Event Sequence
After departing from Zanesville, Ohio, the aircraft climbed to 2500 feet MSL when the engine began to produce a knocking sound. Smoke filled the cockpit and the engine started losing oil. The pilot initiated a turn back to the airport for landing. He reported that the engine continued to run until the aircraft was approximately three-quarters of the way through the downwind leg for Runway 22. At that point, the engine failed completely. The pilot executed a forced landing, touching down approximately 1000 feet short of the runway. The ground conditions were soft, and the landing gear collided with the terrain during the landing.
Examination Findings
A post-accident examination of the engine revealed that the #3 piston had failed and the #3 cylinder was heavily grooved. The #3 cylinder, which had a chrome-plated surface, had been installed approximately 40 flight hours prior to the accident. One of the rings in the #3 piston was also chrome-plated. According to the manufacturer, chrome-plated rings should never be used in chrome-plated cylinders. Additionally, an unauthorized Champion EM-41E hot-running spark plug was used in the #3 cylinder. There was evidence that the initial piston failure was a dome burn-through resulting from detonation on pre-ignition.