FWD 
SEE  C 
B 

FWD  FAN COOLING  (2 LOCATIONS) AC GENERATOR 
C 
Figure 1 (Sheet 2) APU Cooling Air System Components 

L77528
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A
747-400 FAULT ISOLATION/MAINT MANUAL
APU COOLING AIR SYSTEM
COMPONENT  102 SHT FIG.  QTY  ACCESS/AREA  AMM REFERENCE 
FAN - COOLING SCREEN - COOLING AIR INLET  1 2  1 1  317AL, 318AR/310 (APU COMPARTMENT) 317AL, 318AR/310 (APU COMPARTMENT)  49-51-02 49-51-04 

APU Cooling Air System - Component Index
Figure 101

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A

747-400 FAULT ISOLATION/MAINT MANUAL
SEE A
SEE B
FWD
APU COMPARTMENT
COOLING AIR INLET SCREEN
COOLING FAN
FWD
A

APU Cooling Air System - Component Location
Figure 102 (Sheet 1)

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L78078
A
747-400 FAULT ISOLATION/MAINT MANUAL
FWD 
SEE  C 
B 

FWD  AC GENERATOR 
COOLING  (2 LOCATIONS) 
FAN 

C
APU Cooling Air System - Component Location
Figure 102 (Sheet 2)

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A
747-400 MAINTENANCE MANUAL
 COOLING FAN - REMOVAL/INSTALLATION
__________________________________
 1.  General_______
 A.  This procedure has these tasks:
 (1)  
A removal of the cooling fan

 (2)  
An installation of the cooling fan.

 B.  
The cooling fan supplies cooled air for the two APU ac generators, air-cooled oil cooler and the APU compartment. The cooling fan is installed on the load gearbox and above the two APU ac generators.

 TASK 49-51-02-004-001
 2.  Cooling Fan Removal (Fig. 401)___________________
 A.  References
 (1)  
AMM 49-11-01/401, Auxiliary Power Unit

 (2)  
AMM 49-51-04/401, Cooling Air Inlet Screen

 B.  
Access

 (1)  
Location Zones
 221 Control Cabin - Left
 222 Control Cabin - Right
 310 Fuselage - Station 2360 to Station 2792

 (2)  
Access Panels
 317AL APU Access Door - Left
 318AR APU Access Door - Right

 C.  
Prepare for the Removal

 S 864-054
 (1)  
Make sure the APU control switch on the P5 overhead panel is OFF and attach a DO-NOT-OPERATE tag.

 S 864-055

 (2)  
Open these circuit breakers and attach DO-NOT-CLOSE tags:

 (a)  
P6-2 Main Power Distribution Panel
 1) 6K18, APU ALTN CONT

 (b)  
P83 Aft APU Equipment Control and Circuit Breaker Panel 1) APU PRIME CONT

　
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