Operation of both AUDIO BYPASS switches eliminates
the audio mixer and provides a power source directly
from the respective COMM radio. This eliminates all volume
control except for the MSTR VOL (master volume)
control on the applicable audio control panel.
For the pilot, copilot, and flight mechanic to communicate,
both AUDIO BYPASS switches should be in the
BYPASS position. During BYPASS operation the pilot
can only transmit/receive on COMM 1, the copilot on
COMM 2. All audio warnings are inoperative.
Possible Symptoms:
1. Complete loss of audio (all stations)
2. All ICS and transmit functions inoperative
3. Constant squeal or hum heard in headset
Corrective Action:
1. PILOT AND COPILOT AUDIO BYPASS
SWITCHES − BYPASS
2. ICS CIRCUIT BREAKERS (2) − PULL, RESET
(cockpit avionics panel R1 #5 and R5 #5)
3. CONTINUE FLIGHT AS APPROPRIATE