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BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.
MLG EXTENSION-RETRACTION -INTRODUCTION
Purpose
The MLG extension and retraction system extends and retracts the main landing gear and opens and closes the main landing gear doors.
The extension and retraction system also tilts the MLG truck forward wheels up when the gear is in the extended position in flight. It tilts the MLG truck forward wheels down during gear retraction.
Components
Each MLG has these extension and retraction components:
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MLG door-operated sequence valve
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MLG uplock assembly and actuator
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MLG retract actuator
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MLG drag brace-operated sequence valve
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MLG uplock-operated sequence valve
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MLG door priority/relief valve
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MLG door actuator
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MLG door uplock hook and door lock actuator
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MLG side brace downlock actuator
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MLG drag brace downlock actuator.
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MLG truck positioner actuator fuses
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MLG truck positioner actuator
General Description
The center hydraulic system supplies pressure through the autoslat priority valve and the MLG selector/bypass valve to operate the main landing gear. See the leading edge slats section for more information about the autoslat priority valve (SECTION 27-81).
The door-operated sequence valve controls hydraulic pressure to the MLG uplock actuator and the MLG retract actuator.
The MLG drag brace-operated sequence valve and the MLG uplock-operated sequence valve together control hydraulic pressure to these actuators:
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MLG door actuator
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MLG door lock actuator
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MLG side brace downlock actuator
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MLG drag brace downlock actuator.
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MLG truck positioner actuator
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777 AIRCRAFT MAINTENANCE MANUAL
MLG EXTENSION-RETRACTION -INTRODUCTION
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MLG EXTENSION-RETRACTION -GEAR COMPONENT LOCATIONS
General
These extension and retraction components are on each MLG:
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Side brace downlock actuator
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Retract actuator
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Drag brace downlock actuator
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Truck positioner actuator.
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MLG EXTENSION-RETRACTION -GEAR COMPONENT LOCATIONS
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MLG EXTENSION-RETRACTION -WHEEL WELL COMPONENT LOCATIONS
General
These components are in each main gear wheel well:
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MLG door priority/relief valve
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MLG door uplock hook and door lock actuator
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MLG drag brace-operated sequence valve
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MLG uplock-operated sequence valve
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MLG uplock assembly and actuator
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MLG door-operated sequence valve
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MLG door actuator.
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MLG EXTENSION-RETRACTION -WHEEL WELL COMPONENT LOCATIONS
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MLG EXTENSION-RETRACTION -MLG RETRACT ACTUATOR
Purpose The MLG retract actuator supplies the force to retract the main landing gear. Physical Description The retract actuator is a hydraulic piston-type actuator. The actuator retracts to raise the gear and extends when the gear extends. The actuator is not pressurized during gear extension. Training Information Point A removable wing panel permits access to the head end of the actuator from above.
A flow restrictor in the retract port union controls the gear extension rate.
Snubbers on the rod end and the head end of the actuator control actuator speed at the ends of the actuator stroke.
The dry weight of the retract actuator is approximately 240 pounds (109 kilograms). Location The retract actuator is inboard of the main landing gear shock strut. The rod end attaches to the inboard side of the shock strut. The head end attaches to the retract fitting mounted on the trunnion. Two reaction links connect the retract fitting to the wing rear spar.
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MLG EXTENSION-RETRACTION -MLG RETRACT ACTUATOR
EFFECTIVITY BEJ ALL 32-32-00 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：777 AMM 飞机维护手册 起落架 Landing Gear(15)
