Garmin G900X Pilot's Manual - page 158

190-00726-00  Rev. A

Garmin G900X Pilot’s Guide

4-36

AUDIO PANEL AND CNS

4.7  ABNORMAL OPERATION

Abnormal  operation  of  the  G900X  includes  equipment  failures  of  the  G900X  components  and  failure  of 

associated equipment, including switches and external devices.

STUCK MICROPHONE

If the push-to-talk (PTT) Key becomes stuck, the COM transmitter stops transmitting after 35 seconds of 

continuous operation.  An alert appears on the PFD to advise the pilot of a stuck microphone.

The 

COM1 MIC

 or 

COM2 MIC

 Key Annunciator on the Audio Panel flashes as long as the PTT Key remains 

stuck.

Figure 4-45  Stuck Microphone Alert

COM TUNING FAILURE

In case of a COM system tuning failure, the emergency frequency (121.500 MHz) is automatically tuned in 

the radio in which the tuning failure occurred.  Depending on the failure mode, a red X may appear on the 

frequency display.

Figure 4-46  COM Tuning Failure

Emergency Channel 

Loaded Automatically

AUDIO PANEL FAIL-SAFE OPERATION

If there is a failure of the Audio Panel, a fail-safe circuit connects the pilot’s headset and microphone directly 

to the COM1 transceiver.  Audio will not be available on the speaker.

REVERSIONARY MODE

The  red 

DISPLAY  BACKUP

  Button  selects  Reversionary  Mode  for  both  displays.    Reversionary  Mode 

operation displays flight and engine information on both the PFD and MFD, in case of display failure.

See the System Overview Section for more information.

Figure 4-47  Reversionary Mode Button