2-8. TORQUE REQUIREMENTS. Proper torque application cannot be overemphasized. Undertorqued
assemblies can result in premature failure due to fatigue from uneven loads, as well as causing unnecessary wear
of nuts, bolts, and other parts. Overtorqued assemblies can be equally harmful by causing failure of a bolt or nut
by overstressing the threaded areas.
The torque values given in Table II-II are derived from oil-free cadmium-plated threads and are
recommended for all airframe installation procedures where torquing is required, unless otherwise noted in
sections where other values are stipulated. Engine torque values are found in the latest revision of Avco-
Lycoming Special Service Publications No. SSP1776, and propeller torque values are found in Section VIII of
this manual. Table II-IIA lists the torque values for flared fittings of various sizes and material. Important
procedures for torquing assemblies on Piper Aircraft are as follows:
a. Frequently check and/or calibrate the torque wrench.
b. Make sure bolt/screw and nut threads are clean and dry, unless otherwise required. If the threads are to be
lubricated and no torque is specified, reduce recommended nut torque (plus the friction drag torque) by 50%.
c. Unless otherwise specified the charted torque values should be used. Should a bolt or nut be listed and not
its mating fastener, use the lower torque.
d. When using "self-locking fasteners" and hardware with thread sizes 10 through 7/16" add the specified
friction drag torque to the designated torque. Assume a friction drag torque of zero for non self-locking fasteners.
For other bolt sizes, the friction drag torque is determined as follows:
1. Turn nut to "near contact" with the bearing surface (NOT IN CONTACT).
2. Attach a scale type torque wrench and determine the torque required to turn the nut on the bolt before it
contacts the bearing surface. Add this value to the specified torque for the total torque value to be applied.
e. When torquing castellated nuts remember the following:
1. Determine maximum torque value (fr max. torque) and do not exceed when aligning slot and
hole, change washers if necessary.
2. When using castellated nuts on movable joints, tighten nuts only to remove looseness in the joint before
installing cotter pin.
f. Use the latest information from LYCOMING for torquing power plant parts.
g. On critical installations the nut should be permanently marked red after torquing and not be further
tightened or disturbed.
— NOTE —
When flared fittings are being installed, ascertain that the male threads are
properly lubricated. Torque the fittings in accordance with Table II-IIA. For more
details on torquing, refer to FAA Manual AC 43-13-1A.
— CAUTION —
Do not overtorque fittings.
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
HANDLING AND SERV I C I N G
1B3