Casualties unknown

Helicopter Autorotation Training Incident Results in Rotorcraft Damage (N428MS)

Three Forks, MT, US

On July 30, 2007, a Hughes 269C (registration N428MS) was involved in an aviation accident near Three Forks, MT. Investigators recorded the probable cause as: The student pilot's improper execution of the autorotation maneuver, which resulted in loss of tail rotor effectiveness and subsequent loss of control. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

During a training flight, a student pilot practicing an autorotation experienced insufficient tail rotor effectiveness, leading to an uncontrolled spin and ground contact that damaged the aircraft.

What happened

The incident occurred during a routine training flight involving a helicopter. The instructor reported that the crew was conducting practice maneuvers specifically focused on autorotation procedures. As the student pilot initiated the cyclic flare phase of the maneuver, the tail section of the rotorcraft made contact with the runway surface.

Following this initial impact, the student attempted to recover power while the instructor began assisting with control inputs. However, the instructor noted that there was very little tail rotor effectiveness available at that moment. Consequently, the aircraft began an uncontrolled spin. The rotorcraft made additional contact with the ground before coming to a final rest on its left side.

The investigation

Post-acc examination revealed no evidence of mechanical failure or malfunction with the helicopter prior to the accident. The pilot reported that the airframe was functioning normally before the training maneuver began, indicating that the incident was likely due to operational factors rather than equipment failure.

Probable cause

The student pilot's improper execution of the autorotation maneuver, which resulted in loss of tail rotor effectiveness and subsequent loss of control.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20070808X01144. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.