What happened
On 29 May 2016, a Robinson R44 Raven, registration G-EVEE, was conducting a private cross-country flight from Dunkeswell Airfield toward a destination near Stokenchurch. After an initial leg from Cornwall, the pilot refueled at Dunkeswell, taking on 18 USG to reach a total of 25 USG. The pilot's plan was to reach the destination with approximately 40 minutes of reserve fuel.
During the flight, the pilot noted that groundspeeds were lower than anticipated due to environmental factors. While flying south of RAF Benson, the low fuel warning light activated, indicating that only a small amount of fuel remained. In an attempt to reach a nearby farm for an emergency landing, the pilot initiated a right-hand turn. During this manoeuvre, the engine suffered a fuel starvation event, causing power to drop to 50% and the rotor RPM to decrease. The pilot subsequently entered an autorotation and performed a forced landing in a field of standing crop. There were no injuries to the four occupants, though the aircraft sustained damage to its skid assembly.
The investigation
The AAIB examined the flight planning and the circumstances leading to the fuel exhaustion. The investigation established that the pilot had calculated fuel consumption based on an estimated 18 USG per hour. However, the actual flight time was longer than planned due to slower groundspeeds. The investigation also reviewed the pilot's decision-making regarding a potential diversion to Chiltern Park airfield, which was bypassed in favour of continuing to the original destination.
Findings
- The engine power loss was caused by the engine being temporarily starved of fuel during the turn to the landing site.
- The pilot may have misjudged the remaining fuel quantity and underestimated the impact of headwinds on the flight duration.
- The low fuel warning light activates when approximately 3 USG remains, leaving a very limited window for landing safely.