NTSB Identification: LAX08LA196
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Accident occurred Tuesday, June 24, 2008 in Buffalo, WY
Probable Cause Approval Date: 01/29/2009
Aircraft: SCHWEIZER 269C, registration: N432MS
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The helicopter pilot was picking up a biologist who was conducting land surveys. Prior to landing he circled the landing zone to observe the wind conditions. During the landing approach he transitioned out of effective translational lift earlier than expected, and attributed this to a reduced headwind caused by the enclosed terrain. During departure and acceleration to effective translational lift speed, the rotor speed began to decay. The ground speed was faster than he anticipated so he lowered the collective, and added forward cyclic, but could not maintain enough rotor speed for sustained flight. The pilot elected to land the helicopter ahead on a 30-degree uphill slope. After landing, the helicopter rolled back and the tail rotor made contact with the ground causing substantial damage to the tail rotor drive system. After the accident the pilot noted that the winds had shifted 180 degrees from his initial pre-accident observation.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's attempted downwind takeoff that resulted in an aborted takeoff. Contributing to the accident was the unsuitable terrain. Full narrative available
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