Primary finding
Probable cause
The pilot's failure to maintain clearance from power lines during an aerial application flight.
Investigator assessment
Analysis narrative
The pilot was on an aerial application flight and was maneuvering the helicopter at a low altitude. During a decent to a field, the main rotor blade struck a powerline wire. The pilot felt an unusual vibration and performed a precautionary landing. A postflight examination revealed that a main rotor blade sustained substantial damage. No preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation were reported.