Introduction
A helicopter conducting aerial application operations experienced a complete loss of engine power while returning to the loading area. The subsequent forced landing resulted from a mechanical failure.
Sequence of Events
After completing an aerial application flight, the pilot was returning to the loading area when the helicopter sustained a total loss of power. During the subsequent autorotation, the pilot attempted to sideslip the helicopter between almond trees but was unable to do so.
Examination Findings
An examination of the engine and subsequent metallurgical analysis disclosed that the No. 3 cylinder connecting rod bolt had failed due to fatigue. Company maintenance personnel reported that the fatigue was caused by consistent engine overspeed power settings by the pilots flying the helicopter.