7-12A.. Shimmy Damper Disassembly - Piper Navajo PA-31 Service Manual

PIPER NAVAJO SERVICE MANUAL
8. Adjust the rod end bearings of each steering rod to align the nose wheel with the chalk line and to
bring the rudder pedals into neutral angle for and aft. To align the nose wheel straight forward, stand in front of
the nose gear and align the center rib of the tire with the chalk line or lay a straight edge along the side of the
tire and paralleled the straight edge with the chalk line. The neutral angle of the rudder pedals is at station
89.75 and center of the rudder pedal tube. (Refer to Figure 7-4.) One end of each rod must be disconnected and
jam nuts loosened to make this adjustment, but do not attempt to make the adjustment by means of one bear-
ing, but divide the adjustment between the bearings at each end of each rod. Check that rod ends have suffi-
cient thread engagement, reinstall rods and secure jam nuts.
9. To check nose gear steering for its 20 degree maximum right and left travel, mark on each side of
the nose wheel a 20 degree angle line from centerline and wheel pivot point. Turn wheel to maximum travel in
both directions to check for allowable travel. Should travel be exceeded in one direction and not enough in the
other direction, check for possible damage to the Far fork or torque links.
NOTE
With aircraft weight on nose gear turn gear so that play between
one roller and the steering arm is removed. Determine that the
opposite roller has a minimum clearance of 0.00 but when rotat-
ed with finger pressure a light drag is felt. The maximum clear-
ance may not exceed .065 the roller O.D. to be the same within
.062 in. from side to side.
JIG METHOD: Fabricate a jig tool conforming to specifications given in Figure 7-20.
1. Place the airplane on jacks. (Refer to Jacking, Section II.)
2. Level the airplane laterally and longitudinally.
3. Attach the (fabricated) nose wheel jig to the front of the nose wheel at the axle and extend and
attach a plumb bob from a point that is approximately 20 inches forward along the bottom-center row of rivets
as measured from the wheel well opening. (Refer to Figure 7-5.)
4. Clamp the rudder pedals to align in a lateral position. (Refer to Figure 7-3.) Adjust the rod end bear-
ings of each steering control rod to align the plumb bob with the center line marked on the jig and to bring the
pedals in neutral angle for and aft. The neutral angle is at station 89.75 and center of the rudder pedal horizon-
tal tube. (Refer to Figure 7-4.) Do not attempt to make the adjustment by means of one bearing, but divide the
adjustment between the bearings at each end of the steering rods. Check that rod ends have sufficient gripping
thread by ascertaining that a wire will not go through the check hole in the rod, and then tighten locknut
5. To check nose gear steering for its 20
°
+ 1
°
maximum right and left travel, turn the nose wheel with
jig attached in each direction to determine that the plumb bob aligns with the 20 °
+ 1
°
marks on the jig.
7-12a.. SHIMMY DAMPER DISASSEMBLY
a. Gar Kenyon and Parker Hannifin
1. After removing damper assembly from aircraft, wrap with cloth and gently secure unit in a bench
vise with rod end in an "up" position.
2. Draw piston rod assembly up until rod is in the fully extended position.
3. Remove rod end from piston rod assembly and then remove snap ring from piston rod end of
cylinder body.
CAUTION
Do not use sudden jerking motions when removing piston rod
assembly and cap from cylinder body.
4. Grasp piston rod firmly with hand and remove piston rod assembly and cap (bearing) from cylinder
body using gradual pressure outward. After removing rod assembly from cylinder body, slide end cap off of rod.
5. Remove cylinder body from vise and dispose of remaining fluid left in the unit.
6. Remove snap ring securing end cap and remove end cap.
Revised: 2/18/94
LANDING
GEAR AND BRAKE SYSTEM
2E21