Download - SD3-60 AIRCRAFT MAINTENANCE MANUAL - … 23.pdfmusic. 23-11-00 Jun 30/01 ... Check for intelligible transmission and reception. Repeat using hand ... SD3-60 AIRCRAFT MAINTENANCE MANUAL

Jan 31/1123-00-00 EFFECTIVITY: All

zSD3-60 AIRCRAFT MAINTENANCE MANUAL

AMM23-00-00 1.0.0.0COMMUNICATIONS

1. General

This chapter describes the systems installed for the reception and transmission of audio communications to, from and within the aircraft, also audio monitoring and static discharge.

A. V.H.F. Communications

Two independent very high frequency (VHF) transceivers, designated COM1 and COM2 provide amplitude modulated communications in the following frequency ranges:-

(1) 118-135.975 MHz - transceiver Collins type VHF20A Pt No 622-1879-001 (pre mod 7397).

(2) 118-135.975 MHz - transceiver Collins type VHF21A Pt No 622-6389-001 (post mod 7397).

(3) 118-136.975 MHz - transceiver Collins type VHF21A Pt No 622-6389-011 (post mod 8498).

Control units are mounted on panel 1P and provide pre-select facilities.

B. H.F. Communications

This (optional) facility provides long range communications in the following frequency ranges:-

(1) 2 to 23 MHz - Collins type HF220 (post mod A7343).

(2) 2 to 30 MHz - Collins type HF230 (post mod A8375).

The system controller is mounted on panel 1P and incorporates single side band operation.

C. Passenger address

An independent passenger address and chime call is installed for use by pilots and attendant. On failure of main system an emergency system is available to pilots only, utilising speaker amplification sections of the audio centres.

D. Interphone

Pilots and observers may communicate with each other, with the attendant and external ground crew. Amplification is provided through audio centres and redundancy is incorporated.

Jan 31/1123-00-00 EFFECTIVITY: All


E. Audio integrating

Audio control panels are installed at each pilots station to control all incoming and out-going audio signals. Control and amplification is via two Collins 346B-3 audio centres, two Shorts switch panels and two Shorts accessory panels.

F. Static discharge

Static dischargers are fitted to the trailing edges of mainplanes, tailplane and rudder to provide a discharge path for static electricity collected during flight. The purpose is to reduce interference on ADF and HF in particular.

G. Voice recorder

The last 30 minutes of all flight compartment sounds and passenger address is recorded to aid aircraft accident investigation.

H. Tape Player

An auto reverse cassette player is located at the attendant's station to provide boarding music.

Jun 30/0123-11-00 Page 1EFFECTIVITY: All


AMM23-11-00 2.0.0.0V.H.F. COMMUNICATIONS - GENERAL

1. General

A. Details of the VHF Communications system are provided as follows:-

(1) Pre mod A7397. Refer to 23-11-10, pb1.

Transceiver - Collins type VHF-20A Pt No 622-1879-001

Control Unit - Collins type CTL-20 Pt No 622-4523-015

(2) Post mod A7397. Refer to 23-11-20, pb1.

Transceiver - Collins type VHF-21A Pt No 622-6389-001 (Pre Mod A8498)

or

Transceiver - Collins type VHF-21A Pt No 622-6389-011 (Post mod A8498)

Control Unit - Collins type CTL-22 Pt No 622-6520-007



AMM23-11-10 3.0.0.0VHF COMMUNICATIONS - DESCRIPTION & OPERATION(PRE MOD A7397 AIRCRAFT ONLY)

1. Description

A. General

The VHF (very high frequency) communication system provides line of sight two-way amplitude modulated voice communications in the frequency range 118.0 to 135.975 MHz on 720 channels spaced at 25 KHz. Two identical systems are installed designated COM 1 and COM 2.

B. Transceiver : Collins Type VHF-20A

COM 1 transceiver is located in the No.1 (left) avionics bay and COM 2 in the No.2 (right) avionics bay. Each is a solid state unit providing a 20 watt output and having conventional 2 out of 5 frequency selection.

C. Control unit : Collins Type CTL20

Refer to Figure 1.

Two control units marked COM are located on central dashboard panel 1P each having the following displays and controls:-

Two gas, discharge, frequency displays designated COM and PRE. The active frequency is always displayed in the top (COM) position.

Two, concentric, frequency select knobs.

An active/preselect switch having the following positions:-

A TUNE button which lights up (green) when the transceiver is transmitting. Pressing this button tunes the transceiver to the preset frequency. The active frequency is then stored in the bottom display for instant re-activation.

A rotary switch for on/off control with a concentric volume control and a test position. When TEST is selected the squelch circuit is disabled causing a sharp increase in back-ground noise which confirms that the system is active.

ACT Frequency select knobs control upper display and tune the transceiver directly.

PRE Frequency select knobs control the lower display but do not tune the transceiver.



D. Antennas

These are both Dorne & Margolin type DMC60-1. COM1 antenna is mounted on the rear fuselage roof between stations 146 and 176. Hence COM1 is the more suitable of the two for ground use.

E. Additional controls

Selection by the audio panel rotary switches facilitates operation of transceivers directly from a battery either through the audio system or directly into a headset with an alternative transmit button. The purpose of this facility is to enable operation before the main busbars are powered, thus conserving battery charge and to act as an alternative communication channel if difficulties are encountered (spurious transmission in particular).

F. Power supply

Both COM systems have alternative 28V dc power sources as follows:-

Normal power is derived from appropriate avionics busbars via circuit breakers:

Direct battery power is from appropriate battery busbars via circuit breakers:-

2. Operation

A. General

Before starting, ensure that the avionics master switch is OFF.

Select audio panel rotary switch to NORMAL. The battery discharge light is lit and the indicated COM system is operable directly from a battery using headset and handwheel transmit switch.

If both rotary switches are at NORMAL, COM operation is also available via speakers and hand microphones.

Immediately before starting, cancel this selection and check that both battery discharge lights are out (to prevent electrical transient damage).

After starting both engines, select the avionics master switch to ON and select audio rotary switches to the COM 1 or 2 position as required.

CB401 COM 1. Panel 5D LeftCB431 COM 2. Panel 6D Right

CB65 COM 1. Panel 1D LeftCB216 COM 2. Panel 2D Right



B. Tuning

Frequency selection and transceiver test is achieved as indicated in paragraph Refer to C. of the description section of this chapter.

CAUTION: DO NOT TUNE COM TRANSCEIVERS TO THE SAME FREQUENCY OR TO TWO FREQUENCIES THAT CARRY THE SAME TRANSMISSION.

C. Receive mode

Receiption is available via telephones or loudspeakers as covered in the audio section of this chapter. If the transceivers are adjusted correctly, the volume controls on individual controllers may be left at the fully clockwise position and collective volume adjusted on the audio panel.

D. Transmit mode

Microphone and keying selection is via audio panel rotary switches and transmit switches on handwheels or hand microphones. Sidetone is available in the telephones, to encourage correct speech levels.

E. Emergency operation

Emergency COM operation is provided to cover the situation in which a transceiver is in a faulty transmission mode indicated by continuous illumination of the associated TUNE button. In such a case, all communication on the selected frequency is blocked and the corrective action is as follows:-

Switch the offending transceiver OFF and trip its circuit breaker on avionics distribution panel 5D or 6D. Select the rotary switch to EMERGENCY and check that the relevant COM TUNE button is not lit. Resume communication using a headset and the PRESS TO TX button on the audio panel.



VHF Control unitFigure 1



AMM23-11-104.0.0.0V.H.F. COMMUNICATIONS - MAINTENANCE PRACTICES (PRE MOD A7397 AIRCRAFT ONLY)

1. General

V.S.W.R. checks of antennas and feeders. Refer to 23-11-11, pb201.

2. Adjustment/Test

A. Bench checks of VHF transceiver.

Perform in accordance with appropriate equipment maintenance manual with the following provisos:-

(1) Transmitter modulation depth must be adjusted for a carbon microphone input of 0.125V, 150 ohms.

NOTE: Besides bench checking with an oscillator, the modulation must be checked to be 70% to 90% for normal voice levels using a suitable headset or hand microphone.

(2) Adjust transceiver audio outputs to be 5V into 560 ohms when input is 5 microvolts modulated 30%.

B. Function check V.H.F. communications

Special Tools & Equipment:-

Portable VHF wavemeter.

NOTE: The following may be performed in a hangar or on the flight line.

(1) Energise the 28V dc Avionics Busbars.

(2) Ensure undernoted circuit breakers are closed:-

(3) Connect a headset to the first pilot's socket and select COM 1 on first pilot's audio panel rotary and toggle switches. Set audio panel AVIONICS VOL control to its mid position.

NOTE: Check that COM controller panel lighting functions correctly.

(4) Select a frequency on COM 1 which does not coincide with that for any local V.H.F. station. Set volume control to maximum. Check preset squelch control by selecting TEST, noting hiss, selecting TEST OFF and noting lack of hiss.

CB65 (Panel 1D)CB216 (Panel 2D)CB401 (Panel 5D)CB431 (Panel 6D)



(5) Set the first pilot's handwheel switch to R/T. Check for satisfactory sidetone at telephones and for evidence of satisfactory output from COM 1 (upper) antenna using the wavemeter. Repeat this check throughout the frequency range of the transceiver, checking that the TUNE indicator light is on.

NOTE: (a) The internal sidetone preset control must be set such that the operator hears his own voice at a level which encourages speech at normal intensity without shouting or whispering.

(b) The TUNE button will light each time a keyline is closed.

(6) Repeat paras (3) to (5) for COM 2 positioning wavemeter in the vicinity of the lower VHF antenna and selecting for COM 2 on audio control panels.

(7) Check for satisfactory VHF operation - without sidetone - using the first pilot's hand microphone and flight compartment loudspeaker.

(8) Repeat paras (3) to (7) using the second pilot's audio facility.

(9) Select the COM controllers to the frequency of a local station. Initiate test calls with both pilots' headsets. Check for intelligible transmission and reception. Repeat using hand microphones and flight compartment loudspeakers.

(10) Check for satisfactory reception at the flight observers' stations. (No transmission).

(11) Check frequency pre-select by selecting different frequencies on each controller, pressing the TUNE button and check that correct frequency transfer occurs.

(12) Switch off all power.

(13) Select COM 1 NORMAL on No.1 audio panel and check that intelligible transmission and reception with remote stations using headsets, hand microphone and flight compartment loudspeaker is possible.

(14) Repeat para (13) for COM 2 NORMAL on No.2 audio panel.

(15) Select COM 1 EMERGENCY on number 1 audio panel and check that intelligible transmission and reception with remote stations using headset and EMERGENCY PRESS TO TX switch is possible.

(16) Repeat para (15) for COM 2 EMERGENCY on No.2 audio panel.



AMM23-11-11 5.0.0.0V.H.F. COM ANTENNAS AND FEEDERS - MAINTENANCE PRACTICES

1. Adjustment/Test

A. Perform V.S.W.R. tests.

(1) V.S.W.R. test - COM 1 antenna:

(a) Remove the ceiling panel forward of frame 405 in the passenger compartment, and ensure that the COM 1 antenna feeder is securely connected to the COM 1 antenna fly-lead.

(b) Open the access door to the No. 1 Avionic Bay and connect the V.S.W.R. test set to the antenna feeder at the V.S.W.R. check point adjacent to the COM 1 transceiver (1RV2).

(c) Using the relevant procedure, laid down in the test set instruction manual, ensure that the V.S.W.R. for the antennas and antenna feeder does not exceed 1.5 for frequencies of 118MHz, 124MHz and 136MHz.

(d) Disconnect the test set from the V.S.W.R. check point and reconnect the antenna feeder, then close the Avionic Bay access door.

(e) Connect the V.S.W.R. test set to the COM 1 antenna fly-lead after removing the aft passenger compartment ceiling.

(f) Ensure that the V.S.W.R. of the antenna and fly-lead does not exceed 1.8 for frequencies of 118MHz, 124 MHz and 136MHz.

(g) Disconnect the test set, reconnect the antenna feeder and fly-lead and replace the access panel.

(2) V.S.W.R. test - COM 2 antenna

(a) Remove the floor aft of frame 146 and check that the COM 2 antenna feeder is securely connected to the COM 2 antenna connector (2RV8).

(b) Open the access door to the No.2 Avionics Bay and connect the V.S.W.R. test set to the COM 2 antenna feeder, at the V.S.W.R. test point adjacent to the COM 2 transceiver (2RV2).

(c) Ensure that the V.S.W.R. of the antenna and feeder does not exceed 2.0 for frequencies of 118MHz, 124MHz and 136MHz.

Special Tools & Equipment: Approved V.S.W.T. test equipment and instruction manuals eg. Techtest Ltd., antenna test set Type twelve 602 (see tool No.T360-23-01).



(d) Disconnect the test set at the V.S.W.R. test point and reconnect the antenna feeder, then close the No.2 Avionics Bay access door.

(e) Connect the test set to the COM 2 antenna and check that the V.S.W.R. for the antenna does not exceed 2.25 for the frequencies 118MHz, 124MHz and 136 MHz.

(f) Disconnect the test set, reconnect the antenna feeder to the antenna and then replace the floor.



AMM23-11-20 6.0.0.0VHF COMMUNICATIONS - DESCRIPTION & OPERATION(POST MOD A7397 AIRCRAFT ONLY)

1. Description

A. General

The VHF (very high frequency) communication system provides line of sight two-way amplitude modulated voice communications in the frequency range:-

(1) 118 to 135.975 MHz (pre mod A8498) on 720 channels at 25 KHz intervals.

(2) 118 to 136.975 MHz (post mod A8498) on 760 channels at 25 KHz intervals.

Two identical systems are installed designated COM1 and COM 2.

B. Transceiver : Collins Type VHF-21A

COM 1 transceiver is in the No.1 (left) avionics bay and COM 2 in the No.2 (right) avionics bay. Each is a solid state unit providing a nominal 20 watt output and having conventional 2 out of 5 frequency selection.

C. Control unit : Collins Type CTL22

Refer to Figure 1.

Two control units marked COM, located on panel 1P, have the following displays and controls:-

(1) Two LED frequency displays designated COM and PRE. The active frequency is always displayed in the top position.

(2) Two concentric frequency select knobs.

(3) An ACTIVE/preselect push button switch, which when pressed for 2 seconds, enables the frequency select knobs to tune the transceiver directly. Pressing the switch a second time will regain normal operation.

(4) A MEM indicator that illuminates when a preset frequency is shown in the lower frequency display.

(5) A three position XFR/neutral/MEM switch used for the following operations:-

XFR - Transfers preset frequency to active display, retunes the transceiver and places the active frequency in the preset display.

MEM - Repeated selections toggles the preset display between six frequencies stored in the control memory.



(6) A STOre push button switch that allows up to six frequencies to be stored. Operation requires the desired channel to be shown in the upper display and the frequency to be stored in the lower display. Pressing the STO button twice will commit the frequency displayed to memory.

(7) A rotary ON/OFF/SQuelch OFF switch with a concentric volume control.

(8) A TEST button to initiate radio self test.

(9) An light sensor that automatically controls display brightness.

D. Antennas

These are both Dorne & Margolin type DMC60-1. COM 1 antenna is mounted on the rear fuselage roof between stations 395 and 405. COM 2 antenna is mounted beneath the fuselage between stations 146 and 176. Hence COM 1 is rather more suitable of the two for ground use.

E. Additional controls

Selection by the audio panel rotary switches facilitates operation of transceivers directly from a battery either through the audio system or directly into a headset with an alternative transmit button. The purpose of this facility is to enable operation before the main busbars are powered, thus conserving battery charge and to act as an alternative communication channel if difficulties are encountered (spurious transmission in particular).

F. Power supply.

Both COM systems have alternative 28V dc power sources as follows:-

Normal power is derived from the left and right avionics busbars via circuit breakers:

Direct battery power is derived from left and right battery busbars via circuit breakers:-

2. Operation

A. General

Before starting, ensure that the avionics master switch is OFF.

CB401 COM 1 Panel 5D LeftCB431 COM 2 Panel 6D Right

CB65 COM 1 Panel 1D LeftCB216 COM 2 Panel 2D Right



Select audio panel rotary switch to NORMAL. The battery discharge light is lit and the indicated COM system is operable directly from a battery using headset and handwheel transmit switch.

If both rotary switches are at NORMAL, COM operation is also available via speakers and hand microphones.

Immediately before starting, cancel this selection and check that both battery discharge lights are out (to prevent electrical transient damage).

After starting both engines, select the avionics master switch ON and select audio rotary switches to the COM 1 or 2 position as required.

B. Tuning

Frequency selection and transceiver test is achieved as indicated in paragraph Refer to C. of the description section of this chapter.

CAUTION: DO NOT TUNE COM TRANSCEIVERS TO THE SAME FREQUENCY OR TO TWO FREQUENCIES THAT CARRY THE SAME TRANSMISSION.

C. Receive mode

Reception is available via telephones or loudspeakers as covered in the audio section of this chapter. If the transceivers are adjusted correctly, the volume controls on individual controllers may be left at the fully clockwise position and collective volume adjusted on the audio panel.

D. Transmit mode

Microphone and keying selection is via audio panel rotary switches and transmit switches on handwheels or hand microphones. Sidetone is available in the telephones, to encourage correct speech levels.

E. Emergency operation

Upon selection of the push-to-talk button, a two minute timer within the transceiver is activated. If the transmitter is still operating after two minutes, the transceiver automatically turns it off and switches to receive mode.

Should the push-to-talk button remain stuck, damage to the transceiver may be prevented by selecting the rotary switch on the audio panel to EMERGENCY and resuming communications using a headset and the PRESS TO TX button on the audio panel.



VHF Control UnitFigure 1



AMM23-11-20 7.0.0.0V.H.F. COMMUNICATIONS - MAINTENANCE PRACTICES (POST MOD A7397 AIRCRAFT ONLY)

1. General

V.S.W.R. checks of antennas and feeders. Refer to 23-11-11, pb201.

2. Adjustment/Test

A. Bench checks of VHF transceiver

Perform in accordance with appropriate equipment maintenance manual with the following provisos:-

(1) Transmitter modulation depth must be adjusted for a carbon microphone input of 0.125V, 150 ohms.

NOTE: Besides bench checking with an oscillator, the modulation must be checked to be 70% to 90% for normal voice levels using a suitable headset or hand microphone.

(2) Adjust transceiver audio outputs to be 5V into 560 ohms when input is 5 microvolts modulated 30%.

B. Function check V.H.F. communications

Special Tools & Equipment:-

Portable VHF wavemeter.

NOTE: The following may be performed in a hangar or on the flight line.

(1) Energise the 28V dc Avionics Busbars

(2) Ensure undernoted circuit breakers are closed:-

(3) Connect a headset to the first pilot's socket and select COM 1 on first pilot's audio panel rotary and toggle switches. Set audio panel AVIONICS VOL control to its mid position.

NOTE: Check that COM controller panel lighting functions correctly.

(4) Select a frequency on COM 1 which does not coincide with that for any local V.H.F. station. Set volume control to maximum. Check preset squelch control by selecting TEST, noting hiss, selecting TEST OFF and noting lack of hiss.

CB65 (Panel 1D)CB216 (Panel 2D)CB401 (Panel 5D)CB431 (Panel 6D)



(5) Set the first pilot's handwheel switch to R/T. Check for satisfactory sidetone at telephones and for evidence of satisfactory output from COM 1 (upper) antenna using the wavemeter. Repeat this check throughout the frequency range of the transceiver, checking that the TX indicator is illuminated.

NOTE: (a) The internal sidetone preset control must be set such that the operator hears his own voice at a level which encourages speech at normal intensity without shouting or whispering.

(b) The TX indicator will light each time a keyline is closed.

(6) Repeat paras (3) to (5) for COM 2 positioning wavemeter in vicinity of the lower VHF antenna and selecting for COM 2 on audio control panels.

(7) Check for satisfactory VHF operation - without sidetone - using the first pilot's hand microphone and flight compartment loudspeaker.

(8) Repeat paras (3) to (7) using the second pilot's audio facility.

(9) Select the COM controllers to the frequency of a local station. Initiate test calls with both pilots' headsets. Check for intelligible transmission and reception. Repeat using hand microphones and flight compartment loudspeakers.

(10) Check for satisfactory reception at the flight observers' stations. (No transmission).

(11) Check frequency pre-select by selecting different frequencies on each controller, pressing the XFR button and check that correct frequency transfer occurs.

(12) Switch off all power.

(13) Select COM 1 NORMAL on No.1 audio panel and check that intelligible transmission and reception with remote stations using headsets, hand microphone and flight compartment loudspeaker is possible.

(14) Repeat para (13) for COM 2 NORMAL on No.2 audio panel.

(15) Select COM 1 EMERGENCY on No.1 audio panel and check that intelligible transmission and reception with remote stations using headset and EMERGENCY PRESS TO TX switch is possible.

(16) Repeat para (15) for COM 2 EMERGENCY on No.2 audio panel.



AMM23-14-00 8.0.0.0H.F. RADIO - GENERAL

1. General

A. Details of the H.F. Radio system are provided as follows:

(1) H.F. Radio (Collins type H.F.220) post mod A7343. Refer to 23-14-10, pb1.

(2) H.F. Radio (Collins type H.F.230) post mod 8375. Refer to 23-14-20, pb1.



AMM23-14-10 9.0.0.0H.F.RADIO (COLLINS TYPE H.F.220) - DESCRIPTION & OPERATION(POST MOD A7343 AIRCRAFT ONLY)

1. Description

A. General

The installed system is a Collins type H.F.220, providing a lightweight, airborne, long range communications system on frequencies between 2.0 and 22.9999 MHz with single band, compatible AM, split channel, reduced carrier telephone mode and split channel suppressed carrier telephone mode.

The system can be automatically tuned and provides 100 Watts peak envelope power (p.e.p.) with an average 25 Watts r.f. output. The H.F.220 comprises a transceiver, power amplifier, control unit and an antenna coupler.

B. Detail

(1) Transceiver, Collins type TCR220.

The unit operates throughout the frequency range 2.0 to 22.9999 MHz. Within that range 16 channels may be preset with a minimum of 100Hz spacing. Programmed channels operate in half duplex or simplex with directly tuned stations being simplex only.

The unit provides the following modes of operation: USB, AM, A3A and A3J, these modes being selected on the system controller. The transceiver is mounted in the rear baggage compartment. A more detailed description of the unit is provided in the relevant Collins Manual.

(2) Power Amplifier, Collins type PWR200.

The Amplifier, idented RC2, is mounted adjacent to the transceiver.

The unit serves as an h.f. power amplifier capable of producing 100 Watts p.e.p. with an average 25 Watts r.f. output. A more detailed description of the unit is provided in the relevant Collins Manual.

(3) Control Unit, Collins type CTL-220.

Refer to Figure 1.

The controller is mounted on panel 1P, provides all the controls and indications necessary for the management of the system.

Mode Control (OFF/USB/AM/A3A/A3J

- Controls the application of primary power to the system and selects the system operational mode.

Volume control (V) - Concentric with the mode control, adjusts the level of audio gain.



A digital display will provide indication of the selected station frequency.

A more detailed description of the control unit is provided in the relevant Collins manual.

(4) Antenna coupler, Collins type AAC200.

The coupler, idented RC3, is mounted adjacent to the transceiver and power amplifier. The unit matches the impedence of the aircraft antenna to the resistive outputs of power amplifier. Information is generated within the coupler for tuning cycle control of the power amplifier and the transceiver.

A more detailed description of the coupler is provided in the relevant Collins Manual.

2. Operation

The system operates in the following modes:-

Clarifier control (OFF/CLARIFIER)

- Switch portion enables or disables the clarifier function. Turning the control permits turning a received frequency ± 100 Hz (USB or tel modes only). The clarifier disable during transmission.

Channel/frequency Switch (FREQ/CHAN)

- Controls the method of frequency selection.

Channel/frequency Controls

- With the channel/frequency switch selected FREQ, the two frequency controls can select any of 210,000 discrete frequencies. With CHAN selected either switch can select one of the 16 programmed channels.

SQUELCH control - Enables or disables the squelch function. Turning the control sets the squelch threshold.

Channel/frequency card - Pulls out to provide an index of frequency for each preset channel.

U.S.B. - This mode is used to communicate with other stations operating in single sideband on the upper sideband.

AM - This mode is provided to allow communication with the older AM or AME stations. AM is not compatible with stations operating on USB.

Tel A3A - This mode is also a single sideband mode, but with reduced carrier (-18 ± 2dB) pilot carrier. It is generally used for communications with public correspondence coastal stations in the maritime services and various other radio telephone services. Channels 1 through 16 can be programmed for half-duplex operation for Tel modes.

Tel A3J - This mode is also a single sideband mode, but with suppressed carrier. It is used for the same purposes as the Tel A3A mode.



With electrical power supplied the system is energised by selecting the mode control from OFF to the desired operating mode (USB, AM, A3A or A3J).

NOTE: A warm-up time of 15 minutes is required.

The desired frequency/channel is selected via the two central channel/frequency knobs with the FREQ/CHAN switch appropriately selected.

NOTE: Should the preset channel method of selection be required, correlate the channels and frequencies via the pull out channel/frequency card.

The SQUELCH and CLARIFIER controls are turned full counter clockwise and the volume (V) control adjusted to provide a suitable audio level upon signal reception. A tuning cycle is now initiated by momentarily pressing the appropriate aircraft handwheel press-to-transmit switch.

NOTE: The normal tuning cycle requires from 5 to 15 seconds, during which time a 1000Hz tone is audible. Cessation of the tone, within 1 second indicates that the system is ready for use. Should the tone continue for a further 30 seconds, then start to 'beep', the system should be rechanneled and a new tuning cycle initiated.

The SQUELCH should now be adjusted until receiver noise disappears.

NOTE: 1. Adjustment of the SQUELCH control should be reasonably slow as the associated circuitry has a relatively long time constant and over adjustment of the knob may result in loss of some weaker incoming signals.

2. Under some atmospheric conditions, receiver noise may disappear immediately the SQUELCH control is moved from the TEST position. This is normal and the control should be left in this position unless interference or noise requires a higher squelch threshold selection later. When receiving an r.f. signal (USB, Tel A3A or Tel A3J), adjust the clarifier control for maximum clarity or most natural sounding voice.

NOTE: When changing frequency/channel, the antenna coupler automatically returns to a home position. This leaves the antenna retuned to the new frequency, reducing the sensitivity of the receiver. To avoid any missed calls or poor reception, operate the appropriate handwheel transmit switch to initiate an antenna coupler tune cycle for the new frequency, having first verified that the frequency is clear.



H. F. Controller Collins type CTL220Figure 1



AMM23-14-10 10.0.0.0H.F. RADIO (COLLINS TYPE H.F.220 - MAINTENANCE PRACTICES(POST MOD A7343 AIRCRAFT ONLY)

1. Adjustment/test

A. Function check HF system in hangar.

Special Tools & Equipment : Suitable r.f. power meter

(1) Render the aircraft electrically safe. Refer to 12-09-03, pb301.

(2) Disconnect the antenna feeder at the transceiver or power amplifier and connect a thru line wattmeter to the output socket. Connect headsets to relevant sockets.

(3) Energise the left avionics busbar.

(4) Ensure C/B No.411 on panel 5D is closed.

(5) Ensure that the audio system is operational. Refer to 23-51-00, pb201.

(6) Set the first pilot's audio controls to H.F. with the volume controls fully clockwise.

(7) On the H.F. control unit, set the channel selector to channel 1 and set the gain and volume controls fully clockwise. Select A.M. on S.S.B. Transceivers.

(8) Set the first pilot's handwheel switch to R/T and check that the unmodulated AM output power is at least 25 watts.

(9) Speak into the headset microphone and check that the level and quality of sidetone in the telephones is satisfactory. Release the handwheel switch. Repeat using U.S.B. mode.

NOTE: The sidetone preset control must be set such that the operator hears his own voice at a level which encourages speech at normal intensity without shouting or whispering.

(10) Check for satisfactory H.F. operation - without sidetone - using the first pilot's hand microphone and flight compartment loudspeaker.

(11) Check for satisfactory operation using the second pilot's audio facility. Check for satisfactory reception in the observers' headsets.

(12) Switch the transceiver off and check that controller panel lighting functions correctly.

(13) Remove the wattmeter and re-connect the antenna feeder.

(14) Ensure that the H.F. frequency placards in the flight compartment agree with the preset frequencies of the transceiver fitted to the aircraft. Note placard is at bottom of the controller in a pull-out unit.



B. Function check H.F. system on flight line

(1) After 15 minutes warm up, check for intelligible A.M. transmission and reception with remote stations using headsets, hand microphones and flight compartment loudspeakers. Repeat for single sideband operation. Rotate squelch control clockwise until receiver noise just disappears.

(2) HF 220 automatic coupler emits an audio tone when tuning. If this is irritating, the HF audio may be selected OFF during the tuning cycle.

(3) If the antenna coupler does not tune after 30 seconds, the 1000 Hz tone will begin to "beep" indicating a fault. If so, rechannel and initiate a new tuning cycle.



AMM23-14-20 11.0.0.0H.F.RADIO (COLLINS TYPE H.F.230 - DESCRIPTION & OPERATION(POST MOD A8375 AIRCRAFT ONLY)

1. Description

A. General

The installed system is a Collins type H.F.230, providing a lightweight, airborne, longe-range communications system on frequencies between 2.0 and 29.9999 MHz with single sideband, compatible, split channel, reduced carrier telephone mode and split channel suppressed carrier telephone mode.

The system can be automatically tuned and provides 100 Watts peak envelope power (p.e.p.) with an average 25 Watts r.f. output. The H.F.230 comprises a transceiver, power amplifier, control unit and an antenna circuit.

B. Detail

(1) Transceiver, Collins type TCR230

The unit operates throughout the frequency range 2.0 to 29.9999 MHz. Within that range 40 channels may be preset with a minimum of 100Hz spacing. Programmed channels operate in half duplex, simplex or receive only with directly tuned stations being simplex only.

The unit provides the following modes of operation: USB, AM, LSB and TEL these modes being selected on the system controller. The transceiver is mounted in the rear baggage compartment. A more detailed description of the unit is provided in the relevant Collins Manual.

(2) Power Amplifier, Collins type PWR 230


The unit serves as an h.f. power amplifier capable of producing 100 Watts p.e.p. with an average 25 Watts r.f. output. A more detailed description of the unit is provided in the relevant Collins Manual.



(3) Control Unit, Collins type CTL-230

Refer to Figure 1.

The controller is mounted on panel 1P, and provides all the controls and indications necessary for the management of the system.

Pull Mode/100 KHz Control - Pushed in, selects the 100 KHz digit in the frequency display when the FREQ/CHAN switch is in the FREQ position. It has no function with the switch in the CHAN position.Pulled out, with a discrete frequency mode, selected will cycle the system between USB, AM and LSB modes.Pulled out, with one of the 176 preprogrammed ITU channels selected cycles the system between TEL SUP CAR and TEL PLT CAR modes.Should one of the 40 user programmed channels be selected and the PULL MODE knob is pulled out, no mode changes will occur.

OFF/Volume Control (v) - Controls primary power to the entire system and varies the audio gain.

OFF/CLARIFIER Control - Switch position enables or disables the clarifier function. Rotating the control out of the OFF position varies the received freq ± 100 Hz on USB, LSB & TEL modes. The clarifier is disabled on transmit.

CHAN/FREQ switch - Controls the method of frequency selection.

PULL 100/1 KHz control - With FREQ selected and the knobs pushed in, this control varies the 1 KHz digit in the frequency display. With the knob pulled out, the control varies the 100 Hz digit in the frequency display.

1 MHz control - Varies the 1 MHz digit in FREQ mode, and the 100's and 1000's digits in CHAN mode.

S/TST control - Rotating the control varies the squelch threshold. In TST, squelch is disabled.

PGM button - Used when programming the user channels.



(4) Antenna coupler, Collins type AAC 200.

The coupler, idented RC3, is mounted adjacent to the transceiver and power amplifier. The unit matches the impedence of the aircraft antenna to the resistive outputs of power amplifier. Information is generated within the coupler for tuning cycle control of the power amplifier and the transceiver.


2. Operation


With electrical power supplied the system is energised by selecting the OFF/VOLUME control from OFF to the desired volume.


The desired frequency/channel is selected via the two channel/frequency knobs with the FREQ/CHAN switch appropriately selected.

The SQUELCH and CLARIFIER controls are turned fully clockwise and the volume (V) control adjusted to provide a suitable audio level upon signal reception. A tuning cycle is now initiated by momentarily pressing the appropriate aircraft handwheel press-to-transmit switch.

CHAN display - Displays the selected channel number in the CHAN mode, or dashes (----) in FREQ mode.

MODE display - Displays operation mode. (USB, LSB, AM, TEL SUP CAR or TEL PLT CAR).

FREQ KHz display - Displays operating frequency and receiver (R) and transmit (T) annunciations.



LSB - This mode is used to communicate with other stations operating in the single sideband on the lower sideband.

TEL SUP CAR) TEL PLT CAR)

- Telephone mode for public correspondence, telephone ship to shore etc.



NOTE: The normal tuning cycle requires from 5 to 15 seconds, during which time a 1000Hz tone is audible. Cessation of the tone, within 1 second indicates that the system is ready for use. Should the tone continue for a further 30 seconds, then start to 'beep', the system should be rechanneled and a new tuning cycle initiated.

The SQUELCH should now be adjusted slowly until receiver noise disappears.


2. Under some atmospheric conditions, receiver noise may disappear immediately the SQUELCH control is moved from the TEST position. This is normal and the control should be left in this position unless interference or noise requires a higher squelch threshold selection later. When receiving an r.f. signal (USB, Tel A3A or Tel A3J), adjust the clarifier control for maximum clarity or most natural sounding voice.

NOTE: When changing frequency/channel, the antenna coupler automatically returns to a home position. This leaves the antenna retuned to the new frequency, reducing the sensitivity of the receiver. To avoid any missed calls of poor reception operate the appropriate handwheel transmit switch to initiate an antenna coupler tune cycle for the new frequency, having first verified that the frequency is clear.



H.F.Controller Collins type CTL230Figure 1



AMM23-14-20 12.0.0.0H.F. RADIO (COLLINS TYPE H.F.230) - MAINTENANCE PRACTICES (POST MOD A8375 AIRCRAFT)

1. Adjustment/test

A. Function check HF system in hangar

Special Tools & Equipment : Suitable r.f. power meter.


(2) Disconnect the antenna feeder at the transceiver or power amplifier and connect a thru line wattmeter to the output socket. Connect headsets to relevant sockets.



(5) Ensure the audio system is operational. Refer to 23-51-00, pb201.




(9) Speak into the headset microphone and check that the level and quality of sidetone in the telephones is satisfactory. Release the handwheel switch. Repeat using USB and LSB modes.


(10) Check for satisfactory H.F. operation - without sidetone - using the first pilot's hand microphone and flight compartment loudspeaker.

(11) Check for satisfactory operation using the second pilot's audio facility.

Check for satisfactory reception in the observers' headsets.






(1) After 15 minutes warm up, check for intelligible A.M. transmission and reception with remote stations using headsets, hand microphones and Flight Compartment loudspeakers. Repeat for single sideband operation. Rotate squelch control clockwise until receiver noise just disappears.


(3) If the antenna coupler does not tune after 30 seconds, the 1000 Hz tone will begin to "beep" indicating a fault. If so, rechannel and initiate a new tuning cycle.



AMM23-14-30 13.0.0.0H.F. RADIO (COLLINS TYPE H.F. 220) - DESCRIPTION & OPERATION

1. Description

A. General

The installed system is a Collins type H.F. 220, providing a lightweight, airborne, long-range communications system on frequencies between 2.0 and 22.9999 MHz with single sideband, compatible, split channel, reduced carrier telephone mode and split channel suppressed carrier telephone mode.

The system can be automatically tuned and provides 100 Watts peak envelope power (p.e.p.) with an average 25 Watts r.f. output. The H.F. 220 comprises a transceiver, power amplifier, control unit and an atenna circuit.

B. Detail

(1) Transceiver, Collins type TCR 220.

The unit operates throughout the frequency range 2.0 to 22.9999 MHz. Within that range 16 channels may be preset with a minimum of 100Hz spacing. Programmed channels operate in half duplex or simplex with directly tuned stations being simplex only.

The unit provides the following modes of operation: USB, AM, A3A and A3J, these modes being selected on the system controller. The transceiver is mounted in the rear baggage compartment. A more detailed description of the unit is provided in the relevant Collins Manual.

(2) Power Amplifier,Collins type PWR 200.


The unit serves as an h.f.power amplifier capable of producing 100 Watts p.e.p. with an average 25 Watts r.f. output. A more detailed description of the unit is provided in the relevant Collins Manual.

(3) Control Unit, Collins type CTL-220.

The controller is mounted on panel 1P, provides all the controls and indications necessary for the management of the system.

Mode Control (OFF/USB-AM/A3A/A3J)

- Controls the application of primary power to the system and selects the system operational mode.

Volume control (V) - Concentric with the mode control, adjusts the level of audio gain.



A digital display will provide indication of the selected station frequency.

A more detailed description of the control unit is provided in the relevant Collins manual.

(4) Antenna coupler, Collins type AAC 200.

The coupler, idented RC3, is mounted adjacent to the transceiver and power amplifier. The unit matches the impedence of the aircraft antenna to the resistive outputs of power amplifier information is generated within the coupler for tuning cycle control of the power amplifier and the transceiver.


2. Operation


Clarifier control (OFF/CLARIFIER)

- Switch portion enables or disables the clarifier function. Turning the control permits tuning a received frequency ± 100 Hz (USB or tel modes only). The clarifier disable during transmission.

Channel/frequency Switch (FREQ/CHAN)

- Controls the method of frequency selection.

Channel/frequency Controls - With the channel/frequency switch selected FREQ, the two frequency controls can select any of 210,000 discrete frequencies. With CHAN selected either switch can select one of the 16 programmed channels.

SQUELCH control - Enables or disables the squelch function. Turning the control sets the squelch threshold.

Channel/frequency card - Pulls out to provide an index of frequency for each preset channel.



Tel A3A - This mode is also a single sideband mode, but with reduced carrier (- 18±2dB) pilot carrier. It is generally used for communications with public correspondence coastal stations in the maritime services and various other radio telephone services. Channels 1 through 16 can be programmed for half-duplex operation for Tel modes.



With electrical power suppplied the system is energised by selecting the mode control from OFF to the desired operating mode (USB, AM. A3A or A3J).


The desired frequency/channel is selected via the two central channel/frequency knobs with the FREQ/CHAN switch appropriately selected.

NOTE: Should the preset channel method of selection be required, correlate the channels and frequencies via the pull out channel/frequency card.

The SQUELCH and CLARIFIER controls are turned full counter clockwise and the volume (V) control adjusted to provide a suitable audio level upon signal reception. A tuning cycle is now initiated by momentarily pressing the appropriate aircraft handwheel press-to-transmit switch.

NOTE: The normal tuning cycle requires from 5 to 15 seconds, during which time a 1000Hz tone is audible. Cessation of the tone, within 1 second indicates that the system is ready for use. Should the tone continue for a further 30 seconds, then start to 'beep' the system, should be rechanneled and a new tuning cycle initiated.

The SQUELCH should now be adjusted until receiver noise disappears.


2. Under some atmospheric conditions, receiver noise may disappear immediately the SQUELCH control is moved from the TEST position. This is normal and the control should be left in this position unless interference or noise requires a higher squelch threshold selecting later. When receiving an r.f. signal (USB, Tel A3A or Tel A3J), adjust the clarifier control for maximum clarity or most natural sounding voice.

NOTE: When changing frequency/channel, the antenna coupler automatically returns to a home position. This leaves the antenna returned to the new frequency, reducing the sensitivity of the receiver. To avoid any missed calls or poor reception operate the appropriate handwheel transmit switch to initiate an antenna coupler tune cycle for the new frequency, having first verified that the frequency is clear.

Tel A3J - This mode is also a single sideband mode, but with suppressed carrier. It is used for the same purposes as the Tel A3A mode.



H.F. Controller Collins type CTL220Figure 1



AMM23-14-30 14.0.0.0H.F. RADIO (COLLINS TYPE HF-220) - MAINTENANCE PRACTICES

1. Adjustment/test

A. Function check HF system in hangar.

Special Tools & Equipment : Suitable r.f. power meter.


(2) Disconnect the antenna feeder at the No.1 or power amplifier and connect a thru line wattmeter to the output socket. Connect headsets to relevant sockets.






(8) Speak into the headset microphone and check that the level and quality of sidetone in the telephones is satisfactory. Release the handwheel switch. Repeat U.S.B. modes.


(9) Check for satisfactory H.F. operation - without sidetone - using the first pilot's hand microphone and Flight Compartment loudspeaker.

(10) Check for satisfactory operation using the second pilot's audio facility. Check for satisfactory reception in the observers' headsets.



(13) Ensure that the H.F. frequency placards in the flight compartment agree with the preset frequencies of the transceiver fitted to the aircraft. Note placard is at bottom of the controller in a pull-out unit.


(1) After 15 minutes warm up, check for intelligible A.M. transmission and reception with remote stations using headsets, hand microphones and Flight Compartment



loudspeakers. Repeat for single sideband operation. Rotate squelch control clockwise until receiver noise just disappears.


(3) If the antenna coupler does not tune after 30 seconds, the 1000 - Hz tone will begin to "beep" indicating a fault. If so, rechannel and initiate a new tuning cycle.



AMM23-31-00 15.0.0.0PASSENGER ADDRESS SYSTEM - GENERAL

1. General

Details of the passenger address system are provided as follows:-

A. Pre-mod 7542.

(1) Refer to 23-31-10, pb1. PA system.

(2) Refer to 23-31-11, pb1. PA amplifier (Collins type).

B. Post-mod 7542

(1) Refer to 23-31-20, pb1. PA system and PA amplifier (Becker type).

Dec 18/0723-31-10 Page 1EFFECTIVITY: All


AMM23-31-10 16.0.0.0PASSENGER ADDRESS SYSTEM - DESCRIPTION & OPERATION (PRE-MOD 7542)

1. Description

Refer to Figure 1.

A. The passenger address system provides facilities for the pilots or attendant to make announcements over the passenger and lavatory compartment speakers. During normal operation the passenger address amplifier is used. This amplifier also produces chime signals associated with briefing signs and attendant call.

On failure of the main system an emergency system is available, utilising the speaker amplification section of the pilots audio centres and the left passenger compartment speakers.

B. Detail

(1) Passenger address amplifier, Collins Type 346D-2B is designed to provide high quality audio power to the aircraft speakers. It includes microphone inputs for the pilot and attendant. It generates a system of chimes. The installed unit is mounted on the right of the tail fuselage, between frames 508 and 536.5 and is idented RL1. A more detailed description of the amplifier is provided. Refer to 23-31-10, pb1.

(2) Speakers

- Elac Type 47EM/260 (Pre Mod A8654 & A8715)- Kenwood KFC1054 (Post Mod A8654)- Kenwood KFC1058S (Post Mod A8715)

Aircraft are fitted with nine passenger address speakers; eight in the passenger compartment and one in the lavatory. In normal use, the speakers are connected in series along with a resistor in the No.2 Radio Bay. In emergency use (Audio panel rotary switches at EMG PA) either pilot may make announcements with their hand microphones, over the left side speakers.

(3) Pilots passenger address hand microphone, Telex Type TEL-66T-RA.

The hand microphone hangs on a hook on the forward side of the control duct behind the pilots and is plugged into a socket marked PA MIC on right side of duct.

NOTE: If this handset has to be replaced, a microphone of the same type should be used. If this is not available care must be taken to ensure that replacement is compatible with the system and the other microphones used in the audio system.



2. Operation

Refer to Figure 2.

A. Normal operation

(1) Using microphones

(a) Passenger address microphone

The socket for this microphone is permanently connected to the input of the passenger address amplifier. When the push-to-talk button is depressed, the audio is amplified and directed to passenger address speakers only.

The amplifier priority for this microphone overrides the attendants microphone and tape player.

(b) Pilots hand microphone

The PA position of the transmit selector switch connects the pilots hand microphone to the input of the passenger address amplifier. With push-to-talk depressed, signals will be directed to passenger address speakers. Priority switching will override attendants speech and tape player.

The sidetone output of the passenger address amplifier is also connected as an input to the audio control centre. Thus signals are directed through the phone channel to the pilots headphones when the audio panel NORM PA switch is selected up (attendant announcements may be monitored). With PA selected and push-to-talk switch depressed, the receiver inputs to audio system speaker channel are blocked.

(c) Headset microphone

With PA selected and handwheel switch at R/T, the headset microphone will function in the same way as the hand microphone with its push-to-talk switch depressed.

(d) Attendants microphone

The attendants handset socket and audio switch are on the attendants switch panel at the rear of the passenger compartment. With the audio switch in the PA position, the attendants microphone will be connected to the second priority input of the passenger address amplifier. Except for priority switching circuit which overrides the tape player. The amplifier priority switching circuit will prevent signals from the attendants microphone from being amplified if:-



1 Passenger address microphone button is depressed.

or

2 Pilots audio rotary switch is at NORM PA and the associated R/T switch or hand microphone button is operated.

(2) Chimes.

The passenger address amplifier provides chime signals in the speakers as follows:-

(3) Preset Controls

On distribution panel 3D (galley region) are two preset rotary controls labelled SENSITIVITY and VOLUME which are used to select amplifier output without the need to gain access to amplifier internal presets. Chime level is set using the volume control and speech level is set, subsequently, using the sensitivity control.

If difficulties are encountered in which passenger address output from headset and hand microphones is at different levels, adjustment may be effected at an output control incorporated in each hand microphone.

(4) General

Volume is reduced automatically when both engines are stopped. This is achieved by grounding an amplifier output control through the left and right oil pressure relays on panels 1C and 2C. Earth will be connected when both relays are closed i.e. when oil pressure is low on both engines.

The sidetone from passenger address amplifier (pins 12 and 20 on plug 1) is available only when pilots audio selector switch is selected up. To allow for this a 560 ohm loading resistor is connected across these terminals. This resistor is fitted to RTB54 in No. 1 avionics bay.

Hl Chime: Whenever a passenger call switch is pulled. Double HI chimes can result from switch contact bounce.

Hl/LO Chime: When an attendant call button on the pilots audio panel is pressed, a Hi/Lo chime is heard. If the tape player is operating and this button is pressed briefly, the chime is heard as well as the music. If this button is pressed and held, the chime is heard, but the music is interrupted until the button is released.

LO Chime: When a briefing sign is switched on or off a Lo chime is heard. If the tape player is operating this chime will be shortened (bleep).



The auxiliary amplifier output (from pins 13 and 14 on plug 2) is not used and a 6 ohm loading resistor is connected across these terminals.

B. Emergency

If the main system fails, an emergency system is available, utilising the speaker channel of either audio centre. For this system, pilots hand micriphones should be used, since there is no sidetone. The speakers used for emergency system are the four left side speakers.

Control is effected by selecting EMG PA on an audio panel rotary switch and pressing the associated hand microphone button. Relays are then energised which connect appropriate speakers to the audio centre output.

The audio signals from the microphone are amplified by the speaker channel of the audio centre and directed to the passenger address output terminals. The receiver and ADG signals are muted in the speaker channel.

The volume to the passenger address speakers can be controlled by a potentiometer marked PA, this can be adjusted through front of case of either audio centre.

3. Power Supplies

The power supply to the main passenger address amplifier is from a 10 amp circuit breaker No. 135, on the passenger compartment services busbar on panel 3D. Breakers 402 (5D) and 432 (6D) which supply audio centre speaker channels also supply emergency PA control relays.



Passenger Address System - LocationFigure 1



Passenger Address System - Block DiagramFigure 2



AMM23-31-10 17.0.0.0PASSENGER ADDRESS SYSTEM - MAINTENANCE PRACTICES (PRE-MOD 7542)

1. Adjustment/Test

A. Bench test and adjust the amplifier

NOTE: The following highlights and directly refers those actions detailed in Collins Maintenance Manual 523-0768492-251113 (Revision 2) which are significant for the Shorts installation.

(1) With reference to Trouble Shooting Section, make alignment as per para 5. thus:-

(a) Power Amplifier Alignment - make the following initial settings only:-

1 Master gain adjust A3R267 - Full CW

2 Compressor threshold adjust A3R232 - Full CCW

Set master gain adjust A3R267 from 70.7 to 64V

Sidetone adjust A3R34 for 25 mV output

Chime level adjustments as per:-

(2) Carry out performance test as detailed in Testing Section, para. 4, sub-paras:-

A(1) Preliminary set upA(2) Bias offset adjustA(3) Master gain initial adjustA(4) Bass control adjustA(7) Input 1 gain adjustA(8) Compressor adjustA(10) Input 2 adjust (RE(a), apply 1KHZ at 240 mV).A(11) Input 2A adjustA(12) Input 3 adjustA(13) Input 4 adjustA(14) Contour adjust (RE(c) adjust for 'MAX' output).A(17) Sidetone adjustA(19) Calibration adjustA(20) Test tone adjust

para B(4)(c) Hi tone adjust A3R475 to 30V R.M.S.para B(4)(e) Hi/lo adjust A3R478 to 30V R.M.S.para (b(4)(i) Low tone adjust A3R476 to 60V R.M.S.



(a) Input current test

(b) External output control test

(c) External sensitivity control test

(d) Input gain 1 test

(e) Compressor test

(f) Flight/ground decompression test.

B. Function test passenger address system

(1) At panel 3D, set the SENSITIVITY control fully clockwise and PA VOLUME control fully anti clockwise having first slackened lock nuts, if fitted.

(2) Provide electrical power. Refer to 12-09-03, pb301.

(3) Select PASSENGER ADDRESS on the attendants switch panel.

(4) Ensure that both left and right OIL warning modules, on panel 1P, are lit.

(5) Press the button on and speak into the microphone of the attendants handset.

(6) Rotate the PA VOLUME control clockwise until a satisfactory speaker output is obtained and check for adequate speech clarity from the aircraft speakers.

(7) Select PA at the first pilots AUDIO panel (rotary and toggle switches) and check for satisfactory performance using the associated hand microphone.

(8) Press the first pilots handwheel switch to R/T and speak into his headset microphone. Set the associated AUDIO panel -- AVIONICS VOL control to its mid position and check that side tone is at a level which encourages normal speech without shouting or whispering.

(9) Operate the PA system by speaking at a constant level into the hand microphone on the flight compartment central duct. Adjust the preset control in this microphone to give the same PA volume as the headset microphone.

(10) Check that the volume level in the passenger compartment increases slightly when C/B No.16 (1D) and/or C/B No.166 (2D) are tripped. Reset these breakers.

(11) Press and release the CALL button on each pilots audio panel. Check that a Hi/Lo tone is emitted by the speakers.

NOTE: Do not adjust the attendants PA VOLUME control.

(12) Pull and push each passenger call button in turn. Check for Hi tone each time.



(13) Select FASTEN SEAT BELTS and NO SMOKING control switches on panel 10P to ON then OFF. Check for a Lo tone each time.

(14) Check that chime levels are a little too high when the attendant's PA VOLUME control is rotated fully clockwise.

NOTE: This check ensures that there will be an adequate range of chime level adjustment in flight.

(15) Set attendant's PA VOLUME control to provide a comfortable chime level, then adjust attendant's SENSITIVITY control to achieve satisfactory speech level.

(16) Operationally check priority switching function (para C refers).

(17) Select 1st pilot's rotary switch to EMG PA. Check that the left passenger compartment speakers can be operated from the 1st pilot's hand microphone. Adjust the external PA control (R38 in 1st pilot's audio centre) as required.

NOTE: Headset operation of emergency passenger address is not recommended since sidetone is not available.

(18) Function 2nd pilot's PA control facilities as for 1st pilot. Adjust emergency PA level using R38 in the 2nd pilot's audio centre.

(19) Turn amplifier front panel selector to TEST TONE. Check that all speakers (including lavatory) are operating. Return the selector to OFF.

(20) Perform tape player checks (Refer to 23-33-00, pb1.).

C. Perform operational check of priority switching.

(1) Operate the tape player and check for output from the speakers. Check that this output is overridden by selection of the following:-

(2) Operate the Attendant passenger address and check that it is overriden using any of the three flight compartment microphones when selected for passenger address.

D. Engine run checks:

(1) Set engines to provide noise level similar to cruise flight.

Attendant passenger addressPassenger and pilot to attendant call chimesPilot passenger address (using each of the three flight compartment microphones).



(2) Adjust attendant's PA VOLUME control (panel 3D) to provide comfortable chime levels, then:-

(3) Adjust attendant's PA SENSITIVITYcontrol (panel 3D) to provide satisfactory speech level.

(4) Function emergency PA as Hanger checks (17) and (18). Further adjust control R38 in relevant audio centres to provide satisfactory sound level.

E. Flight Checks:

(1) Adjust attendant's PA VOLUME control (panel 3D) to give comfortable chime levels.

(2) Adjust attendant's PA SENSITIVITY control (Panel 3D) to provide satisfactory speech level.



AMM23-31-11 18.0.0.0PASSENGER ADDRESS AMPLIFIER, COLLINS TYPE 346D-2B - DESCRIPTION & OPERATION

1. Description

A. Mechanical

The amplifier is housed in a metal case and mounted on a tray. Electrical connections are made via twin connectors on the rear of the unit which mate with connectors on the mounting tray. An access hole is provided on the lower front portion of the facia panel for adjustment of the master gain control. All other controls are accessible with the dust cover removed.

A 3 position rotary switch and indicator lights are also included on the facia panel for use in testing and calibrating the amplifier, (refer to the appropriate Collins manual).

B. Electrical

The amplifier can accept five audio inputs, each with individual level controls and priority switching.

The output of the unit provides up to 120 watts r.m.s. (short duration) or 30 watts r.m.s. (continuous) high quality audio power to the aircraft speakers. The sidetone output provides 50 mW of audio to 600 ohm headphones.

The unit also incorporates an auxiliary amplifier which is not used on SD3-60.

The chime system is used for signalling throughout the aircraft. The high chime (587 Hz) is the passenger to attendant signal, the high/low chime (587 Hz/494 Hz) is the crew to attendant signal and the low chime (494 Hz) indicates operation of the seat belt or no smoking light switches. Testing and calibration of the amplifier can be performed using the 3-position rotary switch previously mentioned. With the switch selected to TEST a test tone is distributed to the aircraft speakers. Selected to CAL, adjustment to full power can be made using panel mounted light emitting diodes (refer to the relevant Collins manual). The switch is usually selected to NORM, where the amplifier is able to perform its normal functions.

Operational volume will increase automatically when either or both aircraft engines are started and reduce again when they are stopped. Control of this function is via engine oil pressure relays.

2. Operation

The amplifier is operated in conjunction with the aircraft Audio System. Refer to 23-51-00, pb1. Detailed unit operation is contained in the relevant Collins manual.



AMM23-31-2019.0.0.0PASSENGER ADDRESS SYSTEM - DESCRIPTION AND OPERATION (BECKER TYPE PA3100 - POST MOD 7542)

1. General

A. The Becker type passenger address system (PA3100) is similar in operation to the Collins type system (346-2B). This chapter describes the differences between the two systems. Complete system information is provided. Refer to 23-31-00, pb1.

B. The major change to the existing system is the replacement of the Collins PA amplifier with the Becker amplifier PA3100 (3) and, the deletion of Panel 18C.

2. Component Description

A. Public address amplifier - PA3100-3 (Mod 2)

(1) The amplifier is part of the audio integrating system (Refer to 23-51-00, pb1.), providing public address, call signal activation and music ON selection.

(2) The installed unit is mounted on the right of the tail fuselage between frames 595-620 and is identified RL1. The amplifier is a monoblock unit with a 50 pin connector located on the front panel. The unit operates satisfactorily at ambient temperatures of -20 deg C to +55 deg C and up to an altitude of 50 000 ft.

3. Operation

A. The PA system has the following modes of operation:

(1) PA announcements to the cabin by attendant and crew members.

(2) Call signal activation from the cockpit using the CALL pushbutton.

(3) Call signal activation from the cockpit using the NO SMOKING and FASTEN SEATBELTS switches.

(4) Call signal activation from the cabin using the attendant CALL button on the passenger service panel.

(5) Two channel music reproduction from tape player. Refer to 23-33-00, pb1.

B. Normal operation of the PA system utilizes the PA amplifier together with any of the following microphones

(1) The pilots PA microphone.

(2) On selection of the pilots audio rotary switch to PA, the associated pilots hand or boom microphone. (The boom microphone is keyed using the handwheel switch).

(3) The attendants microphone, on selection of PA on the attendants switch panel.



C. The pilots' PA has first priority and overrrides the attendants PA input to the amplifier. When passenger address is keyed, the speakers revert to PA operation and the tape player output is inhibited. Volume is reduced automatically by means of oil pressure operated relays, if both engines are stopped.

D. In the event of failure of the main PA system, an emergency system is available. The emergency system utilizes the speaker amplifier section of the pilots' audio centres and the left passenger compartment speakers. The system is operated from either pilots' hand microphone when the appropriate rotary switch is set to EMGY PA.

4. Power Supplies

A. The power supply to the PA amplifier is from the 28 Vdc passenger compartment busbar, protected by a 3 amp circuit breaker, CB 135, located on panel 3D. The power supplies to the audio centre speaker channels are as follows:

28 Vdc Right busbar, protected by circuit breakers CB 432 (1 amp) Panel 6D

28 Vdc Left Busbar, protected by circuit breaker CB402 (1 amp) Panel 5D.



AMM23-31-20 20.0.0.0PASSENGER ADDRESS SYSTEM - MAINTENANCE PRACTICES BECKER TYPE PA3100 - POST MOD 7542

1. ADJUSTMENT/TEST

A. Bench test and adjust the PA amplifier.

Perform an amplifier/tape player test using the test circuit illustrated in accordance with the following instructions. Refer to Figure 201.

An alternative test method is detailed in Becker manual DV29003.04.

Equipment and materials:

(1) Ensure all buttons on the tape player are not indented and a cassette is not inserted. Check that units are the correct Part No. and that the mod plate on the amplifier is stamped mod 2, 4 or 5.

(2) Connect 28V dc to the cable assy and check the supply appears between pin 18 positive and pin 20 negative on the amplifier plug. Check the supply also appears between pins 1 positive and 16 negative on the tape unit cable assembly.

(3) Connect the microphone and speakers to the test set and connect the test set to the tape player and amplifier.

(4) Switch power on to the test set and adjust to 28 ± 0.5 Vdc.

(5) Set amplifier control R2082 fully counter-clockwise and all test set switches to OFF.

(6) Press the microphone button and speak into the microphone. Check for satisfactory performance from both speakers. Adjust R2082 as necessary. Release the microphone button.

(7) Operate the seat belt, no smoking and call switches in turn. Check for the HI-LO chime output from both speakers in each instance.

(8) Connect a signal generator in place of the microphone in series with a 47 microfarad de-coupling capacitor and wattmeters in place of each of the speakers. Set the output of the signal generator to 50 mA/1KHz.

(9) Set the PA key switch on the test set to ON and check that the amplifier delivers 3.6 ± 0.2 watts, indicated on the wattmeters, to the speaker outputs. Adjust R2082 to achieve these values.

Wattmeter )Suitable local equipment.

2Signal generator ) 1Voltmeter ) 1



(10) Set the PA key switch to OFF.

(11) Check that with the signal attenuation switch to OFF, the wattmeters indicate approximately 3.6 watts.

(12) Set the signal attenuation switch to ON.

(13) Check that the wattmeters now indicate approximately 0.5 watts. Adjust R2031 and R2105 to achieve these values.

(14) Operate the call switch several times and adjust resistor R3075 to give wattmeter peak readings of 10 watts.

(15) Switch off electrical power to the test set and disconnect test set from the amplifier and tape player

B. Function test Passenger Address System.

(1) Provide external electrical power to the aircraft. Refer to 12-09-03, pb301.

(2) Select PASSENGER ADDRESS on the attendants switch panel.

(3) Check that left and right engine oil pressure indicators are illuminated.

(4) Press the transmit button on the attendants handset and speak into the microphone. Check that speech clarity and volume are satisfactory.

NOTE: Keep the handset in the vicinity of the switch panel to avoid feedback interference.

(5) Select PA on first pilots rotary switch and check for satisfactory performance using the associated hand microphone. Operate PA using attendants handset and check that it is overriden when normal PA is operated from the flight compartment.

(6) Press first pilots handwheel switch to R/T and speak into the headset microphone. Set the associated AVIONICS VOL control to the mid position. Gain access to the preset potentiometer in No. 2 avionics bay and slacken lock nuts. Adjust potentiometer to give a side tone level which encourages normal speech without shouting or whispering. Tighten locknuts.



Test CircuitFigure 201



(7) Operate the PA system and speak at a constant audio level into the hand microphone, located at the flight compartment control duct. Adjust the preset control in this microphone to give the same volume on PA as the headset microphone.

(8) Press and release the CALL button on each pilots audio panel. Check that a HI-LO tone is emitted by the speakers.

(9) Pull and push each passenger call button in turn, check that a HI-LO tone is emitted by the speakers each time.

(10) Switch on and off the SEATBELTS and NO SMOKING signs, check that a HI-Lo tone is emitted by the speaker each time.

(11) Select first pilots rotary switch to EMGY PA. Check that the left passenger compartment speakers operate using the first pilots hand microphone.

(12) Pull circuit breaker 16, essential services busbar, Panel 1D, and check that the LH oil pressure warning light extinguishes. At the same time ensure that the PA volume increases. Reset circuit breaker.

(13) Adjust the low level volume, to suit local requirements, using resistor R2031 and resistor R2105.

NOTE: To maintain satisfactory stereo reproduction, both R2301 and R2105 must be adjusted by the same amount.

(14) Perform function test of second pilots PA control facilities as for the first pilot.

(15) Return aircraft to unpowered condition.

C. Passenger address engine run checks.

(1) Set engines to give a noise level similar to cruise flight.

(2) Adjust resistor R3075. to provide satisfactory chime levels.

(3) Adjust resistor R2082 to provide satisfactory speech levels at all locations including galley area and toilet.

(4) Function emergency PA as in B(11) and (12), adjust PA pre-set controls on the audio centres, avionics bays, as required.

D. Passenger address flight checks.

(1) Check for satisfactory operation of all facilities, all areas. Make further adjustments, as required, after landing.



AMM23-33-00 21.0.0.0TAPE PLAYER SYSTEM - GENERAL

1. General

Details of the tape player system are provided as follows:-

A. Pre-mod 7542 (Sharp type).

(1) Tape Player system, Refer to 23-33-10, pb1.

(2) Tape Player. Refer to 23-33-00, pb1.

B. Post mod 7542 (Becker type)

(1) Tape Player System. Refer to 23-33-20, pb1.



AMM23-33-10 22.0.0.0TAPE PLAYER SYSTEM (SHARP UNIT) - DESCRIPTION & OPERATION

1. Description

A. General

This stereo tape player is basically a Sharp model RG-2700P modified for operation on the aircraft, in association with a voltage dropper. Refer to 23-33-11, pb201.

B. Detail

The aircraft 28V DC is switched within the tape player. This switching is performed by the insertion/removal of a cassette. This 28 volts is passed to a voltage dropping circuit on panel 18C where it is stepped down to 14 volts and fed back to the tape player as the operating voltage. The original 28 volts is derived from the TAPE PLAYER circuit breaker on panel 3D (TAIL DISTRIBUTION). Further circuits, associated also with the Passenger Address System (Refer to 23-31-00, pb1.), ensures that precedence is given to P.A. over tape player utilization of the aircraft speakers.

With power supplied and a cassette inserted the tape player will provide continuous play, stopping only when the cassette is removed. At the end of a track the player automatically changes direction of play and reproduces the next track.

2. Operation

With electrical power supplied to the aircraft, and the passenger services busbar, on panel 3D (TAIL DISTRIBUTION), energised, 28V DC is applied to the tape player by closing the TAPE PLAYER circuit breaker on panel 3D. The system is made operational by correctly inserting the chosen cassette.

All other controls necessary for the satisfactory operation of the system are presented on the unit itself. Refer to Figure 1.

CAUTION: USE ONLY HIGH QUALITY CASSETTES TO AVOID TAPE JAMMING, OR THE INTRODUCTION OF FOREIGN BODIES INTO THE MECHANISM. AVOID CASSETTES HAVING TOTAL PLAY TIME EXCEEDING 90 MINUTES (DELICATE TAPES).



Equipment Location & ControlFigure 1



AMM23-33-10 23.0.0.0TAPE PLAYER SYSTEM (SHARP UNIT) - MAINTENANCE PRACTICES

1. Servicing

A. Clean tape player heads.

NOTE: It is advisable that after approximately 30 hours of use that the tape heads should be cleaned by the insertion of a good quality tape head cleaner (e.g. Memorex).

2. Removal/Installation

A. Remove a tape player.


(2) At the tape player location, disconnect the electrical connector and blank both parts of the connector with a suitable blanking material to prevent the ingress of foreign material or damage to the connector.

(3) Remove and retain the bolts and washers securing the player to its mounting bracket and retain them for subsequent refit.

(4) Withdraw the tape player from its mounting bracket.

B. Install a tape player.

(1) Ensure that the aircraft is electrically safe. Refer to 12-09-03, pb301.

(2) Insert the tape player into its mounting bracket and secure in place with the bolts and washers retained from removal.

(3) Remake and secure the electrical connection between the tape player and aircraft wiring.

(4) Perform a function check as detailed in para 3.

3. Adjustment/Test

A. Function check the system.


NOTE: The following assumes that the Passenger Address and Audio System are operational.



Cassette InsertionFigure 201



(2) Ensure that the TAPE PLAYER circuit breaker, on panel 3D, is closed.

(3) Select the cabin attendants audio switch to OFF or INTERPHONE.

(4) Insert a cassette into the tape player unit.

CAUTION: FOR CORRECT METHOD OF INSERTION. REFER TO FIGURE 201.

(5) Adjust the volume, tone and balance controls to obtain a satisfactory stereo output in the passenger compartment speakers. (Lavatory speaker is excluded).

(6) Note the direction the tape is playing by the illuminated direction indicators and press the program select button. Ensure that the direction of play is reversed.

(7) Push the eject/rewind button to the right and check that it operates satisfactorily.

CAUTION: DO NOT USE THE REWIND BUTTON AS AN 'INCHING' CONTROL AS SUCH MAY BREAK OR DAMAGE THE TAPE.

(8) Wind the tape on until it is almost at the end of one channel. Allow it to run on until the end of that track is reached and check that the direction of play is reversed when the next track is heard.

(9) Push in the eject/rewind button and check that the system switches off and the cassette is ejected.

(10) Re-insert the cassette and check that the system is again switched on.

(11) Check that the music is interrupted by the operation of:-

(a) Flight compartment passenger address microphone.

(b) Passenger address using the first and second pilots hand and boom microphones.

(c) Emergency passenger address using the first and second pilots hand microphones.

(d) Operation of either pilots ATTENDANTS CALL button (only while the button is pressed).

(e) When any passenger call knob is held pulled.

(12) Check that the music is not interrupted by operation of the briefing signs (Refer to 33-23-00, pb1.).

(13) Check that the music is interrupted continuously when the attendants handset is set to PASSENGER ADDRESS.

(14) Check that the music does not interfere with audio or communication operation or any other system.



(15) Eject and remove the cassette and return the aircraft to the unpowered state.



AMM23-33-11 24.0.0.0SHARP TAPE PLAYER UNIT - MAINTENANCE PRACTICES

1. Adjustment/Test

A. Modify a standard Sharp model RG-2700P tape player. Refer to Figure 201.

(1) Disconnect and discard the existing connector from the left and right hand channel cores - one black with yellow stripe, one black with white stripe and two black.

(2) Gain access to the inside of the player and retain cover and screws etc., for subsequent refit.

(3) Using suitable material e.g. rubber sleeving, insulate and stow the two black cores in the back of the player.

(4) Install a negative core for the tape player using the black cable supplied (see Detail A for installation) and remove lugs from cable.

(5) Install a 2 amp fuse to the input core (coloured red) fuse carrier (all parts supplied) and remove the lug from the cable.

(6) Refer to detail B. Locate the tape player on/off switch, adjacent to the printed circuit board. Disconnect the red and brown cores from the top and bottom terminals.

(7) Unsolder the top material of the on/off switch from the printed circuit board and carefully bend it up at an angle approx. 45°, thus isolating the switch from the board.

(8) Solder the red and brown cores (see para (6)) and solder them to the printed circuit board. See Detail B.

(9) Solder two new cables preferably Minyvin size 22 (length as required) to the on/off switch. See detail A.

(10) Connect the cable from the top terminal of the on/off switch to pin 5 of the radio spares connector (Part No. 466-179) and cable from the bottom cable to pin 4. (see Detail A and para (11)).

(11) Join four new cables, preferably Minyvin size 22 (length as required) to the existing cables of the player using butt connectors (A-MP type 323994).

(12) Connect the four new cables to the radio spares connector, in the following manner:-

black with yellow stripe extension - pin 1black with white stripe extension - pin 2black - pin 3red - pin 6



Tape player modificationFigure 201



(13) Pins 4 and 5 are connected as detailed in para (10).

(14) Ensure that the inside of the player is clean and undamaged.

(15) Tie new internal cable to existing wiring and ensure that they are secure.

(16) Ensure that the inside of the player is clean and free from damage and that no additional wiring can foul the drive mechanisms.

(17) Replace and secure the unit's cover and screws.

B. Bench check

(1) Remove the cover, retaining it and securing screws for refit.

(2) Check the unit for freedom from damage and corrosion.

(3) Ensure that the modifications detailed in para 1.A. have been carried out.

(4) Replace the cover and its securing screws.

(5) Connect the unit. Refer to Figure 202.

(6) Insert a test cassette into the unit and ensure that it switches on.

(7) Check aurally for an acceptable quality and power of speaker output.

(8) Ensure that the VOLUME TONE and BALANCE controls operate satisfactorily.

(9) Press the PROGRAM button and observe that the direction of play reverses and that the illuminated direction indicator indicates the change.

(10) Check rewind button for satisfactory operation.

CAUTION: THE REWIND BUTTON IS NOT FOR "INCHING", TO USE IT AS SUCH MAY CAUSE DAMAGE TO THE CASSETTE.

(11) Ensure that normal play is resumed when the rewind button is released.

(12) Permit the tape to run to each end and secure that the automatic reverse function operates.

(13) Press the eject button firmly and ensure that the cassette is ejected and the unit switched off.

(14) Disconnect the test connections and replace the unit in the aircraft or repack it to its original standard.



Bench Check ConnectionsFigure 202



AMM23-33-20 25.0.0.0TAPE PLAYER SYSTEM (BECKER TYPE TP3100) - DESCRIPTION AND OPERATIONPOST MOD 7542

1. General

The tape player system in the aircraft gives playback facility of conventional recorded compact-cassettes. The system is similar in operation to the Sharp type system 23-33-10, the main difference being the replacement of the tape player with a Becker type - TP3100-2A.

2. Description

A. The cassette player (Refer to Figure 1.) is a monoblock unit secured into the structure with four Dzus fasteners. The unit is located on the upper centre rear bulkhead of the cloakroom compartment at the rear of the cabin. A 25 pin electrical connection is at the rear of the unit, and the front panel contains the following.

(1) Volume control; a stepless rotary switch which controls the playback sound level to the cabin speakers.

(2) Mode indicators; three green LED indicators which display selected playback mode:

(3) Mode Selector button; a pushbutton switch which selects playback mode.

(4) Fast forward button; a latching pushbutton switch which rapidly increments the cassette tape in the direction of play.

(5) Fast rewind button; a latching pushbutton switch which rapidly increments the cassette tape opposite to direction of play.

NOTE: Fast forward is unlatched by pressing fast rewind, and fast rewind is unlatched by pressing fast forward. Either may be unlatched by pressing the cassette eject button.

indicates track one playback only,

indicates track one and two playback,

indicates AUTOREVERSE.



(6) Cassette eject button; a pushbutton switch, when depressed terminates playback and ejects cassette from unit.

(7) Track selector button; a pushbutton switch which incorporates two LED indicators. With the unit in any mode, depressing the track selector button selects and plays the opposite track, the track in use is indicated with the LED display.

(8) Cassette pit; the loading position for cassette entry.

3. Operation

A. With electrical power supplied to the aircraft and the passenger services busbar, on panel 3D (TAIL DISTRIBUTION), energised, 28 Vdc is applied to the tape player by closing the TAPE PLAYER circuit breaker (CB142) on panel 3D. The system is made operational with the correct insertion of the chosen cassette. All other controls necessary for the operation of the tape player system are on the front panel of the tape player (Refer to Figure 1.).

CAUTION: USE ONLY HIGH QUALITY CASSETTE TAPE TO PREVENT TAPE FOULING OR JAMMING. AVOID THE INTRODUCTION OF FOREIGN OBJECTS INTO THE TAPE MECHANISM. AVOID THE USE OF CASSETTE TAPES WITH A TOTAL PLAY BACK TIME OF 90 MINUTES OR MORE.

B. With the cassette correctly installed, with the full reel to the right, and the requirements of Para. A satisfied, playback will commence. The "track one playback" mode is automatically selected every time power is applied to the unit, in this mode, on completion of track one, the unit will automatically switch OFF and eject the cassette.

When the mode selector buttom is depressed once, "track one and two playback" mode is selected. One completion of tracks one and two the unit will automatically switch OFF and eject the cassette.

With the mode selector button depressed a second time the "AUTOREVERSE" mode is selected. In this mode the unit will continue to repeat playback of tracks one and two until manually selected OFF. Depressing the mode selector button a third time will return the unit to "track one playback" mode.

C. With the power to the unit switched off, or if tape fouling or jamming occurs, the unit will automatically switch OFF amd eject the cassette.

D. Power Supplies

Power to the tape player is from the 28V dc RIGHT PASSENGER SERVICES busbar. The tape player is protected by a 5 amp circuit breaker CB142, on panel 3D.



Tape Player InstallationFigure 1



AMM23-33-20 26.0.0.0TAPE PLAYER SYSTEM (BECKER TYPE TP3100) - MAINTENANCE PRACTICESPOST MOD 7542

1. Servicing

A. Clean tape player heads.

NOTE: It is advisable that after approximately 30 hours of use the tape heads should be cleaned by the insertion of a good quality tape head cleaner, e.g. Memorex.


A. Remove tape player

(1) Make the aircraft electrically safe; open circuit breaker CB 142, panel 3D, and attach placard to prevent inadvertent reset, (Refer to Chapter 12).

(2) Gain access to the tape player in the cloakroom at the rear of the cabin. Disconnect the four Dzus fasteners securing the unit and withdraw the tape player sufficiently to gain access to the electrical connector at the rear of the unit.

(3) Disconnect the electrical connector and remove the unit from the aircraft. To prevent damage or ingress of foreign objects protect both ends of electrical connection using approved blanks.

B. Install tape player

(1) Make the aircraft electrically safe; open circuit breaker CB142, Panel 3D, and attach placard to prevent inadvertent reset. Refer to 12-09-03, pb301.

(2) Remove blanks from tape player and electrical connector, attach electrical connector ensuring correct alignment of the pins.

(3) Locate tape player into the cut-out in the cloakroom aft bulkhead and secure using four Dzus fasteners.

(4) Reset circuit breaker, CB 142, on Panel 3D and remove placards, labels etc.

(5) Perform a function check as detailed in para 3.

3. Adjustment/Test

A. Bench test and adjust the tape player system.

All necessary adjustments are made in the tape player during manufacture. Two further adjustments may be made to the tape player to suit local operating requirements:

(1) Resistor R2042, Right channel volume adjustment.

(2) Resistor R2048, Left channel volume adjustment.



Information regarding the location and adjustment of these resistors can be found in the Becker manual DV29302.03.

B. Function check the tape player system - TP3100.


(2) Ensure the TAPE PLAYER circuit breaker, CB 142, on panel 3D is closed and select attendants audio switch to OFF or INTERPHONE.

(3) The LH mode indicator ( ) should illuminate indicating 'track one' playback mode.

(4) Insert the chosen cassette tape, with full tape reel to The right, into the cassette pit and latch into place. This operation starts the tape drive motor to commence tape playback.

CAUTION: FOR CORRECT METHOD OF CASSETTE INSERTION. REFER TO 23-33-20, FIGURE 1.

(5) Operate the volume control and check that the audio level is continuously variable. Adjust the volume control to obtain satisfactory stereo level from the passenger compartment speakers.

(6) Check the tape player switches OFF and the cassette is ejected at the end of track one.

(7) Press the mode selector button once, the centre mode indicator ( ) should illuminate indicating 'track one and two' playback mode. Check the tape player switches OFF and the cassette is ejected at the end of track two.

(8) Press the mode selector button once again, the RH mode indicator ( ) should illuminate indicating AUTOREVERSE mode. Press the mode selector button again and check the unit returns to the 'track one' ( ) mode.

(9) Press the track selector button a number of times in each mode and check the corresponding track indicator, one or two, is illuminated with the respective track selection.

(10) Press and latch the fast forward and fast rewind buttons alternately. Check the tape rapidly increments in the corresponding direction.

CAUTION: DO NOT USE THE REWIND BUTTONS AS AN "INCHING" CONTROL AS THIS MAY BREAK OR DAMAGE THE TAPE.

(11) Press cassette eject button, check the unit switches OFF and the cassette ejects.

(12) Re-insert the cassette to start playback. Check that the music is interrupted by the operation of:

(a) Flight compartment passenger address microphone.



(b) Passenger address using the first and second pilots hand and boom microphones.

(c) Emergency passenger address using the first and second pilots hand microphones.

(d) Operation of either pilots ATTENDANT CALL button, (only while the button is pressed).

(e) When any passenger call button is held pulled.

(f) Operation of the briefing signs (Refer to 33-23-00, pb1.).

(13) Check that the music is interrupted continuously when the attendants handset is set to PASSENGER ADDRESS.

(14) Check that the music does not interfere with audio or communication operation or any other system.

(15) Connect headphones to the socket on the voice recorder (Refer to 23-73-00, pb1.), and check that speech can be heard when the PA system is in operation.

(16) Trip circuit breakers CB 142, Panel 3D, while the tape is playing and check that the cassette is automatically ejected.

(17) Return the aircraft to an unpowered state.



AMM23-41-00 27.0.0.0INTERPHONE (ATTENDANT AND GROUND CREW SYSTEM) DESCRIPTION & OPERATION

1. Description

A. General

The crew attendants interphone system is an extension of the pilots and observers interphone system. Refer to 23-51-00, pb1.

There is a call light system between attendant and pilots. Refer to 33-23-00, pb1. The pilots can also operate passenger address system chimes to call attendant. Refer to 23-31-00, pb1.

The attendant has a handset socket with a PASSENGER ADDRESS/INTERPHONE changeover switch on the switch panel, in the galley region.

The ground crew HEADSET socket, MIC and TEL sockets are mounted on the external supply plug panel, on the right side of the aircraft. An associated volume control is located forward in the adjacent avionics bay.

(1) Attendants handset, Roanwell Type 502222001-603 or Telex type HS 500

The handset is stowed on the attendants switch panel in the galley region and plugs into a jack on the same panel.

NOTE: If this handset has to be replaced a microphone of the same type should be used. If this is not available, care must be taken to ensure that the replacement is compatable with the system and the other microphones used in the audio system (600 ohm phones, 100 ohm amplified dynamic mic).

(2) Groundcrew headset

It is recommended that the following headset and throat microphone are used, as they resist engine noise:-

(a) HEADSET - AMPLIVOX - E123 wired in parallel and complete with amplifier 22566 wired 18 in. from headset. 9.2 metres cable 17145/AM671.

(b) THROAT MICROPHONE - AMPLIVOX - 17605/1 with AM453. (A separate hand microphone and telephones may be used, or the normal pilot type of headset if so desired).

B. Operation

(1) Pilot/attendant

Attendants PASSENGER ADDRESS/INTERPHONE changeover switch on galley panel, must be in the INTERPHONE position for the attendant to receive or transmit on interphone. Either pilot may communicate with the attendant when the appropriate



ATTENDANT switch is ON using a headset and selecting INT on the handwheel switch. This communication may be individual or collective as selected.

Pilots may also communicate with the attendant via hand microphone and speaker. In this case the following selection is made:-

A volume control for the attendants telephone is provided on panel 3D in the galley region.

(2) Ground Crew

Selections for communications with ground crew are the same as for communication with the attendant.

Ground crew phones volume is selected by a control located forward in the adjacent avionics bay.

(3) Observers

Headset sockets are provided for two observers on the central duct in the flight compartment. Switchgear is arranged so that observers can communicate with the crew when interphone is selected but their microphones are isolated when transmit is selected.

ATTENDANT switch ONATTDT H/MIC switch ONRotary switch ATTDTH/MICSPEAKER VOL As required



Interphone System - Block diagramFigure 1



AMM23-41-00 28.0.0.0INTERPHONE (ATTENDANT AND GROUND CREW SYSTEM) - MAINTENANCE PRACTICES

1. Adjustment/Test

This system is tested and adjusted as part of the audio intergrating system. Refer to 23-51-00, pb201.



AMM23-51-00 29.0.0.0AUDIO INTEGRATING SYSTEM - DESCRIPTION & OPERATION

1. Description

A. General

The audio system provides isolating selection, amplification and distribution of communication and navigation audio signals together with interphone facilities between flight crew members and between flight crew members and ground crew. Passenger address, ground proximity warning and voice recorder are also integrated into the system.

The system provides audio distribution and amplification for transceivers, receivers interphone and passenger address channels.

NOTE: The following description/operation refers to the general case for the actual transceivers installed.

B. Detail

(1) Audio control centre, Collins Type 346B-3.

The two audio control centres are installed in rigid mounted trays, the 1st pilots is in the No. 1 (left) avionics bay, the 2nd pilots in the No. 2 (right) bay.

These units provide control and amplification for the aircraft audio system, accepting audio inputs from receivers and applying them to either the flight compartment speaker or headphones. Two separate audio channels are used, one amplifying the signals to headphone level and one to speaker level.

The audio control centre also acts as a basis for the interphone and emergency passenger address system.

A detailed description of the audio control centre is given in relevant Collins installation and maintenance manuals.

(2) Audio control panel, Shorts SD3-82-6036

Refer to 23-51-06, pb1.

Each pilot has an audio control panel mounted outboard of the dashboard. These panels contain the selection, switching and volume controls for the pilots audio system. It also incorporates a section controlling VHF communication operation direct from battery power.

Receiver selector switches operate remote DC control and provide for selection of communication or navigational audio signals to pilots speaker or headphones. A rotary transmit selector switch connects the crew microphones to up to three transmitter receivers, interphone and passenger address channels. Speaker selection is by means of operating the appropriate volume control..



(3) Speaker

- Elac Type 47EM/260 (Pre Mod A8654 & A8715)- Kenwood KFC1054 (Post Mod A8654)- Kenwood KFC1058S (Post Mod A8715)

Each pilot has two speakers at head level outboard. Speakers are 7 in. x 4 in. elliptical, tropicalised, 4 ohm impedance. One speaker is for general audio. The second is dedicated to ground proximity warning.

(4) Headset, Clement Clarke 'Airlite 62' type MBG EO ABB.

This unit is of conventional pattern incorporating an amplified dynamic microphone. Its lead is terminated by a NATO jack plug.

Alternative types of headset may be used if the following points are observed:-

(a) Telephones must be 600 ohm impedance.

(b) Microphone must be noise cancelling 100 ohm carbon, suitable for 5.5V energising voltage.

(c) Cable terminated by NATO jack plug or US pattern separate mic and tel plugs. (Alternative sockets are provided on the aircraft).

(d) A full aircraft complement of headsets has been assessed in flight on SD3-60 for compatibility and freedom from engine noise pick up or other unsatisfactory performance. This is particularly relevant if different types of headset are used at the same time.

(e) Stethoscope types of headset should be assessed carefully. A blow to the side of the head when certain types are worn can lead to injury.

(5) Hand microphone, Telex type TEL 66T-RA.

This unit is of the amplified, dynamic, noise cancelling type incorporating an output level adjuster.

Alternative types of hand microphone may be used if the following points are observed:-

(a) 100 ohm noise cancelling carbon type.

(b) Incorporating push-to-talk switch.

(c) Lead terminated by US pattern microphone jack plug.

(d) Preferably incorporating output level adjuster; this is helpful for balancing passenger address output levels.

(e) Suitable stowage provided.



(f) Microphone has been assessed in flight on SD3-60 for compatibility, freedom from engine noise pick up or other unsatisfactory performance.

(6) Audio accessory panel, Shorts SD3-82-6003

Two identical panels are provided, one each in the top of avionics bays No. 1 & No. 2. Each incorporates:-

(a) Microphone energiser circuits:

These ensure that pilots and observers headset microphones are supplied with adequate energising voltage (5.5 volts into 100 ohms).

NOTE: Separate energisers are provided for each headset; this avoids a situation where different types of microphones sharing a common energiser could lead to faulty output from one of them.

The energiser circuits consist of simple voltage divider resistor networks with smoothing capacitors and non-reversible de-coupling capacitors.

(b) Transmit relays:

These prevent connection of observers microphones to transceivers, thus maintaining correct microphone loading and avoiding unintentional transmissions.

(c) Interphone relays:

(d) Voice/ident filters from VHF navigation audio:

These enable separation of voice and 1020 Hz identification signals as selected on the audio switch panels.

(e) Relays associated with direct-from-battery audio and VHF communication operation.

(f) DME audio matching transformers.

(g) Various matching resistors.

(7) Microphone and headset sockets

These are located as follows:-

(a) Pilots headsets and hand microphones: below associated audio switch panels.

(b) Observers headsets. at each side of the flight compartment central duct.

(c) Ground crew headset and microphone. adjacent to the ground electrical supply plug.



(d) Attendants handset. on attendants switch panel.

NOTE: Three sockets are provided for each headset, these cater for headsets with NATO single jack plugs or US pattern twin jack plugs.

2. Operation

A. General

Receiver audio signals enter both audio centres and are reduced through isolation resistor networks. Selection of one or more receiver outputs to be relayed to a pilot is by DC controlled solid state AC switching networks and isolation amplifiers which return the signals to headset levels. A separate amplifier in each audio centre raises the signals to speaker level. Collective volume controls are provided for both speaker and phone channels which are effective on all signals except ADF. The latter are controlled in level only by individual controller volume controls in order to facilitate the operation of certain ADF equipment. Speaker selection is by means of associated collective volume control which incorporate an OFF switch. The GPWS speakers operate directly from signals provided by the ground proximity computer.

Separate microphone energisers for each microphone headset are provided in each accessory panel to assure adequate energising voltage (5.5V dc into 100 ohms). Microphone signals are distributed via relays and a rotary switch to the required transceiver, interphone or passenger address system. Hand microphone signals are similarly distributed via the rotary switch. Keying is by means of handwheel INT-OFF-RIT switches or hand microphone buttons distributed by the rotary switch.

The speaker amplifier channel in each audio centre is also used for interphone and emergency passenger address amplification. In order to facilitate normal speaker operation it is necessary to select associated switches to free this amplifier for 'receive' duty.

Speaker muting is provided when a transmission is selected to prevent feedback.

B. Receive mode

(1) Each pilot's system is continuously in the phones receive mode. The speaker receive mode is also active except when the associated:-

(a) Handwheel switch is at R/T or INT.

(b) Rotary switch is at ATTD'T H/MIC or EMG PA.

(c) Hand microphone button is pressed.

(2) Services are selected by audio panel toggle switches to both speaker and phones.

The speaker channel may be selected OFF at its volume control.



(3) Ground proximity audio signals are distributed by the phones without selection an through a pair of dedicated speakers.

(4) Compression amplification is provided to give a relatively even output level with varying inputs.

(5) Navigation (NAV) audio signals are filtered, as selected, to isolate or reject the 1020 Hz identification tone.

(6) Some receivers have their outputs properly loaded by controller volume controls. Others are provided with 560 ohm resistors as required.

C. Transmit mode

(1) Headset microphone.

When a transceiver is selected on a rotary switch and the associated handwheel switch is set to R/T, the transmitter is keyed, speaker is muted and a transmit relay on the accessory panel is de-energised. This relay connects the pilots microphone to the transceiver and disconnects the observers microphone to prevent spurious transmission.

(2) Hand microphone

When the button on a hand microphone is pressed, its output and keyline are connected via the rotary switch to a transceiver, interphone or passenger address as selected.

D. Interphone mode

Interphone amplification is obtained by utilisation of the speaker channel in each audio centre.

(1) Headset interphone

When INT is selected on a handwheel switch, all pilots, observers, ground crew and attendant hear the message spoken into the associated pilot's or observer's headset microphone. Attendant or ground crew to headset interphone is available to individual pilots when their handwheel switch is at INT and the audio panel ATTENDANT switch is at ON. A button on the attendants handset has to be pressed for microphone operation. With the ATTENDANT switches on both audio panels at ON, all crew members will hear all interphone on their telephones.

(2) Hand microphone interphone.

Pilot to attendant and ground crew hand mic/speaker operation is available after the following switch selection:-

- Handwheel switch: OFF- ATTENDANT switch: ON- Rotary switch: ATTD'T H/MIC



- ATTD'T H/MIC switch: ON- Microphone/handset button: press to talk

(3) Interphone volume controls.

Telephone level controls are provided for each pilot/observer, the attendant and groundcrew.

E. Emergency

In the event of pilots telephone channel reception and/or interphone failure, selection of FAIL on the NORM/FAIL switch results in the illumination of an indicator light and connection of pilots and observers telephones to the opposite audio centre. Headset reception and interphone is restored in the following manner:-

(1) Reception

As selected on the other audio panel.

(2) Interphone

Available when both handwheel switches are selected to INT. This action connects all headset microphones to the remaining serviceable interphone channel.

F. Receiver output balancing

Audio management is simplified if adjustments are made to the outputs of receivers. Refer to 23-51-00, pb201. These adjustments result in a roughly equal audio output from each receiver for normally expected input signals. Once so adjusted, receiver volume control management is as follows:-

All receiver volume controls except ADF: fully clockwise.

AVIONICS VOL and ADF VOL controls: As required

G. Passenger address

Refer to 23-31-00, pb1.

Ensure handwheel switch is OFF for emergency operation.

3. Power supplies

28V dc power is distributed to the audio system as follows:-

A. Normal

Left system: Circuit breakers 401, 402 & 403 on left main busbar.

Right system: Circuit breakers 431, 432, & 433 on right main busbar



B. Direct from battery

Provided to enable VHF communication before the main busbars are energised.

Selected by turning the rotary switch to COM DIRECT FROM BATTERY.

Left system: Circuit breakers 64 and 65 on left battery busbar.

Right system: Circuit breakers 215 & 216 on right battery busbar.



Audio Integrating SystemFigure 1



AMM23-51-00 30.0.0.0AUDIO INTEGRATING SYSTEM - MAINTENANCE PRACTICES

1. Adjustment/Test

A. Bench tests

(1) Ensure that Collins 346B-3 audio centres bear the part number 522-3763-002, incorporate Mod.7 and have been bench tested to the requirements of the relevant Collins manual. Audio centres having serial numbers above 4189 or incorporating SB8 have an additional interphone level adjuster which must be set as follows:-

Apply 250 mV at microphone input.

Adjust R325 to obtain 5 mW output.

NOTE: Collins 346B-3 Overhaul Manual Inspection/check, para 4 refers.

(2) Adjust audio outputs of avionic receivers according to the following:-

B. Function test the audio system.

(1) Connect headsets, hand microphones and telephone handsets to all relevant sockets.

(2) Set audio panel STANDBY AUDIO switches to NORM, and all the volume controls to mid positions.

(3) With receiver volume controls set fully clockwise, select individual audio services and check (aurally) for satisfactory crosstalk and breakthrough attenuation through pilots phones and speakers. Adjust switch panel volume controls as required for sensible listening levels.

NOTE: Set SPEAKER VOL control to OFF and adjust AVIONICS VOL control for phones.

Set AVIONICS VOL control fully counterclockwise and adjust SPEAKER VOL control for speakers.

(4) Trip circuit breaker CB 403 and check that first pilot's phones services are lost.

Receiver Type Input Micro Volts Percent Modulation

Load Impedanc Ohms Output Volts

VOR & LOC 5 30 560 6.8Marker 20,000 90 560 10.0DME See makers

manual re aural ident adjustment

- 560 3.4



(5) Set first pilots STANDBY AUDIO switch at FAIL and check that the indicator lights and that first pilot's phones can be used to listen to the services selected on the second pilot's audio panel.

(6) Set first pilot's STANDBY AUDIO switch at NORM and reset circuit breaker CB403.

(7) Repeat paragraphs (4) to (6) for second pilot's phones by tripping circuit breaker CB433, reading second pilot for first pilot and vice versa.

(8) Check for satisfactory boom microphone interphone operation when the associated handwheel switches are set to INT.

(9) Set the cabin attendant's INT/PA switch to INTERPHONE, both pilots handwheel switches to INT and ATTENDANT switches ON.

(10) Press attendant's handset button and adjust attendant's INTERPHONE VOL control (3D) to give a loud but tolerable level in the handset telephone.

(11) Check for satisfactory communication between attendant and both pilots.

(12) Select, in turn, each pilots rotary switch to ATTD'T H'MIC and the associated toggle switch ON. Select both handwheel switches OFF.

(13) Check for satisfactory communication from each pilot to the attendant using hand microphone and speaker. Adjust speaker volume controls as required.

(14) Slacken the grub screw on the attendant's interphone volume control without altering the shaft position. Align the knob pointer with the white line on the panel and tighten the grub screw.

(15) Check for satisfactory communication between ground crew and pilots. Adjust the volume control for ground crew in No. 1 avionics bay as required.

(16) Check that the ground crew and attendants microphones are inactive when both ATTENDANT switches are OFF and active when one switch is ON and the associated handwheel switch is set to INT.

NOTE: Only that pilot's station which has ATTENDANT switch ON and handwheel switch at INT can communicate with the ground crew and attendant stations.

(17) Set both ATTENDANT switches at OFF.

(18) Effect a VHF transmission using the first pilot's hand microphone and loudspeaker, and adjust the ST control at the front of the No.1 346B-3 audio centre for zero loudspeaker sidetone.

(19) Repeat step (17) for the second pilot's audio facility.



(20) Check the observer's interphone points for correct functioning.

NOTE: Each is paralleled with either the first or second pilot's telephones and the observer's microphones are paralleled for interphone only.

(21) Initiate a VHF transmission from the first pilot's headset and check that the left observer microphone is inactive at this time.

(22) Repeat step (21) for second pilots headset and right observer's microphone.

(23) Using a headset with separate microphone and telephone plugs check that:-

(a) Each of the additional socket pairs function.

(b) The sockets are labelled correctly.

(c) The transmitters can be modulated from the pilot's sockets and cannot be modulated from the observer's sockets.



AMM23-51-06 31.0.0.0AUDIO CONTROL PANEL, SHORTS TYPE SD3-82-6036 - DESCRIPTION & OPERATION

1. Description

Refer to Figure 1.

Each pilot has an audio control panel mounted outboard of the dashboard. Cables enter these panels via two sockets at the bottom of each panel, these sockets are idented 'AE' and 'AF'.

The following controls are mounted on each panel:-

A. SPEAKER VOL

Controls associated speaker output. Full anti-clockwise rotation selects speaker OFF.

B. ATTENDANT

(1) Push-button

Operation initiates Hi/Lo chime in passenger compartment to call attendant.

(2) Switch

ON selection enables ground crew and attendants microphone to be connected to interphone when associated handwheel switch is at INT. Communication with an individual pilot is possible if the other pilots handwheel switch is not selected to INT.

C. Receiver selector switches

ON selection connects receivers to both telephones and speaker. If the ATTD'T H'MIC switch is selected, attendant and ground crew are received via speaker. When PA NORM switch is selected, attendant passenger address announcements may be monitored. Switches captioned V or I enable filtered audio to be received thus facilitating reception of identification tones (I) or weather broadcasts (V).

D. Rotary selector switch

This switch selects microphone and keyline to appropriate destinations. The ATTD'T H'MIC position facilitates communication with attendant or ground crew via the hand microphone.

E. Com. direct from battery section

Refer to 23-31-00, pb1.

F. INTERPHONE VOL

Controls interphone volume level in headsets for associated pilot and observer.



G. STANDBY AUDIO

This switch is provided to cover telephone channel reception and/or interphone failure. Selection of FAIL connects associated telephones to the opposite audio centre. Instructions for its use are marked beneath it. An indicator light reminds crews when FAIL is selected.

H. AVIONICS VOL

Controls level of incoming receiver audio signals to the appropriate pilots and observers telephones. An exception is ADF audio signals which are unaffected by this control.

I. Redundant captions

Both panels are built to an identical standard but do not operate identically and are not necessarily fully utilised. Redundant captions are therefore blanked with adhesive tape.

2. Operation

Refer to 23-51-00, pb1.



Audio control panelFigure 1



AMM23-61-00 32.0.0.0STATIC DISCHARGERS - DESCRIPTION AND OPERATION

1. Description

A. General

Static electricity accumulated in flight is dissipated by 10 dischargers located at the trailing edges of aileron, elevators, rudders and fins i.e. four at the tail plane and three each on the left and right wing.



AMM23-61-00 33.0.0.0STATIC DISCHARGERS - MAINTENANCE PRACTICES

1. Adjustment/Test

A. Check resistance of dischargers

Establish that the resistance of each discharger is within 10-160 Megohms.

NOTE: Any dischargers found to be outside quoted limits should be replaced.

2. Inspection/Check

A. Visually check dischargers

(1) At each of the ten dischargers located as described in Description and Operation, check;

(a) The discharger for security of attachment to the retainer, and absence of damage.

(b) The discharger retainer for security of attachment to aircraft structure, and absence of damage.



AMM23-73-00 34.0.0.0VOICE RECORDER SYSTEM (FAIRCHILD TYPE A100A) - DESCRIPTION & OPERATION

1. Description

A. General

The Voice Recorder System provides continuous monitoring of the last 30 minutes of aircraft flight crew communications and flight compartment sounds and preserves that record in the event of an accident. The system continuously records four separate channels of information simultaneously on a half hour endless-loop magnetic tape. The channels are as follows:-

- Channel 1 - Passenger address- Channel 2 - 2nd Pilots audio services and hot microphones- Channel 3 - 1st Pilots audio services and hot microphones- Channel 4 - Area microphone

The recorder automatically erases as it records so that only the last half-hour of recording is retained. As soon as the aircraft has docked, the complete recording may be erased, thus eliminating unauthorised access to the recorded information. Play back is best effected when the recorder is removed from the aircraft.

B. Detail

Refer to Figure 1.

(1) Cockpit Voice Recorder

The recorder, idented MF7, is mounted on the right of the aircraft between stations 593 and 620.

The unit records on four separate channels as explained above. These channels can be tested individually or simultaneously by use of a playback adapter unit. Recorder operation can be monitored visually by a meter on the controller facia or aurally through a phone jack. A more detailed description of the recorder, including erasure and playback is provided in the manufacturer's instruction manual.

(2) Controller

The controller is mounted on 1P panel. It is a self-contained unit comprising, the area microphone, necessary amplifiers and filters, and the monitor meter. It also includes ERASE and TEST buttons. When test is selected a 600 Hz tone is generated and impressed on the tape. The tone can be monitored via a 600 ohm headphone, plugged into the adjacent phone jack and a check is made that the meter is reading in the green section of the dial.

To completely erase all recorded data the ERASE button is depressed for two seconds. This control is inter-linked with the flying controls lock lever so that erasure in flight is impossible. A more detailed description of the controller is provided in the manufacturer's manual.



Voice Recorder System - Component LocationFigure 1



(3) Inertia switch

An inertia switch, idented MF5, is mounted below the voice recorder. The switch is employed in the system to ensure that the recorder stops after a crash landing which does not interrupt electrical power. It is a single pole uni-directional switch designed for horizontal mounting. The contact will close when subjected to forward deceleration equal to or greater than 3g ± 0.15g, thus switching off the system and lighting an amber RECORDER POWER OFF warning lamp mounted on 1P panel.

(4) Amplifier

Two summing amplifiers, one each in No.1 and No.2 Avionic Bays, and idented 1MF8 and 2MF8 respectively, are employed to amplify low level audio signals from each pilots/observers services for application to channels 2 and 3 of the recorder.

2. Operation

Refer to Figure 2.

A. Recording

The Voice Recorder System is operational when circuit breaker CB199 - VOICE RECORDER CONTROL on 2D panel and circuit breaker CB365 VOICE RECORDER on 2D panel are closed. Recordings are made on four channels as explained in para 1.A.

Recording is continuous, the last 30 minutes of recording remaining on the tape.

B. Inertia switch

The main AC power supply to the voice recorder is through the normally closed contact 1-2 of the AC supply relay idented CH on the right equipment panel 2C. In the event of an impact, with a forward deceleration at or greater than 3g ± 0.15g the inertia switch will close, connecting a DC supply from circuit breaker CB199 on 2D panel to energize this relay. With the AC supply relay energized and contacts 1-2 open, the AC supply to the voice recorder is broken, thus preventing the record from being erased. The same circuit also breaks power to the flight data recorder (Refer to 31-31-00, pb1.) via contacts 21-22.

If the inertia switch closes, an amber warning lamp on 1P panel will illuminate indicating RECORDER POWER OFF. Brightness and testing of this lamp is controlled by the TEST/BRT/DIM switch, Central Warning system. Refer to 31-50-00, pb1.

C. Erasing

When the aircraft is docked with the flying controls locked, a supply from circuit breaker CB192 (Refer to 27-70-00, pb1.) is passed through the 'controls-locked' microswitch via a relay idented CJ on panel 2C to the bulk-erase part of the Voice Recorder system. This completes a connection between the ERASE button on the controller and the erase coil in the recorder. Erasure of all recording may then be made by pressing the ERASE button.



D. Test

The TEST facility provides aural and visual indication that the system is properly recording and monitoring on each channel.

Operation of the test button on the controller initiates meter indications and test telephone signals indicating satisfactory operation. Refer to Maintenance Practices for detailed test procedure.



Voice Recorder System-Block DiagramFigure 2



3. Power supplies

Power is derived via circuit breakers on 2D panel. The voice recorder is fed via circuit breaker CB365 - VOICE RECORDER from the right 115V 400Hz AC busbar. The voice recorder amplifiers are driven via circuit breaker CB199 - VOICE RECORDER CONTROL from the 28V DC Essential Services busbar. Power for the bulk erase facility is supplied from circuit breaker CB199 - VOICE RECORDER CONTROL from the 28V DC Essential Services busbar. Power for the bulk erase facility is supplied from circuit breaker CB192 - CONTROL LOCKING via a microswitch associated with the gust lock lever (Refer to 27-70-00, pb1.).



AMM23-73-00 35.0.0.0VOICE RECORDER SYSTEM (FAIRCHILD TYPE A100A) - MAINTENANCE PRACTICES


A. Remove a voice recorder


(2) Isolate power supply to the recorder by opening and tagging circuit breakers CB199 and CB365 (panel 2D).

(3) Locate voice recorder unit in the rear fuselage right side between stations 392 and 422 (access panel 263KZ).

(4) Slacken locking collar wing nuts and slide recorder forward in mounting tray, disengaging from electrical connector.

NOTE: Electrical connectors must be capped when disconnected to prevent damage from dirt or foreign objects.

(5) Remove recorder.

B. Install a voice recorder

(1) Remove protective cap from electrical connector.

(2) Position recorder on mounting tray and slide rearwards to engage with electrical connector.

(3) Secure recorder with locking collars and tighten wing nuts.

(4) Fit access panel 263KZ.

(5) Close circuit breakers CB199 and CB365 (panel 2D).

(6) Perform associated function test detailed in Adjustment/Test.

C. Remove a controller


(2) Open and tag circuit breaker CB365 on panel 1D.

(3) At controller, release four quick release fasteners, ease controller forward and disconnect electrical connector.

NOTE: Electrical connectors must be capped when disconnected to prevent damage from dirt or foreign objects.

(4) Remove controller



D. Install a controller

(1) Remove protective cap from electrical connector.

(2) Reconnect electrical connector to controller and position controller in appropriate housing on panel 5P.

(3) Secure controller with four quick release fasteners.

(4) Close circuit breaker CB365 on panel 2D.

(5) Perform associated function test detailed in Adjustment/Test.

2. Adjustment/Test

A. Introduction

Prior to commencing the tests detailed ensure that the following systems are operational and the appropriate circuit breakers are closed.

(1) COM.1 system. Refer to 23-11-00, pb1.

(2) Audio integrating system. Refer to 23-51-00, pb1.

(3) Central warning system. Refer to 31-50-00, pb1.

B. Equipment and materials

(1) 600 ohm headphones with an American Civil standard phone jack.

(2) Civil Headset having an American Military standard jack plug.

(3) Hand microphone.

C. Preparation

(1) Ensure that all electrical and avionic switches are at a neutral or OFF position.

(2) Connect an external power supply to the aircraft. Refer to 12-09-03, pb301.

(3) Set the ELECTRICAL MASTER switch to EXTERNAL POWER.

(4) Set the AVIONICS MASTER switch to ON.

(5) Ensure that the following circuit breakers are closed (made):-

(a) CB192 - Control Locking

(b) CB199 - Voice Recorder Control



(c) CB365 - Voice Recorder.

(6) Set TEST/BRT/DIM switch on panel 11P to TEST and ensure that RECORDER POWER OFF warning lamp on panel 1P illuminates.

(7) Set TEST/BRT/DIM switch to BRT and ensure that RECORDER POWER OFF warning lamp is extinguished.

(8) Set rotary selector switches on both audio control panels to COM.1.

(9) On the COM.1 controller:

(a) Set the mode selector switch to TR

(b) Turn the frequency selector switch to MAN

(c) Tune to an unused frequency.

D. Function test

NOTE: During the following tests ensure that only one headset or hand microphone is connected into the audio system at any one time.

(1) Connect headphones to the Cockpit Voice Recorder controller HEADSET socket.

(2) Press and hold the controller TEST button.

(3) Check that four 0.8 second bursts of 600 Hz test tone are heard in headphones. This indicates that a test tone has been applied to each channel 1 to 4.

(4) Check that test meter, on controller, is in the green GOOD section for each channel.

NOTE: In the event of a channel failure the needle will not reach the green section.

(5) Release the controller TEST button.

(6) Disconnect headphones from controller.

(7) Connect headphones into monitor socket on recorder front panel, in rear of aircraft.

(8) Connect headset into the appropriate socket below the First Pilot's audio panel.

NOTE: The following tests require the help of an assistant.

(9) Speak normally into the First Pilot's boom microphone. Check that, after a short delay, the voice can be heard in headphones connected to recorder.

(10) Repeat (9) for the headset in the Second Pilot's and two Observer's sockets.

(11) Disconnect headset.



(12) At Second Pilot's audio panel, set rotary switch to PA and connect hand microphone into appropriate socket.

(13) Press the microphone button and speak into microphone. Check that, after a short delay, the voice can be heard in headphones connected to recorder.

(14) Disconnect hand microphone.

(15) Speak into the area microphone on controller. Check that, after a short delay, the voice can be heard in headphones connected to recorder.

(16) Plug headset into socket below First Pilot's audio panel.

(17) Set the First Pilot's handwheel switch to INT.

(18) Speak into the boom microphone.

(19) Check that this can be heard in the headphones connected to the recorder.

(20) Disconnect the headset.

(21) Disconnect the headphones.

E. Function check inertia switch

(1) Locate inertia switch, idented MF5, on right side below voice recorder (access panel 263KZ).

(2) Provide DC and AC power. Refer to 12-09-03, pb301.

(3) Ensure circuit breakers CB199 and CB365 on panel 2D are closed (made).

(4) Trip the inertia switch and check that the RECORDER POWER OFF warning lamp on panel 1P illuminates and that 115V AC IS NOT AVAILABLE at recorder J2 pin 2.

(5) Press the inertia switch reset button and check that RECORDER POWER OFF lamp is extinguished and that 115V AC IS AVAILABLE at recorder J2 pin 2.

(6) Refit access panel 263KZ.

F. Post recording checks

CAUTION: DURING PLAYBACK, WITH THE BIAS OSCILLATOR DISABLED, NO AUDIO INPUT IS TO BE APPLIED TO THE RECORDER. ENSURE THAT ALL HEADSETS/HAND MICROPHONES ARE DISCONNECTED AND THAT NO AUDIO IS APPLIED TO THE AREA MICROPHONE ON THE CONTROLLER.

(1) Trip circuit breaker CB365 on panel 2D.

(2) Disable the bias oscillator by removing the link between RTB69-1 and RTB69-2.



(3) Reset the circuit breaker CB365 on panel 2D.

(4) Plug headphones into monitor socket on recorder.

(5) Check for a satisfactory recording of previous tests.

(6) Unlock the flying controls.

(7) Press and hold the ERASE button, on the controller, for two seconds.

(8) Ensure that the attempted erasure was unsuccessful by checking that the recording of the tests can still be heard.

(9) Lock the flying controls.

(10) Press and hold the ERASE button for two seconds.

(11) Ensure that the recording has been erased by checking that nothing can be heard of the tests, from the tape, on the headphones.

G. Completion

(1) Disconnect headphones from monitor socket of recorder.

(2) Reconnect the bias oscillator by reconnecting the link between RTB69-1 and RTB69-2.

(3) Set all electrical and avionic switches to off or neutral.

(4) Set AVIONICS MASTER switch to OFF.

(5) Set ELECTRICAL MASTER switch to INTERNAL POWER.

(6) Disconnect external power supply. Refer to 12-09-03, pb301.