Standard Practices - Airframe; Torque Wrenches - Piper Dakota Maintenance Manual

GENERAL
This chapter contains general information pertaining to standard aircraft hardware installation and removal
practices. Information included will be very helpful if referred to on a regular basis.
For standard repair practices of a minor nature, refer to AC43.l3.
Testing and inspecting of aluminum castings and machined aluminum parts is accomplished by dye
penetrant method.
Usually, a visual inspection with 10X magnifying glass will show any damage or defect in a repair that is
of a significant nature.
STANDARD PRACTICES — AIRFRAME

TORQUE WRENCHES

Torque wrenches must be checked daily and calibrated with weights and a measured lever arm to ensure
that inaccuracies are not present. Checking one torque wrench against another is not sufficient and is not
recommended. Some wrenches are quite sensitive to how they are supported during tightening. Any
instructions furnished by manufacturers must be followed.
When necessary, use a special extension or adapter wrench together with a torque wrench. A simple
mathematical equation must be worked out to get correct torque readings. Following is the formula (Refer
to figure 20-1):
PIPER AIRCRAFT
MAINTENANCE MANUAL
T - Torque desired at the part.
A - Basic lever length from center of wrench shank to center
of handle or stamped on wrench or listed for that model
wrench.
B - Length of adapter extension, center of bolt to center of
shank.
C - Scale reading needed to obtain desired torque (T).
The formula: C = A x T
A bolt requires 30 foot-pounds. A 3-inch adapter (one-quarter
of a foot or 0.25') is needed to get at bolt. You want scale
reading necessary on a one-foot lever arm wrench to obtain
30 foot-pounds at bolt.
The formula: C = 1 x 30 or C = 30 = 24 ft.-lbs.
R e m e m b e r, the 3-inch adapter must be projecting 3 inches
straight along wrench axis. In general, avoid all complex
assemblages or adapters and extensions of flex joints.
PA-28-236
A + B
EXAMPLE
1 + .25 1.25
1E4
20 - 10 - 00
Page - 20 - 01
Reissued: August 1, 1986