Primary finding
Probable cause
loss of engine power as a result of detonation in the number 2 cylinder for undetermined reasons. A factor in the accident was the unsuitable nature of the forced landing area.
Investigator assessment
Analysis narrative
The airplane lost engine oil pressure followed by seizure of the engine. The flight instructor attempted to glide to a nearby private strip but had insufficient altitude and elected to land gear up on rough level terrain. Evidence of detonation was found in the number 2 cylinder. The number 2 piston was damaged and aluminum from the piston restricted the flow of oil. The number 2 piston rod bearing failed as a result of loss of lubrication. One of the bolts to the number 2 piston rod cap broke, jamming the rotation of the crankshaft. The reason for the detonation in the number 2 cylinder could not be determined.
Source record
Factual narrative
On March 31, 1997, at 0839 hours mountain standard time, a Piper PA-28R-200, N2226T, lost engine power and landed gear up off the airport near Continental, Arizona. The airplane was being operated as an instructional flight by Leading Edge Aviation, Tucson, Arizona. The airplane was substantially damaged. The certified flight instructor received minor injuries and the certificated commercial pilot/student received serious injuries. The local flight originated in Tucson about 0820. Visual meteorological conditions prevailed at the time. The pilots reported the airplane lost engine oil pressure followed by seizure of the engine. The flight instructor attempted to glide to a nearby private landing strip but had insufficient altitude and elected to land gear up on rough level terrain. After the accident, the engine was disassembled and examined by the Federal Aviation Administration (FAA) Airworthiness Inspector. According to the FAA, there was evidence of detonation in the number 2 cylinder. The number 2 piston was found damaged, and aluminum from the piston was found in the engine oil screen restricting the flow of oil. The number 2 piston rod bearing exhibited evidence of heat distress and appeared to the inspector to have failed as a result of loss of lubrication. One of the bolts to the number 2 piston rod cap was found broken, jamming the rotation of the crankshaft. According to the FAA inspector, the reason for the detonation in the number 2 cylinder could not be determined. -