IO-390-D Series Engine Maintenance Manual
72-20
© 2020 Avco Corporation. All Rights Reserved
Page 140
March 2020
IO-390-D Series Engine Maintenance Manual
6.
Crankshaft Inspection
A.
Before cleaning the crankshaft, initially examine the crankshaft gear and crankshaft inner
diameter and external surface for evidence of pitting and wear. These conditions are of
particular importance when they occur on the involutes of the crankshaft gear teeth. Replace
the crankshaft gear if there is any pitting or wear.
B.
Clean the crankshaft per “Crankshaft Cleaning” and “Crankshaft Counterbore Cleaning”
procedures in Chapter 05-30. Prior to inspection, the crankshaft counterbore must be clean,
dry, and free of debris. Make a copy of the Crankshaft Inspection Checklist to record the
condition of the crankshaft and any corrective action.
C.
Continue with the crankshaft inspection. Do not make scores, scratches, or etch markings of
any kind on the crankshaft. A mark in any of these areas can cause the crankshaft to weaken
and to possibly fail.
Crankshaft Inspection Checklist for IO-390-D Series Engines
Engine Model Number__________________ Engine Serial Number:__________________
Engine Time:______________________ Date Inspection Done: _____________________
Inspection done by:______________________________
Item
Comments
Findings/
Corrective Action
Done
Carefully examine all surfaces
of the crankshaft for cracks,
gouges, nicks, dents, or
damage.
If a crack is found, replace the
crankshaft.
Do NOT try to repair
a cracked or damaged
crankshaft.
Acceptable
Replace
Complete a magnetic particle
inspection on the crankshaft.
Refer to the “Non-Destructive
Testing” section in Chapter 05-50.
Acceptable
Replace
Use a flashlight, magnifying
glass, and angled inspection
mirror to visually examine the
inner diameter of the crankshaft
bore (Figure 24), starting at the
crankshaft flange end. Look for
pit marks and corrosion.
"Pitting" looks like holes,
cracks, or fissures of
unspecified depth or direction.
If corrosion is found, replace the
crankshaft.
If pitting is found, complete a
Fluorescent Penetrant Inspection
(FPI) (per the section "Non-
Destructive Testing" in Chapter
05-50).
Acceptable
Replace
Measure the inner diameter of
the crankshaft. Record the
measurement. Refer to Figure
24.
For a crankshaft to be acceptable,
the inner diameter must not be
more than 1.910 in. (4.851 cm). If
the inner diameter of the
crankshaft is more than 1.910 in.
(4.851 cm), replace the crankshaft.
Inner diameter
measurement:
_______ inches
or
______ centimeters
