S 865-102
 (35)
 Shutdown the APU (AMM 49-11-00/201).

 S 865-103

 (36)
 Remove the electrical power (AMM 24-22-00/201).

 S 415-104

 (37)
 Close the thrust reverser halves (AMM 78-31-00/201).

 S 415-105

 (38)
 Install these section 42 wing/body fairings (AMM 06-09-02/201):

 -191AJ
 -192AJ.
 S 415-106
 (39) Close (or install, as applicable) these section 44 access doors and panels (AMM 06-09-03/201):
 -191BL
 -191CL and 192CR
 -191EL
 -191JL
 -191KL and 192KR
 -191ML and 192MR
 -191NL and 192NR
 -192HR.
 S 415-107
 (40) Close these strut access panels (AMM 06-09-09/201):
 -452ER, 452FL, and 452GR
 -462FL and 462HL
 -472FL and 472HL
 -482ER, 482FL, and 482GR.
 S 415-109
 (41) Close the 315A access door (AMM 06-09-05/201).
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 36-11-00
 ALL  ú ú 03 Page 523 ú Feb 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 ENGINE BLEED AIR SUPPLY SYSTEM - INSPECTION/CHECK
_________________________________________________
 1.  General_______
 A.  This procedure contains these three tasks:
 -
Engine Bleed Air Supply System Leakage Check

 -
Engine Bleed, Wing Leading Edge and Body Crossover Duct Audible Leakage Check

 -
APU Pneumatic Duct Audible Leakage Check.

 B.  
The first task monitors the level of leakage in the engine bleed air supply system by pressure decay method with the use of airplane equipment only. The second task examines the engine bleed, wing leading edge and body crossover ducts for condition and leakage. The third procedure examines the APU pneumatic ducts for condition and leakage. The second and third tasks require access to the ducts for inspection and the use of ground air source to perform the leakage check.

 TASK 36-11-00-206-150
 2.  Engine Bleed Air Supply System Leakage Check____________________________________________
 A.  General
 (1)  
This procedure performs a bleed down leakage check of the engine bleed air supply system. This procedure is done with the use of the APU and no additional special equipment. The ducts and equipment located downstream of the high pressure shutoff valve (HPSOV) and the intermediate pressure (IP) check valve on the engine to the APU bleed air shutoff valve located in the wheel well are examined for excessive leakage. The pneumatic ducts between the APU bleed air shutoff valve and the APU are not checked for leakage.

 (2)  
This procedure is intended for use as a diagnostic health check of the engine bleed air supply system for in-service aircraft. It may be used at any interval as necessary to monitor the level of leakage in the engine bleed air supply system.

 (3)  
A recommended method for the use of this procedure is to do the leakage check procedure as follows:

 (a)  
Do the leakage check of the pneumatic manifold.

 (b)  
If the leakage in the pneumatic manifold is more than the recommended maximum leakage limit, do these steps in order: 1) Do the check of each engine for duct leakage.

 a)  If the leakage is not acceptable, locate and repair any leaks in the duct joint or component found on the engine. If there are no obvious leaks, listen for air leakages through the precooler. If there are any obvious air leakages through the precooler, replace the precooler and check for leakages again.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 36-11-00
 ALL  ú ú 02 Page 601 ú Feb 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
 B.
C.
D.
A
747-400 MAINTENANCE MANUAL
 2)  Examine the APU check valve for internal leakage problems. If there are obvious leaks through the APU check valve, replace the APU check valve (AMM 36-11-08/401).
 3)  Locate and repair any leaks that are found at the duct joints.
　
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