What happened
On 21 February 2010, an X’air Hawk, registration G-CESJ, was prepared for flight at Whiterashes Airfield in Aberdeenshire. The aircraft, which had not been operated for several months, required jump leads to start the engine despite a recently charged battery.
During the flight preparations, the two owners of the aircraft intended to perform circuits at the airfield. To facilitate a change of pilots, the engine was left running while the first pilot vacated the cockpit and a second pilot boarded. As a precaution, the wheels had been chocked. However, as the second pilot was boarding, the leg of his overalls caught the throttle lever, inadvertently applying full power.
Because the aircraft is operated from the left seat, where the wheelbrakes are located, the second pilot was unable to reach the brakes or close the throttle. The sudden surge of power caused the X’air Hawk to jump the chotks and depart the runway. The aircraft subsequently collided with a low stone wall and an earth dyke. The impact resulted in the collapse of the nose landing gear, damage to the left landing gear leg, a broken propeller, a shock-loaded engine, and damage to the left wing. The pilot, who was not wearing a seatbelt at the time of the impact, escaped without injury.
The investigation
The investigation was based on the aircraft accident report form submitted by the pilot. The AAIB examined the sequence of events surrounding the pilot changeover and the mechanical state of the aircraft. The investigation established that the engine remained running during the transition between pilots to avoid the inconvenience of a restart, which left the throttle vulnerable to accidental movement.