Piper PA 28-180 N30865 accident near Big Creek, California

Probable cause

The loss of engine power due to the improper installation of an oil pressure sending unit by the pilot, who was not a certificated mechanic, which resulted in a forced landing in mountainous terrain.

NTSB analysis

The pilot, who was a co-owner of the airplane, reported to an air traffic controller about 1 hour into a cross-country flight over mountainous terrain that the engine had lost oil pressure and then power. The pilot performed a forced landing into trees. Postaccident examination revealed that the loss of engine power resulted from oil starvation due to oil leaking from a fractured fitting at the oil pressure gauge/sending unit port on the engine's rear accessory case. An oil pressure sending unit, which the pilot, who was not a certificated mechanic, had installed at this location just before the accident flight, was found dangling by its electrical wiring harness and not supported. The sending unit was not approved for installation on this airplane. It is likely that the fitting fractured because of vibration due to the sending unit's lack of support. The engine operating time between the installation of the sending unit and the fitting fracture was about 1 hour.

Text from the NTSB. Open the NTSB docket for WPR14LA031 for the full record.