Accident Sequence
While en route to the destination airport, the pilot informed air traffic control of a rough running engine and requested the nearest airport. After receiving vectors, the pilot subsequently reported a total loss of engine power and indicated an intention to land on a road. The aircraft touched down in a parking lot, continued approximately 50 feet, and impacted a building, after which a fire ensued.
Witness Report
A witness on the ground reported that the engine sounded as if all cylinders were not firing.
Engine Examination
Post-accident examination of the engine revealed that the number 2 cylinder had become displaced from the crankcase. The connecting rod associated with that cylinder was separated from the crankshaft. The studs used to attach the cylinder to the crankcase were found to be fractured due to fatigue. Continued engine operation after the cylinder separation fractured the connecting rod, producing mechanical damage inside the crankcase.
Maintenance History
According to maintenance records, 22 months before the accident, the engine case was repaired following identification of a crack. The engine was reinstalled and the aircraft returned to service two months later, at which time the engine had accumulated 977 hours since major overhaul. The most recent 100-hour inspection, performed one month prior to the accident, recorded 1,409 hours since major overhaul and noted no anomalies. The investigator could not determine if a specific maintenance action initiated and allowed the fatigue crack to develop.