What happened
While in cruise flight, the pilot experienced a continuous vibration. This was followed by oil covering the windshield and a subsequent loss of engine power. Air traffic control vectored the aircraft toward a nearby airport. However, the pilot failed to communicate intentions for a forced landing over the proper UNICOM frequency. Because an aircraft was positioned ahead, the pilot performed a hard landing on the displaced portion of the runway.
The investigation
Investigators identified several holes in the crankcase located near the number 1 and number 4 cylinders. An examination of the engine determined that the connecting rods for the number 1 and number 4 cylinders had failed.
Metallurgical analysis of the failed components showed high stress low cycle fatigue on the number 4 rod. Additionally, investigators found galling in critical areas on the connecting rods and/or caps for the number 1, 2, and 4 cylinders. The engine, which had been overhauled by the manufacturer, had accumulated approximately 1,252 hours of use.