AO-2005-006

On the night of Tuesday 3 May 2005, Fairchild-Swearingen SA227-AC Metro III aeroplane ZK-POA, operated by Airwork (NZ) Limited, was on a night air transport freight flight with 2 crew and 1790 kilograms of cargo when it suffered an in-flight upset which developed into a spiral dive. The crew did not recover control and the aircraft became overstressed and broke up, to fall in pieces about rural farmland near Stratford. Both crew were killed and the aircraft and cargo destroyed.

The crew was balancing fuel between tanks, flying the aircraft at an excessive sideslip angle with the rudder input trimmed, while on autopilot. The autopilot capability was exceeded and it disengaged, precipitating the upset.

Safety issues identified included:

• the need for a written standard operating procedure for in-flight fuel balancing for operators of this family of aircraft

• the need for the aircraft flight manual to include a limitation and warning that the autopilot be disengaged for in-flight fuel balancing, and to contain a procedure for in-flight fuel balancing.

A safety recommendation to address these issues was made to the Director of Civil Aviation.