ASN Wikibase Occurrence # 287365
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| Date: | Wednesday 19 September 2012 |
| Time: | 11:25 LT |
| Type: |  Bell 206 - B |
| Owner/operator: | Chesapeake Bay Helicopters |
| Registration: | N222GR |
| MSN: | 1638 |
| Year of manufacture: | 1975 |
| Total airframe hrs: | 21667 hours |
| Engine model: | Rolls-Royce 250 C20B |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Mammoth Lakes, California -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Survey |
| Departure airport: | Mammoth Lakes Airport, CA (MMH/KMMH) |
| Mammoth Lakes Airport, CA (MMH/KMMH) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Probable Cause: The pilot's inability to maintain sufficient main rotor rpm while maneuvering in high density altitude conditions, which resulted in a precautionary landing and subsequent rollover.
Accident investigation:
 |
|
Sources:
NTSB WPR12LA426
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 04-Oct-2022 10:09 | ASN Update Bot | Added |
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