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 | 1. Engines | 8-3. Crankshaft Inspection and Repair Requirements
9/8/98
AC 43.13-1B
(a) Loose, sheared, or spalled cap
screws or bolts.
(b) Cracks in the case.
h. Accessory and Drive Inspection.
Check the drive shaft of each accessory, i.e.,
magnetos, generators, external superchargers,
and pumps for evidence of damage.
(2) Disassemble the gear train and in-
spect the propeller shaft, reduction gears and
accessory drive gears for nicks, cracks, or
spalling.
f. Engine-Mount Inspection.
(1) Examine the engine flex mounts
when applicable, for looseness of engine to
mount, distortion, or signs of wear.
(2) Inspect the engine-mount structure
for bent, cracked, or buckled tubes.
(3) Check the adjacent airframe struc-
ture firewall for cracks, distortion, or wrinkles.
(4) Remove engine-mount bolts and
mount hold-down bolts and replace.
8-3. CRANKSHAFT INSPECTION AND
REPAIR REQUIREMENTS. Carefully in-
spect for misalignment and replace if bent be-
yond the manufacturer’s permissible service
limit. Worn journals may be repaired by re-
grinding in accordance with manufacturers’ in-
structions. It is recommended that grinding
operations be performed by appropriately-rated
repair stations or the original engine manufac-
turer. Common errors that occur in crankshaft
grinding are the removal of nitrided journal
surface, improper journal radii, unsatisfactory
surfaces, and grinding tool marks on the jour-
nals. If the fillets are altered, do not reduce
their radii. Polish the reworked surfaces to as-
sure removal of all tool marks. Most opposed
engines have nitrided crankshafts, and engine
manufacturers specify that these crankshafts
must be re-nitrided after grinding.
g. Exhaust-driven Supercharger
(Turbo) Inspection. Sudden stoppage of the
powerplant can cause the heat in turbine parts
to heat-soak the turbine seals and bearings.
This excessive heat causes carbon to develop
in the seal area and varnish to form on the tur-
bine bearings and journals.
NOTE: Rapid deceleration or mo-
mentary slowing of a propeller may
occur due to contact with tall grass,
water, or snow. If this occurs, the en-
gine and propeller should be inspected
in accordance with the manufac-
turer’s instruction or service bulletins.
(1) Inspect all air ducts and connections
for air leaks, warpage, or cracks.
(2) Remove compressor housing and
check the turbine wheel for rubbing or binding,
and coke or varnish buildup.
NOTE: Turbine turbo supercharger
disk seal rubbing is not unusual and
may be a normal condition. Consult
the engine manufacturer’s inspection
procedures and table of limits.
8-4. REPLACEMENT PARTS IN CER-
TIFICATED ENGINES. Engine replacement
parts must be approved under Title 14 of the
Code of Federal Regulations (14 CFR),
part 21. Serviceable parts obtained from the
engine manufacturer, authorized service facil-
ity, and those which are approved Federal
Aviation Administration (FAA)/Parts Manu-
facture Approval (PMA), or Technical Stan-
dard Order (TSO), and meet the requirements
of part 21 are acceptable for use as replace-
ment parts. Used engine parts can be installed
Par 8-2
Page 8-3