What happened
The pilot and passenger were engaged in the second leg of a cross-country flight when, approximately thirty minutes into the flight, a vibration began. This was followed by oil seeping from the engine cowling. Within seconds, the engine failed, and oil coated the airplane windshield.
Due to the lack of forward visibility caused by the oil, the pilot performed a forced landing in an open field. The pilot was unable to stop the aircraft before it struck trees located at the end of the field. Both occupants were not injured.
The investigation
Mechanical examination of the engine revealed that the number two cylinder had separated from the engine. Of the eight cylinder studs, seven had sheared. One stud remained intact and undamaged. An upper stud was found to be partially rusted across, while the remaining portion of that specific stud had sheared cleanly. The engine had undergone an overhaul 362 tach hours prior to the failure at a local facility.