ALT-NORM Switch

You use the ALT-NORM switch to select either normal or emergency operation of the flight interphone system. Each station operates independently.

When you select NORM, the flight interphone system operates as usual.

When you select ALT, the flight interphone system operates in the emergency mode. The only ACP controls that operate are the BOOM-MASK switch and the R/T position of the PTT switch.

The hand-mic does not operate.

When you select ALT on the captain or observer ACP, you hear receiver audio from the VHF-1 transceiver at the headphone and headset jacks. When you key the MIC, the audio and PTT signals go to the VHF-1 transceiver.

When you select ALT on the first officer ACP, you hear receiver audio from the VHF-2 transceiver at the headphone and headset jacks.

When you key the MIC, the audio and PTT signals go to the VHF-2 transceiver.

Purpose

The remote electronics unit (REU) controls audio signals in the flight interphone system.

Physical Description

The REU has these physical properties:

· Length is 17.6 in. (320 mm)

· Height is 7.62 inches (194 mm)

· Width is 3.58 inches (90.0 mm)

· Weight is 7.75 pounds (35.2 kg).

Functions

The REU uses the ACP selections to connect these signals:

· Communication transceiver audio

· Navigation receiver audio

· Passenger address audio

· Service interphone audio

· Flight interphone.

Purpose

The control wheel PTT switch gives push-to-talk input for the boom or oxygen mask microphones.

Description and Controls

The control wheel PTT switch is a three position switch. It is on the outboard horn of the captain’s and the first officer’s control wheel. These are the switch positions:

· MIC - microphone audio and PTT signals go to the communication system you select

· OFF - The ACP PTT switch can key the microphone

· INT - microphone audio goes to the flight interphone system (ACP selection is not changed). The switch is spring loaded to the middle OFF position.

General

You use the audio control panel (ACP) to select the audio for headsets and flight interphone speakers. ACPs also select a communication system.

Дата добавления: 2015-10-26