Robinson Helicopter Company R-44 II N7530F accident near Toutle, Washington

Probable cause

The pilot’s failure to maintain precise altitude control, which resulted in the helicopter entering a settling with power condition while hovering out of ground effect.

NTSB analysis

The pilot said that he was using a long line to lift harvested evergreen tree boughs from his property on the side of a mountain. The helicopter was hovering out of ground effect, and he was looking outside at ground personnel when the flight controls began to feel "mushy." The pilot stated that the helicopter began "settling with power" and descending. He attempted to turn and fly more directly into the wind but then he heard the low rotor rpm horn. He entered an autorotation to an open area, but, on touchdown, the steep sloping terrain caused the helicopter to slide into trees and come to rest on its right side.

The helicopter was hovering out of ground effect, which created a situation conducive to entering a settling with power (vortex ring state) condition, and the pilot needed to maintain precise altitude control to prevent the condition from developing. The pilot reported no preimpact mechanical malfunctions or failures with the helicopter that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for WPR13LA023 for the full record.