Primary finding
Probable cause
The pilot’s failure to see and avoid power lines while maneuvering at a low altitude. Contributing to the accident was the pilot’s failure to adequately identify hazards to flight during agricultural application operation planning.
Investigator assessment
Analysis narrative
The helicopter pilot reported that he was maneuvering at low altitude during an agricultural application flight. While in a left turn, he did not see the power lines until they were very close. He increased the collective to climb, and he banked right to avoid impact. However, the tail rotor struck the power lines, and the helicopter lost tail rotor effectiveness. The pilot conducted an autorotation and landed the helicopter, but the tailboom impacted trees. The helicopter sustained substantial damage to the tail rotor gear box, the tail rotor blades, and the vertical stabilizer. The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.
Source record
Factual narrative
The helicopter pilot reported that he was maneuvering at low altitude during an agricultural application flight. While in a left turn he did not see the power line wires until they were very close. He increased the collective to climb and he banked right to avoid impact. However, the tail rotor struck the power line wires and the helicopter lost tail rotor effectiveness. The pilot autorotated and the helicopter landed, but the tailboom impacted trees. The helicopter sustained substantial damage to the tail rotor gear box, the tail rotor blades and the vertical stabilizer. The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.