Engine Failure During Cruise
A pilot experienced an engine failure while operating in cruise flight at 9,000 feet on an IFR flight plan. According to the pilot, the engine gave a jolt and then failed. He requested and received vectors towards the nearest airport. The pilot reported breaking out of the clouds at 1,700 feet MSL over hilly, wooded terrain. He then made a forced landing in a small, muddy corn field. During the landing roll, the pilot intentionally performed a ground loop to avoid trees at the end of the field, causing the airplane to nose over.
Postaccident Examination
Postaccident examination of the engine revealed that the loss of power was due to a failed exhaust valve in the number 2 cylinder. Metallurgical examination of the fractured valve showed fatigue cracking that originated from multiple origins on opposite sides of the fracture face. The engine had accumulated 1,869 hours total time, with 671 hours since its last major overhaul. Examination found no material imperfections, and the material hardness exceeded the manufacturer's minimum specifications.
Forced Landing Details
The pilot's successful navigation to a suitable area and execution of a forced landing in challenging terrain, followed by a deliberate ground loop, resulted in the aircraft coming to rest inverted in the field. The hilly, wooded terrain and low cloud ceiling presented limited options for a safe landing. The pilot's actions were aimed at minimizing damage by avoiding trees at the field's edge.