36-11-04
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A
747-400 MAINTENANCE MANUAL
 S 864-032
 (23)
 Release the pressure in the pneumatic system if it is not necessary for other operations (AMM 36-00-00/201).

 S 864-033

 (24)
 Remove electrical power if it is not necessary for other operations (AMM 24-22-00/201).

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 36-11-04
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747-400 MAINTENANCE MANUAL
 HIGH PRESSURE SHUTOFF VALVE (HPSOV) - MAINTENANCE PRACTICES
___________________________________________________________
 1.  General_______
 A.  There are two tasks in this procedure:
 -
The HPSOV deactivation

 -
The HPSOV activation.

 B.  
The HPSOV is installed near the high pressure compressor (HPC) case in the 9:00 o'clock position. To deactivate the HPSOV, it is necessary to remove the positioning screw from the valve actuator to release the actuator pressure. The positioning screw is then installed in the switch actuating lever to lock the valve in the CLOSED position.

 C.  
It is necessary to open the left thrust reverser half to get access to the HPSOV.

 TASK 36-11-05-042-013
 2.  The HPSOV Deactivation (Fig. 201)______________________
 A.  References
 (1)
36-00-00/201, Pneumatic System

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

 (3)
IPC 36-11-05 Fig. 1

 B.  
Access

 (1)  
Location Zone
 412 Engine 1 - HPC Case 9 o'clock
 422 Engine 2 - HPC Case 9 o'clock
 432 Engine 3 - HPC Case 9 o'clock
 442 Engine 4 - HPC Case 9 o'clock

 (2)  
Access Panel
 415 Left Thrust Reverser Half - Engine 1
 425 Left Thrust Reverser Half - Engine 2
 435 Left Thrust Reverser Half - Engine 3
 445 Left Thrust Reverser Half - Engine 4

 C.  
Procedure

 (1)
Release the pressure in the pneumatic system (Ref 36-00-00/201).

 (2)
Open the left thrust reverser half (Ref 78-31-00/201).

 (3)
Remove the positioning screw from the actuator cap.

 S 862-002
 S 012-003
 S 042-004
 NOTE: The retaining cable should remain on the positioning screw.
____
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 36-11-05
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747-400
MAINTENANCE MANUAL

SEE  A  BLOCK TERMINAL 
1  2  3 
MANUAL OVERRIDE DRIVE 

PRESSURE REGULATING VALVE (REF)  B SWITCH ACTUATING LEVER 
FWD 
SEE  B 

POSITIONING SCREW
ACTUATOR 
CAP  HIGH PRESSURE 
A  SHUTOFF VALVE 
(HPSOV) 

High Pressure Shutoff Valve Deactivation
Figure 201

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 36-11-05
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747-400
MAINTENANCE MANUAL

 S 042-005
 (4) Install the positioning screw in the switch actuating lever .
 NOTE: This will lock the HPSOV in the CLOSED position.
____
 S 412-006
 (5) Close the left thrust reverser half (Ref 78-31-00/201).
 TASK 36-11-05-442-014
 3. The HPSOV Activation (Fig. 201)
____________________
 A. References
 (1)  
36-00-00/201, Pneumatic System
　
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