S 864-032
 (4)
Release the pressure in the pneumatic system (AMM 36-00-00/201).

 G.
Put the Airplane Back to Its Usual Condition

 S 414-019
 (1)  For the applicable engine, install the access panel 452DL (462DL, 472DL or 482DL) for the midlower forward strut (Ref 06-09-09/201).
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 36-12-02
 ALL  ú ú 01P Page 407 ú Oct 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 FAN AIR MODULATING VALVE - MAINTENANCE PRACTICES
________________________________________________
 1.  General_______
 A.  This procedure contains two tasks. The first task deactivates the fan air modulating valve. The second task activates the fan air modulating valve.
 B.  The fan air modulating valve is installed on the right side of the precooler. It is necessary to open the right half of the thrust reverser to get access to the valve.
 C.  The valve is spring-loaded open. It has a locking crank which permits manual operation of the valve. To deactivate the valve, you must remove the positioning screw. This releases the actuator servo pressure and locks the valve in the 45° position.
 TASK 36-12-04-042-012
 2.  Deactivate the Fan Air Modulating Valve (Fig. 201)_______________________________________
 A.  References
 (1)  
71-11-04/201, Fan Cowl Panels

 (2)  
71-11-06/201, Core Cowl Panels

 (3)  
78-31-00/201, Thrust Reverser System

 B.  
Access

 (1)  
Location Zone 412 Engine 1 - High Pressure Compressor Case 12:00 422 Engine 2 - High Pressure Compressor Case 12:00 432 Engine 3 - High Pressure Compressor Case 12:00 442 Engine 4 - High Pressure Compressor Case 12:00

 (2)  
Access Panel
 416 Right Thrust Reverser Half - Engine 1
 426 Right Thrust Reverser Half - Engine 2
 436 Right Thrust Reverser Half - Engine 3
 446 Right Thrust Reverser Half - Engine 4

 C.  
Prepare to Deactivate the Fan Air Modulating Valve

 S 042-032
 WARNING: DO THE DEACTIVATION PROCEDURE FOR THE THRUST REVERSER TO
_______ PREVENT THE OPERATION OF THE THRUST REVERSER. ACCIDENTAL OPERATION OF THE THRUST REVERSER CAN CAUSE INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT.
 (1)  Do the deactivation procedure for the thrust reverser for ground maintenance (Ref 78-31-00/201).
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 36-12-04
 ALL  ú ú 01P Page 201 ú Jun 10/92
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 
747-400 
MAINTENANCE MANUAL 
SEE A 
FAN AIR 
MODULATING 
VALVE 
FLOW 
3  2  1 
SWITCH  RETAINING 
BRACKET  CABLE 
SEE  B 
TERMINAL 
CLOSE  BLOCK 
AFT VIEW 
A 
POSITIONING SCREW 
OPEN  O-RING 
LOCKING 
CRANK 
B 
Fan Air Modulating Valve Deactivation 
Figure 201 

EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 36-12-04
 ALL  ú ú 01P Page 202 ú Jun 10/88
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 012-014
 (2)  
Open the right fan cowl panel (71-11-04/201).

 S 012-015

 (3)  
Open the right core cowl panel (Ref 71-11-06/201).

 S 012-016
 WARNING:  OBEY THE INSTRUCTIONS IN THE PROCEDURE TO OPEN THE THRUST
_______ REVERSERS. IF YOU DO NOT OBEY THE INSTRUCTIONS WHEN YOU OPEN THE THRUST REVERSER, INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR.
　
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