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A

747-400 MAINTENANCE MANUAL
RAM AIR HEADER DUCT
COOLING AIR CHECK VALVE
RAM AIR DUCT
RAM AIR HEADER DUCT

(EXAMPLE) B
BOLT, NUT AND WASHER (16 LOCATIONS)
AIR CYCLE MACHINE
RAM AIR HEADER DUCT (EXAMPLE)
C
Ram Air Header Duct Installation Figure 401 (Sheet 2)
HEAT EXCHANGER
RAM AIR EXHAUST LOUVERSRAM AIR HEADER DUCT
WATER ASPIRATOR
FLEXIBLE SLEEVE
CLAMP
FAN DIFFUSER AND INLET HOUSING
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 B.
C.
D.
A
747-400 MAINTENANCE MANUAL
 (2)  
AMM 06-09-03/201, Body Section 44 Access Doors and Panels

 (3)  
AMM 21-00-00/201, Air Conditioning

 (4)  
AMM 21-51-03/401, Heat Exchanger

 (5)
AMM 21-51-11/401, Water AspiratorAccess

 (1)  
Location Zone 133 Air Conditioning Equipment Bay, LH 134 Air Conditioning Equipment Bay, RH

 (2)  
Access Panel 191E-L Air Conditioning Access Panel 191M-L Air Conditioning Access Panel 192E-R Air Conditioning Access Panel

Procedure
 S 424-031
 (1)  
Move the ram air header up and forward to its position in the air cooling pack.

 S 424-051

 (2)  
Connect the header duct to the fan diffuser and inlet housing (fan housing) of the air cycle machine.

 (a)  
Move the header duct in the flexible sleeve.

 (b)  
Install the clamp that holds the header duct to the fan diffuser and inlet housing.

 (c)  
Tighten the clamp nut to 45 pound-inches (5.08 newton-meters).

 S 424-052
 (3)  
Install the bolts, washers, and nuts (16 locations) that connect the header duct to the check valve.

 S 424-049

 (4)  
Install the heat exchanger (AMM 21-51-03/401).

 S 424-056

 (5)  
Connect the water aspirator fitting to the heat exchanger and the

 header duct (1 tube and 1 hose) (AMM 21-51-11/401).Do the Installation Test for the Ram Air Header Duct
 S 864-040
 (1)  
Remove the DO-NOT-OPERATE tag from the applicable PACK selector, on the P5 panel.

 (2)  
Operate the applicable air conditioning pack (AMM 21-00-00/201).

 S 864-041
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747-400 MAINTENANCE MANUAL
 S 794-042
 (3) Feel for leaks around the joints of the ram air header duct.
 (a)  If there is air leakage, adjust the connections between the header duct and the other parts.
 E. Put the airplane to its usual condition
 S 864-043
 (1)  
Do the procedure to stop the applicable air conditioning pack (AMM 21-00-00/201).

 S 414-045

 (2)  
Close the applicable access door, 191E-L, 191M-L, 192E-R (AMM 06-09-03/201).

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