EFFECTIVITY BEJ ALL 78-36-00
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D633W101-BEJ May 05/2003
T/R INDICATING AND FAULT DETECTION -SYNC LOCK PROXIMITY SENSOR
EFFECTIVITY BEJ ALL 78-36-00
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D633W101-BEJ Sep 05/2002
PW4000 SERIES ENGINES
777 AIRCRAFT MAINTENANCE MANUAL
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78-36-00
Page 14 D633W101-BEJ May 05/2003
T/R INDICATING AND FAULT DETECTION -T/R POSITION TRANSDUCER (RVDT)
General
The thrust reverser position transducer is the rotary variable differential transducer (RVDT). The RVDT sends the thrust reverser sleeve position data to the electronic engine control (EEC). The EEC will not permit more than idle thrust if the sleeves are less than 60 percent of full extension. The EEC also uses the position data to supply flight deck indication of when the sleeve is not in the fully retracted position, when the sleeve is fully extended, for fault detection and to determine the interlock relay command for the reverse thrust lever interlock actuator.
There is one RVDT on the upper, non-locking hydraulic actuator of each sleeve. Thus, each engine has two RVDTs.
Location
The RVDT is installed on the upper sync shaft flange on each non-locking actuator. You open the fan cowl panels to get access to the RVDTs.
Physical Description
The RVDT has two parts; the transducer and the gearbox. The RVDT is replaced as one unit. The RVDT weighs approximately
2.4 pounds (1.08 kg). The RVDT gearbox is a sealed housing that is installed on the upper hydraulic actuator. The RVDT gearbox in operation is filled with hydraulic fluid. When the RVDT is replaced, the packing between the backup rings on the gearbox must be replaced. The gearbox has a square drive shaft that engages the worm shaft in the non-locking actuator. Internal seals on the gearbox shaft prevents hydraulic fluid contamination of the transducer. The transducer has an electrical connector.
Functional Description
Each RVDT has two sets of coils for channel A and B. The EEC gives an excitation voltage to each channel and receives an output analog signal from the RVDT for that channel.
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