Accident Details
On 12 September 2015 at 0956 UTC, a Robinson R66 helicopter, registered G-LROK, was involved in an accident at Denham Airfield, Buckinghamshire. The aircraft was on a training flight with a single student pilot on board; no passengers were carried. The pilot, aged 49, had 70 hours total flying experience, including 18 hours on type. The helicopter was manufactured in 2015 and powered by one Rolls-Royce 250-C300/A1 turboshaft engine.
Sequence of Events
The student pilot had been training for a Private Pilot License (Helicopter) on the Robinson R44, in which he had flown solo, before transitioning to the R66 approximately 18 flying hours before the accident. On the day of the incident, he completed five dual circuits with his instructor. After landing, the instructor exited the helicopter to allow the student to conduct his first solo flight on the R66. As the student lifted into a hover, the helicopter rolled to the right and the main rotor blades struck the ground. The helicopter came to rest on its side. The student, who sustained minor injuries, was able to vacate the cabin. The instructor, standing approximately 50 yards away, commented that the event appeared to be a dynamic rollover.
Dynamic Rollover
In 1982, the Robinson Helicopter Company issued Safety Notice SN-9 concerning dynamic rollover. The notice states that a dynamic rollover can occur whenever the landing gear contacts a fixed object, forcing the aircraft to pivot about that object instead of its own center of gravity. Once initiated, dynamic rollover cannot be stopped by application of opposite cyclic alone; the most effective way to stop it is to quickly apply down collective.
Outcome
The helicopter sustained damage to the main rotor blades, drive train, transmission bay, tail boom, and windshield. The pilot reported minor injuries.