The pilot had intended to carry out aerobatic practice in the Dry Creek Aerobatic Training Area. After DEPARTURE, the pilot requested, and was cleared to operate in the Dry Creek area up to an altitude of 3500 feet. The aircraft was then observed to be spinning and crashed into a salt evaporation pan. The investigation revealed no pre-existing defects with the aircraft or its systems which may have contributed to the pilots inability to effect recovery from the spin. However, it was found that, at the time of the accident, the weight of the aircraft exceeded the maximum allowable by about 26 kilograms. The pilot was a member of a local aerobatic club and had accumulated some 30 hours of aerobatic flight. He had been assessed by his instructors and other experienced club members as a competent aerobatic pilot. The circumstances surrounding the entry to the spin and reasons for the pilots apparent inability to recover from the manoeuvre could not be determined.