AO-2007-010

At about 1142 on 22 November 2005, ZK-DZG, a Fletcher FU24-950 agricultural aeroplane was on a ferry flight to Whangarei Aerodrome with the pilot and a loader-driver on board when its vertical fin failed. The fin failure made the aircraft uncontrollable and it descended into trees, 10 kilometres from its destination. The aircraft was destroyed and both occupants were killed.
A pre-existing network of cracks in the leading edge of the vertical fin had reached a critical size and had reduced the structural strength of the fin to such a degree that complete failure resulted.
The safety issues identified included the design of the vertical fin and its ongoing maintenance requirements, and the adequacy of the supplemental type certificate process that allowed turbine engines to be fitted to the Fletcher aircraft. The New Zealand Civil Aviation Authority has undertaken a number of corrective actions to address the safety issues with the fin, which should help to prevent a recurrence of accidents of this nature. A safety recommendation was made to the Director of Civil Aviation that he also address the concerns raised regarding the supplemental type certificate process