What happened
On 11 August 2002, a Fournier RF 9 motor glider, registration F-CARF, was preparing for a return flight from Nympsfield, Gloucestershire, to Lydd, Kent. The aircraft, which had arrived from the Netherlands the previous day for a rally, had been refuelled prior to departure. During the takeoff roll on the grass runway, the pilot instructed the co-pilot to retract the landing gear once the aircraft reached an appropriate height.
As the gear was being raised, the pilot noted a reduction of approximately 300 engine RPM. Although the RPM subsequently recovered, the aircraft lost about 10 feet of altitude, and the pilot had to apply right aileron to prevent the left wing from dropping. Realising the aircraft lacked the performance to clear the trees at the end of the runway, the pilot initiated a forced landing straight ahead. During the maneuver, the left wing struck the ground, causing the aircraft to slew 180 degrees and resulting in the engine being torn from its mountings. The two crew members escaped without injury, though they were briefly trapped due to a jammed canopy.
The investigation
Investigators examined the aircraft's performance and the environmental conditions at the airfield. The runway at Nympsfield is a grass surface with variable slopes and cambers, situated at an elevation of 700 feet. Eyewitnesses observed that the aircraft's initial acceleration appeared poor and noted a 'wallowing' motion during the climb. While the pilot reported a momentary drop in RPM, the engine and propeller were found to be unlikely causes of the incident as the RPM recovered and the engine sound remained normal according to observers.
Findings
- The aircraft was likely operating at its maximum take-off weight due to the combination of two occupants, a significant fuel load, and baggage.
- The high elevation of the airfield and the grass runway surface likely contributed to reduced takeoff performance.
- A momentary loss of power occurred during the critical phase of gear retraction.
- The pilot's lack of familiarity with the specific obstacles and contours of the airfield may have influenced the decision-making process.
- Potential aerodynamic interference from moisture on the upper wing surface was considered as a contributing factor.