Piper Navajo PA-31 Service Manual page 401

PIPER NAVAJO SERVICE
MANUAL
7-12b. CLEANING, INSPECTION, AND REPAINTING SHIMMY DAMPER
a. Gar Kenyon and Parker Hannifin
1. After removing O-rings and backup rings from piston rod assembly and end caps, degrease all parts
and dry thoroughly.
2. Visually inspect cylinder body bore for nicks, scratches, or signs of excessive wear. Excessive
scratches in bore or deep scratches necessitate replacement. Any small nicks, scratches, or paint chips on exterior
of cylinder body can be blended using fine (#400 fine grit) sandpaper.
3. Thoroughly clean repaired surface of cylinder body exterior. Paint exposed areas with one coat of
primer, and one coat of white polyurethane enamel.
4. Visually inspect piston rod assembly for excessive nicks, scratches, or deformation. Excessive wear
to rod assembly necessitates replacement. Any light surface scratches may be removed using fine grit sandpaper.
Place piston rod assembly on flat surface and roll. Any piston rods deformed from excessive loading should
be replaced.
5. Inspect end cap for signs of excessive side loading. Results of extreme side loading to end cap will
be elongation or deformation of 0.375 diameter through hole. In the event that this occurs, end cap should be
replaced.
6. Inspect clamp assembly for distortion from excessive loading conditions. Welds on clamp assembly
should also be checked for development of any cracks.
7. Check nut on clamp assembly to make sure locking feature is not damaged or destroyed. Replace if
locking feature is damaged or destroyed.
7-12c. ASSEMBLY OF SHIMMY DAMPER
a. Gar Kenyon and Parker Hannifin
1. Prior to placing O-ring on piston rod assembly, coat with Dow Corning Molykote 55M. After coat-
ing, install O-ring on piston between the two single turn backup rings. A thin coating of Dow Coming
Molykote can also be applied to the piston rod.
2. Coat O-rings with Dow Corning Molykote SSM and install on end cap bearing. O-ring will require
a backup ring on the outboard side.
3. Slide end cap bearing over piston rod and then coat cylinder bore liberally with MIL-H-5606
hydraulic fluid.
4. Insert piston rod assembly into cylinder body being careful not to cut O-rings or backup rings when
installing. Secure end cap with snap ring.
5. Extend piston rod assembly to the fully extended position and then place unit, rod side down, in a
bench vise or suitable holder to aid in filling.
6. With unit secured and rod assembly in extended position, pour 36 ml. or 1.1 to 1.2 oz. of MIL-H-
5606 hydraulic fluid into cylinder body.
7. After filling, coat O-ring with Dow Corning Molykote 55M and install on end cap. Place Stat-o-seal
on screw and install screw onto end cap snugging gently.
8. Install end cap into cylinder body and secure with snap ring.
NOTE
Due to the nature of the design of the unit, the damper must be
bled to allow the piston rod assembly to be fully retracted.
9. Remove unit from vise. Loose screw approximately 2 IQ to 3 turns. Grasp cylinder body with hand
and compress piston rod assembly to the fillly retracted position. When piston contacts end cap (fillly retracted),
snug screw against end cap. Excess fluid should be cleaned off unit and clamp assembly reinstalled and
torqued to 45 to 50 in.-lbs.
NOTE
Unit should be hand stroked 5 complete strokes to check for any
leakage of O-rings. Install on aircraft in reverse order that unit
was removed.
Revised: 2/18/94
LANI)ING GEAR AND BRAKE SYSTEM
2E23