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ú ú ú 01.101 ú BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. Page 209Sep 28/02
A 757 MAINTENANCE MANUAL
(e) Operate the outflow valve toward closed with the cabin altitude manual control.
NOTE:____ You must keep a differential pressure of approximately 2 psi to 3 psi applied to the E/E overboard valve. This is to make sure the E/E overboard valve stays fully closed during the test.
You can use the leakage data you get with the overboard exhaust valve closed. But, you can use it only if the overboard exhaust valve was fully closed during the full test. The E/E overboard valve can be closed with a wood or plastic rod similar to that found on a broom handle.
ú (f) (g) (h) (i) Turn the L and the R pack control selectors on the panel, P5, (for the operation of the air conditioning pack) to OFF. 1) Start the stop watch.Shutdown the APU if it was used (Ref 49-11-00).Stop the pneumatic service cart if it was used.In less than 300 seconds after the air conditioning pack is turned off, make a record of the data. Make five to ten data sets of each of the items that follow:
NOTE:____ Make sure the E/E overboard valve stayed closed. If the E/E overboard valve did not stay fully closed during the leakage test, the pressure/time data will not be correct. The E/E overboard valve can be closed with a wood or plastic rod similar to that found on a broom handle.
(j) 1) The time on the stop watch 2) The cabin differential pressure 3) The cabin temperature 4) The external ambient temperature and pressure.If the test is to be run again, do a 20 minute cool-down time. 1) Do this with the equipment cooling fan operating at zero differential pressure.
NOTE:____ This will make sure the fans will not overheat.
(k) Do a check of the areas that follow for too much leakage.
NOTE:____ This is when the airplane is pressurized with a differential pressure between 3 psi and 4 psi.
1) Make sure the binge drains found on the bottom centerline of the airplane are completely closed.
NOTE:____ The bilge drain valve closes at approximately 2.0 psid.
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ALL ú ú 01.1 Page 210 ú Sep 28/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757 MAINTENANCE MANUAL
2) Do a check of all door and hatch seals for leakage. 3) Do a check of the flight deck windows for leakage. 4) Do a check of the cabin pressure outflow valve seal for
leakage. 5) Do a check of the cabin safety relief valves for leakage. 6) Do a check of the cabin pressure negative relief valve
(2 each) seals for leakage. 7) Do a check or the water service panel seals for leakage. 8) Do a check of all air conditioning and APU duct seals at
the pressure bulkhead penetrations for leakage.
NOTE: These are found in the A/C bay and the aft pressure
____
dome.
9) Do a check of the structure in the forward and aft wheel wells for leakage. 10) Do a check of the control cable seals in the pressure bulkhead penetrations for too much leakage. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 AMM 飞机维护手册 时间限制/维护检查(41)
