What happened
While cruising at 4,500 feet MSL approximately 15 miles north of Bloomington, Indiana, the aircraft began to experience excessive vibration. Upon checking the oil pressure gauge, the pilot observed a reading of zero. In response to the engine failure, the pilot shut down the engine and initiated a forced landing into a nearby field.
As the aircraft began to settle during the descent, the pilot identified a guard rail adjacent to a road directly ahead. The pilot attempted to pull back on the controls to clear the obstacle; however, the airplane lacked sufficient airspeed to do so. The aircraft struck the guard rail and came to a stop. The pilot and passenger were not injured and managed to exit the aircraft before it caught fire and burned.
The investigation
An examination of the engine revealed that the connecting rods for the number 5 and number 6 cylinders were broken. Additionally, investigators located a six-inch by 4-inch hole in the top of the engine crankcase, positioned just above the number 5 and number 6 cylinders.