Synopsis
On 8 October 2008 at approximately 1308 UTC, a Thruster TST MK1 microlight, registration G-MVBT, experienced a power loss shortly after takeoff from Chirk airstrip near Wrexham, Clwyd. The single-engine aircraft, powered by a BMW R100 piston engine, was being operated on a private flight with the sole pilot. The aircraft was destroyed in the accident, and the pilot sustained a fractured spine.
History of the Flight
The pilot, aged 52 and holding a Private Pilot's Licence with 170 hours of flying experience (all on type), had refuelled the aircraft and completed pre-flight and power checks, including a full rpm check and verification of both ignition circuits. He departed from Chirk airstrip on a runway heading of approximately 160°. The wind was light and easterly, with visibility around 30 km.
At about 200 ft above ground level, the engine began to lose power. The pilot immediately initiated a 180° turn back toward the airstrip. He noted that the fuel pressure gauge reading had dropped to a very low level. The engine stopped as he completed the turn, and he realized he would not reach the airstrip. As the aircraft headed toward the A483 road, he elected to turn away from the carriageway, and the aircraft struck a mound of earth short of the road.
The pilot, who was wearing a full harness, switched off the fuel and electrical systems before evacuating the aircraft. He sustained a fractured spine, from which he was expected to make a good recovery.
Engineering Investigation
The aircraft's fuel system included a pre-filter, two automotive electronic fuel pumps installed in parallel, a glass filter, and a regulator. These components were removed and sent to the AAIB for inspection; no significant findings were reported. Both fuel pumps and the regulator were functionally tested and operated satisfactorily. It was not possible to recover the engine or other parts of the fuel system for inspection.
Normal operating procedure was to use the main fuel pump throughout the flight and the additional 'boost' pump for takeoff and landing. On a previous flight, a 'surging' problem had been resolved by activating the booster pump at a significant altitude.
Comments
Given the low fuel pressure reading during the flight, a fuel system problem—possibly due to blockage or fuel contamination—appeared the most likely cause of the power loss. However, it was not possible to state this with any degree of confidence.