19961111035049A

Witness reported that the aircraft wobbled and crashed nose first shortly after takeoff. (.4)according to the pilot, during initial climb, the engine gradually lost power. Subsequently, it crash landed on uneven/rocky terrain and came to rest against trees in an inverted attitude. Density altitude was computed to be about 7,300 feet. 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. No abnormal indications were observed during the subsequent ground check out or takeoff roll. However, during the initial climb, the oil pressure indicator dropped to zero pounds. 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.