What happened
On 21 April 2001, a Martyn JJ Vans RV-6A, registration G-BVRE, was performing a private flight at Barton (Manchester) Airfield. The aircraft completed a standard approach and touched down on the grass surface of Runway 3ert2. During the subsequent landing roll-out, the nosewheel penetrated the wet layer of turf and sank into the underlying soil. This sudden increase in drag caused the nose landing gear leg to collapse. As the gear buckled, the propeller struck the ground, resulting in damage to the propeller and a bent engine crankshaft. The aircraft eventually came to a stop with the lower propeller blade in a vertical position, which the pilot noted helped prevent a full nose-over. There were no injuries to the two occupants.
The investigation
Investigators examined the aircraft and the runway surface following the incident. The inspection of the runway revealed that the nosewheel had carved a furrow approximately 36 metres long into the ground. Structural analysis of the aircraft showed that the high drag loads transmitted through the nose landing gear strut had caused overload damage to the nosewheel leg and the associated fuselage mounting structure, including the firewall.
Additionally, the pilot reported a physical difficulty during the deceleration phase. Once the nosewheel began to sink, the resulting forces caused the pilot's ankle joints to rotate backward to such an extent that releasing pressure on the brakes became difficult.
Findings
- The primary cause of the gear collapse was the nosewheel penetrating the wet turf and sinking into the soil.
- The impact of the propeller with the ground caused damage to the propeller and the engine crankshaft.
- The drag forces were sufficient to cause structural failure in the nose landing gear leg and the fuselage mounting components.
- The pilot's physical ability to operate the brakes was compromised by the extreme rotation of the ankle joints during the deceleration event.