Incident Overview
While cruising at 9,500 feet, the pilot heard a loud metallic bang. Immediately following the noise, the airframe began to shake violently and the engine ran rough. The pilot turned toward a nearby airport, and shortly thereafter the engine suddenly quit.
Emergency Landing
The pilot glided toward the airport and touched down on the 3,300-foot-long runway. However, he had intentionally carried extra speed on approach to provide a maneuvering margin to avoid a large ravine located off the approach end of the runway. After touchdown, the airplane was unable to stop within the runway length and ran off the end, subsequently striking scrub brush.
Postaccident Examination
Examination of the engine revealed that the number three cylinder had separated in half between the Nos. 9 and 10 cooling fins. Metallurgical analysis determined that the fracture was due to a fatigue crack that had originated from a notch and groove on the outer radius of one cooling fin. The notch and groove were painted the same color as the engine.
Maintenance History
The engine had been overhauled 16 hours prior to the accident. During the overhaul, three new cylinders were installed, including the cylinder that failed.