Moravan Zlin-Z326, VH-ILZ, Cardinia, Victoria, on 11 August 1990

Circumstances:

A ground witness heard the aircraft's engine power increase and observed the aircraft pull up, roll over and enter a spin to the right. He estimated the aircraft was about 3000 feet above the ground. The aircraft spun six to eight turns to the right and at about 600 feet above ground level the right spin ceased before the aircraft entered a spin to the left. The left spin stopped after about one turn and the aircraft appeared to be recovering from the dive when it hit the ground in a wings level, 45 degrees nose down attitude. The pilot-in-command, who occupied the rear seat, held a low-level aerobatic approval to operate down to 1000 feet above ground level. He had often spun the aircraft but is reported to have normally recovered after two turns. The other pilot who occupied the front seat, held an aerobatic endorsement but this was his first flight in a Zlin. It is not known which of the pilots was at the controls when the aircraft entered the right spin, however, the aircraft was normally commanded from the front cockpit. Injuries sustained by the pilot-in-command indicate that he was at the controls at the moment of ground impact. The normal technique prior to the entry of an intentional spin in the Zlin is to reduce power to idle. Considering the report that engine power was increased prior to the spin, it is possible that the spin entry was unintentional. It is the recommended practice in the Zlin to recover from a spin after two to three turns. Why the pilot(s) failed to recover from the right spin after two to three turns could not be determined. An examination of the wreckage and associated aircraft documentation did not reveal any fault that may have contributed to the accident. The prevailing weather was not considered a factor.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. Entry to the right spin was possibly unintentional.

2. The pilot at the controls probably experienced some difficulty recovering from the initial spin to the right.

3. Recovery from the right spin was inadequately executed and the aircraft entered a spin to the left.

4. There was insufficient height for the aircraft to recover from the left spin.