On October 3, 2000, a Robinson R22 BETA (registration N8340N) operated by Helistream, Inc. was involved in an aviation accident near Long Beach, CA. Investigators recorded the probable cause as: The dual student's improper use of the collective and the flight instructor's inadequate supervision during the practice hovering autorotation maneuver. A factor was the underlying soft dirt terrain, which promoted the rollover event. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a training flight, a flight instructor directed a student to perform a practice autorotation from a low hover. The student lowered the collective rapidly, causing the helicopter to descend and the left skid to dig in, resulting in a rollover.
Accident Details
On a training flight, a flight instructor (CFI) and a student pilot were performing a practice autorotation. Both were handling the flight controls. The CFI directed the student to enter the autorotation while the helicopter was hovering between 2 and 3 feet above a dirt field. The student responded by rapidly lowering the collective, causing the helicopter to descend. Before the CFI could regain control, the helicopter's left skid touched down in the dirt and dug in. Subsequently, the main rotor blades struck the ground, and the helicopter rolled onto its side.
Preceding Maneuvers
During the five minutes before the accident, the student had successfully performed the training maneuver without exhibiting any unusual difficulties.
Instructor Experience
The CFI had accumulated 1,800 hours of dual instruction experience in the Robinson helicopter. In the 90 days preceding the accident, the CFI had provided 180 hours of instruction to various students in the same type of helicopter.