NTSB Identification: WPR12LA426
14 CFR Part 91: General Aviation
Accident occurred Wednesday, September 19, 2012 in Mammoth Lakes, CA
Probable Cause Approval Date: 06/11/2014
Aircraft: BELL 206 - B, registration: N222GR
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.

While performing an aerial survey of transmission structures and wires in mountainous terrain at an elevation of about 7,500 feet mean sea level, the pilot initiated a climb to clear a ridge ahead. When he realized that there was no response to an increase in collective, and, with the torque nearing 100 percent, he chose to maneuver the helicopter left of a set of wires, avoid approaching terrain, and establish an approach for a precautionary landing to a dirt road. The pilot reported that, during the approach, he was unable to arrest the helicopter’s descent, and, at the same time, he heard a noise that he assumed was the low rotor rpm warning. The helicopter subsequently impacted terrain just short of the road, rolled over on its left side, and was consumed by the postcrash fire. A postaccident examination of the airframe and engine revealed no mechanical anomalies that would have precluded normal operation. At the time of the accident, the nearest weather reporting facility, which was located 10.5 miles west of the accident site, reported wind at 4 knots, gusting to 14 knots, and a temperature of 24 degrees C. The calculated density altitude for the conditions was about 9,742 feet, which would have affected the helicopter’s climb performance.

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

The pilot’s inability to maintain sufficient main rotor rpm while maneuvering in highdensity altitude conditions, which resulted in a precautionary landing and subsequent rollover.

Full narrative available

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