Technical Analysis to Recreational Aviation Australia, Microlight Structural Analysis

The ATSB has amended this report to clarify its role in the assistance that was given to RA-AUS regarding the examination of components recovered from the aircraft. It is possible that some information in the Abstract and Executive Summary of the original report may have conveyed a broader meaning than was intended.

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During the investigation of two fatal microlight accidents, Recreational Aviation Australia (RA-AUS) requested the assistance of the Australian Transport Safety Bureau (ATSB) in conducting technical examination and analysis of parts recovered from the accident sites.

The first accident occurred in Atherton, Qld (registration 32-4456) on 20 October 2005 and the second in Cessnock, NSW (registration 32-4388) on 21 January 2006. During the course of the investigation a third fatal accident was identified. The third accident had occurred in Hexham, NSW (registration T2-2625) in 1996, with coronial findings (0063/96) delivered on 25 March, 1997.

In all three accidents, the failure of the main wingspar had occurred near the wingtip. Qualitative analysis of the structural design and loading of the part during this safety investigation and examination of the coronial findings from the Hexham accident, revealed that the main wingspar had failed under negative 'G' loading. Such loading was likely if the aircraft entered or encountered flight conditions outside the manufacturer's specified flight envelope.