What happened
On 21 May 2014, a Starduster TOO SA 300, registration ZU-TOO, was conducting a private local flight departing from Rand Aerodrome (FAGM). After flying south of the aerodrome, the pilot and passenger returned to the airfield and elected to perform several circuits prior to landing.
During the landing roll on Runway 2xy, the aircraft reached a speed of approximately 35 mph when the pilot experienced sudden rudder stiffness, followed by a total lack of response to rudder inputs. This loss of authority caused the aircraft to veer right, exiting the runway and entering a ground loop. During the maneuver, the left lower wing struck the ground, and the left tire deflated, causing damage to the wheel fairing. The aircraft eventually came to a stop facing the opposite direction of its initial landing heading. There were no injuries to the pilot or the passenger.
The investigation
SACAA AIID investigators examined the aircraft's tail wheel assembly to determine why the rudder became ineffective. The investigation focused on the 'clutch type mechanism' used to lock the tail wheel for directional control during takeoff and landing.
Upon inspection of the assembly, investigators discovered that the tail wheel mechanism pin was out of its proper position. Additionally, damage was found on the top left of the contact plate. This damage allowed the slider to move beyond its intended limit and travel behind the housing, which prevented the clutch assembly from engaging and left the tail wheel in a free-caster mode.