(3)  
Access Panel ~........................................ | 191AL | Air Conditioning Access Door | .......................................... | 192AR | Air Conditioning Access Door | .......................................... | 191BL | Air Conditioning Access Panel | .......................................... | 192BR | Air Conditioning Access Panel | .......................................... | 191EL | Air Conditioning Access Panel | .......................................... | 192ER | Air Conditioning Access Panel | .......................................... | 191FL | Air Conditioning Access Panel | .......................................... | 192FR | Air Conditioning Access Panel | .......................................... | 191HL | Air Conditioning Access Door | .......................................... | 192HR | Air Conditioning Access Door | .......................................... | 191LL | Air Conditioning Access Panel | .......................................... | 192LR | Air Conditioning Access Panel | .......................................... | 191ML | Air Conditioning Access Panel | .......................................... | 192MR | Air Conditioning Access Panel | .......................................... | 191NL | Air Conditioning Access Door | .......................................... | 192NR | Air Conditioning Access Door | 2........…...............................1

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 ALL  ú ú 01 Page 601 ú Oct 10/96
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 B. Procedure
 S 866-001
 (1)  
Make sure the three PACKS switches on the overhead panel, P5, are in the OFF position.

 S 016-002

 (2)  
Open all of the access doors and panels for the air conditioning equipment bay (Ref 06-09-03/201).

 S 216-004

 (3)  
Do the steps that follow to do an inspection of the air conditioning equipment bay:

 (a)
Examine these components for the conditions which follow:

 -
the air cycle machines

 -
the heat exchangers

 -
the water separaters

 -
the bypass valves

 -
the compressor check valves

 -
the flow control and shutoff valves

 -
the ducts 1) Cracks or corrosion on the external side of the component. 2) Cracks, corrosion or dents on the ducts. 3) Support clamps that are loose or damaged. 4) Duct couplings that are loose.

 (b)  
Make sure all the electrical connectors are connected correctly.

 (c)  
Make sure the lockwire on the temperature sensors is not damaged.

 (d)  
Make sure the lockwire on the overheat switches is not damaged.

 (e)  
Do an inspection of the drain hose for the water separator.

 NOTE: Make sure there are no cracks or distortion.
____
 S 866-005
 (4)  Operate all three air conditioning packs (Ref 21-00-00/201).
 S 796-006
 WARNING: THE DUCTS ARE VERY HOT.  IF YOU TOUCH
_______DO NOT TOUCH THE DUCTS.
THE DUCTS YOU CAN GET BURNED.

 (5)  
Do a check for air leakage at all duct joints.

 S 796-010

 (6)
Do a check for air leakage at all temperature sensors and switches.

 (a)  Small air leaks are permitted.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 21-51-00
 ALL  ú ú 01 Page 602 ú Oct 10/96
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 747-400 MAINTENANCE MANUAL
 (b)  Large air leaks are not permitted. 1) If you find a large air leak, adjust the duct joint or the clamp.
 NOTE:____ If the leak continues, replace the packing/o-rings.
 (7)  S 866-007Shut off the air conditioning packs (Ref 21-00-00/201).
 (8)  S 416-008Close all of the access doors and panels to the air conditioning equipment bay.

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