Figure 2-10.-Safety-wire pliers.
them, and by again pulling on the knob, you can
make a tighter twist. The wire should be installed
snugly but not so tight that the wire is over-
TORQUE WRENCHES.-- There are times
stressed. A squeeze on the handles unlocks the
when, for engineering reasons, a definite pressure
pliers, and the wire can then be cut to the proper
must be applied to a nut, bolt, screw, or other
length with the cutting jaws.
fastener. In such cases a torque wrench must be
used. The torque wrench is a precision tool
consisting of a torque-indicating handle and
appropriate adapter or attachments. Use the
Special tools are normally maintained in a
wrench to measure the amount of turning or
central toolroom and signed out when needed. A
twisting force applied to a nut, bolt, or screw.
tool falls into the special category for one of the
The three most common torque wrenches are
following five main reasons.
the deflecting beam, dial indicating, and
1. It is an item of special support equipment.
using the deflecting beam and the dial-indicating
These tools are designed, manufactured, and
torque wrenches, the torque is read visually on
issued for supporting or maintaining one par-
a dial or scale mounted on the handle of the
ticular model of aircraft, engine, or support
2. It is a seldom used tool. When needed, its
use is essential in aircraft maintenance. Most of
the time it would not be required and would just
take up room in the toolbox.
3. It is a high-cost item. A central location is
necessary to permit better use or for security.
4. The large size or awkward shape of the tool
makes it difficult, if not impossible, to put in a
5. It is a instrument type of tool that requires
A wide variety of special tools are furnished
by the manufacturers of the support equipment,
engines, and related equipment. These special
tools are listed in the Allowance List Registers
published by the Aviation Supply Office. Their
use is explained in the manual that covers the
specific support equipment, engine, or item of
equipment for which they were designed. Special
tools that you use frequently may be kept in your
Figure 2-11.-Torque wrenches.
toolbox if permitted by your tool control plan.