According to his log book, the pilot had flown the aircraft on two previous occasions of about 15 minutes duration each. The pilot was briefed by the owner of the aircraft on power settings and speeds. He then took-off into the south from the strip which is aligned approximately north-south. There was a light southerly breeze blowing at the time. The aircraft was seen to make one right-hand circuit, but it could not be determined if the aircraft actually made a landing from that circuit. When the aircraft was on final approach from a second right-hand circuit at an estimated altitude of about 200-300 feet, it entered a turn to the right. As the turn progressed onto a northerly (downwind) heading, the angle of bank became progressively steeper until it was about 90 degrees. The nose then dropped and the aircraft dived to the ground. The first persons on the accident scene experienced difficulty in removing the pilot's motor cycle type safety helmet (with full face enclosure) before resuscitation could be applied. The investigation did not reveal any pre-existing defects that may have caused the accident. Other pilots reported some turbulence and windshear in the area where the accident occurred. The area was inspected by an officer from the Bureau of Meteorology who specialised in micro-meteorology. His opinion was that turbulence or windshear effects at the time of the accident would have been minimal. The pilot had been receiving dual flight instruction from an ultralight flying school. After a dual instructional flight on the morning of the accident, he had been strongly advised by his instructor not to fly solo until he had completed more dual instruction as the instructor believed that the pilot was not sufficiently competent to fly solo. The pilot lost control of the aircraft for reasons which were not determined.