Engine Failure
The flight experienced a complete engine failure when the crankshaft failed. The failure was due to fatigue cracking of the crankshaft cheek between the number 1 and 2 rod bearing journal.
Forced Landing
During the subsequent forced landing, the aircraft collided with trees. The pilot chose not to land on a dirt road because of an unsafe indication on the nose landing gear.
Maintenance History
Examination of the engine's records revealed that the engine had sustained a sudden stoppage in mud 25 flight hours before the crankshaft failure. The engine was not disassembled and inspected at that time, as required by the engine manufacturer.
Additionally, the engine had accumulated 1,788 total flight hours since its last factory overhaul. The manufacturer recommends that the engine be overhauled every 1,600 flight hours.
Conclusion
The accident sequence involved a complete engine failure caused by a fatigue-cracked crankshaft, followed by a forced landing that ended in a tree collision due to the pilot's decision to avoid a dirt road based on an unsafe landing gear indication.