NTSB Identification: WPR11LA220
14 CFR Part 91: General Aviation
Accident occurred Friday, May 13, 2011 in Columbia, CA
Probable Cause Approval Date: 11/07/2012
Aircraft: MD HELICOPTER 369D, registration: N124AL
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 pilot reported that the helicopter was in cruise flight at 12,500 feet mean sea level over mountainous terrain when power stopped being transmitted to the main rotor system. He performed an autorotation to an open area. During the landing, the tail rotor sustained damage to both blades as they went through about 1 foot of snow. After landing, the engine was still running but was not spinning the main rotor blades. Postaccident examination of the airframe revealed no anomalies that would have precluded normal operation. The drive train was fully functional. The engine was run in a test cell, which confirmed that it met specifications for all parameters including performance. The reason for the loss of engine power could not be determined.

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

The loss of power transmission to the main rotor for reasons that could not be determined because postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation of the helicopter.

Full narrative available

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