NTSB Identification: LAX05CA188.
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Accident occurred Wednesday, May 25, 2005 in Jean, NV
Probable Cause Approval Date: 09/13/2005
Aircraft: Robinson R-22 Beta II, registration: N192SH
Injuries: 2 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

During a 180-degree practice autorotation, the main rotor rpm decayed and the helicopter tail boom collided with a boundary fence short of the intended landing spot. As the helicopter rolled out of the 180-degree turn onto final approach, the certified flight instructor and student both noticed that the main rotor rpm had decayed. The student then increased the throttle in attempt to go around and the instructor took the controls. At this point the instructor noticed that the main rotor rpm was at 92 percent and the helicopter was descending. The CFI was unable to stop the decent rate, and the helicopter collided with the fence short of the intended touchdown point and then impacted the terrain. The instructor and student both stated that the helicopter and engine had no mechanical failures or malfunctions during the flight. The density altitude was calculated to be about 5,590 feet.

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

the student's failure to maintain adequate main rotor rpm when performing a180-degree autorotation, and the instructor's inadequate supervision and delayed remedial action. A factor in the accident was the high density altitude.

Full narrative available

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