C ELEX FLT INSTR
SYS SYM GEN

FLT REC EFIS I/P SW
429
XMTR

R EICAS CMPTR  EICAS LOWERDISPLAY SWITCHING
I DISCRETE INPUTSOURCE(SEE TABLE 3)
Flight Data Recorder System SchematicFigure 2 (Sheet 2)
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 (d)  
Manual power switching is accomplished with the ON-NORM-TEST switch on the flight recorder control panel. During normal operation, the switch is set to NORM and power is controlled by the automatic switching network. When the switch is set to either ON or to the momentary TEST position, power is supplied to the system.

 (e)  
The OFF light on the flight recorder control panel is a status indicator. It is controlled by the status relay within the control panel. When the flight recorder system is powered and no faults exist, the status relay is energized and the OFF light is off. 28v dc from the DFDR system status output and a ground from the DFDAMU BITE output energizes the relay. If power is interrupted or if a system fault occurs, the network opens, the status relay de-energizes and the OFF light comes on.

 (2)  Parameter Inputs
 (a)  
The DFDAMU receives inputs from sensors and signals from other airplane systems. The inputs are grouped as analog, discrete, and ARINC 429 digital inputs.

 (b)  
Accelerometer 1) The accelerometer receives 28-volt dc power from the DFDAU. 2) The unit consists of three independent accelerometers, one

 for each axis. Each accelerometer operates as a closed loop servo system that is responsive to linear acceleration along its sensitive axis. An applied acceleration results in a force on a seismic pendulum which disturbs the servos capacitive balanced bridge. As a result of this imbalance, the servo applies current to a torquer coil to return the pendulum to its original position. A sensing resistor in series with the torquer coil, provides a voltage that is proportional to the acceleration input. The voltage is then amplified and output to the DFDAMU.

 (c)  
ARINC 429 DIT Inputs 1) The left and right engine EPR transmitters provide the EPR signals.

 2)  The left or right EICAS computer, via the EICAS select switch provides control surface signals. These signals are: a) Thrust Reverser In-Transit and Deployed b) Left and Right Aileron posiiton c) Left and Right Elevator Position d) Left and Right Rudder Position
　
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