What happened
The pilot was conducting an agricultural spraying operation when he reached the end of a pass. As he initiated a turn to begin the next run, the helicopter collided with a power line. The pilot reported that a quartering tailwind condition caused the aircraft to assume a nose-high attitude at the critical moment. This pitch-up resulted in the tail rotor striking the wire.
Following the impact, the helicopter entered an uncontrolled spin for several turns. The pilot successfully initiated an autorotation to regain control and descend. However, the descent rate was excessive, resulting in a hard landing. The impact force ruptured the fuel lines on the aircraft, which subsequently ignited a fire.
The investigation
The investigation focused on the mechanical failure of the tail rotor system upon contact with the power line. Examination confirmed that the tail rotor blades struck the wire, leading to immediate loss of directional control. Post-accident inspection revealed significant damage to the airframe structure consistent with a hard landing. Fuel lines were found ruptured at multiple points, confirming the source of the post-crash fire.
Findings
The primary factor in this accident was the pilot's failure to maintain adequate clearance from the power line during the turn. Contributing to the severity of the outcome was the hard landing caused by the loss of control following the initial impact. The quartering tailwind likely exacerbated the difficulty in maintaining proper attitude and airspeed during the maneuver.
Safety message
Pilots conducting low-level agricultural operations must remain vigilant regarding overhead obstructions, particularly power lines which can be difficult to see against bright skies or vegetation. Proper planning of spray patterns and turn radii is essential to avoid such hazards.