FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 11. Aircraft Electrical Systems | 14. Terminal Repairs | 11-178. Crimp On Terminal Lugs and Splices
9/27/01
AC 43.13-1B CHG 1
electric contact efficiency. In other words, the
contact pressure on the wire lugs should not in
any way be affected by the loosening of the
stud in the insulator.
d. Support of Wire at Studs. Unless
some other positive locking action is provided,
the lug or wire should be supported next to the
stud to prevent loosening the connection with a
side pull on the wire. Torque recommenda
tions for attaching electrical wiring devices to
terminal boards or blocks, studs, posts, etc.,
are normally found in the manufacturer’s
maintenance instruction manual.
e. Feed-Through Insulator and Stud
Design. Feed-through insulator design should
be such as to prevent a loose insulator from
failing to provide circuit isolation. It should
not be able to move from between the stud and
the structure, thus allowing the two to come
into contact. The assembly should be so de
signed that it is impossible to inadvertently
misassemble the parts so that faults will result.
Also, it is desirable to provide means to pre
vent the feed-through stud from turning while
tightening the connection.
11-178. CRIMP ON TERMINAL LUGS
AND SPLICES (pre-insulated crimp type).
The crimp on terminal lugs and splices must
be installed using a high quality ratchet-type,
crimping tool. We recommend the use of the
proper calibrated tool. Aircraft quality crimp
tools are manufactured to standards. Such
tools are provided with positioners for the wire
size and are adjusted for each wire size. It is
essential that the crimp depth be appropriate
for each wire size. If the crimp is too deep or
not deep enough, it may break or cut individ
ual strands, or it may not be tight enough to
retain the wire in the terminal or connector.
Crimps that are not tight enough are also sus
ceptible to high resistance due to corrosion
build-up between the crimped terminal and the
wire. MIL-C22520/2 or MIL-T-DTl2250G
specification covers in detail the general re
quirement for crimp tools, inspection gages
and tool kits.
a. Hand, portable, and stationary
power tools are available for crimping termi
nal lugs. These tools crimp the barrel to the
conductor, and simultaneously from the insu
lation support to the wire insulation.
11-177. WIRE TERMINALS AND BIND-
ING POSTS. All wire terminals in or on
electrical equipment, except case ground, must
be firmly held together with two nuts or suit
able locking provisions, or should be secured
in a positive manner to equipment in such a
way that no insulation material is involved in
maintaining physical pressure between the
various current carrying members of an electri
cal connection. Terminal studs or binding
posts should be of a size that is entirely ade
quate for the current requirements of the
equipment and have sufficient mechanical
strength to withstand the torque required to
attach the cable to the equipment. All termi
nals on equipment should have barriers and
covers provided by equipment manufacturers.
b. Crimp tools must be carefully in
spected:
(1) Insure that the full cycle ratchet
mechanism is tamper-proof so that it cannot be
disengaged prior to or during the crimp cycle.
(2) If the tool does not function or faults
are found, reject the tool and send the tool to
be repaired.
(3) The tool calibration and adjustments
are make only by the manufacturer or an ap
proved calibration laboratory.
(4) Suitable gages of the Go/No Go
type are available and shall be used prior to
Par 11-174
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