FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 11. Aircraft Electrical Systems | 1. Inspection and Care of Electrical Systems | 11-3. Functional Check of Stand-by or Emergency Equipment
AC 43.13-1B
9/8/98
m. Voltage check of electrical system
with portable precision voltmeter.
n. Condition of electric lamps.
o. Missing safety shields on exposed
high-voltage terminals (i.e., 115/200V ac).
11-3. FUNCTIONAL CHECK OF
STAND-BY OR EMERGENCY EQUIP-
MENT. An aircraft should have functional
tests performed at regular intervals as pre-
scribed by the manufacturer. The inspections
or functional check periods should be clearly
stated in the aircraft maintenance manual,
along with the overhaul intervals.
11-4. CLEANING AND PRESERVA-
TION. Annual cleaning of electrical equip-
ment to remove dust, dirt, and grime is rec-
ommended. Suitable solvents or fine abrasives
that will not score the surface or remove the
plating may be used to clean the terminals and
mating surfaces if they are corroded or dirty.
Only cleaning agents that do not leave any type
of residue must be used. Components must be
cleaned and preserved in accordance with the
aircraft handbooks or manufacturer’s instruc-
tions. Avoid using emery cloth to polish
commutators or slip rings because particles
may cause shorting and burning. Be sure that
protective finishes are not scored or damaged
when cleaning. Ensure that metal-to-metal
electrically bonded surfaces are treated at the
interface with a suitable anti-corrosive con-
ductive coating, and that the joint is sealed
around the edges by restoring the original
primer and paint finish. Connections that must
withstand a highly corrosive environment may
be encapsulated with an approved sealant in
order to prevent corrosion.
CAUTION: Turn power off before
cleaning.
11-5. BATTERY ELECTROLYTE COR-
ROSION. Corrosion found on or near lead-
acid batteries can be removed mechanically
with a stiff bristle brush and then chemically
neutralized with a 10 percent sodium bicar-
bonate and water solution. For Nickel Cad-
mium (NiCad) batteries, a 3 percent solution
of acetic acid can be used to neutralize the
electrolyte. After neutralizing, the battery
should be washed with clean water and thor-
oughly dried.
11-6. ADJUSTMENT AND REPAIR. Ac-
complish adjustments to items of equipment
such as regulators, alternators, generators,
contactors, control devices, inverters, and re-
lays at a location outside the aircraft, and on a
test stand or test bench where all necessary in-
struments and test equipment are at hand.
Follow the adjustment and repair procedures
outlined by the equipment or aircraft manu-
facturer. Replacement or repair must be ac-
complished as a part of routine maintenance.
Adjustment of a replacement voltage regulator
is likely since there will always be a difference
in impedance between the manufacturer’s test
equipment and the aircraft’s electrical system.
11-7. INSULATION OF ELECTRICAL
EQUIPMENT. In some cases, electrical
equipment is connected into a heavy current
circuit, perhaps as a control device or relay.
Such equipment is normally insulated from the
mounting structure since grounding the frame
of the equipment may result in a serious
ground fault in the event of equipment internal
failure. Stranded 18 or 20 AWG wire should
be used as a grounding strap to avoid shock
hazard to equipment and personnel. If the end
connection is used for shock hazard, the
ground wire must be large enough to carry the
highest possible current (0.1 to 0.2 ohms
max.).
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