What happened
On 14 November 2012, a Skyranger Swift, registration G-CEUJ, was conducting a private flight from Sackville Farm Airfield in Bedfordshire. The aircraft had recently undergone maintenance involving the replacement of fuel filters and rubber hoses. Shortly after departing, while climbing at approximately 500 ft, the engine experienced a sudden surge in power. In response to this abnormal engine performance, the pilot aborted the climb and prepared for a precautionary forced landing back at the airfield.
As the aircraft approached Runway 13, the engine surged a second time. To mitigate the risk of further power fluctuations, the pilot switched off the magneto switches prior to touchdown. The aircraft arrived on final approach with excess airspeed and half flaps selected. The landing was heavy and occurred on a downward-sloping section of the runway. Following several bounces, the nosewheel encountered soft ground, causing the nose landing gear to fail. This resulted in the aircraft pitching fore and aft before flipping onto its back. The passenger sustained minor injuries, while the pilot was unhurt.
The investigation
Investigators examined the aircraft and the circumstances surrounding the engine's behavior. The engine, a Rotax 912 ULS, had been ground-tested prior to the flight, with fuel pressure and flow appearing within normal parameters. While the pilot considered the possibility of carburettor icing, the presence of a water jacket heating system made this unlikely.
Witnesses on the ground noted that the aircraft exhibited pitching motions during the landing roll. It was observed that the aircraft may have been traveling on its nosewheel alone at some point, a motion that may have been intensified by the undulating nature of the grass runway and pilot-induced oscillations. The investigation also noted damage to the engine mounts, firewall, propeller, spinner, and nose landing gear.