On August 28, 2006, a Robinson R22 BETA (registration N2649D) was involved in an aviation accident near Frederick, MD. Investigators recorded the probable cause as: The flight instructor's delayed remedial action during a hovering autorotation, which resulted in a hard landing and inadvertent dynamic rollover. 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 and rolled onto its left side after the student pilot initiated a hovering autorotation from about 3 feet.
Incident Overview
During a training flight, a flight instructor and a student pilot were practicing hovering autorotations at an altitude of about 3 feet above the ground. The student, who held a certificated airplane pilot certificate, reduced engine power to begin the maneuver and pushed forward on the cyclic control. As a result, the helicopter began to descend.
Sequence of Events
The flight instructor stated that he took over cyclic control, but the helicopter subsequently impacted the ground "fairly hard and bounced." Following the impact, the student pilot pulled up on the collective control. The left skid remained in contact with the ground, causing the helicopter to roll over onto its left side.
Mechanical Condition
The flight instructor reported that there were no mechanical or performance deficiencies with the helicopter prior to the incident.