What happened
On 9 August 2009, a Jodel D117, registration G-BBPS, was returning to Westfield Farm Airstrip in East Sussex following a short local flight. The pilot performed a standard approach and landed the aircraft from an easterly direction with a gentle touchdown.
Upon touchdown, the pilot initially used the rudder pedals to maintain directional control. Seeking to increase the deceleration of the aircraft, the pilot transitioned to using the brakes. During this process, the aircraft began to swerve toward the left. In an attempt to correct the path, the pilot moved his feet back to the rudder pedals; however, the aircraft continued its departure from the airstrip. The aircraft eventually struck a wooden fence, resulting in damage to the propeller and the left wing. There were no injuries to the pilot.
The investigation
The investigation examined the mechanical operation of the aircraft's ground steering system. On this specific model, the brakes and the rudder pedals operate via separate mechanisms. While the rudder pedals are linked to a steerable tail wheel, the tail wheel can enter a castoring state if it becomes unlatched from the steering mechanism at a certain angle.
Investigators determined that during the landing roll, the tail wheel had become unlatched, which prevented the pilot from using the rudder pedals to steer the aircraft. Furthermore, because the pilot's primary method of steering during this specific landing roll was the rudder rather than differential braking, he was unable to compensate for the loss of steering once the tail wheel began to castor.