Incident Overview
The flight was level at 17,500 feet mean sea level when, 40 minutes into the flight, the engine began to run extremely rough. This condition lasted for approximately 10 to 15 seconds, after which the engine abruptly stopped.
Postaccident Examination
A detailed examination of the engine was conducted following the incident. The investigation revealed that the number 1 connecting rod had failed, resulting in a catastrophic failure of the engine. Further scrutiny of the engine components showed that the number 1 main bearing oil supply hole had been blocked, preventing oil from reaching the number 1 connecting rod.
Bearing and Connecting Rod Findings
Examination of the number 1 main bearing halves disclosed evidence of operational movements on one bearing half. This bearing half had fractured and disintegrated, and the debris blocked the oil supply hole. As a consequence of the oil starvation, the number 1 connecting rod failed.
Conclusion
The failure sequence was initiated by the disintegration of the number 1 main bearing half, which obstructed the oil supply to the connecting rod. The subsequent lack of lubrication caused the connecting rod to fail.