Garmin GMA 347 Installation Manual page 37

3.8.4 Intercom System (ICS) Check
If a monaural headset is plugged into any stereo phone jack position, no
damage will occur to the GMA 347. In the case of plugging a monaural
headset into any passenger position, any stereo listener will lose one
channel when another passenger plugs in a monaural headset.
1. Set the intercom to the ALL mode (Pilot and Copilot LED's off.)
2. Plug in headsets at each ICS position.
3. Adjust squelch and volume for each position and verify that the ICS is working properly.
4. Check Pilot and Copilot ICS positions for isolation and proper operation of volume and squelch
controls.
5. Press and hold the SPKR key for two seconds. Verify that the SPKR key annunciator flashes,
indicating the PA mode, and that microphone audio is heard over the speaker.
3.8.5 Aircraft Receivers Check
1. Select the audio source for each avionics unit installed in the aircraft and check for audio over the
headsets.
2. Check for Pilot/Copilot audio isolation when pressing the Split COM (COM 1/2) key.
3. Press the SPKR key and verify that any selected audio is heard over the speaker.
3.8.6 Clearance Recording Check
1. Allow COM 1 receiver to operate for at least two and one half (2.5) minutes of active operation.
2. Press the PLAY key once to play back the latest recorded memory block of COM 1 audio.
3. Press the PLAY key again to play the previous memory block of COM 1 audio. Continue
stepping backward into the memory blocks until listening to the first block of audio. A total of
2.5 minutes of audio is recorded.
4. Verify that after playing back the full 2.5 minutes of stored audio, that the playback system audio
stops.
3.8.7 Music System Check
1. Set the intercom to the ALL mode (Pilot and Copilot LED's off.)
2. Connect a stereo audio source to MUSIC 1. Verify that stereo audio is heard over the Pilot and
Copilot headset positions.
3. Tune a station on COM 1 and verify that the sound is muted by active COM 1 audio (break
squelch on COM 1 if necessary).
4. Connect a stereo music source to MUSIC 2. Verify that stereo audio is heard in the passenger
headsets.
GMA 347 Installation Manual
190-00325-01
NOTE
Page 3-13
Revision A