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时间:2011-04-01 19:20来源:蓝天飞行翻译 作者:航空
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 G.  A flap load limiter system is provided to automatically retract the trailing edge flaps to prevent excessive airloads on the flaps. The system operates between 30 and 40 units of flap extension as indicated by air pressure from pitot static system. When airspeed increases to the point where airloads are excessive, air pressure activates switches or a computer which sends a signal to the ARINC 429 receiver which provides electrical power to actuate a hydraulic valve to retract flaps from 40 to 30 units and back to 40 units when airspeed is reduced. On airplanes with flap load relief light, the flap load relief light comes on when the flap load limiter system is operating.
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 27-51-00
 ALL  ú ú 04 Page 29 ú Mar 15/90
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
 TRAILING EDGE FLAP SYSTEM - TROUBLE SHOOTING
____________________________________________
 1. General
_______
 A. Flap Drive System Stalling/Lockout In-Flight Problems
 (1)  
In order to minimize occurrence of flap drive system stalling or lockouts in service, proper maintenance procedures, proper flap operating procedures, and system pilot reporting procedures are required. Flap components should be kept as clean as possible and lubricated at regular intevals to minimize friction. Drive system loads are greatly increased by excessive airspeed since loads vary as the velocity squared and overplacard speeds will always cause lockout. Therefore, flaps should be operated at speeds recommended in the 737 Pilots' Training Manual. Pilots reporting a flap drive lockout should record the following information to assist trouble shooting: (1) airpseed, (2) extension or retraction, (3) flap setting, (4) whether flaps can be positioned electrically, (5) whether flaps can be reversed hydraulically, and (6) note any lateral trim change during lockout.

 (2)  
Some component failures and jamming can increase drivescrew load but require multiple failure to increase loads into the lockout range. Other components are especially effective in causing lockout due to system geometry and transmission torque brake settings. The following items can cause lockout when acting alone (i.e., no other components failed or jammed):

 (a)  
Power unit gearbox, angle gearbox, or right angle gearbox jam

 (b)  
Flap drive transmission jam

 (c)  
Flap drive ball nut failure

 (d)  
Structural failure and/or interference

 (e)  
Nos. 2, 3, 4, 5, 6 or 7 midflap carriage aft or forward flight roller jam

 (f)  
Transmission output bearing jam at any location

 (g)  
Torque brake improperly set

 (h)  
Asymmetry shutoff due to drive system shearout or misrig of asymmetry system


 NOTE: Flap jackscrews and carriages are identified from left
____ to right across the wing. For example, flap jackscrew No. 1 is outboard screw of left outboard flap.
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 27-51-00
 ALL  ú ú 01 Page 101 ú Jun 25/84
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
 (3)  
The flap drive system is most susceptible to lockouts in the flaps 30 to 40 range where the highest airloads exist. If the lockout occurs in the flaps 0 to 25 range structural interference, drive gearing failure, jammed transmissions, foreign object damage or hydraulic system failure are the most probable causes. If a lockout occurs, proceed to check the airplane according to the trouble shooting chart under the trouble headings, "Flaps will not extend hydraulically or electrically in flaps 0 to 25 range inflight," and "Flaps will not extend hydraulically or electrically in flaps 25 to 40 range inflight."

 (4)  
The items are listed in the trouble shooting chart in descending order of effectiveness for causing lockout but also weighted in order of probability of occurrence. If airpline experience shows that a particular item is chronic problem, that item should be checked first.

 (5)  
If the flaps fail to extend hydraulically but will extend at the same airpseed electrically, the hydraulic system should be checked.
 
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