(2)
Communications and navigation audio, which is monitored with the flight interphone system components, is checked as part of the requirements of the respective communication and navigation systems test.
B. Prepare to Test
(1)
Provide electrical power
(2)
Check that all interphone and interphone dual power source circuit breakers on panel P6 are closed.
(3)
Turn on both flight interphone loudspeakers.
C. Test Flight Interphone System
(1)
At captain's, first officer's, and observer's audio selector panels, push and turn on INT audio switch, push INT microphone selector switch, and set BOOM-MASK switch to BOOM.
(2)
Using boom microphone/headset assemblies, establish communications between flight compartment stations by holding audio selector panel PTT switch to I/C position. Check that audio is loud and clear between stations and can be set to comfortable listening level with INT audio switch.
(3)
Perform step (2) by actuating each pilot's control wheel PTT switch to INT position.
(4)
At each audio selector panel, set BOOM-MASK switch to MASK.
(5)
Using oxygen mask microphones, establish communication between flight compartment stations by holding audio selector PTT switch to I/C position. Check that audio is loud and clear between stations.
(6)
At each audio selector panel, set BOOM-MASKS switch to BOOM.
(7)
At each audio selector panel, turn on ADF-1 audio switch and set filter switch to V.
(8)
Turn on ADF-1 system (Ref 34-57-0) and tune in audio signal.
(9)
Check that audio output from captain's and first officer's loudspeakers is loud and clear and that audio volume varies through comfortable listen range as loudspeaker volume control is turned.
(10)
Check that both speakers mute when any PTT switch is actuated at each station.
(11)
At each audio selector panel, set filter switch to R.
(12)
Tune in range signal and check that audio is loud and clear in headphones.
(13)
Turn off ADF-1 system (Ref 34-57-0).
(14)
Remove electrical power if no longer required.
Sep 20/81 23-52-01 Page 501
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
FLIGHT INTERPHONE SYSTEM - TROUBLE SHOOTING
EFFECTIVITY
Airplanes with Digital Flight Interphone
1. General
A. Trouble shooting the flight interphone system is relatively easy due to duplication of components within the system. Interchanging suspected faulty components with known good components will quickly isolate the faulty components. If the flight interphone system is completely inoperable, the remote electronics unit is faulty. Corrective action is to replace the remote electronics unit.
B. Interphone loudspeaker failure can usually be detected by comparison between headphone audio and the loudspeaker audio. If audio is not available to either one, the audio selector panel is faulty.
C. Isolation of a faulty control wheel PTT switch can be determined by first making a comparison with the control panel PTT switch. If oronasal mask mike audio can be completed using the control panel PTT switch but not when using the control wheel PTT switch, the fault is either with the control wheel PTT switch or the control panel. If the control panel is then replaced with a known good control panel and oronasal mask mike audio still can not be completed using the control wheel PTT switch, the fault is with the control wheel PTT switch.
5C8
Jun 20/88 23-52-02 Page 101
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
FLIGHT INTERPHONE SYSTEM - ADJUSTMENT/TEST
EFFECTIVITY
Airplanes with Digital Flight Interphone System
1. System Test - Flight Interphone System
A. General
(1) The flight interphone system test when performed in its entirety provides assurance that the system is functioning properly and is ready for use.
B. Prepare for Test
(1)
Provide electrical power (Ref. 24-22-00 MP)
(2)
Verify the following interphone circuit breakers on overhead circuit breaker panel P6 are closed: CAPT and F/O-BAT INPH PWR, CAPT and F/O-INPH 2 PWR, CAPT and F/O and OBS-AUDIO.
(3)
Turn SPKR control knob on captain and first officer audio selector panels fully counterclockwise to off.
