Northern Airborne Technology SM251 Installation And Operation Manual

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Installation and Operation Manual

Model 251

Passenger Speaker Amplifier

SM251

ISSUE 2.00

Northern Airborne Technology Ltd.

1925 Kirschner Road

Kelowna, BC, Canada.

V1Y 4N7

Telephone (250) 763-2232

Facsimile (250) 762-3374

Issued on the authority of Northern Airborne Technology Ltd.

Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Prepared By: Checked By:

The status of this installation and operation manual is controlled by issue shown on the title page. The status of each section is controlled by revision shown in the footer of each page. All revisions affecting sections of this manual have been incorporated into the latest issue.

ISSUE/REVISION RECORD

Manual Issue

Number

Section

Revision Number

Revision Description Issue Date

2.00 Rewritten in full NAT format Oct 28, 2009 Section 1 Rev: 1.00

Section 2 Rev: 1.00

Section 3 Rev: 1.00

Installation and Operation Manual

ENG-FORM: 820-0114.DOT

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.

Page ii

Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Section Title

1. Description

1.1 Introduction

1.3

1.4

1.4.1

1.4.2

1.4.3

1.4.4

Design Features

Specifications

Electrical Specifications

Physical Specifications

Environmental Specifications

Product Approval

Unit Nomenclature 1.5

2. Installation

2.1 Introduction

2.2 Unpacking and Inspection

2.2.1 Warranty

2.3

2.4

Continued Airworthiness

Installation Procedures

2.4.1

2.4.2

2.4.3

Warnings

Cautions

Cabling and Wiring

2.4.5

2.4.6

2.4.7

Electrical Installation

Operating Modes

Wiring Diagram

2.4.9

2.5

2.6

2.7

Post-Installation Checks

Adjustments and Connections

Accessories Required But Not Supplied

Installation Drawings

3. Operation

3.1 Introduction

Page

1-1

1-2

1-4

2-1

2-2

2-3

2-4

2-5

2-8

2-9

2-10

2-11

3-1

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Page iii

Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Section 1 Description

1.1 Introduction

Information in this section consists of product description, design features and specifications for the

Model 251 Passenger Speaker Amplifier. All derivative product information shall be contained in the applicable manual supplement, which may be obtained from Northern Airborne Technology Ltd. as required.

Review all notes, warnings and cautions.

1.2 Product Description

The Model 251 Passenger Speaker Amplifier is a remotely controlled, electronic unit that operates upon command from remote switches and potentiometers in the cockpit or cabin of the aircraft.

1.3 Design Features

The Model 251 provides Seat Belt and No Smoking sign chime tones, a Cabin Call ringer tone, ADF, Pilot

Select Comm. (PSC), Briefer, and Cabin Paging audio (all in mono) to the cabin speakers. It also provides audio from an external AM/FM stereo receiver/cassette tape or CD player (in stereo) to the cabin speakers and auxiliary monitor outputs.

The left and right speaker amplifier channels are each powered through separate internal fuses so that a failure in one speaker channel will not disable the other speaker channel or the remaining control circuitry.

The left and right monitor outputs are powered from a third power supply circuit.

A musical chime tone is provided to the cabin speakers to alert the passengers of a change in the Fasten

Seat Belt or No Smoking sign status. A Cabin Call ringer tone is also provided to the cabin for a cockpit to cabin intercom system. The chime and ringer tones do not pass through either of the electronic attenuators.

Each left and right speaker amplifier output rating is 28 Watts into 2 ohms (30 Watts typical) or 49 Watts into 1 ohm. Both speaker amplifier outputs are internally protected against open and short circuits as well as over-temperature (>105°C).

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Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Specifications 1.4

1.4.1 Electrical Specifications

Power Supply:

INPUTS :

ADF:

PSC:

28 Vdc, 5 ampere maximum.

Two individual, switched audio inputs for ADF1 and ADF2.

Input level is 7.75 Vrms.

One switched audio input compatible with the Pilot Select COMM output of dB Systems cockpit audio control amplifiers (such as

Models 438 and 700), which provides a 1.00 Vrms signal produced from a summation of selected COMM, DME and MKR receivers. The PSC input can also be used for TV audio or other similar audio.

TV: One switched audio input for TV (or other device). Input level is

1.00 Vrms.

Stereo Left: One switched differential audio input for the left audio channel from an AM/FM Stereo receiver/tape or CD deck (or other device). Input level is maximum 0.45 Vrms. (at maximum source volume) and audio LO is not common to that of other inputs.

Stereo Right: Same as stereo left, switched by the same control input as stereo left.

Brief: One switched audio input for automated cabin briefer audio.

Input level is 1.00 Vrms.

PA MIC: The microphone input used for cabin paging audio supplies bias current and is compatible with carbon and amplified dynamic microphones. Input level is 0.25 Vrms.

Paging Volume: Controls level of PA MIC and brief audio inputs to the PA sidetone and left and right speaker outputs. Volume control range is 30 dB (minimum) controlled by a 10,000-ohm, 1/2-Watt, linear pot. Maximum volume is with maximum resistance.

Receiver Volume: Controls level of ADF, PSC and TV audio inputs to the left and right speaker outputs. Volume control range is 30 dB (minimum) controlled by a 10,000-ohm, 1/2-Watt, linear pot. Maximum volume is with maximum resistance.

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Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

OUTPUTS :

Right Speaker: The right speaker amplifier is designed for speech and music signals.

Rated power specification is the maximum power the amplifier can continuously deliver into the maximum rated load without clipping.

Rated Power

49 W

28 W

15 W

Load

1 ohm (40 Watts typical)

2 ohms (30 Watts typical)

4 ohms (18 Watts typical)

Left Speaker:

Right Monitor:

Same as right speaker specification

Delivers up to 26 milliwatts into 600 ohms continuously. Factory calibration is 1.6 mW (1 Vrms).

Left Monitor:

PA Sidetone:

Same as right monitor specification

Chime Tone:

6.7 milliwatts (2 Vrms) into 600 ohms continuous.

Rated and continuous power ratings are the same.

Generated and supplied to left and right speaker and monitor outputs when 12 to 32 Vdc is applied to or removed from connector pins P50-31 or P50-32.

A 790 Hz tone followed by a 610 Hz tone (2-tone, HI/LO) is factory set for 3.5 VPP (at speaker outputs), adjustable from 1.0 to 6.9 VP-P and is also available at monitor outputs.

Ringer Tone: Generated and supplied to left and right speaker and monitor outputs when a ground signal is applied to connector pin P50-33.

Ringer tone is 700

75 Hz tone, ON for 1.8

0.1 second, then OFF for 3.2

0.1second, repeating. Factory set for 1.5 VP-P (700 Hz component) (at speaker outputs), adjustable from 0 to 5.2 VPP.

Frequency Response: Upper and lower frequency limits are adjustable. Stereo, ADF,

TV, and PSC inputs to speaker and monitor outputs are flat within 3 dB from 40 Hz to 20,000 Hz. All other inputs to speaker, monitor, or PA sidetone outputs flat within 3 dB from 300 Hz to

6,000 Hz.

Harmonic Distortion (Thd+N): Less than 0.30 percent distortion, for stereo and less than 1% for

ADF, TV and PSC to all outputs (40 Hz to 20 KHz). Less than

3% for PA and briefer to all outputs (300 Hz to 6 KHz).

Isolation Between Channels: 60 dB, minimum.

Output Noise: Greater than 75 dB below rated, all outputs.

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1.4.2

Height

Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Physical Specifications

2.470"

Width

Weight

Mounting

7.800" max. including flanges and excluding mating connectors

2.6 lbs

Bulkhead Mount (four (4) #8 screws)

1.4.3 Environmental Specifications

Temperature: -55 to +70°C (Operating) Thermal fold-back of the speaker outputs occurs if the heatsink temperature reaches 105°C.

-55 to +85°C (Survival)

Operating Altitude: 70,000 feet max

Shock 15g (any axis)

Vibration RTCA/ DO-160C category CL

Qualification of the Model 251 Passenger Speaker Amplifier was completed in accordance with

RTCA/DO-160C Environmental Categories [A2F2]-BA(CL)XXXXXXZ(BZ)AAATZ(XXC2)XX

Note: Refer to Environmental Qualification Form located in Section 2 of this Manual for complete details of the environmental categories.

1.4.4 Product Approval

FAA: TSO-C50c (RTCA/DO-214 Class I b, RTCA/DO-160C)

1.5 Unit Nomenclature

Examples of derivative products are given below. For full information contact Customer Service & Repair

Model 251-001 Low pass filters adjusted for -3 dB attenuation at 90 Hz on left and right speaker outputs.

High pass filters adjusted for -3 dB attenuation at 20 Khz on left and right speaker outputs.

Designed for use with 4-inch speakers.

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Model 251-002

Model 251-003

Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Identical to 251 Base Model. Part number 251-002 was created to prevent a conflict with an existing part number 251 in customer part system.

Identical to 251 Base Model with the following exceptions: a) Briefing audio is to output through the right speaker only. b) The receiver inputs and switches are not available. c) The briefer switch input is externally grounded, disabling the Stereo

Left input and the Stereo Right input.

Section 1 ends

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Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Section 2 Installation

2.1 Introduction

Information in this section consists of unpacking and inspection procedures, installation procedures, post-installation checks and installation drawings for the Model 251 Passenger Speaker Amplifier.

Review all notes, warnings and cautions.

2.2 Unpacking and Inspection

Unpack the equipment carefully and locate the warranty card. Inspect the unit visually for damage due to shipping and report all such claims immediately to the carrier involved. Check that all items listed below are present before proceeding and report any shortage immediately to your supplier:

- Warranty Card

- Certificate of Conformity or Release Certification

2.2.1 Warranty

All Northern Airborne Technology Ltd. products are warranted for 2 years from date of installation by an authorized Northern Airborne Technology Ltd. dealer, to be free of defects in workmanship or performance. This warranty covers all materials and labour, but is exclusive of any transport to deliver the defective unit to and from Northern Airborne Technology Ltd. or its designated warranty repair center, or any labour to remove or re-install the defective unit in the aircraft. Contact Northern Airborne Technology

Ltd. for any questions regarding this warranty, its applicability to your units and/or for return authorization.

Northern Airborne Technology Ltd. is the final arbitrator concerning warranty administration. Units which have been physically damaged, burned, immersed in water or otherwise abused beyond the scope of normal use will not be considered for warranty. WARRANTY IS VOID UNLESS THE PRODUCT IS

INSTALLED BY AN AUTHORIZED NORTHERN AIRBORNE TECHNOLOGY LTD. DEALER . Product for which a warranty card is not returned shall be warranted from date of manufacture.

2.3 Continued Airworthiness

Maintenance of the Model 251 Passenger Speaker Amplifier is ‘on condition’ only. Periodic maintenance of this product is not required.

2.4 Installation Procedures

Installation Notice

This product must be installed in accordance with the installation instructions provided in the latest issue of this Installation and Operation Manual. Check the Publication Index at www.northernairborne.com for the issue status of the manual. The latest issue of the manual may be downloaded from the same website. All risk associated with installation of this product contrary to these instructions shall be the responsibility of the installing agency.

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2.4.1 Warnings

Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

WARNING:

High volume settings can cause hearing damage.

Set the headset volume control to the minimum setting prior to conducting tests, and slowly increase the headset volume to a comfortable listening level.

2.4.2 Cautions

CAUTION:

Do not bundle any lines from this unit with transmitter coax feed lines. Do not bundle any audio or DC power lines from this unit with 400 Hz synchro wiring or AC power lines. Do not position this unit next to any device with a strong alternating magnetic field such as an inverter, motor or blower, or significant audio interference will result.

In all installations, use shielded cable exactly as shown, and ground only as indicated. Significant problems may result from not following these guidelines.

Failure to follow the installation and wiring instructions provided in this manual for power and ground connections, including the rating of the circuit breaker, may lead to damage in the power input circuitry of the unit.

2.4.3 Cabling and Wiring

All wire shall be selected in accordance with the original aircraft manufacturer's Maintenance Instructions or AC43.13-1B Change 1, Paragraphs 11-76 through 11-78. Unshielded wire types shall qualify to

MIL-W-22759 as specified in AC43.13-1B Change 1, Paragraphs 11-85, 11-86, and listed in Table 11-11.

For shielded wire applications, use Tefzel MIL-C-27500 shielded wire with solder sleeves (for shield terminations) to make the most compact and easily terminated interconnect. Follow the Wiring Diagram in

Section 2.4.7 as required.

Allow 3" from the end of the shielded wiring to the shield termination to allow the connector hood to be easily installed. Refer to the Wiring Diagram in Section 2.4.7 for shield termination details. Note that the hood is a "clamshell" hood, and is installed after the wiring is complete.

Maintain wire segregation and route wiring in accordance with the original aircraft manufacturers

Maintenance Instructions.

Unless otherwise noted, power, ground and speaker wiring shall be a minimum of 20 AWG, and all others shall be a minimum of 22 AWG. Refer to the Wiring Diagram for additional specifications. Check that the ground connection is clean and well secured, and that it shares no path with any electrically noisy aircraft accessories such as blowers, turn and bank instruments or similar loads. Power to this unit must be supplied from a separate circuit breaker or fuse (fast blow), and not attached to any other circuit breaker without additional protection. Verify that the selected circuit breaker size and wire gauge are adequate for the installation using the techniques specified in AC43.13-1B Change 1, Paragraphs 11-47 through 11-51 and 11-66 through 11-69.

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Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Mechanical Installation 2.4.4

The Model 251 is designed to be mounted in virtually any pressurized or unpressurized location within an aircraft fuselage. The unit can be mounted either vertically or horizontally (with the heatsink facing up) using four (4) #8 mounting screws. The mounting location must provide adequate ventilation to allow heat dissipation. No shock or vibration isolators are required.

The Model 251 must be mounted to a clean metal surface which is electrically bonded to the aircraft ground plane. The unit is finished with a coating which prevents corrosion. This film is electrically conductive and should not be removed for electrical bonding.

2.4.5 Electrical Installation

All inputs and operating modes are electronically switched. Ground signals, supplied by manual switches in the cockpit, enable the electronic switches in the Model 251. The circuitry is arranged to give audio priority to paging, briefer, and chimes; the PA MIC, BRIEF, and Seat Belt/No Smoking chime switch signals mute the Stereo Left, Stereo Right, ADF 1, ADF 2, PSC, and TV audio inputs. PA, briefer, and chimes will automatically enable speakers even if the speaker switch is off. Microphone bias current is available from the Model 251 for the PA MIC microphone input.

Electronic attenuators are employed to control paging volume and master receiver (ADF 1, ADF 2, PSC, and TV) volume. Each attenuator has approximately 30 dB (minimum) of range and is controlled by a remote volume potentiometer. The potentiometers required are zero to 10,000 ohms, linear taper; maximum resistance provides maximum volume. The audio source (stereo tape cassette player, etc.) for the Stereo Left and Right inputs should have its own external volume control attenuator for the Stereo

Input to Speaker and Monitor Output audio channels. The left and right stereo inputs are fully floating

(differential type).

The chime or ringer levels heard in the passenger speakers may be adjusted (see section 2.5).

The control switches shown will switch low current loads and should have a DC rating of 28 Vdc.

The paging and receiver volume control pots required are linear taper, zero to 10,000 ohms, 1/2 watt or greater. Electrically, the pots are wired to provide maximum resistance to the Model 251 for full volume

(fully clockwise rotation).

Speaker enable inputs are provided to allow remote ON/OFF switching for the left and right speakers.

A remote electronic speaker mute control is also provided. The mute control can be connected to the aircraft’s Weight-On-Wheels switch to lower speaker volume upon landing when lower cabin ambient noise levels are present and less speaker volume is needed. The speaker mute control drops speaker level by approximately 1/2 (-6 dB) when grounded.

Left and right stereo monitor outputs are provided for connecting to a cabin headphone amplifier or headphone audio distribution system. The monitor outputs are line-level (1 Vrms adjustable) outputs that carry the same audio signals as the speaker outputs. Unlike the speaker outputs, the monitor outputs cannot be deselected or muted independently of the normal input switching circuits.

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Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Operating Modes 2.4.6

The operating modes of the Model 251 are established when either a ground (low) signal or a 12 to 32

Vdc (high) signal is applied as shown below to the listed connector pin:

Pin No.

P50-16

Control

Signal

Low

Identification

ADF 1 Switch

Function

Connects ADF 1 input audio to left and right speaker and monitor outputs.

P50-15 Low ADF 2 Switch

Connects ADF 2 input audio to left and right speaker and monitor outputs.

Connects Pilot Select Comm (PSC) input audio to left and right speaker and monitor outputs.

Connects TV input audio to left and right speaker and monitor outputs.

P50-5

P50-25

Low

P50-31*

P50-32*

Stereo Switch

Briefer Switch

Connects stereo left and stereo right input audio to left and right speaker and monitor outputs, respectively.

Connects PA MIC input audio to PA sidetone, left and right speaker, and monitor outputs. Opens ADF, PSC, TV, and stereo input audio circuits.

Connects briefer input audio to PA sidetone, left and right speaker, and monitor outputs. Opens ADF, PSC, TV, and stereo input audio circuits.

Chime tone to left and right speaker and monitor outputs.

Opens ADF, TV, PSC, and stereo inputs.

Chime tone to left and right speaker and monitor outputs.

Opens ADF, TV, PSC, and stereo inputs.

P50-33 Low Cabin Call Ringer tone to left and right speaker and monitor outputs.

P50-34 Low Hook Switch Disables ringer tone.

P60-3 Low Speaker Mute Mutes (lowers volume -6 dB) left and right speaker outputs.

*An application or removal of a High signal at pins P50-31 and P50-32 will provide a chime tone at left and right speaker outputs regardless of speaker enable status.

Note : P50-XX is a pin on the 37-pin connector, P50

P40-XX is a pin on the 25-pin connector, P40

P60-XX is a pin on the 9-pin connector, P60

The amplifiers are adjusted for acceptable listening output levels into the proper loads with ADF receiver inputs of 7.75 Vrms, stereo audio inputs of 0.45 Vrms, PSC, TV, and Briefer audio inputs of 1.00 Vrms and PA MIC input of 0.25 Vrms. With the volume controls set to maximum volume position, these inputs will provide 7.5 Vrms (28 watts) into 2 ohms at each speaker output. The ADF receiver input levels are achieved when receivers are set for 100 milliwatts into 600 ohms. If levels are greatly exceeded at any of the inputs, the audio will become distorted due to peak clipping, and audio bleed-through will occur.

However, the amplifiers will not be damaged.

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2.4.7

Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Wiring Diagram

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Wiring Diagram (continued)

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Wiring Diagram (continued)

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P40 (25-pin connector):

Pin Function

Left Spkr Out HI

Left Spkr Out LO

28 VDC

Right Spkr Out LO

Right Spkr Out HI

13 Right Spkr Out HI

P50 (37-pin connector):

Pin Function

Audio Common (except stereo)

PA MIC HI

Paging Volume

Briefer Audio HI

Stereo Switch

Left Input HI

Left Input LO

Right Input LO

Right Input HI

No Connection

Receiver Volume Control

No connection

TV Switch

PSC Switch

ADF2 Switch

ADF1 Switch

ADF1 Audio HI

TV Audio HI

PSC Audio HI

P60 (9-pin connector):

Pin Function

Right Monitor Output HI

Right Monitor Output LO

Speaker Mute

Left Monitor Output LO

Left Monitor Output HI

Pin Function

Left Spkr Out HI

No connection

Power Ground

28 VDC

Chassis Ground

No connection

Right Spkr Out HI

Pin Function

Audio Common (except stereo)

Audio Common(except stereo)

No connection

PA Key

Briefer Switch

No connection

Audio Common(except stereo)

No connection

Smoking Sign Switch

Seat Belt Sign Switch

Cabin Call Switch

Hook Switch

PA Sidetone HI

Audio Common(except stereo)

ADF2 Audio HI

Pin Function

No Connection

Speaker Enable

No Connection

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Post-Installation Checks 2.4.9

2.4.9.1 Voltage/Resistance Checks

Do not attach the Model 251 until the following conditions are met.

Check the following: a) Check P40 pins <6> <7> <8> and <21> for +28 Vdc relative to ground. b) Check P40 pins <17> <18> <19> and <20> for power ground (less than 0.5

). c) Check P40 pin <22> for chassis ground (less than 0.5

). c) Check P50 pins <33> <34> <16> <14> <13> <25> and <5>, and P60 pins <3> and <8> for continuity to ground (less than 0.5

) when the relevant switches are closed.

2.4.9.2 Power On Checks

Power up the aircraft’s systems and confirm normal operation of all functions.

Upon satisfactory completion of all performance checks, make all required log book entries, electrical load, weight and balance amendments and other documentation as required by your local regulatory agency before releasing the aircraft for service.

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SM251 Installation and Operation Manual

Adjustments and Connections 2.5

Internal screwdriver potentiometer adjustments are accessible, after removal of the Model 251 end plate, to set various chime or ringer levels heard in the passenger speakers.

Figure 1: Internal Trim Pot Adjustments

2.6 Accessories Required But Not Supplied

Installation kits p/n D09SV-IKC, D25SV-IKC & D37SV-IKC (crimp) are required to complete the installation. The kits consist of the following:

D09SV-IKC consists of:

Quantity Description NAT Part No.

D-min 9 Socket Housing

MS Crimp Socket

9 Pin JVL Hood/Locklever

20-21-009

20-26-901

20-29-090

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D25SV-IKC consists of:

Quantity

Description

D-min 25 Socket housing

MS Crimp Socket

25 pin JVL Hood/Locklever

NAT Part No.

20-21-025

20-26-901

20-29-250

D37SV-IKC consists of:

Quantity

Description

D-min 37 Socket Housing

MS Crimp Socket

37 Pin JVL Hood/Locklever

NAT Part No.

20-21-037

20-26-901

20-29-370

2.7 Installation Drawings

TYPE

Model 251

251\251\521-0 1.00 Passenger Speaker Amplifier Environmental Qual. Form

1.52 Passenger Speaker Amplifier Outline 251

Section 2 ends following the above documents

1000 and up

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ENVIRONMENTAL QUALIFICATION FORM

Description:

Passenger Speaker Amplifier

Document #:

251\251\521-0

NAT Part #:

251-xxx

TSO#:

TSO-C50c

Manufacturer’s Specification and/or Other Applicable Specification:

RTCA DO-160C

Manufacturer:

Wulfsberg Electronics Division

Address:

6400 Wilkinson Drive, Prescott, AZ USA 86301

Prepared By: Checked By: Approved By:

Conditions Section Description of Conducted Tests

Temperature and Altitude

Low temperature

High temperature

In-flight loss of cooling

Altitude

Decompression

Overpressure

Temperature Variation

4.0

4.5.1

4.5.2, 4.5.3

4.5.4

4.6.1

4.6.2

4.6.3

5.0

Categories A2 and F2

-55°C Operating Low Temperature

+70°C Operating High Temperature

No cooling required

+70,000 feet

+8,000 feet to +55,000 feet

-15,000 feet

Category B

Operational shocks and crash safety

Operational shocks

Crash safety

Vibration

Explosion Proofness

Waterproofness

Fluids susceptibility

Sand and dust

Fungus resistance

7.0

7.2

7.3

8.0

9.0

10.0

11.0

12.0

13.0

Operational and Crash shocks per DO-160C, paragraphs. 7.2.1, 7.3.1, 7.3.2 and 7.3.2.2

(without shock mounts)

Equipment meets Operational Shocks requirement during application of 15g Crash

Shock

Categories C and L (without shock mounts)

Curve L upper test frequency was extended from 150 Hz to 2000 Hz at 3g PK

Category X, no test performed

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Conditions

Salt spray

Magnetic effect

Power input

Section

14.0

15.0

16.0

Description of Conducted Tests

Category X, no test performed

Class Z

Categories B and Z

Equipment met requirements for Emergency

Electrical System Operation per DO-160C subparagraph 16.5.2.1 b (3)

Category A

Voltage spike

Audio frequency conducted susceptibility

Induced signal susceptibility

Radio frequency susceptibility

Emission of radio frequency energy

Lightning induced transient susceptibility

17.0

18.0

19.0

20.0

Change No. 3

21.0

22.0

Change No. 2

Category A

Category T

Category Z

Category XXC2

Lightning direct effect 23.0 Category X, no test performed

Icing 24.0 Category X, no test performed

REMARKS

Model 251-[ ] was qualified to the environmental test requirements of RTCA DO-160C by similarity to

Models 250-[ ] and 700-[ ].

For Model 250-[ ]:

-Tests of DO-160C, Sections 4.0 (paragraphs 4.5.1, 4.5.2, & 4.5.3), 5.0, 16.0, and 18.0 were conducted at

dB Systems, Inc. in Redmond, Washington.

-Tests of DO-160C, Sections 4.0 (paragraphs 4.6.2 & 4.6.3) and 20.5 (radiated susc.) were conducted at

Sundstrand Data Control Inc. in Redmond, Washington.

-Tests of DO-160C, Sections 4.0 (paragraph 4.6.1), 7.0, 8.0, 15.0, 17.0, 19.0, 20.4 (conducted susc.), 21.0, and 22.0 were conducted at Eldec Corporation in Lynnwood, Washington.

For Model 700-[ ]:

-Tests of DO-160C, Sections 4.0 (paragraphs 4.5.1, 4.5.2 & 4.5.3), 5.0, 16.0 (except subparagraph 16.5.2.3 b), and 18.0 were conducted at dB Systems, Inc. in Redmond, Washington.

-Tests of DO-160C, Sections 4.0 (paragraphs 4.6.1, 4.6.2 & 4.6.3), 7.0, 8.0, 15.0, 16.0 (subparagraph

16.5.2.3b),17.0, 19.0, 20.0, 21.0 and 22.0 were conducted at Sundstrand Data Control, Inc. in Redmond,

Washington.

- Tests of DO-160C, Section 6.0, were conducted at Eldec Corporation and meet requirements based on

similarity to Models 207 and 407.

End of Environmental Qualification Form

Rev: 1.00 Jul 28, 2009 Page 2 of 2

ENG-FORM: 521-0102.DOT

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.

Model 251 Passenger Speaker Amplifier

SM251 Installation and Operation Manual

Section 3 Operation

3.1 Introduction

Information in this section consists of functional and operational procedures for the Model 251 Passenger

Speaker Amplifier. .

3.2 General Information

The Model 251 Passenger Speaker Amplifier is a remotely controlled, electronic unit that operates upon command from remote switches and potentiometers in the cockpit or cabin of the aircraft.

The Model 251 provides Seat Belt and No Smoking sign chime tones, a Cabin Call ringer tone, ADF, Pilot

The left and right monitor outputs are powered from a third power supply circuit.

A musical chime tone is provided to the cabin speakers to alert the passengers of a change in the Fasten

The Model 251 Passenger Speaker Amplifier has no operator accessible controls. During installation, it may be determined that internal level adjustments are required. Qualified personnel only shall complete internal level adjustments.

Section 3 ends

Section 3 Rev: 1.00

ENG-FORM: 806-0114.DOT

Issue 2 Page 3-1

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.

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