Accident Overview
The airplane sustained substantial damage when it nosed over during a forced landing after an in-flight loss of engine power. The certified flight instructor (CFI) and the private pilot sustained serious injuries. According to the CFI, the flight's purpose was to meet the dual instruction requirements of the Wings Program.
Pilot Statement
The CFI's accident report stated: "Upon the completion of the turn the engine lost about 50 [percent] of its power. We thought that we could make it to Kingman Airport and started a course for it. [Approximately three and a half] miles from the airport the engine stopped [abruptly] the prop continued to windmill we made an approach to a wheat field. The pilot made a very good approach and a smooth landing. After approximately 400 ft of ground roll we encountered a terrace. It appears that this caused the nose wheel to shear off. With nothing to support the nose it caused the airplane to flip over on its back."
Maintenance History
The last annual inspection of the airframe and engine was on September 2, 2004, and the tachometer read 3,191.7 hours at that time. That annual inspection's endorsement indicated that the number two and four cylinders were removed during that inspection. The number two cylinder was found with an eroded exhaust and was replaced with an overhauled cylinder.
On-Scene Examination
On-scene examination of the bottom of the fuselage revealed a trail of oil on its left side. Examination of the engine revealed a hole in the top of the crankcase near the number two cylinder. Examination of the oil pressure line from the engine to the turbocharger revealed a loose "B" nut. The tachometer read 3,192.1 hours on-scene.
Engine Disassembly Findings
The engine was disassembled and internal examination revealed that the rod ends for the number one and number two cylinders were discolored, deformed, and separated from the crankshaft. The crankshaft was discolored. The discoloration present was consistent with the heat produced by a lack of lubrication. The examination revealed silver colored and copper colored debris in the oil sump. That debris was consistent with bearing material.
The tee fitting and pressure line with the loose "B" nut were removed from the engine case. The line's end and tee fitting's end were capped off and a fluid under pressure was supplied to the tee fitting. That fluid was observed leaking from the loose "B" nut.