Piper Arrow IV, Maintenance Manual

Page: 696 / 752

GENERAL.
This chapter contains miscellaneous charts which are applicable to various chapters and systems covered
in this manual. All electrical schematics are also included in this chapter.
TORQUE REQUIREMENTS.
The torque values given in Chart 9102 are derived from oil-free cadmium-plated threads and are
recommended for all airframes installation procedures when torquing is required, unless otherwise noted in
sections where other values are stipulated. Engine torque values are found in the latest revision of Lycoming
Overhaul Manual, and propeller torque values are found in Chapter 61 of this manual. Chart 9101 lists the
torque values for flared fittings of various sizes and material.
The importance of correct application can not be over emphasized. Undertorque can result in unnecessary
wear of nuts and bolts as well as the parts they are holding together. When insufficient pressures are applied,
uneven loads will be transmitted throughout the assembly which may result in excessive wear or premature
failure due to fatigue. Overtorque can be equally damaging because of failure of a bolt or nut from
overstressing the threaded areas. There are a few simple, but very important, procedures that should be
followed to assure that the correct torque is applied:
1. Calibrate the torque wrench periodically to assure accuracy and recheck frequently.
2. Unless otherwise specified, torque all nuts to the applicable torque in the recommended nut chart. If
the nut (or the bolt) is listed but not its mating fastener, use the lower torque specified for the listed nut (or
bolt).
—NOTE—
If normal operating requires movement between any of the
components being clamped together, tighten the nut (or bolt) only
enough to insure intended operation of the assembly.
3. Bolts should be clean and dry unless otherwise specified. If the threads are to be lubricated and no
torque is specified, reduce the recommended nut torque (including the friction drag torque) by 50%.
4. For thread sizes 10 through 7/16, add the friction drag torque for all self-locking fasteners as specified
in the friction drag torque table. For non-self-locking fasteners, assume the friction drag torque to be zero.
5. For other bolt sizes, determine the friction drag torque by turning the nut to near contact with the
bearing surface. Attach a scale type torque wrench to the nut and determine the torque required to turn the nut
on the bolt (before the nut makes contact with the bearing surface). Add this, the friction drag torque, to the
specified torque to get the final torque.
—NOTE—
If the bolt is stationary and the nut is torqued, use the lower side
of the torque range. If the nut is stationary and the bolt is
torqued, use the higher side of the torque range.
6. When torquing castellated nuts, begin with minimum torque (plus friction drag), but do not exceed
maximum torque (plus friction drag) when trying to align slot or nut with the hole in the bolt shank. If they do
not align, change washers and try again. When using castellated nuts on movable joints, do not torque as
described above; tighten nut only enough to remove looseness in the joint and then install the cotter pin.
91-00-01
Page 91-01
Revised: December 21, 1981
3H9
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL