Oil Filters

The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts.


Cessna Model 172S Skyhawk SP

Possible Contaminated Oil Filter

Following a scheduled oil and filter change, the technician noted lower-than-normal oil pressure at idle. The new filter (p/n CH48110-1) was replaced and oil pressure indication was normal. Examination of the replaced filter noted some paint chips had been removed in the flange area. The submitter suspects that a paint chip could have contaminated the filter, causing it to go into bypass. These filters are packaged in cardboard boxes. There was no damage noted to the box containing the filter.

Part total time: 0.0 hours

Cessna Model T206H Turbo Stationair

Abraded, Cracked Oil Filter

After landing for fuel, the pilot noted oil was visible long the entire bottom of the fuselage. Investigation led to the vacuum pump cooling shroud assembly, which had loosened, rotated and come in contact with the oil filter. The abrasion, with engine running and system pressurized, caused an approximate one-inch crack to develop, allowing oil to escape the system. Four liters of oil topped off the crankcase, the filter was replaced and the shroud repositioned. No further oil leaks noted.

Part total time: unknown


Diamond DA20C1

Damaged Bypass Valve

During the ground run following a scheduled oil and filter change, oil pressure failed to rise above 10 psi. The engine was immediately shut down. After swapping oil pressure sender and gauge, and inspecting/resurfacing the oil pressure relief valve, a certified pressure gauge was used and gauge accuracy verified. At this point, the oil filter (p/n CH48109-1) was replaced and oil pressure was found well into the green. The removed oil filter was cut open and revealed damage to the valve opposite the coil spring the filter’s base. The coil spring was noted as possibly being distorted when compared to another spring. The inside of the replaced oil filter can showed impact marks. The good oil filter was from the same batch and date code.

Part total time: 0.0 hours

Piper PA-28-161 Warrior II

Defective Oil Filter Threads

Upon removing the oil filter (p/n AA48111) during an engine oil change, the filter seemed to be very difficult to break loose. After its eventual removal, it was noticed that the threaded stud was still threaded into the engine, though not tightly.

Part total time: 60.0 hours

Piper PA-36-300 Pawnee Brave 300

Faulty Oil Filter

After an oil change with a new filter (p/n AA481102), the engine pumped oil overboard. Examination revealed the oil filter mounting stud was only threaded to a length of approximately 0.2500 of an inch.

Part total time: 0.0 hours


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