What happened
On 4 September 2011, a Comp Air 8 SS52, registration ZU-EYV, was completing a local pleasure flight when it landed at Tzaneen (FATZ) in Limpopo province. During the landing roll on Runway 20, the pilot lost directional control of the aircraft. In an effort to stabilize the aircraft, the pilot applied the brakes, but this maneuver caused the aircraft to pitch forward onto its nose. The impact resulted in the propeller striking the runway. There were no injuries to the pilot or the passenger, though the aircraft suffered significant damage to the propeller, starter-generator, and tail wheel assembly.
The investigation
The investigation into the incident focused on the mechanical state of the aircraft and the sequence of the landing roll. Investigators examined the tail wheel lock assembly and the tail-wheel-assembly bracket. The inquiry confirmed that the pilot was properly licensed and rated for the aircraft type, and that maintenance records indicated the aircraft had been maintained according to required standards. Meteorological conditions at the time of the incident were clear, with good visibility and light winds.
Findings
Technical examination revealed that the tail wheel lock assembly failed to engage the wheel in the centered position. This failure was attributed to wear on the front face of the lock pin, which prevented it from extending from the mounting axle. Consequently, the tail wheel was free to swivel in various directions upon touchdown, causing the loss of directional control.
Furthermore, while the primary cause was the lock failure, investigators noted that the tail-wheel-assembly bracket suffered an overload failure when the pilot released the brakes and the tail dropped. Although existing cracks were found in the bracket, they were not determined to be the primary cause of the incident.
Safety action
To enhance aviation safety, it is recommended that the inspection schedule for this aircraft type be reviewed. Specifically, the tail wheel lock assembly should be inspected every 100 hours of operation or during every annual inspection, whichever occurs first.