FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 7. Aircraft Hardware, Control Cables, and Turnbuckles | 7. Safetying | 7-126. Securing Oil Caps, Drain Cocks, and Valves
9/8/98
AC 43.13-1B
c. To prevent failure due to rubbing or
vibration, safety wire must be tight after in-
stallation.
d. Safety wire must be installed in a man-
ner that will prevent the tendency of the part to
loosen.
e. Safety wire must never be over-
stressed. Safety wire will break under vibra-
tions if twisted too tightly. Safety wire must
be pulled taut when being twisted, and main-
tain a light tension when secured. (See fig-
ure 7-3a.)
f. Safety-wire ends must be bent under
and inward toward the part to avoid sharp or
projecting ends, which might present a safety
hazard.
g. Safety wire inside a duct or tube must
not cross over or obstruct a flow passage when
an alternate routing can be used.
ends, leave at least four to six complete turns
(1/2 to 5/8 inch long) after the loop. When
removing safety wire, never twist the wire off
with pliers. Cut the safety wire close to the
hole, exercising caution.
h. Install safety wire where practicable
with the wire positioned around the head of the
bolt, screw, or nut, and twisted in such a man-
ner that the loop of the wire fits closely to the
contour of the unit being safety wired.
7-125. TWISTING WITH SPECIAL
TOOLS. Twist the wire with a wire twister as
follows. (See figure 7-4.)
CAUTION: When using wire twist-
ers, and the wire extends 3 inches be-
yond the jaws of the twisters, loosely
wrap the wire around the pliers to
prevent whipping and possible per-
sonal injury. Excessive twisting of the
wire will weaken the wire.
(1) Check the units to be safety wired to
make sure that they have been correctly tor-
qued, and that the wiring holes are properly
aligned to each other. When there are two or
more units, it is desirable that the holes in the
units be aligned to each other. Never overtor-
que or loosen to obtain proper alignment of the
holes. It should be possible to align the wiring
holes when the bolts are torqued within the
specified limits. Washers may be used (see
paragraph 7-37) to establish proper alignment.
However, if it is impossible to obtain a proper
alignment of the holes without undertorquing
or overtorquing, try another bolt which will
permit proper alignment within the specified
torque limits.
(2) To prevent mutilation of the twisted
section of wire, when using pliers, grasp the
wires at the ends. Safety wire must not be
nicked, kinked, or mutilated. Never twist the
wire ends off with pliers; and, when cutting off
a. Grip the wire in the jaws of the wire
twister and slide the outer sleeve down with
your thumb to lock the handles or lock the
spring-loaded pin.
b. Pull the knob, and the spiral rod spins
and twists the wire.
c. Squeeze handles together to release
wire.
7-126. SECURING OIL CAPS, DRAIN
COCKS, AND VALVES. (See figure 7-4a.)
When securing oil caps and drain cocks, the
safety wire should be anchored to an adjacent
fillister-head screw. This method of safety
wiring is applied to wingnuts, filler plugs, sin-
gle-drilled head bolts, fillister-head screws,
etc.; which are safety wired individually.
When securing valve handles in the vertical
position, the wire is looped around the threads
of the pipe leading into one side of the valve,
Par 7-124
Page 7-21