Cessna 210 N3997Y accident near Romona, California

Probable cause

A total loss of engine power due to oil starvation as a result of the failure of an oil filter adapter fiber gasket.

NTSB analysis

The airplane engine’s rpm became erratic, and the pilot decided to divert. About 5 miles from the intended airport, the airplane began to shake, and the pilot made an off-airport landing.

Postaccident examination revealed several holes in the engine crankcase. The oil filter adapter was found loose, and the fiber gasket was protruding beyond the castings. Removal of the oil filter adapter revealed that the fiber gasket had torn. The failure of the fiber gasket allowed oil to exit the engine, resulting in oil starvation and a subsequent total loss of engine power.

During postaccident testing, the gasket failure in the accident adapter could not be replicated, and the reason for the failure could not be determined. The testing did reveal that the adapters were difficult to install properly and that, when the proper torque was achieved, the adapter housing could still be rotated about its hub when manual pressure was applied, indicating that the housing was loose. In response to this accident investigation, the supplemental type certificate holder issued a service bulletin that stated that the adapter should be inspected for oil leakage and gasket damage. The service bulletin also provided detailed instructions to eliminate rotation of the housing during installation and identify rotation after installation.

In addition, the Federal Aviation Administration issued an airworthiness directive that requires operators to replace the oil filter adapter fiber gasket with a copper gasket to prevent an engine power loss due to oil starvation.

Text from the NTSB. Open the NTSB docket for WPR19LA166 for the full record.