FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 6. Corrosion, Inspection, and Protection | 5. Visual Corrosion Inspection Guide for Aircraft | 6-71. Engine Frontal Areas
AC 43.13-1B
9/8/98
f. Inspect thick alloy skin surfaces for
pitting, intergranular corrosion, and exfoliation
of the metal. Look for white or gray deposits
around countersunk fastener heads and raised
areas or bumps under the paint film.
g. Inspect composite skins for corrosion
of attachment fasteners.
6-70. WATER ENTRAPMENT AREAS.
Inspect area around edge of drain holes for cor
rosion and ensure that drain holes are not
blocked by debris.
6-71. ENGINE FRONTAL AREAS.
a. Inspect reciprocating engine cylinder
fins, engine cases, and cooling air ducts for
damage to exterior finish and corrosion.
b. Inspect radiator cooler cores for cor
rosion.
6-72. ELECTRONIC PACKAGE COM-
PARTMENTS.
a. Inspect circuit-breakers, contact
points, and switches for evidence of moisture
and corrosive attack.
b. Treatment of corrosion in electrical
and electronic components should be done by
or supervised by qualified personnel familiar
with the function of the unit involved.
6-73. FLEXIBLE HOSE ASSEMBLIES.
b. Replace any defective, damaged,
twisted, or bulging hoses.
6-74. SANDWICH PANELS. Inspect
edges of sandwich panels for damage to the
corrosion protection finish or sealant and for
corrosion.
6-75. CONTROL CABLES.
a. Inspect control cables for bare spots in
the preservative coating and corrosion.
b. If external corrosion is found, relieve
tension on the cable and check internal strands
for corrosion. Cables with corrosion on inter
nal strands should be replaced. External cor
rosion should be removed by a clean, dry,
coarse rag or fiber brush. A preservative
should be applied after removal of external
corrosion.
6-76. INTEGRAL FUEL CELLS.
a. Inspect top coat finish for breaks,
peeling, lifting of surface, or other damage.
b. Inspect aircraft structure for top coat
finish damage from pitting or intergranular
corrosion.
6-77. ELECTRICAL CONNECTORS.
a. Inspect electrical connectors for
breaks in potting compound and corrosion of
pins and wires.
a. Inspect hose assemblies for chafing,
weather-checking, hardening, discoloration,
evidence of fungus, torn weather protective
coatings or sleeves, and corrosion of fittings.
b. If the electrical connector is sus-
pected of having moisture intrusion, disas
semble the connector, clean the connector, and
inspect it for corrosion.
6-78.6-88. [RESERVED.]
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Par 6-69