Primary finding
Probable cause
The pilot’s failure to maintain clearance from powerlines during a low-level aerial application flight.
Investigator assessment
Analysis narrative
The pilot reported that he observed several power lines when performing reconnaissance flights prior to beginning spraying operations. He attempted to avoid them as he began applying the fungicide to the corn field; however, the helicopter impacted a green, thin power line “less than the diameter of a pencil” that the pilot had not previously observed. The helicopter began to vibrate and became difficult to control. The pilot initiated a 180° right turn to avoid trees and the helicopter impacted the ground, which resulted in substantial damage to the fuselage and empennage. The pilot stated that the helicopter had no preimpact mechanical malfunctions or failures that would have precluded normal operations.