Incident Overview
The flight experienced a rapid drop in oil pressure shortly after engine RPM increased abruptly. Within minutes, RPM decreased and the engine failed. While attempting a forced landing in darkness, the aircraft struck an object just before touchdown.
Investigation Findings
Examination revealed that the oil line to the governor had failed. The line had been replaced recently, and the aircraft had accumulated only five flight hours since the repair. The fracture occurred due to fatigue at the forward end of the line, which was beveled for a fitting.
Component Differences
According to the investigation, the original oil line specified by the engine manufacturer is part number 75A69, fabricated from AMS 5566 stainless steel. The failed line, however, was made from a low carbon steel alloy. It failed after only five hours of operation.