On July 24, 2007, a Robinson R22 BETA II (registration N147SH) was involved in an aviation accident near Boise, ID. Investigators recorded the probable cause as: The student pilot's failure to maintain rotor rpm resulting in an excessive descent rate and a hard landing. Factors in the accident were the student's failure to relinquish the controls, and the CFI's inadequate supervision. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a training flight, a helicopter experienced a hard landing after a practice autorotation. The student allowed rotor rpm to decay, leading to a struggle for control between the student and instructor. The helicopter spun and came to rest on its left side.
Incident Overview
A flight instructor reported an incident that occurred during a training flight involving a practice autorotation. The event took place while the student was performing the fifth such maneuver of the session.
Sequence of Events
According to the instructor, during the practice autorotation, the student permitted the rotor rpm to decrease to a level that prompted the certified flight instructor (CFI) to intervene. The CFI attempted to take over the controls and execute a run-on landing. However, both the student and the CFI then struggled with one another for control of the helicopter.
This struggle continued until the helicopter contacted the ground with significant force. During the impact, the helicopter spun around and ultimately came to rest on its left side.
Outcome
The helicopter sustained damage as a result of the hard landing and subsequent roll onto its side. No further details about the aircraft or individuals involved were provided in the report.