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 | 11-126. Flammable Fluids and Gases
9/8/98
AC 43.13-1B
11-122. MOISTURE PROTECTION,
WHEEL WELLS, AND LANDING GEAR
AREAS.
a. Wires located on landing gear and in
the wheel well area can be exposed to many
hazardous conditions if not suitably protected.
Where wire bundles pass flex points, there
must not be any strain on attachments or ex-
cessive slack when parts are fully extended or
retracted. The wiring and protective tubing
must be inspected frequently and replaced at
the first sign of wear.
sunlight when aircraft are parked for extended
periods should also be taken into account.
Wires such as in fire detection, fire extin-
guishing, fuel shutoff, and fly-by-wire flight
control systems that must operate during and
after a fire, must be selected from types that
are qualified to provide circuit integrity after
exposure to fire for a specified period. Wire
insulation deteriorates rapidly when subjected
to high temperatures. Do not use wire with
soft polyethylene insulation in areas subject to
high temperatures. Use only wires or cables
with heat resistance shielding or insulation.
b. Wires should be routed so that fluids
drain away from the connectors. When this is
not practicable, connectors must be potted.
Wiring which must be routed in wheel wells or
other external areas must be given extra pro-
tection in the form of harness jacketing and
connector strain relief. Conduits or flexible
sleeving used to protect wiring must be
equipped with drain holes to prevent entrap-
ment of moisture.
11-125. MOVABLE CONTROLS WIR-
ING PRECAUTIONS. Clamping of wires
routed near movable flight controls must be
attached with steel hardware and must be
spaced so that failure of a single attachment
point can not result in interference with con-
trols. The minimum separation between wir-
ing and movable controls must be at least
1/2 inch when the bundle is displaced by light
hand pressure in the direction of the controls.
11-123. PROTECTION AGAINST PER-
SONNEL AND CARGO. Wiring must be in-
stalled so the structure affords protection
against its use as a handhold and damage from
cargo. Where the structure does not afford
adequate protection, conduit must be used, or a
suitable mechanical guard must be provided.
11-124. HEAT PRECAUTIONS. Wiring
must be routed away from high-temperature
equipment and lines to prevent deterioration of
insulation. Wires must be rated (reference
paragraph 11-66 and 11-67) so that the con-
ductor temperature remains within the wire
specification maximum when the ambient
temperature, and heat rise, related to current
carrying capacity are taken into account. The
residual heating effects caused by exposure to
11-126. FLAMMABLE FLUIDS AND
GASES. An arcing fault between an electrical
wire and a metallic flammable fluid line may
puncture the line and result in a fire. Every ef-
fort must be made to avoid this hazard by
physical separation of the wire from lines and
equipment containing oxygen, oil, fuel, hy-
draulic fluid, or alcohol. Wiring must be
routed above these lines and equipment with a
minimum separation of 6 inches or more
whenever possible. When such an arrange-
ment is not practicable, wiring must be routed
so that it does not run parallel to the fluid
lines. A minimum of 2 inches must be main-
tained between wiring and such lines and
equipment, except when the wiring is posi-
tively clamped to maintain at least 1/2-inch
separation, or when it must be connected
Par 11-115
Page 11-53