(b)  
Wing leading edge ducts

 (c)  
Crossover manifold upstream of the air-conditioning pack flow control and shutoff valves (pack valves)

 (d)  
APU duct forward of the APU firewall.

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 36-11-00
 ALL  ú ú 02 Page 515 ú Jun 10/95
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 S 795-054
 (30) Do the flowmeter leakage check procedure or the pressure decay leakage check procedure.
 H. Flowmeter Leakage Check Procedure
 S 795-055
 (1)  
Measure the air flow that is necessary to keep the duct pressure between 44-46 psig.

 (a)  
Make sure that the airflow is less than 290 CFM at 45 psig and 70 F for new or refurbished airplanes.

 (b)  
If the airplane is not new or refurbished, then make sure that the airflow is less 390 CFM at 45 psig and 70 F.

 S 865-056
 (2)  
Let the pneumatic system pressure decrease to 0 psig.

 S 485-057

 (3)  
If the pneumatic system leakage is more than the permitted limit, it is possible that there is leakage through the pack valves:

 (a)  
Remove the pack valves (AMM 21-51-01/401).

 WARNING:_______MAKE SURE THE BLOCK-OFF PLATES ARE INSTALLED CORRECTLY. IF THE BLOCK-OFF PLATES ARE NOT CORRECTLY INSTALLED, THEY CAN CAUSE INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT.
 (b)  
Install the 2TE65B40004 block-off plates on the upstream flanges of the pack valve inlets.

 (c)  
Do the leakage test again.

 S 365-058
 (4)  Repair the leakage sources as necessary until the leakage is less than the permitted limit.
 S 865-082
 WARNING: MAKE SURE THAT PERSONS AND EQUIPMENT ARE CLEAR OF THE LE AND TE
_______ FLAPS AND FLAP DRIVE MECHANISMS BEFORE YOU MOVE THE FLAP CONTROL LEVER. WITH HYDRAULIC POWER REMOVED, THE FLAPS WILL MOVE AUTOMATICALLY BY ELECTRICAL POWER WHEN YOU MOVE THE FLAP CONTROL LEVER.
 (5)  Retract the leading edge flaps with the alternate
 extension/retraction system (AMM 27-81-00/201).

 I. Pressure Decay Leakage Check Procedure
 S 865-059
 (1)  Shut down the ground air source.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 36-11-00
 ALL  ú ú 02 Page 516 ú Jun 10/96
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 S 975-060
 (2)  Write the L or R MANIFOLD DUCT PRESSURE at 5 second time increments:
 ~................................... | Time (seconds) | Pressure | ..................................... | 0 | __________ | ..................................... | 5 | __________ | ..................................... | 10 | __________ | ..................................... | 15 | __________ | ..................................... | 20 | __________ | ..................................... | 25 | __________ | ..................................... | 30 | __________ | ..................................... | 35 | __________ | ..................................... | 40 | __________ | 2..................…................1
 S 975-061
 (3)  
Put the data points on the Bleed Air Duct Leakage Test Limits graph (Fig. 501). Compare the data points to the curves on Fig. 501.

 S 485-062

 (4)  
If the pneumatic system leakage is more than the permitted limit, it is possible that there is leakage through the pack valves:

 (a)  
Remove the pack valves (AMM 21-51-01/401).

 WARNING: MAKE SURE THE BLOCK-OFF PLATES ARE INSTALLED CORRECTLY.
_______ IF THE PLATES ARE NOT INSTALLED CORRECTLY, THEY CAN CAUSE INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT.
 (b)  
Install the 2TE65B40004 block-off plates on the upstream flanges of the pack valve inlets.

 (c)  
Do the leakage test again.

 S 365-063
 (5)  Repair the leakage sources as necessary until the leakage is less than the permitted limit.
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：747-400 AMM 飛機維護手冊 氣動系統(tǒng) PNEUMATIC SYSTEM(42)