23-40-00  INTERPHONE SYSTEM Back

A. System Function

The interphone system lets the flight crew speak to each other, the cabin crew and the ground crew.

B. System Components

The primary components of the system is the ground-crew jack box. (Ref. Fig. 1 and Fig. 2)

C. System Operation

  1. The audio signals from the ground crew are sent to the No. 1 Audio Control Panel (ACP) (Ref. 23-51-00) through the ground-crew jack box. These audio signals are then sent as output to the flight crew headsets. Audio signals from the flight crew microphones are sent to the ground-crew jack box through the No. 1 ACP.
  2. The audio signals from the cabin crew are sent to the No. 1 and the No. 2 ACP from the Cabin Audio System (CAS) (Ref. 23-31-00). These audio signals are then sent as outputs to the flight crew headsets. The audio signals from the flight crew microphones are sent to the CAS through the No. 1 and the No. 2 ACP.
  3. The pilot, the co-pilot and the third crew member speak to each other through the interphone bus.

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