Sikorsky S-55B N855TC accident near Brewster, Washington

Probable cause

The pilot did not maintain main rotor rpm while hovering in gusting wind conditions.

NTSB analysis

The helicopter pilot was conducting a low-level flight over orchards for the purpose of drying cherry trees. The orchard was bordered by a series of power lines, and a gusting, variable wind was present at the time of the flight. During a low hovering pass over the orchard, a gust of wind pushed the helicopter toward power lines. In an attempt to avoid the power lines, the pilot increased collective pitch, and the helicopter began to climb. During the climb, the main rotor rpm decayed and the nose of the helicopter yawed to the right. The pilot lowered the collective and increased the engine power in an effort to regain main rotor rpm; however, the helicopter descended into the orchard. The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operations, and that the accident could have been prevented if the flight had been conducted after the wind diminished.

Text from the NTSB. Open the NTSB docket for WPR11LA356 for the full record.