Overview
According to the pilot, during the initial climb after takeoff, the engine gradually lost power. Subsequently, the aircraft crash landed on uneven and rocky terrain, coming to rest in an inverted attitude against trees. The density altitude at the time was computed to be about 7,300 feet.
Pilot's Account
The pilot reported that prior to the flight, when he first started the engine, no indication of oil pressure was observed. He shut down the engine and purchased 1 quart of oil, which he added. During the subsequent ground check-out and takeoff roll, no abnormal indications were observed. However, during the initial climb, the oil pressure indicator dropped to zero pounds.
Engine Examination
A teardown examination of the engine was performed. The crankshaft assembly revealed signatures consistent with heat distress in the number 2 main journal area. The oil pump's drive shaft was found broken. A foreign metal object was observed wedged between the teeth of the pump's driving and driven gears, and the engagement end of the oil pump drive shaft was found sheared off. The foreign object resembled a small bolt or screw, which was not used in the manufacture of the engine.