What happened
On 22 February 2022, a Glasair II-S RG, registration G-IIRG, was conducting a private flight from North Weald Airfield to RNAS Yeovilton. During the flight, the pilot elected to keep the retractable landing gear in the extended position due to previous difficulties with the gear mechanism. While cruising near Marlborough at 2,5 and 00 feet in moderate turbulence, the engine began to run roughly.
After performing various cockpit checks without success, the pilot switched the fuel selector from the main wing tank to the auxiliary header tank. Although the engine briefly returned to normal operation, it lost all power approximately 15 seconds later. The pilot declared a MAYDAY and identified a suitable grass field for an emergency landing. The aircraft struck the ground heavily on an upslope, causing the landing gear to collapse and push into the upper wing skins. The aircraft then slid across the field before hitting a post and wire fence. There were no injuries to the pilot or the passenger.
The investigation
The AAIB examined the fuel system and the circumstances leading to the engine failure. The investigation established that the aircraft was equipped with a main wing tank and a 30-litre header tank. While the wing tank contained sufficient fuel, the header tank was found to be empty following the accident. The investigation also noted that the aircraft's fuel gauges did not provide a reading for the header tank level, and the pilot had not checked its contents prior to departure.
Findings
- The engine failure was caused by fuel starvation following the selection of an empty header tank.
- The initial engine roughness was likely caused by air entering the fuel supply, potentially due to a combination of turbulence and the aircraft's sideslip condition while flying with gear extended.
- The pilot's decision to switch to the header tank led to the total loss of power once the residual fuel in the fuel lines was exhausted.
- The heavy impact during the forced landing was influenced by the uphill slope of the landing site and the difficulty of judging height during a low sun angle.