TM 55-1520-228-BD
CHAPTER 11
ELECTRICAL AND AVIONICS SYSTEM
BDAR FIXES SHALL BE USED ONLY IN COMBAT OR FOR TRAINING
AT THE DISCRETION OF THE COMMANDER.
(AUTHORIZED TRAINING FIXES ARE LISTED IN APPENDIX E.)
IN EITHER CASE, DAMAGES SHALL BE REPAIRED BY STANDARD
PROCEDURES AS SOON AS PRACTICABLE.
Section 1.
11-1. SCOPE.
This chapter provides
methods for assessing battle damage,
deferring damage repair, and repairing
electrical and avionics systems.
Extensive repairs to complicated com-
ponents or line replaceable units (LRUs)
are not expected to be made in the
field.
Therefore, more emphasis is
placed on common repairs to intercon-
necting cables and simple electrical and
avionic components.
11-2. ASSESSMENT PROCEDURES.
(See Table 11-1 for assessment logic.)
a. Wire Identification. The most
difficult and time consuming part of
electrical and avionics battle damage
assessment is wire identification.
Added and repaired wiring should be
identified to aid in troubleshooting.
If time permits,
tape or sleeving at
each end of added wiring of a material
suitable for the ambient temperature
range may be used. Typical wire and
circuit identification schemes are shown
in Figure 11-1 and Table 11-2.
Appendix F lists and depicts the major
components, cable routes, and wiring
terminations for the more complex
avionics systems.
b.
Circuit Function. The unit
number and circuit designation letter
INTRODUCTION
It is used to distinguish between wires
in the same circuit. The wire segment
letter is used to distinguish between
conductor segments (a wire segment be-
tween two terminals or connections). The
wire size number is used to identify the
gage of the wire or cable. The ground,
phase, or thermocouple letter(s) are
used as suffixes to the wire identifi-
cation code to further identify certain
wires.
Ground wires are identified with
an N suffix. Phase letters A, B, or C
are added to identify the phase of wires
that are in the three-phase wiring of
alternating current (AC) systems.
For
thermocouple wire, the following suffixes
are added to the identification code:
AL (Alumel), CR (Chromel), FE (Iron),
CN (Constantan), and CU (Copper).
c.
Deferral.
Repair of systems and
subsystems, which have adequate redun-
dancy or are not critical to mission
accomplishment, may be deferred if safety
of flight is not significantly degraded.
Requirements must be examined to deter-
mine if relaxed criteria for repair and
aircraft performance can be accepted.
The commander may defer combat main-
tenance and battle damage repair, even
if doing so places operational limita-
tions on the aircraft.
identify the type of circuits. The wire
number consists of one or more digits.
11-1
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