NTSB Identification: WPR10CA470
14 CFR Part 137: Agricultural
Accident occurred Saturday, September 25, 2010 in Gaston, OR
Probable Cause Approval Date: 03/16/2011
Aircraft: BELL 47G, registration: N7860S
Injuries: 1 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The pilot reported that he completed his last forest spray application for the day and was landing on a trailer used for transporting the helicopter. As the skids touched down on the trailer, he lowered the collective to the full down position. The helicopter abruptly tilted aft on the skid heals, and he applied up collective. The helicopter started to rotate to the right and he was unable to counter the rotation with the left anti-torque pedal. The pilot closed the throttle as the helicopter rotated 180 degrees to the right. The helicopter then contacted the side of the trailer and came to a full stop. The pilot reported that the trailer was parked on an uneven surface and that the slope and his abrupt movement of the collective resulted in the tail rotor coming into contact with the trailer. The pilot also felt that the accident could have been avoided if the trailer were on level terrain and he had waited to lower the collective until after establishing positive and complete skid contact with the surface of the trailer. The pilot reported no mechanical failures or malfunctions with the helicopter at the time of the accident.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's failure to maintain tail rotor clearance while landing on a transport trailer positioned on an uneven surface.

Full narrative available

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