Failsafe Operation; Transceiver Operational Check; Intercom System (Ics) Check - Garmin GMA 347 Maintenance Manual

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LED Annunciators
Verify proper operation of the LED annunciators.
Marker Beacon Annunciations
Verify proper operation of the Marker Beacon annunciators.
Volume and Squelch Controls
Turn the volume and squelch controls and verify proper operation.
Photocell
Cover and uncover the photocell and verify proper operation.
Beep Tone
When a beep tone is generated by the Audio Panel, the tone should be audible at the pilot's
headset left output (when enabled, the beep tone is output (for ~25mS) whenever a key is
pressed on the keypad of the audio panel).
Panel Dimming
Vary the Vbus voltage and observe proper dimming operation. Note: the 14V or 28V dimming
bus could be at fault.
3.2.3 Failsafe Operation Check
1. Turn the unit off by rotating the pilot intercom knob counter clockwise.
2. Check the failsafe operation by exercising the COM 1 microphone, microphone key and
monitoring received COM 1 audio over the headphone's left earpiece.
3. Turn the unit back on to continue testing.
3.2.4 Transceiver Operational Check
1. Perform a ramp test radio check by exercising the installed transceivers, microphone,
microphone key and audio over the headphone.
2. Verify that communications are loud and clear and PTT operation is correct.
3.2.5 Intercom System (ICS) Check
Stereo headsets are recommended if stereo jacks are installed.
1. Set the intercom to the ALL mode [Pilot ISO LEDs off].
2. Plug in headsets at each ICS position.
For helicopter operation using a two‐stage Intercom/PTT switch, prior to using
the keyed‐intercom mode, the VOX level should be set by adjusting the VOX
knob while the first detent is actuated and held.
3. Adjust squelch and volume for each position and verify that the ICS is working properly.
GMA 347 Maintenance Manual
190‐00325‐02
NOTE
NOTE
Page 3‐7
Rev. A