Loss of control involving Pitts S-2A, VH-SZA, 4 km north-east of Clyde, Victoria

The pilot departed Moorabbin with one passenger on board and flew to the designated Moorabbin aerobatic training area with the probable intention of practising aerobatic manoeuvres. The pilot was approved to perform aerobatic manoeuvres down to 500 feet. The passenger was an experienced flying instructor who also held an approval for low level aerobatics down to 500 feet, but he was not experienced on the Pitts S2A aircraft.

Only one known witness saw the aircraft in the last few seconds before impact. Her attention was attracted to the aircraft by its loud engine noise. She briefly observed the aircraft performing an aerobatic manoeuvre while descending towards the ground at an angle of about 45 degrees. The aircraft was travelling in a westerly direction when it disappeared behind a row of Cyprus trees and impacted the ground about 300 metres north-west of her location. Subsequently the witness was shown a video of Pitts aircraft performing various aerobatic manoeuvres. The manoeuvre she identified as what she saw VH-SZA perform was a descending snap roll to the left.

Airframe and engine damage indicated that the aircraft was rotating to the left when it impacted the ground in a steep nose down attitude. Propeller damage indicated that the engine was at a low power setting at impact. No fault has been detected with the engine.

The right rudder cable attachment to the rudder horn was found to have pulled out of the Nicopress copper sleeve/swage thereby disconnecting the right rudder cable from the rudder. A similar disconnect was found with the left rudder cable at the pilot-in-command's left pedal. It was determined that the correct copper sleeves were used on the correct one eighth inch diameter rudder cables but that the swaging had been carried out with the Nicropress jaws that were appropriate for a five thirty second inch cable. Four Nicopress copper sleeves were under swaged. Specialist examination subsequently concluded that the improperly constructed rudder cables probably failed at impact and not in flight.

The reason why the two pilots failed to recover the aircraft from an aerobatic manoeuvre could not be determined.

Significant Factor

The following factor was considered relevant to the development of the accident:

1. The aircraft was engaged in low level aerobatics and struck the ground for undetermined reasons.