What happened
On 2 August 2010, an Avid Speedwing, registration G-RAFV, was returning to the Firs Farm airstrip following a local circuit familiarisation flight. During the evening landing, which was conducted in light winds, the pilot reported that the initial touchdown was straight and well-controlled. However, while the aircraft was still rolling, the pilot lost directional control despite maintaining full aft stick input. A rightward yaw developed, causing the aircraft to veer off the strip. The ground loop concluded when the aircraft struck deep tractor ruts located alongside the runway. The impact resulted in the collapse of the right-hand landing gear and caused damage to the lower fuselage tubes, the cockpit cross truss, and the wheel axles. There were no injuries to the two occupants, who exited the aircraft through the pilot's door.
The investigation
The investigation examined the circumstances of this event as well as a previous incident involving the same aircraft on 22 June 2010. In the June event, a co-owner had experienced a loss of directional control at a lower speed of approximately 20 knots. Investigators found that in both instances, the tailwheel mechanism was prone to breaking out and castoring freely due to weak centering springs, which required only minimal lateral force to trigger. This mechanical issue made maintaining directional control on the ground extremely difficult. Following the rectification of the spring issue, the pilot noted that the aircraft's ground handling had significantly improved. It was also noted that neither of the two incidents had been initially reported to the AAIB by the pilots, as they were unaware of the statutory reporting requirements.
Findings
- The primary cause of the loss of control was the tailwheel's tendency to castor freely due to insufficient tension in the centering springs.
- The aircraft's excursion from the runway was terminated by the impact with deep tractor ruts.
- The mechanical defect in the tailwheel assembly was present during both the June and August 2010 incidents.