At about 0910, on 11 April 2012, an Ayres Corporation S2R-G10 Thrush aircraft, registered VH-WDD, collided with terrain in a fallow wheat field about 36 km north-west of Moree, New South Wales while on a ferry flight from St George, Queensland to Moree. The owner-pilot was fatally injured and the aircraft was destroyed by impact forces and an intense fuel-fed fire.
What the ATSB found
The ATSB found that the aircraft departed controlled flight and the pilot was unable to recover before impact with the ground. On the basis of the evidence available to the ATSB, it was not possible to determine with any certainty the reasons for the loss of control.
There was no evidence of any mechanical fault with the aircraft that could have contributed to the accident. A number of other possible factors could not, however, be completely discounted: pilot incapacitation; aircraft handling, such as to avoid a bird or flock of birds or other deliberate manoeuvring by the pilot; or a mechanical problem which could not be identified during the post-accident site and aircraft examinations.
Although it did not contribute to the accident, an issue was identified with the potential to affect the safety of agricultural operations in S2R-G10 Thrush aircraft in Australia. The aircraft’s permitted load-carrying capability, based on its published maximum take-off weight, was very low in comparison with other agricultural aircraft types. The aircraft type’s operational history indicated that it could be operated at higher loads, but the absence of a more practical published weight limit increased the risk of pilots flying at weights where the aircraft had not been fully tested for safety.
What has been done as a result
In June 2012, Statewide Aviation, the Australian distributor for Ayres aircraft, in consultation with the Civil Aviation Safety Authority, commenced developing a Supplemental Type Certificate (STC) for some Ayres Thrush variants. This STC would permit an increase in the aircraft's maximum take-off weight, and is expected to be available to Thrush owners in October 2013.
Although the investigation did not determine why the aircraft departed controlled flight, the potential for the operation of the emergency cut-off lever in Garrett-engined Thrush aircraft to prevent significant control difficulties in the event of a serious engine or propeller problem was highlighted.