What happened
On 24 October 2013, a Pitts S-1S Special, registration G-BOXH, was performing a private flight when it encountered difficulties during landing at Peterborough/Conington Airport. As the aircraft touched down on the asphalt of Runway 28, it was subjected to a violent tailwheel shimmy. After rolling approximately 100 metres along the runway, the aircraft began to veer toward the left.
Despite the pilot applying full right rudder, the aircraft failed to correct its course and departed the paved surface, heading toward a fence located roughly 25 to 30 metres from the runway edge. In an attempt to regain control, the pilot applied full power and right rudder. While the aircraft appeared to respond to these inputs, the left lower wing collided with a fence post, causing the aircraft to yaw further toward the fence. The sequence of impacts continued as the propeller, cowling, and right lower wing struck the fence before the aircraft reversed direction and came to a stop. There were no injuries to the pilot.
The investigation
Investigators examined the aircraft to determine the cause of the loss of directional control. The inspection revealed that the right-hand tailwheel steering link had fractured. This breakage left the spring on the left side of the assembly to pull the wheel in that direction, resulting in the uncontrolled leftward movement. The pilot suggested that the fracture was likely caused by a combination of mechanical wear and the intense vibrations from the tailwheel shimmy.