Piper Comanche PA-24 Service Manual page 84

Tires.
2-40.
Servicing Tires.
2-41.
The tires should be maintained at the pressure specified in Table II-I. When checking tire pressure,
examine the tire for wear, cuts, bruises and slippage.
NOTE: At tire change, in PA-24-400 complete inspection per paragraph 6-72a.
A. Tire Balance
Proper balancing is critical for the life of aircraft tires. If a new tire is balanced upon installation it
will usually remain balanced for the life of the tire without having any shimmy or flat spots.
1. Tire Balancer
An inexpensive balancing fixture that will balance almost any light aircraft tire can be made
from the materials shown in Figure 2-15a.
(a) Chamfer top edges of -3 sides, leaving 1/16 inch flat on top of the inboard edge. Rivet -2
tee's to -3 sides using AN 470-AD5 rivets, with 2 inch spacing, and using AN 426-AD5
rivets ( 2 inch center to center ) to secure -2 tee's to -1 base. If tee extrusion is unavailable,
heavy angle extrusion could be used. -3 sides must be vertical.
(b) The -4 axle must slide through the -8 pipe, the -5 nuts are made by reaming the existing
threads in the AN 365-624 nuts with an R drill, then tapping them with a 1/8-27 pipe tap.
(c) The -6 spacers were made from 1/2 inch aluminum tubing, the two lengths of spacers are
suitable for balancing most any aircraft wheel.
(d) The -7 bushings may be made from one inch phenolic or aluminum using a 1-1/2 inch
hole saw to cut out the smaller bushing and a 1-3/4 hole saw to cut out the larger. By
inserting a 1/4 inch long threaded bolt through the pilot hole and securing with a washer
and nut, a drill press and file may be used to make the off-set on the bushing. The turned-
down part should just slide inside the bearing race and then ream the pilot hole to slide
over the -8 pipe threads.
(e) The -8 pipe was made from a piece of 1/8 inch black pipe and threaded with a 1/8-27 pipe
die, this will be thread 3 inches in from each end of the pipe.
2. Procedure
Balance tires as follows:
(a) Mount the tire and tube (if one is used) on the wheels, but do not install the securing bolts.
Install the wheel bearings in the wheels; then, using the -7 bushings, -6 spacers, and -5
nuts, install the wheel/tire assembly on the -8 pipe. Secure the -5 nuts finger tight so that
the wheel halves touch each other. Be sure the bolt holes are aligned. Insert the -4 axle
through the -8 pipe and place the wheel in the center of the balancer. Make sure the axle is
only on the chamfered edges of the balancer and that it is at 90° to the sides of the
balancer.
(b) Release the tire. If it is out of balance it will rotate, coming to rest with the heaviest point
on the bottom. Tape a 1/2 ounce patch across the top center of the tire. Rotate the tire 45°
and release it again. If the tire returns to the same position, add a 1 ounce patch and again
rotate the tire and release it. Continue this procedure until the tire is balanced.
II - HANDLING AND SERVICING
PIPER COMANCHE SERVICE MANUAL
1C8B
04/01/09