Garmin GTN 6 series Maintenance Manual page 71

6.3.3.2.4 NAV Audio Check
Ensure the GMA 35 and each installed NAV receiver is powered on.
1. Tune the NAV receiver to a local VOR station.
2. Ensure the Morse code identifier is being received over the crew headsets.
3. If the audio is not heard, verify the wiring to the audio panel.
4. Ensure the audio volume is sufficient for all anticipated cockpit noise conditions.
Repeat steps 1 through 4 for each installed NAV receiver.
6.3.3.2.5 Alert Audio Check
If there is an alert audio source connected to the GMA 35, the interface should be verified as described
below.
1. Cause the alert audio source to produce audio. (e.g., if a traffic system is installed, command the
traffic system into self-test mode; if a HTAWS system is installed, command the HTAWS system
into self-test mode.)
2. Verify that the alert audio source is heard in the pilot and copilot headsets and that the audio
volume is sufficient for all anticipated cockpit noise conditions. Adjust the audio volume level as
needed. For modification of configuration settings, refer to the GTN 6XX/7XX AML STC
Installation Manual.
3. If the alert audio source is not heard in the crew headsets, check the wiring from the source to the
GMA 35 alert audio inputs.
Repeat steps 1 through 3 for each alert audio source connected to the GMA 35.
6.3.3.2.6 Intercom System (ICS) Check
NOTE
If a monaural headset is plugged into any stereo phone jack position, no damage will
occur to the GMA 35. 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. Place the audio panel into ALL ICS mode (refer to the GTN 725/750 Pilot's Guide, P/N 190-
01007-03) so that all ICS positions hear all others.
2. Deselect or turn off other audio sources (MKR, transceivers, receivers, alerts). Some
configurations may mute passenger intercom audio to crew when rotorcraft audio is present.
3. From the pilot headset position, verify the pilot, copilot, and all passenger mic inputs can be heard
in the pilot's headset when speaking into the mic input under test (adjust pilot ICS volume if
necessary).
4. Speak into the pilot's mic and verify that pilot mic audio is heard in the copilot headset (adjust
copilot ICS volume if necessary) and in each passenger headset (adjust passenger ICS volume if
necessary).
190-01007-B1
Rev. 1
GTN 6XX/7XX Part 27 AML STC Maintenance Manual
Page 6-7