What happened
On 7 July 2018, a modified Rutan Long-Ez, registration G-BPWP, was conducting a private flight from Biggin Hill to Dunkeswell Airfield. During the approach to Runway 04, the engine suddenly ceased operation while the aircraft was on its base leg. The pilot, attempting to manage the engine failure, prepared for a forced landing in a field located in the undershoot of the runway.
As the aircraft neared the ground, the pilot identified a fence obstructing the intended landing site and performed a left-hand manoeuvre to avoid it. This movement resulted in a heavy touchdown on the left mainwheel and nosewheel. The impact caused significant structural damage to the aircraft, including the failure of the landing gear components and damage to the wing and canard. The pilot sustained serious injuries, while the passenger suffered minor injuries.
The investigation
The AAIB examination of the aircraft and its systems revealed that the engine and propeller were undamaged and the fuel system was clear of debris. Investigators found that the aircraft was being operated using a mixture of Avgas 1 and 95 octane unleaded Mogas in the left fuel tank, while the right tank contained Avgas 100LL.
Analysis of the fuel samples confirmed the presence of a Mogas and Avgas mixture. The investigation also noted that the electrical fuel booster pump was in the 'off' position at the time of the accident. Furthermore, while the pilot had used carburettor heat during the downwind leg, the heat was set to 'cold' prior to the engine failure. The investigation considered the impact of high ambient temperatures and the specific characteristics of the fuel being used.