Incident Overview
During cruise flight, an airplane suffered an engine cylinder barrel failure, necessitating a forced landing on unsuitable terrain. The landing resulted in substantial damage to the aircraft.
Cylinder Repair History
The failed cylinder had been previously repaired by a Federal Aviation Administration (FAA) Approved Repair Station. It had been installed on the aircraft only 11 hours prior to the accident.
Post-Accident Examination Findings
Examination of the engine after the accident revealed that the number 3 engine cylinder steel barrel had separated completely around its circumference, a 360-degree fracture. Detailed inspection of the failed cylinder barrel identified fatigue cracking that originated from a rusty area on the cylinder barrel. Additionally, the cooling fins exhibited rust damage that had the appearance of being profiled by filing or grinding.
Conclusion
The investigation documented the cylinder barrel failure and the presence of fatigue cracking from a corroded region, as well as the unusual appearance of the cooling fin damage.