3

Any voltage-output pressure transducer

Any voltage-output sensor

011-04202-20

N/A

N/A

Uses custom user-defined calibration (voltage to pressure)

Uses custom user-defined sensor calibration

*Items with a Garmin part number may be included in a G3X Sensor Kit (

Section 24.2

), and are available

individually from Garmin Dealers

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G3X/G3X Touch Installation Manual - Engine/Airframe Sensor Installation

Page 24-1


SENSOR TYPE

COMPATIBLE

SENSORS


VDO 320-XXX series)

GARMIN PART

N/A

NUMBER*

NOTES

RTD (e.g. UMA 1B3XR series)

N/A


Custom

Temperature

Rotax 965531 (thermistor) N/A

Rotax 966385 (thermistor) N/A

Type J thermocouple N/A

Type K thermocouple

MS28034 (MIL-T-7990

RTD)

N/A

N/A

Cylinder Head

Temperature

(CHT)


VDO 320-XXX series)

Type J Thermocouple

Type K Thermocouple

(Alcor 86253)

Type K Thermocouple

(other)

Rotax 965531

Rotax 966385

N/A

N/A

494-70000-00

N/A

N/A

N/A

Discrete Inputs

Active High or Low:

Canopy Warning, Gear

Down Reminder, etc.

N/A


Pressure Sensor,150 PSIG 011-04202-30

Uses custom user-defined calibration (0-150 psiG pressure to torque)

Engine Torque

Exhaust Gas

Temperature

(EGT)

Any voltage-output torque transducer

Type K thermocouple

(Alcor 86255)

Type K thermocouple

(other)

N/A

494-70001-00

N/A

Uses custom user-defined calibration (voltage to torque)

*Items with a Garmin part number may be included in a G3X Sensor Kit ( Section 24.2

), and are available individually from Garmin Dealers

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Page 24-2


SENSOR TYPE

COMPATIBLE

SENSORS

EI FT-60

EI FT-90

EI FT-180

GARMIN PART

NUMBER*

494-10001-00

N/A

N/A

0-70 gal/hr

0-125 gal/hr

0-250 gal/hr

NOTES

Fuel Flow

(two sensors required for differential fuel flow)

Floscan Series 200

Floscan 231

Any frequency-output fuel flow transducer

N/A

N/A

N/A

0-60 gal/hr

0-90 gal/hr

Uses custom user-defined calibration (0-5 kHz frequency to fuel flow)

0-15 psiG

Fuel Pressure



Kavlico P4055-75G

UMA EU07D

UMA 1EU35G

UMA 1EU70D

UMA 1EU70G

UMA 1EM2K

Any voltage-output pressure sensor

Any capacitive fuel quantity sensor (requires external conversion to voltage or frequency)

011-04202-10

011-04202-20

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

0-75 psiG

0-75 psiG

0-7 psi differential

0-35 psiG

0-70 psi differential

0-70 psiG

0-2500 psiG


Uses custom user-defined calibration (voltage or frequency to fuel quantity)

Fuel Quantity

Any resistive fuel quantity sensor

Any voltage-output fuel quantity sensor

Any frequency-output fuel quantity sensor

N/A

N/A

N/A

Uses custom user-defined calibration (voltage to fuel quantity)

Uses custom user-defined calibration (voltage to fuel quantity)

Uses custom user-defined calibration (frequency to fuel quantity)



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Page 24-3


SENSOR TYPE

Manifold

Pressure

Miscellaneous

Pressure

Oil Temperature

COMPATIBLE

SENSORS

Kavlico P4055-30A-E4A

Kavlico P500-30A-E4A

UMA 1EU50A

GARMIN PART

NUMBER*

494-30004-01

N/A

N/A

N/A UMA 1EU70A


Kavlico P4055-5020-3 011-04202-20



UMA 1EM2K


N/A

N/A

N/A

Jabiru (VDO 320-021)

Rotax 965531

Rotax 966385


VDO 320-XXX series)

Type K Thermocouple

N/A

N/A

N/A

N/A

N/A

0-30 psiA, 0-60 inches Hg





0-75 psiG

0-150 psiG

0-2500 psiG

NOTES


UMA 1B3-2.5R RTD 494-70004-00


Oil Pressure

MS28034 (MIL-T-7990

RTD)

Jabiru (VDO 360-003)

N/A

N/A



Rotax 456180 N/A

Rotax 956413

Rotax 956415

UMA 1EU150G

Any voltage-output pressure sensor

N/A

N/A

N/A

N/A

0-150 psiG

0-150 psiG




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Page 24-4


SENSOR TYPE

Position Sensor

COMPATIBLE

SENSORS

Any trim servo with integrated position potentiometer

Any standalone potentiometer

Electronic Ignition

Jabiru Alternator Output

JPI 4208XX (Slick/Bendix magneto, pressurized)

Rotax Trigger Coil

UMA 1A3C-2

GARMIN PART

N/A

N/A

N/A

N/A

N/A

NUMBER*

NOTES

Uses custom user-defined calibration (voltage to position)

Uses custom user-defined calibration (voltage to position)

1-4 pulses/revolution

Single phase, 6 pulses/revolution

N/A

N/A

N/A

RPM

UMA 1A3C-4

UMA T1A9-1 (Slick magneto)

UMA T1A9-2 (Bendix magneto)

Turbine engine RPM

(requires Sandia ST26 signal converter)

494-50005-00

494-50005-01

N/A

Uses custom user-defined calibration (0-1000 Hz to RPM)

Any frequency-output RPM sensor

N/A

Uses custom user-defined calibration (0-1000 Hz to RPM)

Turbine Inlet /

Outlet /

Interstage

Temperature

(TIT/TOT/ITT)

Type K thermocouple N/A



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Page 24-5

The Engine inputs being monitored are displayed as gauges on the EIS display (Figure 24-1) and also on

the MFD Engine Page.

Figure 24-1 EIS Display (Engine Bar)

The following list of gauges, (if configured) are specifically required by FAR 91.205 and will always be displayed on the EIS display (engine bar). Other gauges will be displayed as space permits based on a predefined priority and user selections.

RPM

Fuel Quantity

Oil Temperature Oil Pressure

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Page 24-6

24.2 Engine Sensor Applications

24.2.1 Lycoming/Continental Engine Applications

Table 24-2 and Table 24-3 list Garmin sensor kits available for G3X installations with 4-cylinder and

6-cylinder Lycoming and Continental piston engines. Refer to Sensor Interface drawings in Section 31

for sensor wiring guidance.

Table 24-2 Contents of G3X Sensor Kit, 4 Cylinder Lycoming/Continental (K00-00512-00)

Item

Fuel Flow Transducer, EI FT-60

Kavlico P4055-5020-4 Pressure Sensor, 150 PSIG

Manifold Pressure Transducer, Powered, 30 psi, Absolute, w/connector, Kavlico P4055-30A-E4A

Type K Thermocouple, 3/8-24 Threaded, CHT, Alcor 86253

Type K Thermocouple, Clamp, EGT, Alcor 86255

RTD, Oil Temperature, UMA 1B3-2.5R

Shunt, Ammeter, +/-50 mV, 100 amps, UMA 1C4

Garmin P/N

494-10001-00

011-04202-30

494-30004-01

494-70000-00

494-70001-00

494-70004-00

909-D0000-00

Quantity

1

1

1

1

1

4

4

Table 24-3 Contents of G3X Sensor Kit, 6 Cylinder Lycoming/Continental (K00-00513-00)

Item

Fuel Flow Transducer, EI FT-60


Manifold Pressure Transducer, Powered, 30 psi, Absolute, w/connector, Kavlico P4055-30A-E4A

Type K Thermocouple, 3/8-24 Threaded, CHT, Alcor 86253


RTD, Oil Temperature, UMA 1B3-2.5R

Shunt, Ammeter, +/-50 mV, 100 Amps, UMA 1C4

Garmin P/N

494-10001-00

011-04202-30

494-30004-01

494-70000-00

494-70001-00

494-70004-00

909-D0000-00

Quantity

1

1

1

1

1

6

6

For 8-cylinder Lycoming engine applications, refer to Section 24.2.5

.

For retrofit applications, where a G3X system is installed in a completed aircraft with a Lycoming/

Continental engine, refer to

Section 24.2.6

.

24.2.1.1 Lycoming/Continental RPM

Engine speed for Lycoming and Continental engines may be sensed by an RPM sensor mounted on the mechanical tach drive, a sensor mounted on the magneto, or via the digital tach signal output from an electronic ignition system. Refer to

Section 24.3.5

.

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Page 24-7

24.2.1.2 Lycoming/Continental Fuel Pressure

Fuel pressure sensors for Lycoming and Continental engines are not included in the Garmin sensor kits, due to differences between pressure ranges for carbureted and fuel-injected engines. For monitoring

Lycoming/Continental engine fuel pressure, select a sensor from Table 24-1

as appropriate:

• Fuel-injected engines typically use the Kavlico P4055-5020-3 sensor (0-75 psiG, Garmin part number 011-04202-20).

• Carbureted engines typically use the Kavlico P4055-5020-2, sensor (0-15 psiG, Garmin part number 011-04202-10)

NOTE

Lycoming EIS display ranges are typically set to correspond with the pressure at the inlet to the fuel injector. Continental EIS display ranges are typically set to correspond to unmetered fuel pressure values.

24.2.1.3 Lycoming iE2

The G3X system is capable of monitoring the following engine parameters from the Lycoming iE2

FADEC digital interface, when connected via a GEA 24:

• RPM

• Manifold pressure

• Oil pressure

• Oil temperature

• Exhaust gas temperature

• Cylinder head temperature

• Turbine inlet temperature

• Fuel pressure

• ECU bus voltage

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Page 24-8

24.2.2 Rotax Engine Applications

Refer to the Sensor Interface drawings in Section 32 for all Rotax engine applications.

24.2.2.1 Rotax 912

Table 24-4 lists the Garmin sensor kit available for G3X installations with Rotax 912 engines.

Table 24-4 Contents of G3X Sensor Kit, Rotax 912 (K00-00514-00)

Item Garmin P/N

G3X External Components for Rotax 912 RPM Signal (see Table 24-5 ) 011-02348-00

Manifold Pressure Transducer, Powered, 30 psi, Absolute, w/ connector, Kavlico P4055-30A-E4A



494-30004-01

011-04202-10

494-70001-00

Shunt, Ammeter, +/-50 mV, 100 Amps, UMA 1C4 909-D0000-00

Quantity

1

1

1

2

1

Rotax engine RPM is sensed via a connection to the engine trigger coil. The external components listed in

Table 24-5 are required for use with the GSU 73 (see Figure 32.3).

Table 24-5 Contents of G3X External Components for Rotax 912 RPM Signal Kit

(011-02348-00)

Item

Silicon Diode, 1A, 200V

7.5 V Zener Diode

300 Ω Resistor, 1%, 0.5 W

Garmin P/N

680-00006-D0

682-00012-00

902-A300R-F0

Quantity

2

1

2

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Page 24-9

24.2.2.2 Rotax 914

Table 24-6 lists the sensors used for G3X installations with Rotax 914 engines. Order all sensors in the

Rotax 912 sensor kit (K00-00514-00) except the 494-30004-03 fuel pressure sensor. Instead, use the

UMA 1EU07D differential fuel pressure sensor.

Table 24-6 Rotax 914 Sensors

RPM

Sensor Type

Manifold pressure

Oil pressure

Oil temperature

Exhaust gas temperature

Details/Part Number

Use Rotax tachometer output along with external components from

011-02348-00 kit

Use Kavlico P4055-30A-E4A (494-30004-01)

Use Rotax-supplied sensor

Use Rotax-supplied thermistor

Use Type K thermocouple (494-70001-00)

Cylinder head temperature Use Rotax-supplied thermistor

Fuel pressure Use UMA 1EU07D differential fuel pressure sensor

Fuel flow Use EI FT-60 (494-10001-00) or Floscan 201B-6

24.2.2.3 Rotax 912iS/915iS

The G3X system is capable of monitoring the following engine parameters from the Rotax 912iS/915iS

FADEC digital interface, when connected to the dedicated FADEC CAN interface on a GEA 24:

• RPM


• Manifold air temperature

• Oil pressure

• Oil temperature


• Coolant temperature

• Fuel flow

• ECU bus voltage

• Throttle position

• Percent Power (Rotax 915iS only)

See

Figure 32-2.2

for GEA 24 to Rotax FADEC wiring information.

Fuel pressure for Rotax FADEC engines may be monitored using one of the two following methods:

• Use UMA 1EU70D differential sensor for fuel pressure.

• With a GDU 4XX system, select an appropriate fuel pressure sensor from

Table 24-1 as

appropriate, and configure the sensor to display fuel pressure relative to manifold pressure (see

Section 35.4.32.11

).

Refer to Section 24.2.10

for information about FADEC engine status display.

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Page 24-10

24.2.3 Jabiru Engine Applications

Table 24-7 lists the sensors used in G3X installations with Jabiru engines. See

Section 33

for Jabiru engine sensor wiring information.

Table 24-7 Jabiru Sensors

RPM

Sensor Type

Manifold pressure

Oil pressure


Use Jabiru tachometer output from alternator

Use Kavlico P4055-30A-E4A (494-30004-01)

Use Jabiru-supplied VDO pressure sensor, or Kavlico P4055-150G-E4A

(494-0004-00)

Oil temperature


Use Jabiru-supplied VDO 50-150°C thermistor, or any compatible RTD such as UMA 1B3XR series

Use Jabiru-supplied Type K thermocouples

Cylinder head temperature Use Jabiru-supplied Type J thermocouples

Fuel pressure Use Kavlico P4055-5020-2 (011-04202-10)

Fuel flow Use EI FT-60 (494-10001-00) or Floscan 201B-6

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Page 24-11

24.2.4 UL Power Engine Applications

The G3X system is capable of monitoring the following engine parameters from the UL Power FADEC digital interface, when connected to the dedicated FADEC CAN interface on a GEA 24:

• RPM


• Oil pressure

• Oil temperature

• Cylinder head temperature


• Fuel pressure

• Fuel flow

• ECU bus voltage

Refer to Section 24.2.10

for information about FADEC engine status display.

For UL Power engine installations that do not support a digital interface to the GEA 24, the engine sensors

shown in Table 24-8 may be used.

Table 24-8 UL Power Sensors

RPM

Sensor Type Details/Part Number

Use ECU tachometer output and select "Electronic Ignition

(2 pulses/revolution)"

Use Kavlico P4055-30A-E4A (494-30004-01) Manifold pressure

Oil Pressure

Oil temperature

Fuel flow

Kavlico P4055-5020-4 Pressure Sensor, 150 PSIG (011-04202-30)

Use UMA 1B3-2.5R RTD (494-70004-00)

Exhaust gas temperature Use Type K thermocouples

Cylinder head temperature Use Type K thermocouples

Fuel Pressure Kavlico P4055-5020-30 (011-04202-20)

Use ECU fuel consumption pulse output and select "Custom" fuel flow configuration. UL Power specifies a pulse frequency of 170 Hz at

72 L/hour, which suggests an initial scale factor of 32176.

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Page 24-12

24.2.5 Other Piston Engine Applications

In addition to the engines described previously, the G3X system's engine/airframe inputs can be configured for use with a variety of other engine types.

Sensors for Other Piston Engines - Many other piston engines can be monitored using the supported

engine sensors shown in Table 24-1

, along with custom engine sensor configuration as described in

Section 34.4.19

for GDU 37X units, or Section 35.4.32

for GDU 4XX units.

RPM

Sensor Type

Manifold pressure

Oil pressure

Oil temperature


Turbine inlet temperature

Carburetor temperature

Fuel pressure

Fuel flow

Coolant pressure

Coolant temperature (or other temperature)

Hydraulic pressure (or other pressure)

Other parameters

Table 24-9 Sensors for Other Piston Engines

Cylinder head temperature


Use any supported sensor from

Table 24-1

, or select "Custom" configuration and enter frequency-to-RPM calibration


Table 24-1

, or select "Custom" configuration and enter voltage-to-pressure calibration


Table 24-1



Table 24-1

Use Type K thermocouples. Up to 6 cylinders are supported, or up to 12 cylinders in a GDU 4XX system with dual GEA 24 EIS units.

Use Type J or Type K thermocouples. Up to 6 cylinders are supported, or up to 12 cylinders in a GDU 4XX system with dual GEA 24 EIS units.

Use Type K thermocouples


Table 24-1


Table 24-1



Table 24-1

, or select "Custom" configuration and enter pulses-per-gallon calibration


Table 24-1


Use "Custom" temperature configuration with RTD, thermistor, or thermocouple

Use appropriate Kavlico pressure sensor or select "Custom" configuration and enter voltage-to-pressure calibration


Table 24-1

Large Piston Engines - A GDU 4XX system with dual GEA 24 EIS units installed can monitor a single engine with up to 12 cylinders, including radial engines. For large single-engine applications, cylinders

1-6 are connected to GEA 24 #1 and cylinders 7-12 are connected to GEA 24 #2. (see

Section 26.5.16

)

Twin Piston Engines - A GDU 4XX system with dual GEA 24 EIS units installed can monitor twin piston engines with up to 6 cylinders each (see

Section 24.2.8

).

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Page 24-13

24.2.6 Retrofit Engine Applications

When installing a G3X system in a completed aircraft with a typical piston engine, it is generally possible

to reuse a number of the existing engine sensors that may already be present. Consult Section 30

for general engine sensor wiring guidance that can be applied to existing sensors.

RPM

Sensor Type

Manifold Pressure

Oil Pressure

Oil Temperature

Exhaust Gas

Temperature

Cylinder Head

Temperature

Table 24-10 Retrofit Engine Sensors

Notes on Suitability for Reuse

Sensors that provide a digital output signal can be used without modification, if calibration characteristics are known.

Do not connect G3X RPM inputs directly to magneto P-leads.

Sensors that provide a voltage output can be used without modification, if calibration characteristics are known.

Sensors that provide a resistance or current output may require replacement with a supported sensor (e.g. 494-30004-01).


Sensors that provide a resistance or current output may require replacement with a supported sensor (e.g. 011-04202-30).

Existing sensors are generally likely to require replacement with a supported sensor (e.g. 494-70004-00).

Type K thermocouples can be used without modification. The GEA 24 J242 connector matches the pinout used by certain other engine monitoring systems.

Type J or K thermocouples can be used without modification. The GEA 24

J242 connector matches the pinout used by certain other engine monitoring systems.

Turbine Inlet

Temperature

Type K thermocouples can be used without modification.

Fuel Pressure

Fuel Flow

Bus Current

Fuel Quantity


Sensors that provide a resistance or current output may require replacement with a supported sensor (e.g. 494-30004-02 or 494-30004-03).

Most sensors that provide a digital output signal can be used without modification, if calibration characteristics are known.

Many existing installations use Floscan or Electronics International fuel flow sensors that are directly supported by the G3X system.

Most shunt-type or Hall-effect sensors can be used without modification, if calibration characteristics are known.

Most sensors that provide a resistance, voltage, or frequency output can be used without modification. New fuel quantity calibration will be performed during G3X system installation.

For capacitive fuel quantity measurement, a third-party capacitance-tofrequency or capacitance-to-voltage converter is required; the G3X system does not support direct connection to capacitive fuel tank probes.

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Page 24-14

Sensor Type

Control Surface

Position

Table 24-10 Retrofit Engine Sensors

Notes on Suitability for Reuse

Most potentiometer-type sensors can be used without modification. New position calibration will be performed during G3X system installation.

24.2.7 Turbine Engine Applications

Turbine Engines - Many turbine engines can be monitored using the supported engine sensors shown in

Table 24-1

, along with custom engine sensor configuration as described in

Section 35.4.32

for GDU 4XX

displays. Turbine engines are not supported by the GDU 37X display.

Torque

Sensor Type

N1 / N2 RPM

Oil pressure

Oil temperature

Turbine inlet or outlet temperature

Table 24-11 Sensors for Turbine Engines


Two separate turbine engine RPM gauges can be displayed. Select

"Custom" configuration for GEA 24 RPM1 / RPM2 inputs and enter frequency-to-RPM calibration. A Sandia ST26 tachometer signal converter is typically required to provide proper digital signal conditioning.

Use Kavlico P4055-5020-4 (011-04202-30) for pressures under 150 PSI and enter pressure-to-torque calibration, or select "Custom" and enter voltage-to-torque calibration

Use any supported sensor from Table 24-1 , or select "Custom"

configuration and enter voltage-to-pressure calibration

Use any supported sensor from Table 24-1

Use Type K thermocouple

Fuel pressure

Fuel flow

Hydraulic pressure (or other pressure)

Other parameters

Use supported Kavlico or UMA pressure sensor, or select "Custom" configuration and enter voltage-to-pressure calibration


configuration and enter pulses-per-gallon calibration


configuration and enter voltage-to-pressure calibration

Use any supported sensor from Table 24-1

24.2.8 Twin-Engine Applications

A GDU 4XX system using two GEA 24 units can monitor data from two engines with up to 6 cylinders each. Engine #1 is connected to GEA 24 #1, and engine #2 is connected to GEA 24 #2. Data from both engines is presented on the same GDU display. Due to its larger display size, the GDU 46X is preferred over the GDU 45X or GDU 47X for twin-engine applications.

The two GEA 24s in a twin-engine installation use the same input configuration for analog and digital inputs, with a configuration choice to allow data for a particular input to be monitored from both GEA 24s, or from #1 only. The second GEA 24 may also be used to support additional discrete inputs. For information on configuring twin-engine sensor inputs, see

Section 35.4.6

and Section 35.4.32.3

.

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Page 24-15

24.2.9 Rotorcraft Applications

Rotorcraft engine monitoring can be accomplished with a GDU 4XX system, using the engine sensor application information in

Section 24.2.1

through Section 24.2.7

. Typically, the GEA 24 RPM 1 input is

used to monitor rotor RPM.

Sensor Type

Rotor RPM

Engine RPM

Other engine sensors

Table 24-12 Sensors for Rotorcraft Applications

Details

Select "Custom" configuration for GEA 24 RPM1 input and enter frequencyto-RPM calibration. A Sandia ST26 tachometer signal converter may be required to provide proper digital signal conditioning.

Select appropriate configuration for GEA 24 RPM 2 input as described in

Section 24.2.1

through

Section 24.2.7

.

Select appropriate sensors and configuration as described in

Section 24.2.1

through Section 24.2.7

.

A GDU 4XX system using two GEA 24 units can be used to monitor engine information for a twin-engine

rotorcraft, as described in Section 24.2.8

.

24.2.10 FADEC Engine Status

When used with a digital interface to a FADEC engine, FADEC status and maintenance information can be viewed in configuration mode. To view FADEC status, access the configuration mode System

Information page and highlight the FADEC item. The specific FADEC status data that is displayed (Figure

24-2) will vary based on the configured engine type.

Figure 24-2 Configuration Mode FADEC Interface Status

In normal mode, caution and warning indications from the FADEC interface are displayed in the form of

CAS messages. Refer to the G3X Touch Pilot’s Guide (190-01754-00) for further information.

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Page 24-16

24.3 Engine Sensor Installation

NOTE

The following sections contain general guidance on engine and airframe sensor installation. This information is provided for reference only. The installer should always follow any installation guidance and instructions provided by the applicable engine, sensor, or kit-plane manufacturer. Additionally, all installation practices should be done in accordance with AC 43.13-1B.

Section 30

, Section 31

, Section 32

, and Section 33 contain interface drawings for sensor installations using

the Garmin sensor kits, and for other sensor installations.

24.3.1 CHT (Cylinder Head Temperature)

Both Type J and Type K grounded thermocouples are supported for cylinder head temperature (CHT) measurements. Type K thermocouples are more commonly used for CHT.

To maintain measurement accuracy, appropriate thermocouple extension wire must be used to connect the

CHT probe sensor wires directly to the inputs of the GEA 24/GSU 73. To minimize risk of breakage, it is recommended that a high-quality stranded (as opposed to solid) thermocouple wire be used. For Type K thermocouples, one such example of appropriate wire is TT-K-22S Type K thermocouple wire from Omega

Engineering.

Thermocouple extension wire lengths may vary between cylinders for installation convenience; there is no requirement to use the same length of thermocouple extension wire for each engine cylinder. However, for each individual thermocouple lead, the positive and negative wires should be the same length. When attaching thermocouple extension wire with splices or connectors, the connections for an individual pair of positive/negative wires should be located close together to ensure they are exposed to similar ambient temperatures.

NOTE

If ungrounded thermocouples are used, the low side must be connected to a GEA 24/

GSU 73 ground pin.

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Page 24-17

24.3.1.1 Lycoming/Continental CHT Sensor Installation

Garmin sensor kits for Lycoming and Continental engines include Alcor 86253 Type K thermocouple probes (Garmin P/N 494-70000-00). Refer to Alcor CHT Installation Instructions (P/N 59167) for complete installation details. Engine manufacturer’s guidance should always be consulted for proper location of CHT probes. A finger sized loop should be provided to allow sufficient strain relief of the probe assembly, and care should be taken to ensure that no chafing of the wires occurs.

Figure 24-3 CHT Probe Package

Figure 24-4 CHT Probe Well

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Figure 24-5 One Piece CHT Probe Installed

24.3.2 EGT (Exhaust Gas Temperature)

Type K grounded thermocouples are supported for exhaust gas temperature (EGT) measurements.

NOTE

If ungrounded thermocouples are used, the low side must be taken to a GEA 24/ GSU 73 ground pin.

To maintain measurement accuracy, Type K thermocouple extension wire must be used to connect the EGT probe sensor wires directly to the inputs of the GEA 24/GSU 73. To minimize risk of breakage, it is recommended that a high quality stranded (as opposed to solid) thermocouple wire be used. One such example of appropriate wire TT-K-22S Type K thermocouple wire from Omega Engineering.

Thermocouple extension wire lengths may vary between cylinders for installation convenience; there is no requirement to use the same length of thermocouple extension wire for each engine cylinder. However, for each individual thermocouple lead, the positive and negative wires should be the same length. When attaching thermocouple extension wire with splices or connectors, the connections for an individual pair of positive/negative wires should be located close together to ensure they are exposed to similar ambient temperatures.

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24.3.2.1 EGT Sensor Installation

General Installation Guidance – Garmin sensors kits include Alcor 86255 Type K thermocouple probes

(Garmin P/N 494-70001-00). Refer to Alcor EGT Installation Instructions (P/N 59180) for complete installation details. Engine manufacturer’s guidance should be consulted and followed for proper location of EGT probes.

Perform the following steps and refer to Figure 24-6

, Figure 24-7 , and Figure 24-8 to install an EGT

sensor.

1. EGT probes (Figure 24-6) should optimally be mounted a minimum 2 inches and a maximum of 4

inches from the cylinder exhaust port flange on a flat portion of the exhaust tube. For highly supercharged engines, the EGT probe should optimally be mounted a minimum 5 inches and a maximum of 7 inches from the cylinder exhaust port flange on a flat portion of the exhaust tube.

To maintain consistent readings across cylinders, all probes should be mounted an equal distance from the exhaust flanges.

2. Carefully center punch the probe hole locations so that the external portion of the probe does not interfere with any other parts of the engine or cowling (

Figure 24-7 ). It may be desirable to angle

the probes towards the rear of the engine to allow efficient wire routing back to the cockpit. If angling the probes towards the rear of the engine, take care to ensure that sufficient clearance is provided to service the spark plugs.

3. Carefully insert probe into the exhaust pipe and tighten the clamp snugly with screwdriver

(35 in-lbs torque max.).

4. Connect the EGT probes to the thermocouple extension wire. Provide strain relief for the assembly by either fastening the probe leads to the valve covers with a clamp, or by tying the extension wire to the intake tubes or other suitable location. A finger-sized loop should be provided to allow appropriate strain relief, and care should be taken to ensure that no chafing of the wires occurs. See

Figure 24-8 for an example of an installed EGT probe.

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Figure 24-6 EGT Package


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Figure 24-7 Exhaust Pipe Drilled

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Figure 24-8 Installed EGT Probe Orientation


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24.3.3 Oil Temperature

Oil temperature can be measured using the specific resistance temperature detector (RTD) and thermistor sensors listed in

Table 24-1 .

24.3.3.1 Lycoming/Continental Oil Temperature Sensor Installation

Garmin sensor kits for Lycoming and Continental engines include the UMA 1B3-2.5R platinum RTD probe (Garmin P/N 494-70004-00). This probe is designed for oil temperature probe wells with 5/8-18 threads.

General Installation Guidance – Refer to the applicable engine manual for proper location of the oil temperature sensor. The sensor is usually installed near the oil filter.

1. Cut the safety wire and remove the existing vent plug (Figure 24-9), if installed.

2. To prevent galling of the threads, apply a small amount of engine oil to the probe threads.

3. Ensure that an unused copper crush gasket is present on the probe, and install the probe into the engine (black side of crush gasket down).

NOTE

Crush gaskets can only be used once. A new gasket must be installed any time the probe is removed and installed.

4. Tighten the probe to the torque as specified by the engine manufacturer.

5. Safety-wire the probe to the engine case as appropriate.

6. Connect the supplied connector to the appropriate inputs on the GEA 24/GSU 73 as referenced in the G3X interconnects in

Section 31 . Secure the connector and wire assembly to an appropriate

location in the engine compartment to provide strain relief.

Figure 24-9 Vent Plug Figure 24-10 Oil Temperature

Probe

Figure 24-11 Oil

Temperature Probe Installed

(Crush Gasket Not Shown)

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24.3.4 Pressure (Fuel, Manifold, Oil, and Coolant)

Select the pressure sensor from

Table 24-1

that is best suited for the aircraft system and installation location. Maximum system operating or surge pressures must not exceed the sensor's rated pressure.

General Mounting Methods – The specified pressure transducers provide for two different mounting options:

Figure 24-12 Pressure Transducer Mounting a) Sensor body secured to the engine mount or firewall via an appropriately sized Adel clamp

(preferred)

OR b) Mounted to a transducer mounting block located on the firewall. UMA sensor mounting may require the use of a stainless steel AN911 fitting (union).

WARNING

The sensor must not be mounted directly to the engine. Mechanical failure of the sensor could result in leaks and loss of pressure.

WARNING

Test all fuel, oil, and coolant pressure sensors for leakage following installation and prior to flight.

Installation Guidance:

1. Hoses and fittings - Fuel and oil hoses installed in the engine compartment should meet TSO-C53a

Type C or D (fire resistant) and rated for the pressure, temperature, and be compatible with the fuel or oil. Sensor hoses must be routed as far away from the aircraft exhaust system as practical and no closer than 6 inches. Fittings should be AN/AS-spec or Mil-spec.

2. Sensors - Do not install sensors directly below fittings or components that may leak flammable fluid. To prevent water from settling in the fuel pressure sensor and causing freeze damage, install sensor with the electrical connector angling upward or with a hose/line with an upward bend that will trap heavier water before entering the sensor.

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3. Routing - Line fittings, routing, alignment, bonding, and support spacing should be installed as defined in the aircraft maintenance manual or Section 8-31 of AC 43.13-1B, Aircraft Inspection and Repair

4. Mount the sensor using one of the two methods noted above.

5. Refer to the applicable engine manual to identify the appropriate connecting port on the engine for the parameter being sensed. The male threads on Kavlico sensors are designed to mate with a 1/8”

NPT female thread. The female threads on UMA sensors are designed to mate with a 1/8” NPT male thread. Thread sealant or tape should be used for the NPT threads. To reduce the risk of system contamination, a minimal amount of sealant or tape should be applied leaving at least two threads at the end of the fitting clear of all sealant/tape.

WARNING

The fuel and oil pressure fittings on the engine port should have a restrictor hole where appropriate to minimize potential fluid loss in the event of breakage.

NOTE

A restrictor or snubber fitting (not available from Garmin) may be installed (between the hose and the sensor) to dampen manifold pressure fluctuations. One example is the PS-8G fitting from Omega Engineering.

6. Connect the supplied connector to the appropriate inputs of the GEA 24/GSU 73 as referenced in

the Sensor Interface Drawings in Section 31 through

Section 33

. Secure the connector and wire assembly to an appropriate location in the engine compartment to provide strain relief.

NOTE

Kavlico P4055 pressure sensors use Packard Metri-Pack 150 connectors.

7. To avoid fuel pressure sensor damage or rupture, verify the aircraft fuel system nominal and surge pressures will not exceed the rated operating pressure of the sensor. Verify that pressure caused by thermal expansion of fuel in the pressure sensor line is not trapped by the fuel shut-off valve or other components.

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24.3.5 RPM (Revolutions Per Minute)

24.3.5.1 Lycoming/Continental RPM Sensor Installation

The following two types of mechanical RPM sensors are supported:

UMA 1A3C-2, UMA 1A3C-4 Standard mechanical tach drive sensors

The standard mechanical tach drive sensor is installed on the engine accessory case:

1. Remove the cap from the tachometer drive output (Figure 24-13) from the back of the engine.

2. Insert adapter tang into slotted keyway in sensor drive port.

3. Screw tach sensor onto threaded driver port, ensuring that the adapter tang on the sensor aligns with the slotted keyway in the drive port (Figure 24-14).

4. Connect the supplied connector to the appropriate inputs on the GEA 24/GSU 73 as referenced in the G3X interconnects in Section 31 . Secure the connector and wire assembly to an appropriate location in the engine compartment to provide strain relief.

The body of the sensor unit can be offset slightly to eliminate potential interference with other engine accessories. If the interference cannot be alleviated by offsetting the sensor directly, the builder may either install a magnetic pickup sensor or use a short tachometer drive extension cable to remote mount the sending unit to the engine mount (or other suitable location)

Figure 24-13 Tachometer Drive Output Figure 24-14 Installed Tachometer Sensor

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UMA N/T1A9-X, JPI 4208XX - Magnetic pickup tach sensors:

The magnetic pickup tach sensor is installed in the magneto bleed port. It is recommended that it be installed in the non-impulse magneto, but it can be installed in the impulse magneto if only one magneto exists (engines with single electronic ignition). The UMA N/T1A9-X sensors are suitable for nonpressurized magnetos only. JPI 4208XX RPM sensors are available in different versions for both pressurized and non-pressurized magnetos. Given that the bleed port size on Slick and Bendix magnetos differ, the installer should verify that the sensor part number is appropriate for the magneto type.

1. Remove the existing vent plug from the magneto bleed port (Figure 24-15).

2. Lightly apply thread sealer such as Loctite 242 (or equivalent) to the threads of the sensor. Be careful not to apply too much, and ensure sealer is applied only to the threads and not the pickup face itself.

3. Install the sensor into the port ( Figure 24-17 ). The sensor should be installed finger tight plus 1/6 turn. Do not over-tighten.

4. Connect the supplied connector to the appropriate inputs on the GEA 24/GSU 73 as referenced in the G3X interconnects in

Section 31 . Secure the connector and wire assembly to an appropriate

location in the engine compartment to provide strain relief.

Figure 24-15 Magneto Bleed Port

NOTE

There are two plugs on a Slick/Unison 43xx series magneto (Figure 24-16) where the tach

sender could fit. The one closest to the rotating magnet, with the hex-shaped plug, is correct. The one on the opposite side, with a round plug, is incorrect.

CORRECT TACH SENSOR PORT

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WRONG PORT

CORRECT TACH

SENSOR PORT

WRONG PORT

Figure 24-16 Plugs on Slick/Unison 43XX Magneto


Page 24-26

Figure 24-17 Magneto Tach Sensor Installed

24.3.5.2 Electronic Ignition RPM

For engines with electronic ignition, RPM can be sensed via a digital tach signal output from the electronic ignition system. The G3X system provides configurations for ignition systems that output 1 through 4 pulses per crankshaft revolution, or a custom RPM input configuration may be used to accommodate other types of electronic ignition.

Aircraft with dual electronic ignition systems can connect the tachometer signal output from the second

ignition to the GEA 24/GSU 73 RPM2 input (see Figure 31-2

). The RPM value displayed on the RPM gauge will be the higher of the two RPM signals.

NOTE

Electronic ignition systems with open-collector tachometer signal outputs may require a pull-up resistor between the tachometer signal output and +5VDC or +12VDC.

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24.3.5.3 P-Lead RPM Sensing

CAUTION

Only a MOD Level 2 GEA 24 can be connected directly to a P-Lead. Do not connect

MOD Level 1 or MOD Level 0 units directly to a P-Lead. The MOD Level status can be determined by checking the serial tag on the unit.

For a direct connection, the GEA 24 measures the electrical signal generated by the primary magneto coils or “P-Leads” from both engine magnetos. The connections can be made to the magneto P-Lead stud or to the P-Lead wire at the ignition switch as shown in

Figure 31-4 . If the magneto does not have a ring

terminal stud, connect the GEA 24 to the ignition switch. Otherwise, connect it to whichever minimizes the wire length to the GEA 24.

When making a connection directly to a P-Lead, a 400kΩ (±10%) resistor needs to be installed. To prevent

errant shorts to ground in case of a broken or shorted wire, (as outlined in Figure 25-14 ) the wire length

between the P-Lead connection and the resistor must not exceed six inches. Shielded wires must be used.

Use a resistor that is 400K ohm (±10%), 0.5W, rated to maintain resistance and power rating at 150°C, and qualified to MIL-R-10509.

Following the installation of the P-Lead signal wires, verify the continuity of each magneto P-Lead to airframe ground while the ignition key is OFF. If there is evidence of discontinuity in the magneto P-Lead grounding circuit, it must be corrected before further engine maintenance or checks. Continuity can only be measured if the magneto points are open or the wire is disconnected from the magneto. Use a magneto timing light to ensure the ohmmeter will not measure false continuity through the points or coil windings.

WARNING

Do not turn the propeller and stay clear of the propeller arc when installing the P-Lead signal wires.

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24.3.6 Fuel Quantity

24.3.6.1 Resistive Type Fuel Quantity Sensors

Resistive type fuel quantity sensors with a 0–500 Ω range are currently supported. Wiring methods vary based on the GEA 24/GSU 73 channel being used. Please see

Section 30

through Section 33

for proper wiring considerations.

CAUTION

For composite and tube-and-fabric airframe installations that include a GEA 24, it is recommended to install 2 - 2.2 kΩ resistors as shown in

Section 30 , to improve the

grounding path in the event of lightning strike. This is optional for metal aircraft, either wiring method can be used. The additional components have no effect on GSU 73 fuel inputs. When in-line resistors are installed, use "Voltage" configuration setting, if in-line resistors are not installed, use "Resistive" configuration setting.

24.3.6.2 Capacitive Type Fuel Quantity Sensors

Capacitive fuel quantity sensors require the use of an external transducer to convert capacitance to either a frequency or a voltage.

Fuel quantity transducers that convert capacitance to a voltage of up to 28V may be used, including 0-5V and 0-12V transducers. Examples of this type of transducer include the Skysports and Westach units.

Voltage-output fuel quantity transducers may be connected to any of the four fuel quantity inputs on the

GEA 24, or to any of the four analog fuel quantity inputs on the GSU 73 (FUEL 1/2/3/4).

Fuel quantity transducers that convert capacitance to a frequency of up to 50 kHz may be used. Examples of this type of transducer include the Princeton, Vision Microsystems, and EI P-300C units. The transducer's output waveform must meet the requirements of the GEA 24/GSU 73 digital inputs (see

Section 26.5.8

for the GEA 24 and Section 26.15.8

for the GSU 73). When using a GEA 24, frequencyoutput fuel quantity transducers may be connected to any of the four fuel quantity inputs (FUEL 1/2/3/4).

When using a GSU 73, frequency-output fuel quantity transducers must be connected to the two digital fuel quantity inputs (CAP FUEL 1/2).

NOTE

Vision Microsystems capacitive level senders used with a GSU 73 may require installing a

5 kΩ pull-down resistor at the sensor output.

NOTE

The GEA 24 and GSU 73 can provide +5V or +12V excitation voltage to capacitive fuel quantity transducers. The power supply output pins on the GEA 24 and GSU 73 are designed for low-current transducers only. Transducers that require higher supply currents, including Princeton capacitive fuel quantity transducers, may require power to be supplied from the aircraft electrical bus instead.

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24.3.7 TIT (Turbine Inlet Temperature) Sensor

The G3X system supports Type K grounded thermocouples for sensing turbine inlet temperature (TIT), turbine outlet temperature (TOT), or inter-turbine temperature (ITT). This type of sensor is applicable to all turbocharged or turbine engines.

To maintain measurement accuracy, appropriate thermocouple extension wire must be used to connect the

TIT probe sensor wires directly to the inputs of the GEA 24/GSU 73. To minimize risk of breakage, it is recommended that a high-quality stranded (as opposed to solid) thermocouple wire be used. For Type K thermocouples, one such example of appropriate wire is TT-K-22S Type K thermocouple wire from Omega

Engineering. When attaching thermocouple extension wire with splices or connectors, the connections for an individual pair of positive/negative wires should be located close together to ensure they are exposed to similar ambient temperatures.

NOTE

If ungrounded thermocouples are used, the low side must be connected to a GEA 24/

GSU 73 ground pin.

24.3.8 Bus Voltage Monitor

Bus voltage is normally sensed from an external voltage signal connected to a GEA 24/GSU 73 analog

input (refer to Section 30

for interface drawings). Optionally, the GEA 24/GSU 73 can be configured to measure bus voltage without requiring an external connection, by sensing the voltage of its power supply

inputs. See Voltage portion of Section 34.4.19.3.2


for GDU

4XX systems (Volts 1 and Volts 2 Inputs) for configuration guidance.

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24.3.9 Bus Current

Electrical current can be sensed by the G3X system either by Hall Effect current sensors or via the use of a traditional ammeter shunt.

24.3.9.1 Ammeter Shunt Installation

The UMA 1C4 ammeter shunt included in Garmin sensor kits (Garmin P/N 909-D0000-00) is a 100 Amp/

50 mv shunt. Other ammeter shunts with different specifications can be supported via calibration

adjustments. See Current portion of Section 34.4.19.3.2


for

GDU 4XX systems (Volts 1 and Volts 2 Inputs) for configuration guidance.

General Installation Guidance – The ammeter shunt has two holes in the base for mounting with #10 screws. The current-carrying wires are attached to the large 1/4” lugs, while the current sense wires are attached via the use of #8 ring terminals.

Figure 24-18 Ammeter Shunt

NOTE

It is important that no metal portion of the shunt touch any other portion of the aircraft or exposed wiring. Large voltages and current are present in the shunt, and an electrical short or fire could result from inadvertent contact.

The shunt should be installed in-line with the current being sensed. As noted below, the appropriate wire should be cut and attached to each of the large ¼” lugs. A 1A fuse or other form of circuit protection must be installed between the shunt and the applicable GEA 24/GSU 73 inputs to prevent inadvertent damage to the GEA 24/GSU 73. Connect the two sense wires (attached to the #8 terminals) to the appropriate inputs on the GEA 24/GSU 73 as referenced in the G3X interconnects in

Section 30

through Section 33

. If the ammeter readings are shown with the opposite polarity, check to see if the sense wire connections are reversed.

An alternator ammeter shunt should be installed inline in the alternator output (“B” terminal). A battery ammeter shunt should be installed between the battery positive terminal and the battery contactor.

Depending on the location of the alternator or battery relative to its supported electrical bus, it is typically desirable to install the shunt on the firewall near where the alternator or battery output would normally penetrate the firewall.

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24.3.9.2 Hall Effect Current Sensor

Hall Effect current sensors can be used to sense electrical current via induced magnetic fields, without direct connection to high-current conductors.

The default Hall Effect current sensor supported by the G3X system is the AMPLOC KEY100. This sensor outputs 2.5V at zero amps, with a sensitivity of 15.9 mV/Amp up to +/- 100A. Other Hall Effect sensors with different specifications can be supported via calibration adjustments. See Current portion of

Section 34.4.19.3.2


for GDU 4XX systems for configuration

guidance.

24.3.10 Fuel Flow

Fuel flow in the G3X system is sensed via a mechanical transducer which converts the movement of fuel to a series of digital pulses.

For engines with a fuel return line, a second flow sensor must be used to measure the quantity of unused fuel that is returned from the engine to the fuel tank. Connect the return fuel flow sensor to the GEA 24/

GSU 73 FUEL FLOW 2 input (see Figure 30-2.1

). The value displayed on the fuel flow gauge will be the difference between the main (supply) fuel flow and secondary (return) fuel flow measurements.

24.3.10.1 K-Factor Adjustment

The number of electrical pulses sensed per gallon of fuel flow is referred to as the K-Factor. The G3X system uses the configured K-Factor to convert pulse frequency to fuel flow. When installing the fuel flow sensor, the installer should take note of number on the tag attached to the sensor (if applicable). This number is the calibrated K-Factor of the sensor. For sensors that are not supplied with a specific calibration value, use the default K-Factor value provided.

Although each fuel flow sensor has a default K-Factor value, aspects unique to each installation will affect the accuracy of the initial K-Factor, and as a result the K-Factor must generally be adjusted up or down for accurate fuel flow measurement.

If the fuel usage reported by the G3X system differs from the actual fuel usage, as measured at the fuel pump (or other trusted method of measurement), use the following formula to calculate a corrected

K-Factor, which can then be used to calibrate the fuel flow.

Corrected K-Factor = ( [G3X reported fuel used] x [previous K-factor] ) / [actual fuel used]

Refer to the K-Factor portion of

Section 34.4.19.4

for (GDU 37X) or Section 35.4.32.13

(for GDU 4XX) for information on entering K-Factor calibration.

24.3.10.2 Electronics International Fuel Flow Sensor Installation

Garmin sensor kits include the Electronics International FT-60 “red cube” fuel flow sensor (Garmin P/N

494-10001-00). Refer to Electronics International document # 1030032 for FT-60 installation guidance.

The default K-Factor for the FT-60 is 68,000 pulses/gallon. No sensor specific calibration is required for the FT-60, but variations in the installation can affect the K-Factor as described above.

Other Electronics International FT-series fuel flow sensors are also supported; consult the manufacturer for installation guidance.

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24.3.10.3 Floscan Fuel Flow Sensor Installation

The information below is taken from the Floscan Series 200 Flow Transducer Application Notes:

1. The inlet and outlet ports in series 200 flow transducers have ¼” NPT threads. Use only ¼” NPT hose or pipe fittings to match. When assembling fittings into the inlet and outlet ports, DO NOT

EXCEED a torque of 15 ft. lbs. (180 inch lbs.), or screw the fittings in more than 2 full turns past hand tight WHICHEVER HAPPENS FIRST. Floscan Instrument Co., Inc. will not be responsible for cracked castings caused by failure to use ¼” NPT fittings, over-torquing the fittings, or assembling them beyond the specified depth.

2. A screen or filter should be installed upstream of the flow transducer to screen out debris which could affect rotor movement or settle in the V-bearings. As turbulence upstream of the transducer affects its performance, there should be a reasonable length of straight line between the transducer inlet and the first valve, elbow, or other turbulence producing device.

3. Install the flow transducer with wire leads pointed UP to vent bubbles and ensure that the rotor is totally immersed in liquid. For maximum accuracy at low flow rates, the transducer should be mounted on a horizontal surface.

Some additional mounting considerations should be noted as follows:

1. When installing the NPT fittings into the transducer, use fuel lube such as EZ TURN © or an equivalent thread sealer. Teflon tape should NEVER by used in a fuel system.

2. To minimize inaccuracies caused by turbulence in the fuel flow, the sensor should be mounted with approximately 5-6” of straight tubing before and after the sensor. If special circumstances exist that prevent an extended length of straight tubing before and after the sensor, then a gently curved hose may be acceptable. 45 degree or 90 degree elbow fittings should NOT be used immediately before or after the sensor.

3. Specific sensor mounting location is left to the builder. Ideally, the sensor should be placed prior to the fuel distribution device (carburetor or fuel injection distribution device).

4. On a Continental fuel injected engine, the transducer must be located between the metering unit and the flow divider valve.

5. Sensor wires should be connected to the appropriate inputs on the GEA 24/GSU 73 as referenced

in the G3X interconnects in Section 30

through Section 33

.

The Floscan 201B-6 (201-030-000) fuel flow sensor K-Factor value can range from 28,000 to 31,000 pulses/ gallon.

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The G3X default K-Factor for the 201B-6 is 29,500 pulses/gallon. Some Floscan fuel flow sensors come with a tag that lists the K-factor number measured during unit calibration (see Figure 24-19).

NOTE

If the Floscan tag shown in Figure 24-19 is lost, the serial number of the Floscan sensor can be supplied to Floscan to obtain the calibrated K-factor value.

Actual K Factor measured at

16 GPH

Figure 24-19 Example Floscan Fuel Flow Sensor

The tag shown in Figure 24-19 lists a K-Factor of 16-2890. The first two digits (16) represent Gallons Per

Hour, while the last four digits (2890) represent the number of electrical pulses (divided by 10) output by the sensor per gallon of fuel flow. The numbers on the tag are used in determining the K-Factor to be entered as part of the Fuel Flow Calibration described in Section 34.4.19.4 (for GDU 37X) and

Section 35.4.32.13

(for GDU 4XX). To determine this number, a zero should be added to the four digit number on the tag. In the example above after adding the zero to 2890, the resulting K-Factor to be entered on the Fuel Flow Calibration page would be 28900.

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24.3.11 Carburetor Temperature Sensor

24.3.11.1 Lycoming and Continental Engine Sensor Installation

The UMA 1B10R platinum resistance temperature detector (RTD) is applicable to all carbureted

Lycoming and Continental engines that accept a temperature probe with ¼-28 threads.

General Installation Guidance:

1. Locate and remove the threaded ¼-28 brass plug (Figure 24-20 and Figure 24-21) on the side of the carburetor as shown in Figure 24-20. If a threaded plug is not present (as is the case with many older carburetors), consult the engine and/or carburetor manufacturer for instructions on how to drill and tap the lead plug adjacent to the butterfly valve.

2. Install a very small amount of thread lubricant on the probe threads and insert into the carburetor

(Figure 24-22).

3. Connect the supplied connector to the appropriate inputs of the GEA 24/GSU 73 as referenced in

the G3X interconnects in Section 31

and Section 32

. Secure the connector and wire assembly to an appropriate location in the engine compartment to provide strain relief.

Figure 24-20 Carb Temp

Sensor Mounting Location


Sensor Mounting Location w/Screw Removed


Sensor Installed

24.3.12 Position Sensor

In general, most potentiometer-type resistive position sensors can be used with the G3X system. Typically these sensors take the form of a 0–5k Ω or 0–10k Ω variable resistor. Electric trim motors with integrated position potentiometers do not require separate position sensors.

Each position sensor installation will vary widely according to the aircraft, motion being sensed, and mechanical installation. A standalone position sensor should ideally be mounted such that the full travel of the sensor is just slightly greater than the full travel of the control surface.

Refer to the appropriate trim motor or position sensor installation manual and G3X interconnects in

Section 30 for proper wiring connections. Section 34.4.19.3.2 (for GDU 37X systems) and

Section 35.4.27.1 (for GDU 4XX systems) provides calibration instructions.

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25 CONNECTOR INSTALLATION INSTRUCTIONS

NOTE

Ensure that backshell connectors are fully tightened. Loose connectors may cause vibration-related performance issues that are difficult to troubleshoot.

25.1 Cable Connector Installation

Coaxial cables are required for antenna connections for GPS, XM, transponder, comm, VHF Nav, ADS-B, and video functions.

1. Route the coaxial cable to the unit location. Secure the cable in accordance with good aviation practices.

2. Trim the coaxial cable to the desired length and install the BNC or TNC connector per the connector manufacturer’s instructions for cable preparation.

25.2 Jackscrew Backshell Assembly

25.2.1 Shield Block Installation Parts

Table 25-1 and Table 25-2 list the parts needed to install a Shield Block, the item numbers in these tables

correspond to Figure 25-1

. Parts listed in Table 25-1 are supplied in the LRU Connector Kits (see

Table 1-4

). Parts listed in Table 25-2 are to be provided by the installer.

Table 25-1 Parts supplied for a Shield Block Installation ( Figure 25-1 )

Item #

1

6

12

13

14

15

Description

Cast Backshell Housing

Contacts

Clamp

Screw,4-40x.375,PHP,SS/P,w/Nylon

Cover

Screw,4-40x.187,FLHP100,SS/P,w/Nylon

GPN or MIL spec

125-00175-00

336-00094-00

115-01078-04

211-60234-10

115-01079-04

211-63234-06

Item #

2

3

4

5

Table 25-2 Parts not supplied for a Shield Block Installation ( Figure 25-1

)

Description

Multiple Conductor Shielded Cable (2-conductor shown in

Figure 25-1

)

Drain Wire Shield Termination (method optional)

Braid, Flat (19-20 AWG equivalent, tinned plated copper strands

36 AWG, Circular Mil Area 1000 -1300)

Floating Shield Termination (method optional)

GPN or MIL spec

Parts used depend on method chosen




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G3X/G3X Touch Installation Manual - Connector Installation Instructions

Page 25-1

Item #

7

8

9

10

11

Table 25-2 Parts not supplied for a Shield Block Installation ( Figure 25-1 )

Description

Ring terminal, #8, insulated, 18-22 AWG



Screw, PHP, 8-32x.312", Stainless

Screw, PHP, 8-32x.312", Cad Plated Steel

Split Washer, #8, (.045" compressed thickness) Stainless

Split Washer, #8, (.045" compressed thickness) Cad-plated steel

Flat Washer, Stainless, #8, .032" thick, .174"ID, .375" OD

Flat washer, Cad-plated Steel, #8, .032" thick, .174"ID, .375" OD

Silicon Fusion Tape

GPN or MIL spec

MS25036-149

MS25036-153

MS25036-156

MS51957-42

MS35206-242

MS35338-137

MS35338-42

NAS1149CN832R

NAS1149FN832P

-

NOTE

In Figure 25-1, “AR” denotes quantity “As Required” for the particular installation.

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Page 25-2

Figure 25-1 Shield Install onto a Jackscrew Backshell (78 pin example)

25.2.2 Backshell Assembly (refer to Figure 25-1)

1. Insert the crimped wire harness contacts (6) into the D-sub connector.

2. Wrap the cable bundle with silicone fusion tape (11) where the strain relief clamps the bundle.

3. Place the smooth side of the backshell strain relief clamp (12) across the cable bundle.

4. Secure strain relief with three 4-40 x 0.375 pan head screws (13).

5. Attach the cover (14) to the backshell using the supplied screws (15).

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Page 25-3

6. Install a ring terminal onto the cable shield drains, grouping wires as appropriate for the connector.

See following note.

7. Place the following items on the 8-32 x 0.312 pan head shield terminal screw (8) in the order they are presented.

a) Split washer (9) b) Flat washer (10) c) First ring terminal (7) d) Second ring terminal (if necessary)

8. Insert the pan head shield terminal screw (8) into a tapped hole on the shield block.

NOTE

Each tapped hole on the shield block may accommodate up to two ring terminals. It is preferred that only two wires be terminated per ring terminal. This necessitates the use of a #8 ring terminal, insulated, 14-16 AWG (MS25036-153). If only a single wire is left or if only a single wire is needed for this connector, a #8 ring terminal, insulated, 18-22 AWG

(MS25036-149) can be used. If more wires exist for the connector than two per ring terminal, it is permissible to terminate a maximum of three wires per ring terminal.

9. Secure connector to mating connector on avionics device using the knurled thumb screws. The end of each thumb screw accepts a 3/32” hex wrench (

Figure 25-9

) to aid in securing the connector.

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Page 25-4

25.2.3 Shield Termination Technique – Method A.1 (Standard)

NOTE

For the following steps please refer to Figure 25-1

and Figure 25-2.

1. The appropriate number of Jackscrew Backshells will be included in the particular LRU connector kit.

Figure 25-2 Method A.1 for Shield Termination

Backshell

1

2

3

4

5

-

Table 25-3 Shielded Cable Preparations for Garmin Connectors

Number

Std/HD

9/15

15/26

25/44

37/62

50/78

1.25

1.5

1.5

1.5

1.5

2.25

2.5

2.5

2.5

2.5

1.75

2.0

2.0

2.0

2.0

Window

(inches)

2.75

3.0

3.0

3.0

3.0

Window

(inches)

5.25

5.5

5.5

5.5

5.5

Ideal

(inches)

4.25

4.5

4.5

4.5

4.5

2. At one end of a shielded cable (item 2, Figure 25-1 ) measure a distance between “Window Min” to

“Window Max” (Table 25-3) and cut a window (max size 0.35”) in the jacket to expose the shield

(item 4, Figure 25-2). Use caution when cutting the jacket to avoid damaging the individual braids

of the shield. When dealing with a densely populated connector with many cables, it may prove beneficial to stagger the windows throughout the “Window Min” to “Window Max” range. If staggering is not needed the “Ideal Window” length is recommended.

Suggested tools to accomplish the window cut:

• Coaxial Cable Stripper

• Thermal Stripper

• Sharp Razor Blade

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Page 25-5

3. Connect a Flat Braid (item 4, Figure 25-2 ) to the shield exposed through the window of the

prepared cable assembly (item 2, Figure 25-1 ) from step 2. The Flat Braid should go out the front

of the termination towards the connector. It is not permitted to exit the rear of the termination and loop back towards the connector (

Figure 25-2

). Make this connection using an approved shield termination technique.

NOTE

FAA AC 43.13-1B Chapter 11, Section 8 (Wiring Installation Inspection Requirements) may be a helpful reference for termination techniques.

Preferred Method:

Slide a solder sleeve (item 3,

Figure 25-1 ) onto the prepared cable assembly (item 2, Figure 25-1

) and connect the Flat Braid (item 4,

Figure 25-2

) to the shield using a heat gun approved for use with solder sleeves. It may prove beneficial to use a solder sleeve with a pre-installed Flat Braid versus having to cut a length of Flat Braid to be used. The chosen size of solder sleeve must

accommodate both the number of conductors present in the cable and the Flat Braid (item 4, Figure

25-2 ) to be attached.

Solder Sleeves with pre-installed Flat Braid

A preferred solder sleeve would be the Raychem S03 Series with the thermochromic temperature indicator (S03-02-R-9035-100, S03-03-R-9035-100, S03-04-R-9035-100). These solder sleeves come with a pre-installed braid and effectively take the place of items 3 and 4,

Figure 25-2 . For detailed instructions on product use, reference Raychem installation

procedure RCPS 100-70.

Raychem recommended heating tools:

•HL1802E

•AA-400 Super Heater

•CV-1981

•MiniRay

•IR-1759

Individual solder sleeves and Flat Braid

Solder Sleeves:

Reference the following MIL-Specs for solder sleeves.

(M83519/1-1, M83519/1-2, M83519/1-3, M83519/1-4, M83519/1-5)

Flat Braid:

If the preferred Raychem sleeves are not being used, the individual flat braid selected should conform to ASTMB33 for tinned copper and be made up of 36 AWG strands to form an approximately 19-20 AWG equivalent flat braid. A circular mil area range of 1000 to 1300 is required. The number of individual strands in each braid bundle is not specified. (e.g.

QQB575F36T062)

NOTE

Flat Braid as opposed to insulated wire is specified in order to allow continuing air worthiness by allowing for visual inspection of the conductor.

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Page 25-6

Secondary Method:

Solder a Flat Braid (item 4, Figure 25-2 ) to the shield exposed through the window of the prepared

cable assembly (item 2,

Figure 25-1

). Ensure a solid electrical connection through the use of acceptable soldering practices. Use care to avoid applying excessive heat that burns through the insulation of the center conductors and shorts the shield to the signal wire. Slide a minimum 0.75

inches of Teflon heat shrinkable tubing (item 3, Figure 25-2

) onto the prepared wire assembly and shrink using a heat gun. The chosen size of heat shrinkage tubing must accommodate both the number

of conductors present in the cable and the Flat Braid (item 4, Figure 25-2 ) to be attached.

Teflon Heat Shrinkable Tubing:

Reference the following MIL-Spec for Teflon heat shrinkable tubing (M23053/5-X-Y).

4. At the same end of the shielded cable (item 2, Figure 25-1

) and ahead of the previous shield

termination, strip back “Float Min” to “Float Max” ( Table 25-3

) length of jacket and shield to

expose the insulated center conductors ( Figure 25-2 ). The “Ideal Float” length may be best to build

optimally.

Preferred Method:

The jacket and shield should be cut off at the same point so no shield is exposed. Slide 0.75 inches

minimum of Teflon heat shrinkable tubing (item 5, Figure 25-2 ) onto the cable and use a heat gun

to shrink the tubing. The chosen size of heat shrinkage tubing must accommodate the number of conductors present in the cable.

Secondary Method:

Leave a max 0.35 inches of shield extending past the jacket. Fold this 0.35 inches of shield back

over the jacket. Slide a solder sleeve (item 5, Figure 25-2

) over the end of the cable and use a heat gun approved for solder sleeves to secure the connection. The chosen size of solder sleeve must accommodate the number of conductors present in the cable.

5. Strip back approximately 0.17 inches of insulation from each wire of the shielded cable (item 2,

Figure 25-3) and crimp a contact (item 6, Figure 25-3) to each conductor. It is the responsibility of

the installer to determine the proper length of insulation to be removed. Wire must be visible in the inspection hole after crimping and the insulation must be 1/64 – 1/32 inches from the end of the

contact as shown in Figure 25-3.

6

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2

Figure 25-3 Insulation/Contact Clearance


Page 25-7

NOTE

For the item numbers in the following steps 6-13 please refer to Figure 25-1 ..

6. Insert newly crimped pins and wires into the appropriate connector housing location as specified by the installation wiring diagrams.

7. Cut the Flat Braid (item 4) to a length that, with the addition of a ring terminal, will reach one of the tapped holes of the Jackscrew backshell (item 1). An appropriate amount of excess length without looping should be given to the Flat Braid (item 4) to allow it to freely move with the wire bundle.

NOTE

Position the window splice to accommodate a Flat Braid (item 4) length of no more than 4 inches.

8. Guidelines for terminating the newly cutoff Flat Braid(s) (item 4) with insulated ring terminals

(item 7):

• Each tapped hole on the Jackscrew Backshell (item 1) may accommodate only two ring terminals (item 7).

• It is preferred that only two Flat Braid(s) (item 4) be terminated per ring terminal. Two Flat

Braids per ring terminal will necessitate the use of a Ring terminal, #8, insulated, 14-16

AWG (MS25036-153).

• If only a single Flat Braid is left or if only a single Flat Braid is needed for this connector a

Ring terminal, #8, insulated, 18-22 AWG (MS25036-149) can accommodate this single Flat

Braid.

• If more braids exist for this connector than two per ring terminal, it is permissible to terminate three braids per ring terminal. This will necessitate the use of a Ring terminal, #8, insulated, 10-12 AWG (MS25036-156).

9. Repeat steps 2 through 8 as needed for the remaining shielded cables.

10. Terminate the ring terminals to the Jackscrew Backshell (item 1) by placing items on the Pan Head

Screw (item 8) in the following order: Split Washer (item 9), Flat Washer (item 10) first Ring

Terminal, second Ring Terminal (if needed) before finally inserting the screw into the tapped holes on the Jackscrew Backshell. Do not violate the guidelines presented in Step 8 regarding ring terminals.

11. It is recommended to wrap the cable bundle with Silicone Fusion Tape (item 11)

(GPN: 249-00114-00 or a similar version) at the point where the backshell clamp and cast housing will contact the cable bundle.

NOTE

Choosing to use this tape is the discretion of the installer.

12. Place the smooth side of the backshell clamp (item 12) across the cable bundle and secure using the three screws (item 13). Warning: Placing the grooved side of the clamp across the cable bundle may risk damage to wires.

13. Attach the cover (item 14) to the backshell (item 1) using the two screws (item 15).

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Page 25-8

25.2.4 Shield Termination Technique - Method A.2 (Daisy Chain)

In rare situations where more braids need to be terminated for a connector than three per ring terminal it is allowable to daisy chain a maximum of two shields together before coming to the ring terminal

(Figure 25-4). All other restrictions and instructions for the shield termination technique set forth for

Method A.1 are still applicable.

NOTE

The maximum length of the combined braids should be approximately 4 inches.

Figure 25-4 Method A.2 (Daisy Chain) for Shield Termination

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Page 25-9

25.2.5 Shield Termination – Method B.1 (Quick Term)

If desired, the drain wire termination (item 3,

Figure 25-4

) and the floating shield termination (item 5,

Figure 25-4

) can be effectively combined into a “Quick Term”. This method eliminates the float in the cable insulation and moves the placement of the window which was described by the dimensions “Window

Min” and “Window Max” from Method A. This technique is depicted in

Figure 25-5

.

NOTE

The original purpose for separating the shield drain termination (item 3, Figure 25-4 )

from the float termination (item 5,

Figure 25-4

) in Method A was to allow for a variety of

lengths for the drain wires so that the shield drain terminations (item 3, Figure 25-4 )

would not all “bunch up” in the harness and to eliminate loops in the drain wires. If

Method B is chosen, as described in this section, care must be taken to ensure that all drain shield terminations can still be inspected. With connectors which require a large number of shield terminations it may be best to use Method A. This will allow the drain

shield terminations (item 3, Figure 25-4 ) a larger area to be dispersed across.

Using this method, the instructions from Section 25.2.3

(Method A) are followed except that:

1. Step 2 is eliminated

2. Steps 3 and 4 are replaced by the following:

At the end of the shielded cable (item 2,

Figure 25-1

), strip “Quick Term Min” to “Quick Term

Max” (

Table 25-4 ) length of the jacket to expose the shield. Next trim the shield so that at most

0.35 inches remains extending beyond the insulating jacket. Fold this remaining shield back over the jacket.

Connect a Flat Braid (item 4,

Figure 25-1

) to the folded back shield of the prepared cable assembly. The flat braid should go out the front of the termination towards the connector. It is not permitted to exit the rear of the termination and loop back towards the connector (

Figure 25-5 ).

Make this connection using an approved shield termination technique.

NOTE

FAA AC 43.13-1B Chapter 11, Section 8 (Wiring Installation Inspection Requirements) may be a helpful reference for termination techniques.

Preferred Method:

Slide a solder sleeve (item 3, Figure 25-1 ) onto the prepared cable assembly (item 2, Figure 25-1 ) and connect the Flat Braid (item 4, Figure 25-1

) to the shield using a heat gun approved for use with solder sleeves. It may prove beneficial to use a solder sleeve with a pre-installed Flat Braid versus having to cut a length of Flat Braid to be used. The chosen size of solder sleeve must accommodate both the number of conductors present in the cable and the Flat Braid (item 4,

Figure 25-1 ) to be attached.

NOTE

Reference Section 25.2.3

for recommended solder sleeves and flat braid. The same recommendations are applicable to this technique.

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Page 25-10

Secondary Method:

Solder a Flat Braid (item 4, Figure 25-5) to the folded back shield on the prepared cable assembly

(item 2, Figure 25-1 ). Ensure a solid electrical connection through the use of acceptable soldering

practices. Use care to avoid applying excessive heat that burns through the insulation of the center conductors and shorts the shield to the signal wire. Slide a minimum of 0.75 inches of Teflon heat

shrinkable tubing (item 3, Figure 25-5) onto the prepared wire assembly and shrink using a heat gun.

The chosen size of heat shrinkage tubing must accommodate both the number of conductors present in

the cable as well as the Flat Braid (item 4, Figure 25-5) to be attached.

Teflon Heat Shrinkable Tubing:

Reference the following MIL-Spec for general Teflon heat shrinkable tubing (M23053/5-X-Y)

Figure 25-5 Method B.1 (Quick Term) for Shield Termination

Backshell Size

1

2

3

4

5

Table 25-4 Shielded Cable Preparations – (Quick Term)

Number of Pins

Std/HD

9/15

15/26

25/44

37/62

50/78

Quick Term Min

(inches)

1.25

1.5

1.5

1.5

1.5

Quick Term Max

(inches)

2.25

2.5

2.5

2.5

2.5

Quick Term

Float (inches)

1.75

2.0

2.0

2.0

2.0

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Page 25-11

25.2.6 Shield Termination-Method B.2 (Daisy Chain-Quick Term)

In rare situations where more braids need to be terminated for a connector than three per ring terminal it is allowable to daisy chain a maximum of two shields together before coming to the ring terminal

(Figure 25-6). All other restrictions and instructions for the shield termination technique set forth for

Method B.1 are still applicable.

NOTE


Figure 25-6 Method B.2 (Daisy Chain-Quick Term) for Shield Termination

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Page 25-12

25.2.7 Daisy Chain between Methods A and B

In rare situations where more braids need to be terminated for a connector than three per ring terminal and a mixture of Methods A and B have been used, it is allowable to daisy chain a maximum of two shields

together from a Method A termination to a Method B (Figure 25-7). All other restrictions and instructions

for the shield termination technique set forth for Method A and B are still applicable.

NOTE


Figure 25-7 Daisy Chain between Methods A and B

25.2.8 ID Program Pins (Strapping)

NOTE

The GDU 37X rear connector (J3701) is electrically isolated. For installations using programming pins, a ground pin must be tied to the connector shell.

ID Program Pins provide a ground reference used by the hardware as a means of configuration for system identification. The following instructions will illustrate how this ground strapping should be accomplished with the Jackscrew Backshell:

1. Cut a 4 inch length of 22 AWG insulated wire.

WARNING

Flat Braid is not permitted for this purpose. Use only insulated wire to avoid inadvertent ground issues that could occur from exposed conductors.

2. Strip back approximately 0.17 inches of insulation and crimp a contact (item 6, Figure 25-3

) to the

4” length of 22 AWG insulated wire. It is the responsibility of the installer to determine the proper length of insulation to be removed. Wire must be visible in the inspection hole after crimping and the insulation must be 1/64 – 1/32 inches from the end of the contact as shown in

Figure 25-3

.

3. Insert newly crimped pins and wires into the appropriate connector housing location as specified by the installation wiring diagrams.

4. At the end opposite the pin on the 22 AWG insulated wire strip back 0.2 inches of insulation.

5. Terminate this end via the ring terminals with the other Flat Braid per Steps 8 through 11

( Section 25.2.3

) pertaining to shield termination. If this ground strap is the only wire to terminate, attach a Ring terminal, #8, insulated, 18-22 AWG (MS25036-149).

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Page 25-13

25.2.9 Splicing Signal Wires

NOTE

Figure 25-8 illustrates that a splice must be made within a 3 inch window from outside the

edge of clamp to the end of the 3 inch max mark.

WARNING

Keep the splice out of the backshell for pin extraction, and outside of the strain relief to avoid preloading.

Figure 25-8 shows a two wire splice, but a maximum of three wires can be spliced. If a third wire is

spliced, it is located out front of splice along with signal wire going to pin.

Splice part numbers:

•Raychem D-436-36/37/38

•MIL Spec MIL-S-81824/1

This technique may be used with shield termination methods: A.1, A.2, B.1, B.2, C.1 and C.2.

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Figure 25-8 D-Sub Spliced Signal Wire illustration


Page 25-14

25.3 Jackscrew Connector Installation

The D-sub connectors in a G3X/G3X Touch system use metal backshells with a convenient shield block for grounding the cable shields, and knurled jackscrews to attach the connector to the mating connector on the avionics module. The jackscrews should be tightened to 6-8 in. lbs. with a small slotted screwdriver, or

a 3/32” hex tool (preferred, Figure 25-9).

NOTE

It is important to ensure that connectors are fully tightened. Loose connectors may cause vibration-related performance issues that are difficult to troubleshoot.

The connector jackscrews are also pre-drilled to accept safety wire where additional security is desired. It is generally not a requirement to safety wire these connectors, especially when tightened with a hex tool.

Do not tighten more than 8 in. lbs. to prevent damage to the mating hardware.

Figure 25-9 Jackscrew Hex Driver

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Page 25-15

25.4 Thermocouple Installation into a Backshell

Table 25-5 lists parts needed to install a Thermocouple, the item numbers correspond to Figure 25-10 and

Figure 25-11 . Parts for this installation are included in the Thermocouple Kit (011-00981-00), which is

included in the G3X w/GSU 73 Installation Kit (K10-00017-00).

Table 25-5 Thermocouple Kit GPN 011-00981-00

Item #

1

2

3

Description

3” Thermocouple, K type

Pins #22 AWG

Screw

Qty. Needed

1

2

1

PN or MIL spec

925-L0000-00

336-00021-00

211-60234-08

1. Strip back approximately 0.17 inches of insulation from both the positive and negative

thermocouple leads (item 1, Figure 25-10) and crimp a pin (item 2, Figure 25-10) to each lead. It is

the responsibility of the installer to determine the proper length of insulation to be removed. Wire must be visible in the inspection hole after crimping and the insulation must be 1/64 – 1/32 inches

from the end of the contact as shown in Figure 25-10.

2

1

Figure 25-10 Insulation/Contact Clearance

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Page 25-16

NOTE

Refer to

Figure 25-11

for all item numbers in the following steps 2-5.

2. Insert newly crimped pins and wires (items 1 & 2) into the appropriate connector housing (item 4) location as specified by the installation specific wiring diagram.

3. Place thermocouple (item 1) body onto backshell (item 5) boss. Upon placing the thermocouple

(item 1) body, orient it such that the wires exit downward.

4. Attach thermocouple (item 1) tightly to backshell (item 5) using screw (item 3).

5. Attach cover (item 6) to backshell (item 5) using screws (item 7).

Figure 25-11 Jackscrew Backshell Thermocouple Installation

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Page 25-17

Section 22 GTR 20 (VHF Communications Radio) Installation. Garmin G3X Touch for Experimental Aircraft, GDU 465, GDU 455, G3X, GDU 460, GDU 450

19 GSU 25/25B/25C/25D (AHRS/AIR DATA SENSOR UNIT)

INSTALLATION

20 GSU 73 (SENSOR UNIT) INSTALLATION

21 GTP 59 (TEMPERATURE PROBE) INSTALLATION

22 GTR 20 (VHF COMMUNICATIONS RADIO) INSTALLATION

23 GPS/XM ANTENNA INSTALLATION

GA 55 STUD MOUNT

GA 55A FLANGE MOUNT

GA 56 STUD MOUNT

24 ENGINE/AIRFRAME SENSOR INSTALLATION

Actual K Factor measured at

16 GPH

25 CONNECTOR INSTALLATION INSTRUCTIONS

Related manuals

Table of contents

Section 22 GTR 20 (VHF Communications Radio) Installation. Garmin G3X Touch for Experimental Aircraft, GDU 465, GDU 455, G3X, GDU 460, GDU 450

19 GSU 25/25B/25C/25D (AHRS/AIR DATA SENSOR UNIT)

INSTALLATION

20 GSU 73 (SENSOR UNIT) INSTALLATION

21 GTP 59 (TEMPERATURE PROBE) INSTALLATION

22 GTR 20 (VHF COMMUNICATIONS RADIO) INSTALLATION

23 GPS/XM ANTENNA INSTALLATION

GA 55 STUD MOUNT

GA 55A FLANGE MOUNT

GA 56 STUD MOUNT

24 ENGINE/AIRFRAME SENSOR INSTALLATION

Actual K Factor measured at

16 GPH

25 CONNECTOR INSTALLATION INSTRUCTIONS

Related manuals

Garmin

Nexus

Frigidaire

FPRU19F8WF

Garmin

GSU 73

Garmin

Nexus

Garmin

G3X Touch™ for Certificated Aircraft

Table of contents