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Problem
Irregular or low oil
pressure (Cont.)
High oil consumption Incorrect grade of oil
12-30
Page 82
Table 1 (Cont.)
Fault Isolation Guide
Cause
Failed or failing
bearings
NOTICE: Metal in the
oil suction screen or oil
filter is a sign of
excessive bearing wear
New rings are
incorrectly seated.
Piston rings are worn or
incorrectly installed
OR
Cylinder barrels are
glazed or worn too
much
Worn valve guides
Oil leaks
Oil siphoned from
engine during flight
YO-233-B2A Engine Maintenance Manual
TEO-540-A1A Engine Maintenance Manual
Corrective Action
Disassemble the engine for
bearing inspection and
replacement.
Use correct grade of oil.
For break-in, operate the engine at
65% - 75% power for the first 50
– 100 hours.
1. Complete the cylinder
compression check.
2. Complete the borescope
inspection.
NOTICE: Listen for a hissing
sound around the rings which is
an indication of air leaks at the
breather entrance of the
crankcase.
3. Remove the cylinders, replace
the piston rings, and deglaze
the cylinder barrels
1. Remove the cylinders from
the engine.
2. Remove the valves.
3. Measure the guides for wear.
4. Replace the guides that are
worn or out of limits.
Examine the external area of the
engine for leaks, identify and
correct the cause of any leak.
1. Verify that the oil filter cap is
secure, and the oil access door
closes correctly.
2. Make sure that the breather
hose is accurately cut and
installed to prevent siphoning.
© 2021 Avco Corporation. All Rights Reserved
Ref.
OHM
IOM
Appendix A
72-30
OHM
OHM
February 2021
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