What happened
On 23 August 2008, a Gardan GY8/80-180 Horizon, registration G-BYME, was conducting a private flight from Bagby, Yorkshire, to Panshanger, Hertfordshire. The flight was accompanied by three passengers. After an uneventful outbound leg, the return journey commenced. During the flight, the pilot observed that the main fuel gauge readings were lower than anticipated but attributed this to potential gauge inaccuracies.
While flying at 2,000 ft approximately 6 miles from Bagby, the engine began to falter and subsequently stopped. The pilot identified a field for a forced landing and deployed the landing gear and flaps. However, the deployment of the gear and flaps increased the descent rate, causing the aircraft to strike a hedge before reaching the intended field. The impact caused the aircraft to overturn onto its roof. All four persons on board escaped the wreckage without injury.
The investigation
The investigation focused on the fuel management and the accuracy of the performance data used for flight planning. It was established that the main tanks had run out of fuel during the flight. While the aircraft was equipped with an auxiliary tank containing approximately 15 litres of fuel, the pilot had not selected this source when the engine failed.
Investigators also examined the aircraft's Operating Manual. They discovered a significant error in the fuel consumption curves, where the data for litres per hour was incorrectly aligned with the graphical representation. This discrepancy led the pilot to underestimate his actual fuel consumption rate. Specifically, while the pilot calculated a consumption of 38 litres per hour, the actual rate was approximately 46 litres per hour.
Findings
- The primary cause of the engine failure was fuel exhaustion in the main tanks.
- The pilot's fuel planning was based on erroneous data within the aircraft's Operating Manual regarding fuel consumption curves.
- The pilot did not utilize the available fuel in the auxiliary tank during the engine failure.
- The deployment of landing gear and flaps during the forced landing increased the glide angle, leading to the undershoot of the chosen field.