Incident
A pilot reported that during cruise flight, the airplane suddenly began shaking violently. After reducing power, the shaking diminished but did not stop. The pilot identified a suitable field and attempted an off-airport landing. Upon touchdown, the nose wheel dug into the ground, causing the airplane to nose over.
Damage
The accident resulted in damage to the propeller, nose landing gear, wings, and vertical tail.
Investigation
Examination of the engine revealed that the number 5 piston had fragmented. The engine had last been overhauled on April 23, 1993, and had accumulated 740 hours since that overhaul. Logbook records indicated that the piston was a Superior Air Parts unit, part number SA640518.