(2)
Ground Lock Assemblies (Ref 32-00-01)
B. Prepare for Adjustment
(1)
Jack airplane for gear retraction (Ref Chapter 7, Jacking Airplane).
(2)
Ensure electrical power is available.
(3)
Connect external hydraulic test bench.
(4)
Pressurize hydraulic system B (Ref 29-12-0 MP).
(5)
Remove ground lock assemblies (Ref 32-00-01) from landing gear being repaired.
C. Adjust Main Gear Wing Door
(1)
Operate test bench and regulate hydraulic pressure and flow to slowly retract gear.
(2)
Move landing gear control lever to UP position and retract gear.
(3)
Move landing gear control lever to OFF position.
(4)
Apply a preload of 50 to 100 pounds at center of inboard edge of door.
NOTE: Apply preload using 1.00-inch wide minimum loading clips. Keep preload to a minimum value, if possible. The loading clip is a customer fabricated clip made from 0.06 inch thick by 1.0 inch wide (minimum) material capable of transferring loads of approximately 110 pounds.
(a)
Ensure preload breaks contact between stops and door.
(b)
Ensure gap at preload does not exceed 0.10 inch.
(5)
Check fair of wing door with preload applied. The wing door must fair with wing profile within + 0.10 inch of wing profile.
NOTE: Landing gear control lever must be in OFF position each time fair is checked to ensure proper results.
(6)
If wing door does not fair with wing profile, extend gear and adjust actuating rod assembly to obtain proper fair.
NOTE: Change in adjustment of wing door may affect adjustment of shock strut doors. Refer to 32-13-11 to check adjustment of shock strut doors.
(7)
Repeat steps (2) thru (4) until tolerances are met.
NOTE: If finer adjustment is required, shims may be added between special bolt head and stabilizing beam. Equal thickness of shim must be installed under each bolt head.
D. Restore Airplane to Normal
(1)
Determine whether there is further need for electrical and hydraulic power on airplane; if not, shut down sources.
(2)
Lower airplane and remove jacks.
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NOSE GEAR - DESCRIPTION AND OPERATION
1. General
A. The nose gear supports the forward end of the fuselage and provides directional control while the airplane is on the ground. (See figure 1.) It includes a drag brace, shock strut, and torsion links, and is hydraulically actuated to retract forward and up into a wheel well recessed into the lower nose section of the airplane. The shock strut consists of inner and outer cylinders. The upper part of the outer cylinder is "Y" shaped with arms extending to the sidewalls of the wheel well. Trunnion pins connect the gear to airplane structure. The "Y' arms and pins provide lateral stability. The gear rotates about the trunnion pins during extension and retraction. Refer to 32-33-0 for information on nose gear extension and retraction. Shocks and bumps during taxi, takeoff, and landing are absorbed by the shock strut which contains oil and is charged with compressed air or nitrogen. Longitudinal stability is provided by a hinged drag brace which folds upward and aft during gear retraction. (See figure 3.) For steering, the shock strut inner cylinder turns within the out cylinder. Torsion links connected at their upper end to a steering collar and at their lower end to the shock strut inner cylinder transmit a turning moment supplied by hydraulically actuated steering cylinders.
2. Nose Gear Shock Strut
A. The nose gear shock strut is the main supporting member of the nose gear. The shock strut includes an inner cylinder and an outer cylinder, metering pin assembly, upper and lower orifice assemblies, and upper and lower cam assemblies (See figure 2.) The shock strut is attached to the nose wheel well structure by trunnions which are a part of the outer cylinder. Pins are inserted through the trunnion ends into bearings attached to the wheel well structure. A steering collar clamped around the outer cylinder is connected to the upper torsion link and the upper torsion link is connected to the lower torsion link by an apex pin.
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Nov 15/66 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 32-21-0 Page 1
B. The inner cylinder and nose wheel axles are machined from a single forging. The fixed centering cam attached to the top of the inner cylinder mates with a similar cam in the outer cylinder when the inner cylinder extends. As these cams engage the nose wheels will attain a straight forward position to ensure proper fit in the wheel well on retraction. This also ensures the nose wheels to be straight forward when landing. Upper and lower bearings provide sliding surfaces for movement of the inner cylinder in and out the outer cylinder. Annular grooves in the lower bearing provide space for the storage of two sets of spare O-ring seals. These spare seals are replacements for like seals installed between the inner cylinder and the lower centering cam, and between the lower centering cam and the outer cylinder.
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