What happened
On 15 April 2012, an EAA Biplane, registration G-BBMH, was positioned at the Runway 01 holding point at RAF Benson, Oxfordshire, for a pre-takeoff procedure. The aircraft was stationary on a westerly heading, with a steady wind of 14 knots reported from 010°.
While the pilot was performing a power check at 1,500 rpm, specifically during a carburettor heat check, the aircraft's attitude began to shift. The pilot observed the tail lifting despite applying full aft control. In an attempt to stabilize the aircraft, the pilot closed the throttle, released the wheel brakes, and shut down the engine. However, the aircraft continued to tip forward, causing the propeller and spinner to strike the ground. The aircraft came to rest on its nose and main wheels. There were no injuries to the pilot, though the engine and propeller sustained possible shock-loading damage.
The investigation
Investigators examined the sequence of events leading to the nose-over. The airfield fire service attended the scene and assisted the pilot in righting the aircraft. The pilot subsequently reported that the aircraft's switches were set to the safe position and the aircraft was vacated from the runway.
Findings
- The aircraft was undergoing a routine power check at a holding point.
- The pilot noticed the tail rising while performing a carburettor heat check.
- A wind shift, in conjunction with a forward centre of gravity, likely contributed to the aircraft tipping forward.
- Although the aircraft's centre of gravity was within prescribed limits, the combination of environmental and physical factors led to the loss of stability.