VG-21 Squadron




General Notes

For the main gears there should be no fuel in the side being reworked and only one side should be reworked at a time.

Material required:
Strut Seal P/N 1859, Strut Cap 0-Rings MS28775-116, 221 Hydraulic oil MIL-H-5606
Gear Lube, SAE #90 or Chain Saw Bar Oil, Automotive silicone sealant

Ref. Varga MM Sections 2.10.l and 6.5.1 thru 6.6.1. as required. Torque hardware per section 2.8 of the MM.

Position Aircraft for Seal Replacement
Elevate nose gear and place cinder block under nose wheel.
Jacking under main gear axle, elevate aircraft and place cinder blocks under each main wheel.

Install wheel chocks.

Remove Gear Inner Strut (Ref. Fig 6.4)


Remove “DOT” plug on wing upper surface and loosen 7/16 strut bolt at center of gear outer strut 6 turns.

Note: This is a critical step. Make sure the 5/8 socket makes 100% contact. An impact wrench is suggested.

Raise wing high enough to remove inner strut, (24 inches between floor and bottom of outer cylinder), and support aircraft per MM 2.10.2

Note: A length of water piper inserted into the axle is helpful at this point

Remove bolts attaching brake caliper to gear. Remove axle nut and remove wheel.

Remove hardware attaching torque link to inner strut, and gear bushing seal clamp (28).
Use care not to bend clamp. Place support or jack under inner cylinder.

Unthread the 7/16 bolt at top of outer strut. Inner cylinder is now free to be
withdrawn from outer cylinder by removing jack or support.

Remove the 3 socket head cap screws (24) from upper plastic bushing and slide off the upper bushing (19) and end cap (23). Dump oil from inner cylinder.

Slip off the lower plastic bushing (3) and the worn seal (18). Clean and inspect all removed parts for reinstalling.

Install new seal, P/N 18591, and note the following: Seal has a single lip and if installed lip “up” it will keep oil in better. If installed lip “down” it will keep dirt out better than it keeps oil in.

Reinstall Lower Bushing

Apply a thin coat of silicone sealant to outer surfaces of lower plastic bushing and the new seal to prevent leakage of oil at the outer strut.
Reassemble upper strut cap/bushing assy. In reverse order of the disassembly. Tighten the socket head screws (24) but do not over torque

Reinstall Gear Inner Strut (ref. 112.6.4)

Carefully insert inner strut into outer strut. A mechanics “bullet” in the outer cylinder location for the strut bolt (4) will help in positioning plunger (27).

Using jack, compress springs and reinstall strut bolt (4) finger tight.

With lower strut bearing and new seal in place secure by installing seal clamp.

Reconnect torque link using retained hardware. Install cotter pins,

Reinstall wheel assy. Torque axle nut. Install cotter pin.

Reinstall brake caliper. Check wheel rotation,

Service Gear Per Section 2,14,2 3

Pump ‘A cup of Auto Gear Lube 90# or Chain Saw Bar Lube oil into outer cylinder for lubrication of upper and lower plastic bearings. Install screw (49).


Lift aircraft, remove supports, and lower aircraft on to its gears.

Remove strut bolt (4). Pump, (very slowly),1 and 2/3’s cup of MIL 5606 into the inner cylinder. Reinstall strut bolt (4) and torque.

Operate recoil action of landing gear by lifting of wing several times and check that the MIL 5606 oil level is 7” down from top of outer cylinder. Install screw (49) in strut bolt (4). Install wing “DOT” plug. Verily gear moves without binding.