Accident Summary
The pilot reported that while cruising at an altitude of 5,500 feet mean sea level, the engine began to run rough and gradually lose power. Attempts to reach an airport were unsuccessful as the engine subsequently lost all power. The airplane subsequently contacted trees and cartwheeled into an open field.
Engine Examination
Post-accident inspection of the engine revealed detonation and disintegration of the number two piston. Additionally, seven spark plugs exhibited metal fouling. Bench testing of the fuel system, including the fuel distributor, lines, and nozzles, showed no discrepancies. Similarly, both magnetos, magneto timing, and the ignition harness were found to be without discrepancies.
Maintenance History
According to the manufacturer's service bulletin 91-8, the recommended time between overhaul (TBO) for the IO-520 engine is 1,700 hours. At the time of the accident, the engine had accumulated 1,560 hours since its last overhaul. The number two cylinder had been replaced 817 hours prior to the accident. All six cylinders had been replaced at different times within the previous 998 hours.