On August 27, 2005, a Robinson R22 BETA (registration N845SH) was involved in an aviation accident near Boise, ID. Investigators recorded the probable cause as: Inadequate communications between the certified flight instructor and student pilot, and the student pilot's delay in relinquishing controls resulting in a hard landing during a practice autorotation. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During the tenth power recovery autorotation, a struggle for control led to a hard landing and substantial damage to the helicopter. The instructor reported no verbal transfer of control.
Incident Overview
A helicopter instructor pilot and a student pilot were practicing power recovery autorotations at the Boise airport. During the tenth practice autorotation, the student pilot was on the controls when the instructor observed a lower than normal main rotor RPM, approximately 94 percent.
Control Transition
The instructor pilot elected to take the controls to make necessary inputs for recovery. However, during the transition at an altitude of about 60 feet above ground level, a struggle for control ensued. This delayed corrective action, resulting in a hard landing.
Damage and Aftermath
The hard landing caused substantial damage to the helicopter. The instructor pilot noted that he does not recall verbalizing the transfer of control to the student pilot.