A pigtail of one-fourth to one-half inch (three
to six twists) should be made at the end of the wiring.
This pigtail must be bent back or under to prevent it
from becoming a snag.
The safety wire must be new upon each
When you secure castellated nuts with safety
wire, tighten the nut to the low side of the selected
torque range, unless otherwise specified. If necessary,
continue tightening until a slot aligns with the hole.
All safety wires must be tight after installation,
but not under such tension that normal handling or
vibration will break the wire.
Apply the wire so that all pull exerted by the
wire tends to tighten the nut.
Twists should be tight and even, and the wire
between the nuts should be as taut as possible without
Use cotter pins to secure bolts, screws, nuts, and
pins. Some cotter pins are made of low-carbon steel,
while others consist of stainless steel, and thus are more
resistant to corrosion. Use stainless steel cotter pins in
locations where nonmagnetic material is required.
Regardless of shape or material, use all cotter pins for
the same general purposesafetying. Figure 5-27
shows three types of cotter pins and how their size is
Whenever uneven-prong cotter pins are
used, the length measurement is to the end of the
Cotter pin installation is shown in figure 5-28. Use
castellated nuts with bolts that have been drilled for
cotter pins. Use stainless steel cotter pins. The cotter
pin should fit neatly into the hole, with very little
sideplay. The following general rules apply to cotter pin
! Do not bend the prong over the bolt end beyond
the bolt diameter. (Cut it off if necessary.)
! Do not bend the prong down against the surface
of the washer. (Again, cut it off if necessary.)
! Do not extend the prongs outward from the
sides of the nut if you use the optional
! Bend all prongs over a reasonable radius.
Sharp angled bends invite breakage. Tap the
prongs lightly with a mallet to bend them.
What is the purpose of safetying aircraft
What is the most common method of safety
What are the two methods of safetying
turnbuckles used by the military services?
What type of cotter pin should you use when
nonmagnetic material is required?
two primary functions of washers as used in
Washers used in aircraft structures may be grouped
into three general classesplain, lock washers, and
Figure 5-27.Types of cotter pins.
Figure 5-28.Cotter pin installations.