Primary finding
Probable cause
The mechanic’s incorrect installation of the oil temperature gauge probe in the oil filter adapter and failure to test run the engine for oil leaks after the installation, which resulted in a total loss of oil and the pilot’s decision to perform a precautionary landing. Contributing was the pilot’s long/fast landing, which resulted in a runway overrun.
Investigator assessment
Analysis narrative
The pilot reported that the accident flight was the first flight after an annual inspection was completed and a new oil filter adapter was installed. As part of the installation, the mechanic installed the oil temperature gauge probe into the oil filter adaptor housing. The engine was not test run and inspected for oil leaks following the installation. Before the flight, the pilot completed an engine run-up and prolonged taxi to ensure the engine was near operating temperature. During the run-up he did not notice any abnormalities and the engine gauges were indicating correctly. The takeoff and entrance into the traffic pattern were uneventful until the upwind leg when he noticed the oil pressure gauge indicated 0 psi and the engine made unusual sounds, but the engine was still running. He completed at 180° turn and set up for landing on another runway with a tailwind. The airplane was high and fast on approach, then landed long and ran off the end of the runway. The airplane nosed over in a snowbank and came to rest inverted resulting in substantial damage to both wings and empennage. After the accident, the pilot accessed the engine compartment and removed the oil filler cap where he observed no remaining oil in the engine. Postaccident examination of the airplane revealed engine oil was observed covering the engine compartment, surrounding areas, and the leading edges of the airplane. Oil was added to the engine and a functional test run was completed. An oil leak was observed from the oil temperature gauge probe that was installed in the back of the oil filter adaptor. The oil temperature probe threaded into the housing, but the oil temperature probe was not seated properly and remained loose after the attachment nut was tightened.; it could not be seated without utilizing a specific adaptor fitting. The adaptor fitting was removed from the old housing and installed onto the new oil filter adaptor. After installation, the oil temperature probe seated properly.