777 AIRCRAFT MAINTENANCE MANUAL
MAIN LANDING GEAR AND DOORS -MLG DOORS
EFFECTIVITY BEJ ALL 32-10-00
Page 11
D633W101-BEJ Jan 05/2002
777 AIRCRAFT MAINTENANCE MANUAL
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32-20-00
Page 1 D633W101-BEJ Jan 05/2002
NOSE LANDING GEAR AND DOORS -INTRODUCTION
General
The nose landing gear absorbs landing forces and holds the forward part of the airplane weight when the airplane is on the ground. The nose gear also steers the airplane on the ground.
The nose landing gear doors open to permit gear operation and close to aerodynamically seal the NLG wheel well.
Nose Landing Gear
The nose landing gear is a conventional two wheel gear. A drag strut assembly holds the nose gear in the extended or retracted position. A lock link assembly moves to the over-center position to lock the drag strut in either position.
These are the nose landing gear components:
*
NLG drag strut assembly
*
NLG lock link assembly
*
NLG torsion links
*
NLG shock strut.
Nose Landing Gear Doors
Two forward and two aft doors aerodynamically seal the nose gear wheel well to reduce drag.
The forward doors attach to the outer edge of the NLG wheel well. A hydraulic actuator opens and closes the forward doors.
The aft doors attach to the outer edge of the wheel well. They connect to the shock strut and move mechanically with the gear during extension and retraction.
Training Information Point
There is a tow fitting forward of the shock strut between the nose landing gear tires.
There is also a tow fitting aft of the shock strut between the nose landing gear tires (not shown).
You can disconnect the torsion links to permit the nose landing gear to move greater than the normal steering limits (70 degrees).
The nose landing gear doors are made of composite materials.
You use the alternate extension system to operate the forward NLG doors on the ground.
See the alternate extension system section for more information on the NLG door operation (SECTION 32-35).
Nose wheel well baffles on the left and right sides of the wheel well decreases landing gear door vibrations during gear operation.
EFFECTIVITY BEJ ALL 32-20-00
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D633W101-BEJ Sep 05/2002
NOSE LANDING GEAR AND DOORS -INTRODUCTION
EFFECTIVITY BEJ ALL 32-20-00
Page 3
D633W101-BEJ Jan 05/2002
NOSE LANDING GEAR AND DOORS -SHOCK STRUT
Purpose
The nose landing gear shock strut absorbs airplane landing forces and transmits vertical loads to the airplane structure.
Physical Description
The nose landing gear shock strut is a standard forged steel air-oil shock strut. It has an inner and an outer cylinder.
Compressed dry nitrogen is in the upper part of the shock strut. BMS3-32 hydraulic fluid is in the lower part of the shock strut.
Torsion links on the aft part of the shock strut connect the inner and outer cylinders.
Centering cams inside the shock strut center the nose wheels when the shock strut extends.
Shock Strut Seals
A static seal and a dynamic seal keep the nitrogen and the hydraulic fluid in the shock strut. The static seal is between the lower bearing and the outer cylinder. The dynamic seal is between the lower bearing and the inner cylinder.
There are two spare static seals, one spare dynamic seal, and backup rings for the spare dynamic seal in the shock strut. The spare seals permit change of faulty seals without removal of the inner cylinder.
Training Information Point
The dynamic seal is not the same as the spare dynamic seal. The spare dynamic seal is more flexible. This permits installation of the spare dynamic seal on to the larger diameter of the spare seal carrier.
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