EFFECTIVITY BEJ ALL 78-36-00
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D633W101-BEJ May 05/2003
T/R INDICATING AND FAULT DETECTION -INDICATIONS
EFFECTIVITY BEJ ALL 78-36-00
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D633W101-BEJ May 05/2003
T/R INDICATING AND FAULT DETECTION -FUNCTIONAL DESCRIPTION -EEC INPUTS
General
The electronic engine control (EEC) gets data from thrust reverser (T/R) sensors to make sure these conditions occur:
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The isolation valve sends pressure to the hydraulic actuators only during thrust reverser extend and retract operation
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The engine operates above idle thrust only when the thrust reverser is in the fully extended position
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The flight deck gets proper indication of normal and non-normal thrust reverser operation.
This data comes from the hydraulic pressure switch on the isolation valve and the rotary variable differential transducers (RVDT).
Hydraulic Pressure Switch
The hydraulic pressure switch signal goes to both channels of the EEC. The switch closes when the isolation valve is open. If the switch shows that the valve is open without an open command from the EEC, the EEC sends a signal to the AIMS to show advisory and status messages.
If the isolation valve does not open when it gets an EEC command to open, the EEC sends a signal to the AIMS for the central maintenance computing system (CMCS) maintenance messages.
Thrust Reverser Position Transducer (RVDT)
Each EEC channel gets data from the rotary variable differential transducer (RVDT) on each non-locking (upper) hydraulic actuator. The EEC uses this data to:
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Operate the thrust lever interlock actuator
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Send indication data to the AIMS
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Schedule reverse thrust.
When either T/R sleeve extension is 5 percent, the EEC sends a signal to the AIMS to show the amber REV indication on the EICAS display. This tells the flight crew that the T/R is released and in transit.
When the average of the sleeve extensions is 60 percent, the EEC sends a signal to the ELMS to operate the thrust lever interlock actuator. This removes the block that prevents the flight crew from commanding more than reverse idle thrust.
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