What happened
On 22 September 1998, a Rotorway Executive 90, registration G-MAMC, was conducting a private training flight at Cumbernauld Airport near Glasgow. The flight was intended as a refresher session for the aircraft owner, who was being instructed by a manufacturer-sponsored instructor. During the transit to the designated exercise area, the crew had identified a section of the airfield characterized by rutted and boggy ground.
As the flight progressed, the instructor demonstrated maneuvers before handing control to the owner to practice take-offs, spot turns, and landings. While the owner's handling of the aircraft initially showed some instability, it improved sufficiently to allow for several successful maneuvers. However, during the final landing attempt, the left skid of the helicopter contacted a patch of the previously noted boggy ground. This contact caused an uncontrollable roll, during which the main rotor struck the surface. The impact resulted in the aircraft rolling onto its side and caused severe disruption to the airframe.
The investigation
The investigation was based on the aircraft accident report submitted by the pilot and a statement provided by the aircraft owner. The investigation established that the aircraft was a home-built helicopter that had been granted a Permit to Fly earlier in 1998. The crew, consisting of one pilot and one passenger, were both wearing four-point harnesses at the time of the impact.
Findings
- The primary cause of the accident was the aircraft drifting over a patch of boggy, rutted ground that had been observed earlier in the flight.
- The impact of the rotor with the ground led to substantial damage to the airframe.
- Despite the severity of the roll, there were no fatalities and the passenger sustained only minor injuries.
- The occupants were able to exit the helicopter through the shattered cockpit area following the accident.