What happened
On 4 July 1998, a Dromader M18 A, registered as ZS-NHY, was involved in an incident during a commercial operation near Nelspruit. The aircraft had been engaged in a fire bombing mission and had recently departed from Elandshoogte with the intention of landing at Nelspruit. Upon completing its mission and attempting to land, the aircraft experienced intense tail wheel shimmy. This vibration was severe enough to result in the structural failure of the tail wheel support arm.
The investigation
The investigation into the incident was hampered by significant difficulties in establishing contact with the pilot. Due to these communication gaps, the available information regarding the event was quite limited at the time of the report's compilation. Investigators focused on the mechanical sequence occurring during the landing phase, specifically looking at the impact of the shimmy on the aircraft's landing gear components.
Findings
While the investigation could not reach a definitive conclusion, several contributing factors were identified. The primary issue was the failure of the tail wheel support arm caused by extreme oscillation. Investigators noted two primary probabilities: the pilot may have performed a hard landing that placed excessive stress on the component, or the tail wheel shimmy damper may have been in a defective state, failing to suppress the vibration.