747-400 AMM 飞机维护手册 EXHAUST 2(61)

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 (3)  Thrust Reverser Stowing
 (a)  
Retraction operates in basically the same manner as extension. Differences are as follows: when the reverse thrust lever is returned to idle, the control switch for the thrust reverser opens to break the circuit. The auto restow circuit maintains power to the isolation valve which was energized when the translating sleeve began its movement aft. A five second delay keeps isolation valve energized after the sleeve is fully stowed, to ensure the center actuator is able to lock.

 (b)  
When the thrust reverser control switch in the thrust lever is moved to the off position it opens the electrical circuit to the deploy relay. The deploy relay de-energizes and opens the circuit to the sync locks. This causes the sync lock solenoid to de-energize and lock.

 (c)  
The proximity sensor for the auto restow, mounted on the aft torque box below the center actuator, sends a signal "target far" to the proximity cards in the proximity switches electronic unit (PSEU) any time the translating sleeve is not stowed.

 (d)  
The target far (logic 1) or target near (logic 0) from the proximity sensors for the auto restow of the left hand or right hand thrust reverser are directed to an OR gate in the PSEU logic card. Input of logic 1 from either proximity sensor results in a logic 1 output which after a 5 second time delay causes the PSEU driver card to ground the T/R STOW relay circuit. The T/R STOW relay (R7311, R7312, R7313, R7314) energizes and completes on electrical circuit which maintains hydraulic power to the isolation valve.

 (e)  
Returning the reverse thrust lever to idle also opens the circuit for the directional control valve which de-energizes the DCV solenoid. The DCV is spring biased to the stow position which directs hydraulic power to the actuator rod-ends and connects actuator head ends to return. This causes the actuators to retract at a rapid rate.

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 78-34-00
 ALL  ú ú N01 Page 17 ú Feb 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
THRUST REVERSER DIRECTIONAL CONTROL VALVE - REMOVAL/INSTALLATION
________________________________________________________________
 1.  General
_______
 A.  The removal and installation of the directional control valve is necessary if it has malfunctions or hydraulic leaks.
 B.  The Directional Control Valve for the thrust reverser shall be referred to as the DCV for this procedure.
 C.  This procedure has two tasks. The first removes the DCV. The second task gives instructions to install the DCV.
 D.  You can get access to the DCV through the forward fairing panels.
 TASK 78-34-01-004-029-N00
 2.  Remove the Directional Control Valve (DCV)
__________________________________________
 A.  References
 (1)  
AMM 27-62-00/501, Spoiler/Speedbrake Control System

 (2)  
AMM 78-31-00/201, Thrust Reverser System

 (3)  
AMM 78-34-02/401, Thrust Reverser Flow Control Tee

 (4)  
IPC 78-34-01 Fig. 1

 B.  
Access

 (1)  
Location Zone
 450 Strut - Engine 1
 460 Strut - Engine 2
 470 Strut - Engine 3
 480 Strut - Engine 4

 (2)  
Access Panel 451A and 451B #2 and #3 Forward Fairing, Engine 1 461A and 461B #2 and #3 Forward Fairing, Engine 2 471A and 471B #2 and #3 Forward Fairing, Engine 3 481A and 481B #2 and #3 Forward Fairing, Engine 4

 C.  
Prepare to Remove the DCV.

 S 044-014-N00
 WARNING: DO THE DEACTIVATION PROCEDURE FOR THE SPEED BRAKE CONTROL
_______ SYSTEM. IF YOU DO NOT DO THIS, THE SPOILERS CAN MOVE QUICKLY WHEN YOU MOVE THE THRUST LEVERS. THIS CAN CAUSE INJURY TO PERSONS AND DAMAGE TO EQUIPMENT.
 (1)  
Do the deactivation procedure for the Speed Brake Control System (AMM 27-62-00/201).

 S 864-015-N00

 (2)
Make sure the forward thrust levers are in the idle position.

 (a) Install the DO-NOT-OPERATE tag to the thrust levers.
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 78-34-01
　
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