CHART 9102. RECOMMENDED NUT TORQUES
The proper application of torque is very important. Undertorque can result in excessive wear of nuts and
bolts as well as the parts they are holding together. When insufficient pressures are applied, uneven loads are
transmitted throughout the assembly which can result in excessive wear or premature failure due to fatigue.
Overtorque can be equally damaging and result in failure of a bolt or nut from overstressing the thread areas.
The following procedures will help ensure that the correct torque is applied:
1. Torque (self-locking fasteners) — Add friction torque from chart A for sizes 8 through 7/16 to
recommended torque from chart B to get final torque. This is the actual torque wrench reading.
2. Torque (castellated and non-self-locking nuts) — Use only torque given in chart B. Unless otherwise
specified, when castellated nuts are used with a cotter pin on moving joints, do not torque the nut. Turn
nut onto bolt until proper grip is established and alignment with cotter pin hole is achieved. Then
install cotter pin.
GENERAL REQUIREMENTS
l. Calibrate torque wrench periodically to ensure accuracy.
2. Ensure that bolt and nut threads are clean and dry (unless otherwise specified by manufacturer). If bolt
or nut is lubricated prior to tightening, torque range should be reduced 50 percent.
3. Use a bolt length long enough to prevent bearing loads on threads. The complete chamfer or end radius
of bolt or screw must extend through nut.
4. Unique torques specified in the text of this manual supersede torques in chart A and B.
5. Refer to the latest revision of Lycoming SSP l776 for torques on pans used on Lycoming engines.
6. A maximum of two AN960 washers maybe added under bolt heads or nuts to correct for variations in
material thickness within tolerances permitted.
7. Limitations of use of self-locking nuts, bolts, and screws including fasteners with non-metallic inserts
are as follows:
a. Fasteners incorporating self-locking devices must not be reused if they can be run up using only
fingers. They may be reused if hand tools are required to run them up, providing there is no
obvious damage to the self-locking device prior to installation.
b. Bolts 5/16 inch diameter and over with cotter pin holes may be used with self-locking nuts. Nuts
with non-metallic locking devices may be used in this application only if the bolts are free from
burrs around the cotter pin hole.
c. Do not use self-locking nuts at joints which subject either the nut or the bolt to rotation.
d. Never tap or rethread self-locking fasteners. Do not use nuts, bolts, or screws with damaged
threads or rough ends.
91 - 01 - 00
Page 91 - 02
Reissued: August 1, 1986
3A20
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
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