FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 11. Aircraft Electrical Systems | 9. Environmental Protection and Inspection | 11-121. Precautions
AC 43.13-1B CHG 1
9/27/01
b. Care should be taken to avoid sharp
bends in wires that have been marked with the
hot stamping process.
11-118. SLACK. Wiring should be installed
with sufficient slack so that bundles and indi-
vidual wires are not under tension. Wires con-
nected to movable or shock-mounted equip-
ment should have sufficient length to allow
full travel without tension on the bundle.
Wiring at terminal lugs or connectors should
have sufficient slack to allow two retermina-
tions without replacement of wires. This slack
should be in addition to the drip loop and the
allowance for movable equipment. Normally,
wire groups or bundles should not exceed
1/2-inch deflection between support points, as
shown in figure 11-9a. This measurement may
be exceeded provided there is no possibility of
the wire group or bundle touching a surface
that may cause abrasion. Sufficient slack
should be provided at each end to:
a. Permit replacement of terminals.
11-119. POWER FEEDERS. The power
feeder wires should be routed so that they can
be easily inspected or replaced. They must be
given special protection to prevent potential
chafing against other wiring, aircraft structure,
or components.
11-120. RF CABLE. All wiring needs to be
protected from damage. However, coaxial and
triaxial cables are particularly vulnerable to
certain types of damage. Personnel should ex-
ercise care while handling or working around
coaxial. Coaxial damage can occur when
clamped too tightly, or when they are bent
sharply (normally at or near connectors).
Damage can also be incurred during unrelated
maintenance actions around the coaxial cable.
Coaxial can be severely damaged on the inside
without any evidence of damage on the out-
side. Coaxial cables with solid center con-
ductors should not be used. Stranded center
coaxial cables can be used as a direct replace-
ment for solid center coaxial.
b. Prevent mechanical strain on wires.
11-121. PRECAUTIONS.
c. Permit shifting of equipment for main-
tenance purposes.
11-118A. DRIP LOOP IN WIRE BUNDLE.
A drip loop is an area where wire is dressed
downward to a connector, terminal block,
panel, or junction bo. In additional to the
service termination and strain relief, a trap or
drip loop shall be provided in the wiring to
prevent fluid or condensate from running into
the above devices. (see Figure 11-9b) Wires
or groups of wires should enter a junction box
or piece of equipment in an upward direction
where practicable. Where wires must be
routed downwards to a junction box or unit of
electric equipment, the entry should be sealed
or adequate slack should be provided to form a
trap or drip loop to prevent liquid from
running down the wires in the box or electric
unit.
a. Never kink coaxial cable.
b. Never drop anything on coaxial cable.
c. Never step on coaxial cable.
d. Never bend coaxial cable sharply.
e. Never loop coaxial cable tighter than
the allowable bend radius.
f. Never pull on coaxial cable except in a
straight line.
g. Never use coaxial cable for a handle,
lean on it, or hang things on it (or any other
wire).
Page 11-52
Par 11-117