S 035-118

 (13)
 Remove the ICU altitude switch breakout box:

 (a)  Open these circuit breakers:
 1)  P6 Main Power Distribution Panel a) 6L6, CABIN PRESS MAN L b) 6L7, CABIN PRESS MAN R c) 6J28, CABIN PRESS AUTO A d) 6J29, CABIN PRESS AUTO B e) 6J30, CABIN PRESS ICU CONT L f) 6J31, CABIN PRESS ICU CONT R
 2)  P414 Left Power Distribution Center a) 414M8, CABIN PRESS ICU L b) 414B8, CABIN PRESS ICU R
 (b)  
Remove the ICU altitude switch breakout box from the ICU's and the connectors DM7950B and DM7951B.

 (c)  
Install connector DM7950B on the left ICU and DM7951B on the right ICU.

 F.  Put the Airplane Back to its Usual Condition
 S 865-119
 (1)  Close these circuit breakers:
 (a)  P6 Main Power Distribution Panel
 1) 6L6, CABIN PRESS MAN L
 2) 6L7, CABIN PRESS MAN R
 3) 6J28, CABIN PRESS AUTO A
 4) 6J29, CABIN PRESS AUTO B
 5) 6J30, CABIN PRESS ICU CONT L
 6) 6J31, CABIN PRESS ICU CONT R

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747-400 MAINTENANCE MANUAL
 (b)  P414 Left Power Distribution Center
 1) 414M8, CABIN PRESS ICU L
 2) 414B8, CABIN PRESS ICU R

 S 865-120
 (2)  Remove the electrical power, if it is not necessary (AMM 24-22-00/201).
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747-400 MAINTENANCE MANUAL
 PRESSURIZATION OUTFLOW VALVE - REMOVAL/INSTALLATION
___________________________________________________
 1.  General_______
 A.  There are two tasks in this procedure. There is one task for the removal and one task for the installation of the left and the right pressurization outflow valves. The procedure has these parts:
 (1)  
The removal of power to the valves

 (2)  
The removal of the access panel from the aft bulkhead of the bulk cargo compartment

 (3)  
The removal of the valve

 (4)  
The installation of the valve

 (5)  
A test of the valve.

 B.  For the replacement of the outflow valve actuator assembly (ac motor, dc motor and gear housing), refer to AMM 21-31-07/401. For the replacement of the ac motor, refer to AMM 21-31-06/401. For the replacement of the dc motor, refer to AMM 21-31-08/401.
 TASK 21-31-01-004-001
 2.  Pressurization Outflow Valve Removal (Fig. 401)____________________________________
 A.  Standard Tools and Equipment
 (1)  Knife, plastic (nonmetallic)
 B.  References
 (1)  AIPC 21-31-01, Fig. 2
ACCESS DOOR

Pressurization Outflow Valve Installation
Figure 401 (Sheet 1)

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747-400
MAINTENANCE MANUAL

3. DC MOTOR 
CONNECTOR 
DC MOTOR  4. AC MOTOR 
CONNECTOR 
2. SCREEN  AC MOTOR 
5. POTENTIOMETER 
CONNECTOR 
POSITION 
POTENTIOMETER 
SEE  B 
7. SCREW 
8. WASHER 
9. NUT 
1. OUTFLOW 
VALVE 
ASSEMBLY  6. BONDING JUMPER 
(2 LOCATIONS)  10. BOLT 
A  GEAR CASE  11. WASHER 
LAMINATED SHIM 
(2 LOCATIONS) 
BRACKET 

SEALANT 
　
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