History of Flight
On 13 September 2003, a Grob G115A (registration G-RAFA) departed RAF Wyton on a training flight with an instructor and a student. The student was handling the controls. As the aircraft reached approximately 200 ft above ground level and the flaps were being retracted, the engine began to falter and lose power, though the propeller continued windmilling. The instructor took control and executed the forced landing checklist. During these checks, it was discovered that the fuel cock was already in the 'OFF' position. The instructor completed a successful forced landing in a field beyond the airfield perimeter. The aircraft sustained no damage, and neither crew member was injured.
Fuel Cock Description
Early versions of the Grob 115, including the G115A, feature a single fuselage fuel tank and a fuel cock on the centre console with two positions: 'ON' and 'OFF'. Later models (G115C, G115E, and Grob Tutor) have wing fuel tanks and a fuel tank selector in a similar location, with the ON/OFF cock repositioned to the rear of the centre console.
Comment
The aircraft involved, G-RAFA, was a Grob 115A model. The student had also flown the Grob Tutor with the RAF. It is likely that prior to the before-takeoff power assurance checks, the student instinctively changed the position of the selector immediately behind the elevator trim wheel, as was done on the Tutor. On the G115A, this action would have turned the fuel cock to 'OFF'. Sufficient fuel remained for takeoff before the supply downstream of the cock was exhausted. Comparison of G-RAFA's fuel cock markings with the Flight Manual revealed differences and omissions in colour scheme and markings, which may have made it more difficult for the pilots to identify the fuel cock's position before takeoff.