FAA Advisory Circular 43.13-1B
Acceptable Methods, Techniques, and Practices
Aircraft Inspection and Repair
AC 43.13-1B | 8. Engines, Fuel, Exhaust, and Propellers | 5. Inspection of Propellers | 8-91. General
9/8/98
SECTION 5. INSPECTION OF PROPELLERS
AC 43.13-1B
8-91. GENERAL. All propellers, regardless
of the material from which they are made,
should be regularly and carefully inspected for
any possible defect. Any doubtful condition,
such as looseness of parts, nicks, cracks,
scratches, bruises, or loss of finish should be
carefully investigated and the condition
checked against repair and maintenance speci-
fications for that particular type of propeller.
Any propeller that has struck a foreign object
during service should be promptly inspected
for possible damage in accordance with the
propeller manufacturer’s prescribed procedures
and, if necessary, repaired according to the
manufacturer’s instructions. If the propeller is
damaged beyond the repair limits established
by the propeller manufacturer, and a replace-
ment is necessary, install the same
make/model approved or alternate as specified
in the equipment list, applicable FAA Aircraft
Specification, Type Certificate Data Sheet
(TCDS), or Supplemental Type Certificate
(STC). A sample manufacturer’s propeller in-
spection checklist is shown in table 8-2. It
shows the items to be inspected and the in-
spection intervals.
8-92. WOOD OR COMPOSITION PRO-
PELLERS AND BLADES. Wood propellers
are usually found on low-power, reciprocating
engines while composition (Carbon fiber,
Kevlar) propellers are used on high horse-
power reciprocating and turbine engines. Due
to the nature of wood, these propellers should
be inspected frequently to assure airworthi-
ness. Inspect for defects such as cracks, dents,
warpage, glue failure, delamination defects in
the finish, and charring of the wood between
the propeller and the flange due to loose pro-
peller mounting bolts. Composition propellers
should be inspected in accordance with the
propeller manufacturer’s instructions.
a. Fixed-pitch propellers are normally
removed from the engine at engine overhaul
periods. Whenever the propeller is removed,
visually inspect the rear surface for any indi-
cation of cracks. When any defects are found,
disassemble the metal hub from the propeller.
Inspect the hub bolts for wear and cracks at the
head and threads, and if cracked or worn, re-
place with new equivalent bolts. Inspect for
elongated bolt holes, enlarged hub bore, and
for cracks inside the bore or anywhere on the
propeller. Repair propellers found with any of
these defects. If no defects are found, the pro-
peller may be reinstalled on the engine. Before
installation, touch up with varnish all places
where the finish is worn thin, scratched, or
nicked. Track and balance the propeller, and
coat the hub bore and bolt holes with some
moisture preventive such as asphalt varnish.
In case the hub flange is integral with the
crankshaft of the engine, final track the pro-
peller after it is installed on the engine. In all
cases where a separate metal hub is used, make
a final balance and track with the hub installed
on the propeller.
b. On new, fixed-pitch propeller instal-
lations, inspect the bolts for proper torque after
the first flight and after the first 25 hours of
flying. Thereafter, inspect and check the bolts
for proper torque at least every 50 hours. No
definite time interval can be specified, since a
bolt’s proper torque is affected by changes in
the wood caused by the moisture content of the
air where the airplane is flown and stored.
During wet weather, some moisture is apt to
enter the propeller wood through the holes
drilled in the hub. The wood then swells, and
because expansion is limited by the bolts ex-
tending between the two flanges, some of the
wood fibers become crushed. Later, when the
propeller dries out during dry weather or due
Par 8-91
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