FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 12. Aircraft Avionics Systems | 2. Ground Operational Checks for Avionics Equipment (Electrical) | 12-9. Inspection of Avionics System
9/27/01
AC 43.13-1B CHG 1
SECTION 2. GROUND OPERATIONAL CHECKS FOR AVIONICS EQUIPMENT
(ELECTRICAL)
12-8. GENERAL. When the operating or
airworthiness regulations require a system to
perform its intended function, the use of the
Technical Standard Order (TSO) equipment or
the submission of data substantiating the
equipment performance is strongly recom
mended. An operation check of avionics is the
responsibility of the pilot in command. How
ever, it is recommended that after replacement
of equipment during 100 hour or annual in
spections, an operational check of avionics
equipment be performed. The accomplish
ments of these checks must be done in accor
dance with the recommendations and proce
dures set forth in the aircraft’s flight manual
instructions published by the avionics equip
ment manufacturers.
(4) Check to assure that the radios and
instruments are secured to the instrument
panel.
(5) Check that all avionics are free of
dust, dirt, lint, or any other airborne contami
nates. If there is a forced air cooling system, it
must be inspected for proper operation.
Equipment ventilation openings must not be
obstructed.
(6) Check the microphone headset
plugs and connectors and all switches and
controls for condition and operation. Check
all avionics instruments for placards. Check
lightening, annunciator lights, and cockpit in
terphone for proper operation.
12-9. INSPECTION OF AVIONICS
SYSTEMS.
a. The inspection shall include the fol
lowing:
(1) Inspect the condition and security of
equipment including the proper security of
wiring bundles.
(2) Check for indications of overheating
of the equipment and associated wiring.
(7) The circuit breaker panel must be
inspected for the presence of placarding for
each circuit breaker installed.
(8) Check the electrical circuit switches,
especially the spring-load type for proper op
eration. An internal failure in this type of
switch may allow the switch to remain closed
even though the toggle or button returns to the
OFF position. During inspection, attention
must be given to the possibility that improper
switch substitution may have been made.
(3) Check for poor electrical bonding.
The bonding requirements are specified by
equipment manufacturers. Installation cabling
should be kept as short as possible, except for
antenna cables which are usually precut or
have a specific length called out at installation.
Proper bonding on the order of 0.003 ohms is
very important to the performance of avionics
equipment.
b. Inspect antennas for:
(1) broken or missing
insulators
(2) lead through insulators
(3) springs
(4) safety wires
antenna
(5) cracked antenna housing
Par 12-8
Page 12-3