FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 11. Aircraft Electrical Systems | 6. Aircraft Electrical Wire Selection | 11-78. Substitutions
AC 43.13-1B CHG 1
9/27/01
sources. Such military or original equipment
manufacturer (OEM) wire used on aircraft
should only have originated from these defined
wire mills. Aircraft wire from other unau
thorized firms, and fraudulently marked with
the specified identification, must be regarded
as “unapproved wire,” and usually will be of
inferior quality with little or no process control
testing. Efforts must be taken to ensure ob
taining authentic, fully tested aircraft wire.
b. Plating. Bare copper develops a sur
face oxide coating at a rate dependent on tem
perature. This oxide film is a poor conductor
of electricity and inhibits determination of
wire. Therefore, all aircraft wiring has a coat
ing of tin, silver, or nickel, that have far slower
oxidation rates.
(1) Tin coated copper is a very common
plating material. Its ability to be successfully
soldered without highly active fluxes dimin
ishes rapidly with time after manufacture. It
can be used up to the limiting temperature of
150 °C.
(2) Silver-coated wire is used where
temperatures do not exceed 200 °C (392 °F).
(3) Nickel coated wire retains its prop
erties beyond 260 °C, but most aircraft wire
using such coated strands have insulation sys
tems that cannot exceed that temperature on
long-term exposure. Soldered terminations of
nickel-plated conductor require the use of dif
ferent solder sleeves or flux than those used
with tin or silver-plated conductor.
c. Conductor Stranding. Because of
flight vibration and flexing, conductor round
wire should be stranded to minimize fatigue
breakage.
d. Wire Construction Versus Applica-
tion. The most important consideration in the
selection of aircraft wire is properly matching
the wire’s construction to the application envi
ronment. Wire construction that is suitable for
the most severe environmental condition to be
encountered should be selected. Wires are
typically categorized as being suitable for ei
ther “open wiring” or “protected wiring” ap
plications. MIL-W-5088L, replaced by
AS50881A, wiring aerospace vehicle, Appen
dix A table A-I lists wires considered to have
sufficient abrasion and cut-through resistance
to be suitable for open-harness construction.
MIL-W-5088L, replaced by AS50881A, wiring
aerospace vehicle, Appendix A table A-II lists
wires for protected applications. These wires
are not recommended for aircraft interconnec
tion wiring unless the subject harness is cov
ered throughout its length by a protective
jacket. The wire temperature rating is typically
a measure of the insulation’s ability to with
stand the combination of ambient temperature
and current related conductor temperature rise.
e. Insulation. There are many insulation
materials and combinations used on aircraft
electrical wire. Characteristics should be cho
sen based on environment; such as abrasion re
sistance, arc resistance, corrosion resistance,
cut-through strength, dielectric strength, flame
resistant, mechanical strength, smoke emis
sion, fluid resistance, and heat distortion. An
explanation of many of the abbreviations is
identified in the glossary.
11-78. SUBSTITUTIONS. In the repair
and modification of existing aircraft, when a
replacement wire is required, the maintenance
manual for that aircraft must first be reviewed
to determine if the original aircraft manufac
turer (OAM) has approved any substitution. If
not, then the OAM must be contacted for an
acceptable replacement.
a. MIL-W-5088L, replaced by AS50881A,
wiring aerospace vehicle, Appendix A lists wire
types that have been approved for military
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