Accident Description
According to the pilot, the aircraft was approximately one-quarter mile from the airport at an altitude of 50 feet during the initial climb when the engine began to experience a severe vibration. Shortly thereafter, the engine stopped abruptly. The pilot identified the only available landing area, a muddy field, and executed a landing. During the ground roll, the aircraft nosed over.
Engine Examination
A preliminary examination of the engine revealed that the crankshaft was seized and would not rotate. Partial disassembly of the engine disclosed that it had sustained a catastrophic internal failure. Specifically, the No. 5 piston, which is the master piston, was found outside its respective cylinder. The connecting rod associated with that piston was elongated and bent. The rod end cap was attached on one side but separated on the other. Evidence of heat and stretching was observed near the crankpin area of the rod. Due to the extent of internal damage, the bearing could not be examined.
Findings
The investigation determined that a catastrophic internal engine failure occurred, resulting in a complete loss of engine power. The pilot's selection of a muddy field as the landing area was appropriate given the circumstances, though the soft terrain likely contributed to the nose-over during the landing roll.