o. Kapton Wiring. Kapton wire MIL-W-81381 is
applications. The insulation is tape of polyimide or
polyimide-fluorocarbon films. The conductors are silver
or nickel plated copper, or a high-strength copper alloy.
At present Kapton wiring is being phased out on new
aircraft and is restricted to ballistically hardened areas.
The preferred wire is MIL-W-22759 which cannot be
mixed in the same wire bundle as Kapton wire. Refer to
TM 55-1500-323-24 for inspection, stripping, and
installation of connectors on Kapton wiring. Kapton
maintenance is performed. Slight flaking of top coat is
acceptable, however this is considered as a first stage of
inspection shall be performed at regular intervals to
determine if further deterioration occurs. Excessive
flaking or other damage (cuts, chaffing, etc) to insulation
requires that the wire be replaced.
3-2. Troubleshooting . Troubleshoot electrical circuits
and components when malfunctions cannot be readily
located. Use procedures outlined below.
Omit operational check in cases
operational check could result in
damage to the aircraft.
a. Operational Check. Perform an operational
check of the system involved to determine when it is
functioning in accordance with the applicable aircraft
maintenance manual. When a malfunction exists,
perform the following procedures:
(1) Obtain a wiring diagram of system
involved. Be sure wiring diagram is current and
applicable to particular model aircraft.
performance requirements of the system.
(3) Recall similar situations and check
Equipment Improvement Recommendation (EIR) file.
(4) Examine aircraft maintenance forms to
see what maintenance has been performed on system
or general area of system or components.
(5) Decide on all possible component and
wiring malfunctions which could cause system to
perform as it does. A typical electrical system
schematic is shown in figure 2-4.
(6) Of all possible faults or troubles found in
step (5), decide which troubles are most probable cause
of malfunctions and proceed to test circuits or
components with test equipment.
troubleshooting electrical circuits
(7) Upon location of defective component or
b. Precautions. Use of test equipment designed
primarily for high potential voltage testing on aircraft
electrical cabling can be extremely hazardous in those
areas where fuels, explosive vapors, or fumes are
present in the aircraft. The term high potential voltage
testing as used herein is described as that condition of
approaching maximum insulation breakdown limits as
specified to determine leakage resistance between wire
insulation, conductors, conductor pairs, or groups of
conductors individually insulated within an insulated
cable jacket. High potential voltage or insulation
breakdown testing of aircraft electrical wiring and
cabling will be conducted as a last resort after all
previous methods of detecting faulty cabling have been
accomplished. These methods will consist of continuity,
visual inspection, common voltmeter and ohmmeter
checks, and other methods not involving high potential
voltage tests. The following procedures will apply where
tests, employing high potential testers, are made to
check aircraft electrical cabling and wiring involving
those areas where fuels, fumes, or explosive vapors
may possibly be present:
(1) It will be the responsibility of all
personnel using high potential voltage test apparatus to
trace the physical location of the circuit being tested and
determine if explosive vapors, fuels or fumes, are
present in any areas of this circuit.
(2) When explosive vapors, fuels, or fumes
are determined to be present and adequate ventilation
or air circulation is not provided, the following two
paragraphs will apply:
(a) If fumes or vapors can be
removed by isolating fuel from the areas involved by
means of shutoff or bypass valves, only that portion of
the fuel system which is isolated must be drained and