Figure 2-57.—Types of cotter pins.
AIRCRAFT SAFETYING METHODS
Learning Objective:
Identify the various
safety methods used on aircraft hardware.
You will come in contact with many different
types of safetying materials. These materials are used
to stop rotation and other movement of fasteners.
They are also used to secure other equipment that may
come loose due to vibration in the aircraft.
COTTER PINS
Cotter pins are used to secure bolts, screws, nuts,
and pins. Some cotter pins are made of low-carbon
steel, while others consist of stainless steel and are
more resistant to corrosion. Also, stainless steel
cotter pins may be used in locations where
nonmagnetic material is required. Regardless of
shape or material, all cotter pins are used for the same
general purpose—safetying. Figure 2-57 shows three
types of cotter pins and how their size is determined.
NOTE: Whenever uneven prong cotter pins
are used, the length measurement is to the end
of the shortest prong.
SAFETY WIRE
Safety wire comes in many types and sizes. You
must first select the correct type and size of wire for
the job. Annealed corrosion-resistant wire is used in
high-temperature, electrical equipment, and aircraft
instrument applications. All nuts except the
self-locking types must be safetied; the method used
depends upon the particular installation.
Figure 2-58 shows various methods commonly
used in safety wiring nuts, bolts, and screws.
Examples 1, 2, and 5 of figure 2-58 show the proper
method of safety wiring bolts, screws, square head
plugs, and similar parts when wired in pairs.
Examples 6 and 7 show a single-threaded component
wired to a housing or lug. Example 3 shows several
components wired in series. Example 4 shows the
proper method of wiring castellated nuts and studs.
Note that there is no loop around the nut. Example 8
shows several components in a closely spaced, closed
Figure 2-58.—Safety wiring methods.
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