Audio Control Panels (ACP)
An ACP is installed at the Captain, First Officer, and Observer stations. Each
panel controls an independent crew station audio system and allows the
crewmember to select the desired radios, navigation aids, interphones, and PA
systems for monitoring and transmission.
Transmitter selectors on each ACP select one radio or system for transmission
by that crewmember. Any microphone at that crew station may then be keyed to
transmit on the selected system. Receiver switches select the systems to be
monitored. Any combination of systems may be selected. Receiver switches
also control the volume for the headset and speaker at the related crew
stations. Audio from each ACP is monitored using a headset/headphones or
the related pilot’s speaker.
Audio warnings for altitude alert, ground proximity warning, collision avoidance,
and windshear are also heard through the speakers and headsets at preset
volumes. They cannot be controlled or turned off by the crew.
The MASK-BOOM switch allows selection of the oxygen mask microphone or
the boom microphone. The MASK–BOOM switch does not affect the operation
of the hand microphone.
Normal Audio System Operation
The Captain, First Officer, and Observer audio systems are located in a
common remote electronics unit in the E/E compartment. They function
independently and have separate circuit breakers. The audio systems are
normally controlled by the related ACPs through digital or computerized control
circuits.
An ACP is installed at the Captain, First Officer, and Observer stations. Each
panel controls an independent crew station audio system and allows the
crewmember to select the desired radios, navigation aids, interphones, and PA
systems for monitoring and transmission.
Transmitter selectors on each ACP select one radio or system for transmission
by that crewmember. Any microphone at that crew station may then be keyed to
transmit on the selected system. Receiver switches select the systems to be
monitored. Any combination of systems may be selected. Receiver switches
also control the volume for the headset and speaker at the related crew
stations. Audio from each ACP is monitored using a headset/headphones or
the related pilot’s speaker.
Audio warnings for altitude alert, ground proximity warning, collision avoidance,
and windshear are also heard through the speakers and headsets at preset
volumes. They cannot be controlled or turned off by the crew.
The MASK-BOOM switch allows selection of the oxygen mask microphone or
the boom microphone. The MASK–BOOM switch does not affect the operation
of the hand microphone.
Normal Audio System Operation
The Captain, First Officer, and Observer audio systems are located in a
common remote electronics unit in the E/E compartment. They function
independently and have separate circuit breakers. The audio systems are
normally controlled by the related ACPs through digital or computerized control
circuits.
