What happened
On 22 July 2000, a Gulfstream AA-5B, registration G-BFXX, was conducting a re-familiarisation flight near Staple and Tawney, Essex. The flight, which included a pilot and a flying instructor, began as a navigation exercise from Stapleford Airfield to Haningfield Reservoir. The outbound leg proceeded without incident, with the aircraft maintained between 2,000 and 2,500 feet.
Upon returning to Stapleford for landing practice, the aircraft was positioned downwind at 1,200 feet. During the transition to the base leg, the pilot reduced engine RPM to approximately 1,500–1,600. When the pilot attempted to increase power, the engine RPM failed to rise, though the engine continued to run smoothly at a reduced power setting. Despite attempts to switch fuel tanks and verify the booster pump, the engine performance did not improve. As the aircraft turned onto final approach, the instructor took control and attempted to adjust the mixture and use the fuel primer; however, the engine ceased running at an altitude of roughly 400 to 600 feet.
The crew initiated a forced landing in a nearby wheat field. After transmitting a brief MAYDAY message, the pilot reduced airspeed to 40 knots to clear obstacles. As the aircraft flared above the crop, the resistance from the wheat caused the nose to pitch down abruptly, resulting in a heavy landing on all three wheels. The impact bent the nose landing gear and the propeller.
The investigation
Investigators examined the aircraft's fuel system and engine components following the incident. While initial pre-flight fuel samples had shown small amounts of water, subsequent samples from both tanks appeared clear. However, a detailed engineering inspection of the engine revealed significant quantities of water within the carburettor, the mechanical fuel pump, the engine intake pipes, and the fuel hoses located in the engine bulkhead.