What happened
On 17 December 2016, a Rotorsport UK MTOsport, registration G-SIXG, was conducting a training flight at an altitude of approximately 2,000 ft amsl. During the flight, the aircraft struck a bird, which triggered intense vibrations throughout the airframe. This mechanical stress continued until the propeller blades became detached from the engine.
In response to the loss of the propeller, the pilot initiated an emergency procedure to perform a forced landing in a field near Hope Farm, Braithertwaite, Caldbeck. While the pilot successfully identified and avoided power cables running alongside the field, the low position of the sun obscured the visibility of additional cables spanning across the landing area. As the aircraft approached the ground, it struck one of these transverse cables, which caused the aircraft to stop abruptly and tip onto its side. The occupants were able to exit the aircraft without assistance, though the passenger sustained one minor injury.
The investigation
The AAIB investigation focused on the sequence of events leading from the initial bird strike to the final impact with the cables. The investigation examined the mechanical failure of the propeller assembly following the impact with the bird and assessed the environmental conditions, specifically the visibility issues caused by the sun's position during the approach to the field.