What happened
On 10 August 2013, a Pitts S-1S, registration G-EEPJ, was performing a private landing at Leicester Airport. During the initial phase of the landing, the aircraft was controlled via aerodynamic rudder authority rather than tailwheel steering. As the aircraft slowed to a fast taxi speed, it began an uncommanded turn to the right. The pilot attempted to correct the deviation with left rudder inputs, but the turn intensified. This motion eventually caused the tailwheel to unlock, resulting in a 180-degree clockwise rotation. The force of this movement overloaded the left landing gear struts, causing them to collapse and fold beneath the airframe. Consequently, the left wing and propeller tips struck the runway, causing damage to the lower wing surface and aileron. The pilot sustained no injuries and was able to vacate the aircraft.
The investigation
The investigation focused on the mechanical cause of the sudden loss of steering. Examination of the tailwheel assembly revealed that the left-side ring, which connects the chain and spring from the rudder to the tailwheel steering T-bar, had become detached. A closer inspection showed that the connecting split ring was missing. The pilot noted that while the steering had previously felt "sloppy," recent maintenance had removed a link from the chains to reduce slack in the system. The pilot searched for the missing ring at both Breighton and Leicester but could not locate it.
Findings
- The aircraft's steering capability at low speeds was dependent on the mechanical linkage between the rudder and the tailwheel.
- The detachment of the left side ring from the tailwheel steering assembly caused the loss of directional control.
- The loss of steering control led to the tailwheel unlocking, which initiated the ground loop and subsequent landing gear collapse.