History of the Flight
The accident occurred on 19 February 2019 at 1138 UTC near East Lound, Doncaster, during a circuit training flight for a student working toward a Helicopter Private Pilot's License. The commander, a 24-year-old commercial pilot with 650 hours total (117 on type), was conducting the training. The weather was CAVOK with light winds. Because the circuit at Doncaster's training school was busy, the commander chose to use a local grass airstrip.
The student had been progressing well and had recently completed a first solo flight. Five circuits and landings had been completed, followed by a debrief. The student was controlling the helicopter for the subsequent lift-off. As the helicopter became light on the skids, it began to roll slightly to the right. The student recognized this, stopped raising the collective, and applied a small amount of left cyclic. This correction was insufficient to fully stop the right roll. The student then abruptly applied full left pedal. The helicopter yawed left, lifted from the ground onto the back of the skids, then bumped forward and right. The front right portion of the skid caught the ground, and the helicopter rolled to the right, coming to rest on its right side. Both occupants exited without injury. The commander recalled the event lasted approximately two seconds.
Dynamic Rollover
Dynamic rollover occurs when a helicopter rolls about a fixed point, typically a wheel or skid. As the helicopter rolls, main rotor thrust tilts in the same direction, causing further roll. Beyond a certain angle, cyclic control cannot prevent the helicopter from rolling onto its side. The effect is more pronounced with a right roll on this helicopter because tail rotor thrust also contributes to right roll.
Analysis
As the helicopter became light on the skids, the student pilot applied full left pedal in reaction to the right roll. This caused the helicopter to enter a dynamic rollover. The commander was unable to react quickly enough to prevent the accident.
Additional Observations
The commander reflected that he may have been more relaxed due to the student's prior good performance and that he should have been closer to the controls during the lift. However, instructors must balance prompt intervention with allowing a student to make and correct errors for learning. The student reported that recent fixed-wing flight training may have contributed to the accident.