Nat AA38-301 Operating instructions

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.

Installation and Operation Manual

AA38-3xx Series

Local ICS Loop

SM37

ISSUE 4.11

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AA38-3xx Series Local ICS Loop

SM37 Installation and Operation Manual

Installation and Operation Manual Page iii

ENG-FORM: 820-0114.DOT

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Table of Contents

Section Title Page

1. Description

1.1 Introduction 1-1

1.2 Product Description 1-1

1.3 Design Features 1-1

1.4 Specifications 1-1

1.4.1 Electrical Specifications 1-1

1.4.2 Physical Specifications 1-3

1.4.3 Environmental Specifications 1-3

1.4.4 Product Approval 1-3

1.5 Unit Nomenclature 1-3

2. Installation

2.1 Introduction 2-1

2.2 Unpacking and Inspection 2-1

2.2.1 Warranty 2-1

2.3 Continued Airworthiness 2-1

2.4 Installation Procedures 2-2

2.4.1 Cautions 2-2

2.4.2 Cabling and Wiring 2-2

2.4.3 Installation Options 2-2

2.4.4 Post-Installation Checks 2-4

2.5 Adjustments and Connections 2-4

2.5.1 Audio Levels 2-4

2.6 Accessories Required But Not Supplied 2-5

2.7 Installation Drawings 2-5

3. Operation

3.1 Introduction 3-1

3.2 General Information 3-1

3.3 Controls and Indicators 3-1

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Section 1 Description

1.1 Introduction

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

AA38-3xx Series Local ICS Loop. All derivative product information shall be contained in the applicable

manual supplement, which may be obtained from NAT as required.

Review all notes, warnings and cautions.

1.2 Product Description

The AA38-300 Local ICS Loop provides intercom functions for eight users with operation in HOT MIC or

VOX mode. A switch-selectable NAT or Andrea tie line allows connection to multi-unit systems and radio

or music can be connected at the AUX input.

The AA38-301 Local ICS Loop is functionally identical to the AA38-300 but has two fully independent

AA38-300 PCB assemblies mounted inside the enclosure and can therefore provide the same intercom

functions for sixteen users.

1.3 Design Features

The AA38-3xx Series remote bulkhead mounted units contain all the circuitry to support a wide variety of

ICS Loop applications, particularly isolation/ICS amplifier use, where the output is required to be headset

or line level.

The compact size and low weight of the AA38 allows mounting in restricted locations and the mapped

interconnect makes installation simple to carry out.

Built-in LED annunciators speed up airframe trouble-shooting by providing an indication of power to the

AA38 and VOX operation.

Level adjustments are provided for ICS level and AUX Input level.

1.4 Specifications

1.4.1 Electrical Specifications

Input Power

Input Voltage 27.5 Vdc, with reverse and over-voltage protection

32.2 Vdc max.

Input Current 0.66 Amps Max. @ 27.5 Vdc

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Input Signals

Quantity 8 Mic channels

(AA38-300) 1 ICS tie channel

1 Aux input channel

Quantity 16 Mic channels

(AA38-301) 2 ICS tie channels

2 Aux input channels

Audio Level 250 mVrms for mic inputs

0.34 Vrms for NAT ICS tie input

2.8 Vrms for Andrea ICS tie input

2.5 Vrms for Aux input

Impedance 150

10% for mic inputs

1.6k

10% for NAT ICS tie input

250

10% for Andrea tie input

940

10% for Aux input

Circuitry Type All mics are single-ended inputs

Tie lines are single-ended inputs

Aux line is single-ended input

Better than -60 dB input-to-input crosstalk (Mic to Aux to ICS)

Output Signals

Quantity 8 Headset outputs

(AA38-300)

Quantity 16 Headset outputs

(AA38-301)

Rated Level Headset output 7.7V rms or 100 mW (20 dBm) into 600

Impedance 30 10%. (Headset output)

Circuitry Type Balanced output for high common mode noise rejection

Audio Frequency Response

Intercom <3 dB from 350 Hz to 3000 Hz

RX <3 dB from 350 Hz to 6000 Hz

Distortion <10% THD @ Rated power output

Audio Noise Level >60 dB down from rated output (without signal)

Output Regulation <10% distortion /

3 dB max. of rated output power at 400% and

75% of rated load

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1.4.2 Physical Specifications

AA38-300 AA38-301

Height

Max.

1.31"

(33.3 mm)

2.31”

(58.7 mm)

Depth 4.60" (116.8 mm) max. including connector

Width 4.50" (114.3 mm) max. including flanges

Weight

Max.

0.55 lbs

(0.25 Kg)

1.01 lbs

(0.45 Kg)

Mounting Bulkhead mount with four 10-32 screws

Material/

Finish

5052-H32 brushed aluminum with chromate conversion finish

Connectors Filtered male 37-pin D-subminiature.

connector with jack posts.

Two filtered male 37-pin

D-subminiature. connector with

jack posts.

1.4.3 Environmental Specifications

Temperature -30 to +55 C (operating)

-55 to +85

C (survival)

Altitude 25,000 feet max.

Humidity 95%

Qualification of the AA38-300 Local ICS Loop was completed in accordance with

DO-160C Env. Cat. B4-CA[BMN]XXXXXXZBABBTZXXX.

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-170 Class 1a)

Note: Applicable to AA38-300 and AA38-301 units serial number 3000 and up.

1.5 Unit Nomenclature

AA38-300 Intercom functions for eight users

Selectable NAT ICS or Andrea Tie Line

ICS volume, AUX volume and VOX controls

Live and VOX Intercom modes

VOX operation LED and 28 Vdc Power LED

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SM37 Installation and Operation Manual

Section 1 Rev: 1.00 Issue 4 Page 1-4

ENG-FORM: 800-0114.DOT

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.

AA38-301 Intercom functions for sixteen users

Selectable NAT ICS or Andrea Tie Lines

ICS volume, AUX volume and VOX controls

Live and VOX Intercom modes

VOX operation LED and 28 Vdc Power LED

Section 1 ends

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Section 2 Rev: 1.00 Issue 4 Page 2-1

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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 AA38-3xx Series Local ICS Loop.

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 NAT 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 NAT or its

designated warranty repair center, or any labour to remove or re-install the defective unit in the aircraft.

Contact NAT for any questions regarding this warranty, its applicability to your units and/or for return

authorization. NAT 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 NAT DEALER. Product for which a warranty card is not returned shall be warranted from

date of manufacture.

2.3 Continued Airworthiness

Maintenance of the AA38-3xx Series Local ICS Loop is ‘on condition’ only. Periodic maintenance of this

product is not required.

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2.4 Installation Procedures

2.4.1 Cautions

CAUTION:

In all installations, use shielded cable exactly as shown and ground as

indicated. Significant problems may result from not following these guidelines.

All audio installations can be seriously degraded by incorrect wiring and

shielding and may result in abnormal cross-talk, hum and ground-loop noise.

Be especially careful with all microphone wiring and tie line wiring, as these

lines carry the lowest level signals in the aircraft.

2.4.2 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 connector map in

Section 2.7 as required.

Allow 3" from the end of the shielded wiring to the shield termination to allow the connector hood to be

easily installed. Reference the interconnect drawing in Section 2.7 for shield termination details. Note that

the hood is a "clamshell" hood, and is installed after the wiring is complete. Aircraft harnessing shall

permit the unit to be lowered from the panel for easy access to all side adjustments. Do NOT mount the

unit until all adjustments have been performed.

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

Maintenance Instructions.

Unless otherwise noted, all wiring shall be a minimum of 22 AWG, except power and ground lines, which

shall be a minimum of 20 AWG. Reference the Interconnect drawing 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.

2.4.3 Installation Options

The AA38-300 can be configured for up to three NAT Tie Lines, or one Andrea Tie Line and each

‘section’ of the AA38-301 can be configured separately for these options.

The switches that determine the installation configuration are ICS GAIN switches 1, 2, 3, and 4, and ICS

MODE switches C1/C2 and C3/C4, accessible through the left hand side of the unit. Refer to Figures 1, 2

and 3 to determine the proper switch settings.

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AA38-3xx Series Local ICS Loop

SM37 Installation and Operation Manual

Section 2 Rev: 1.00 Issue 4 Page 2-3

Figure 1: Switch Configurations

The rocker switches used to configure the AA38 for the appropriate tie line option are visible through the

ICS MODE opening(s) in the side of the unit. The diagrams below show one set of rocker switches for the

AA38-300 and two for the AA38-301.

OR

Figure 2: ICS MODE Switch positions for

1, 2, or 3 NAT ICS Tie Lines

Figure 3: ICS MODE Switch Positions

for ANDREA Tie Lines

Mode Switch Positions

1 NAT ICS Tie Line ICS GAIN switch #1 DOWN, ICS GAIN switches # 2, 3, and 4 UP

ICS MODE switch: C1/C2 to C2 and C3/C4 to C4 (See figure 2)

2 NAT ICS Tie Lines ICS GAIN switch #2 DOWN, ICS GAIN switches # 1, 3, and 4 UP

ICS MODE switch: C1/C2 to C2 and C3/C4 to C4 (See figure 2)

3 NAT ICS Tie Lines ICS GAIN switch #3 DOWN, ICS GAIN switches # 1, 2, and 4 UP

ICS MODE switch: C1/C2 to C2 and C3/C4 to C4 (See figure 2)

ANDREA Tie Lines ICS GAIN switch #4 DOWN, ICS GAIN switches # 1, 2, and 3 UP

ICS MODE switch: C1/C2 to C1 and C3/C4 to C3 (See figure 3)

Table 1

Mode and Switch Positions

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Section 2 Rev: 1.00 Issue 4 Page 2-4

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2.4.4 Post-Installation Checks

2.4.4.1 Voltage/Resistance Checks

Do not attach the AA38-3xx until the following conditions are met.

Check the following for the AA38-300:

a) Check P101 pin 1 for +28 Vdc relative to ground.

b) Check P101 pin 20 for continuity to ground (less than 0.5

).

Check the following for the AA38-301:

a) Check P1 and P2 pin 1 for +28 Vdc relative to ground.

b) Check P1 and P2 pin 20 for continuity to ground (less than 0.5

).

2.4.4.2 Power On Checks

Power up the aircraft’s systems and confirm normal operation of all functions of the AA38-3xx. Refer to

Section 3 (Operation) for specific operational details.

a) Check for correct radio audio and adjust for acceptable level.

b) Run through all installed functions and check the ICS functions for all users.

c) Check preset adjustments are completed before aircraft departure. Refer to Section 2.5 for

details of adjustments.

Notes: 1) Significantly different headsets may have different mic characteristics.

2) The David Clark M-7 mic is much more active than their M-4 or M-1 microphones and may

aggravate headset imbalance if used in a mixed system.

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.

2.5 Adjustments and Connections

The unit is shipped from the factory with all internal adjustments set to the normal test levels. Once

installed in the aircraft, it may be desirable to change some of these settings to best suit the local

operating environment. The internal adjustments are located along the right side of the unit.

2.5.1 Audio Levels

Adjust ICS VOL and AUX VOL to desired levels. Clockwise rotation of these controls will increase audio

volume level.

Setting the ICS VOX control fully clockwise sets the AA38 to ‘live’ mode. Adjusting it counter clockwise

sets the level which activates the VOX mode.

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Section 2 Rev: 1.00 Issue 4 Page 2-5

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2.6 Accessories Required But Not Supplied

Installation kit p/n AA38-IKC (crimp) is required to complete the installation.

AA38-IKC consists of

Quantity Description NAT Part No.

1 D-min 37 Socket Housing 20-21-037

37 MS Crimp Socket 20-26-901

1* Jack Screw Set 20-27-002

1* Lock Clip Set 20-27-004

1 37 Pin Connector Hood 20-29-038

* Use as required.

Note: Two kits will be required for the AA38-301.

2.7 Installation Drawings

DOCUMENT REV. DESCRIPTION TYPE SERIAL NO.

AA38-300

AA38\300\403-0 1.00 Local ICS Loop Interconnect 1622 and up

AA38\300\405-0 1.00 Local ICS Loop Connector Map 1622 and up

AA38\300\521-0 1.02 Local ICS Loop Environmental Qualification Form 3000 and up

AA38\300\922-0 1.00 Local ICS Loop Mechanical Installation 1622 to 2999

AA38\300\922-0 1.10 Local ICS Loop Mechanical Installation 3000 to 3284

AA38\300\922-0 1.20 Local ICS Loop Mechanical Installation 3825 and up

AA38-301

AA38\301\403-0 1.00 16 Place Local ICS Loop Interconnect 2067 and up

AA38\301\403-1 1.00 16 Place Local ICS Loop Interconnect 2067 and up

AA38\301\405-0 1.00 16 Place Local ICS Loop Connector Map 2067 and up

AA38\301\922-0 1.02 16 Place Local ICS Loop Mechanical Installation 2067 and up

Section 2 ends following the above documents

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