high-temperature, electrical equipment and aircraft
What are the two most commonly used types
instrument applications. All nuts except the
self-locking types must be safetied; the method used
What manual provides torquing information
depends upon the particular installation.
for a large variety of nuts, bolts, and screws
Figure 3-47 shows various methods commonly
used in aircraft construction?
used in safety wiring nuts, bolts, and screws. Examples
1, 2, and 5 of figure 3-47 show the proper method of
AIRCRAFT SAFETYING METHODS
safety wiring bolts, screws, square head plugs, and
LEARNING OBJECTIVE: Identify the
similar parts when wired in pairs. Examples 6 and 7
various safety methods used on aircraft
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
You will come in contact with many different types
castellated nuts and studs. Note that there is no loop
of safetying materials. These materials are used to stop
around the nut. Example 8 shows several components
rotation and other movement of fasteners. They are also
in a closely spaced, closed geometrical pattern, using
used to secure other equipment that may come loose
the single-wire method. The following general rules
due to vibration in the aircraft.
apply to safety wiring:
1. All safety wires must be tight after installation,
but not under so much tension that normal handling or
Cotter pins are used to secure bolts, screws, nuts,
vibration will break the wire.
and pins. Some cotter pins are made of low-carbon
2. The wire must be applied so that all pull
steel, while others consist of stainless steel and are
exerted by the wire tends to tighten the nut.
more resistant to corrosion. Also, stainless steel cotter
pins may be used in locations where nonmagnetic
3. Twists should be tight and even, and the wire
material is required. Regardless of shape or material, all
between nuts as taut as possible without overtwisting.
cotter pins are used for the same general
Wire between nuts should be twisted with the hands.
purpose--safetying. Figure 3-46 shows three types of
The use of pliers will damage the wire. Pliers may be
cotter pins and how their size is determined.
used only for final end twist before cutting excess wire.
NOTE: Whenever uneven prong cotter pins are
Annealed copper safety wire is used for sealing
used, the length measurement is to the end of the
first aid kits, portable fire extinguishers, oxygen regular
emergency valves, and other valves and levers used for
emergency operation of aircraft equipment. This wire
can be broken by hand in case of an emergency.
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
When all adjusting and rigging on the cables is
completed, safety the turnbuckles as necessary. Only
Figure 3-46.--Types of cotter pins.
Figure 3-47.--Safety wiring methods.