Emergency Circuits

The REU gives power for the ACP. You lose ACP power when for these conditions:

· REU has no power

· ACP has the ALT selection.

These conditions occur when you lose power in the ACP:

· The ALT/NORM relay has no power

· The data line to the REU identifies MASK/BOOM selection

· 28 volts from MD&T goes through the ALT/NORM relay contacts to the VHF 1 mic selector switch lamp for the captain and observer, and VHF 2 mic selector switch lamp for the first officer.

General

These components send a push-to-talk (PTT) signal to the remote electronics unit (REU):

· Audio control panel (ACP) radio-intercom PTT switches

· Control wheel PTT switches

· Remote mic switches

· Hand microphone PTT switches.

Set the radio-intercom PTT switch on the ACP to R/T to send a PTT signal to a communications system. Set the switch to I/C to talk on the flight interphone system.

Push the remote mic switch on the glareshield to send a PTT signal to a communication system.

Set the control wheel PTT switch to MIC to send a PTT signal to a communications system. Set the switch to INT to talk on the flight interphone system.

The observer can only send a PTT from the hand microphone or ACP.

General

The remote electronics unit (REU) controls the communication between these:

· Three flight deck stations

· Service interphone

· Flight interphone

· All related electronics equipment.

The REU contains three identical station cards. The cards are for these crew members:

· Captain

· First officer

· Observer.

The REU also has an audio accessory unit (AAU) card. The card contains circuitry for flight and service interphone, alert tone generation and various audio accessory functions.

REU cards process these signals:

· REU inputs

· REU outputs

· AAU signals

REU Inputs

Each station card in the REU receives audio from these sources:

· Flight compartment microphones

· Communication transceivers

· Navigation receivers

· Passenger address amplifier

· AAU card aural alerts.

The station cards get control inputs from the audio control panels (ACPs) and microphone push-to-talk (PTT) switches.

The mux receiver, in the REU, sends a data clock to the ACP.

The ACP replies back with crew selected receiver audio, navigation signals, volume and particular transmitter.

The mux receiver responds to the crew inputs and sends control signals to the following circuits:

· Receiver circuits

· Mic/PTT select logic

· Transmitter circuits

· Speaker mute/volume logic.

The receiver circuits receive audio inputs from the communication and navigation systems, passenger address amplifier, service interphone and flight interphone. The circuits process the crew selected audio. The audio goes to summing amplifiers. The summing amplifiers send the audio to the speaker mute/volume logic circuits, CVR amplifier and headphone amplifier.

The mux receiver sends boom/mask and interphone PTT signals to the mic/PTT select logic. The mic/PTT select logic processes input microphone audio and PTT signals. It routes(направлять) the selection to the transmitter circuits. The mic/PTT select logic circuits process speaker mute signals and hot mic audio.

The transmitter circuits route the microphone audio and/or PTT to the selected communication system.

The speaker mute/volume logic circuits process flight compartment speaker muting and set the speaker volume to the level as commanded from the mux receiver.

REU Outputs

Each station card sends audio to these:

· Headphones

· Headsets

· Voice recorder

· Flight compartment speakers from CAPT and F/O station cards

· Communication transceivers

· Passenger address amplifier.

The station cards also send PTT signals to the communication transceivers and the passenger address amplifier.

AAU Signals

The AAU uses these audio signals:

· Altitude alert

· Ground proximity alert

· Flight interphone

· Service interphone.

The flight control computers (FCCs) send an altitude alert discrete to the AAU card. This input starts a C-chord generator.

The ground proximity computer and the weather radar receiver transmitter send alert audio to the AAU card. The AAU card combines this audio with the output from the altitude alert tone generator and sends it to each station card summing amplifier.

The summing amplifier combines the AAU alert audio with TCAS audio. Station cards amplify these signals and send them to these components:

· Voice recorder

· Headphones

· Headsets

· Speakers.

The flight interphone amplifier amplifies microphone audio from station cards. Microphone audio goes to the flight interphone jack.

The AAU card amplifies audio from the external flight interphone jack and sends it to station cards.

The service interphone amplifier amplifies these inputs:

· Audio from attendant handsets

· Audio from service interphone jacks

· Microphone audio when service interphone is set on the

ACP.

This audio goes to service interphone jacks and station cards.

Дата добавления: 2015-10-26