What happened
On 29 May 2005, a Europa XS, registration G-JAPS, was conducting an endurance test flight near Fishburn. The flight, which included a test pilot and an owner acting as an observer, was part of a series of tests following the recent construction of the aircraft. After approximately 90 minutes of stable flight at 1,500 ft, the engine began to misfire and the engine speed fluctuated erratically between 2,000 and 4,000 rpm.
Attempts to stabilize the engine by adjusting the throttle were unsuccessful. Despite the pilot switching the fuel supply from the main to the reserve tank and activating the auxiliary pump, the engine power continued to decline. Unable to maintain altitude, the pilot prepared for a forced landing in a field near Hulam Farm. During the landing flare, the left wingtip struck the uneven ground, causing the aircraft to flip onto its back. The two crew members escaped the wreckage with minor injuries, though the aircraft was damaged beyond economical repair.
The investigation
The AAIB conducted a field investigation and examined the engine and fuel systems. The investigation included a review of data from an R-DAT device, which recorded engine parameters every six minutes, and a detailed inspection of the fuel components.
Investigators considered several potential causes for the power loss, including carburettor icing, vapour lock, and fuel starvation. While the weather conditions suggested a possibility of carburettor icing, the presence of a turbo-charger likely mitigated this risk. Vapour lock was considered unlikely given the stable flight duration and lack of recorded temperature or pressure fluctuations. The fuel system was found to be clean and capable of providing adequate flow.
Findings
- The only anomaly identified was a loose main fuel jet needle within the right carburettor's piston housing.
- This loose needle could cause the fuel-air mixture to become enriched, though the manufacturer noted such a defect should not typically cause the observed engine symptoms.
- Fuel starvation to one or both carburettors remains a possible cause, as the loose needle might have caused the component to float or vibrate cyclically, potentially disrupting normal operation.