Incident Overview
A helicopter conducting a low-altitude powerline patrol mission descended and subsequently collided with upsloping terrain. The event resulted in damage to the aircraft.
Investigation Findings
Post-accident examination revealed that the clutch spring assembly was fractured. The fracture involved the assembly retainer end, which had separated from the main assembly. The retainer wall exhibited severe wear at the location where the separation occurred.
Component Function
The clutch spring assembly is designed to engage the belt drive system. This system transmits engine power to the main transmission, enabling rotor operation.
Maintenance History
The helicopter had accumulated over 11,000 total flight hours prior to the incident. The most recent inspection of the clutch spring assembly took place approximately one month before the accident during a scheduled 100-hour inspection. A review of maintenance records indicated that the assembly had never been replaced previously.