NTSB Identification: LAX05LA278.
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Accident occurred Saturday, March 26, 2005 in Los Banos, CA
Probable Cause Approval Date: 04/25/2006
Aircraft: Robinson Helicopter Company R22 Beta, registration: N820SH
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 made a hard landing following a loss of engine power during a practice autorotation. The instructor pilot reported that while in cruise he simulated a loss of engine power. The student, who was studying to become a flight instructor, initiated an autorotation to a field. When the instructor attempted to apply engine power following the practice autorotation, the engine "immediately quit." The instructor applied full collective to cushion the landing, but the helicopter landed hard in the field, structurally damaging the tail boom and the fuselage. Following the accident, the operator returned the helicopter to their facility and test ran the engine. No anomalies were noted, and they believed the conditions were suitable for the development of carburetor ice during the autorotation. Review of archived weather data for the day of the accident revealed the closest weather observation facility reported the temperature and dew point as 6 and 5 degrees Celsius, respectively. Plotting of those temperatures on a carburetor icing probability chart revealed that conditions likely existed for serious icing at any power setting.

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

the instructor pilot's failure to apply carburetor heat during a simulated engine failure, which resulted in a total loss of engine power due to carburetor icing.

Full narrative available

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