What happened
At 1157 on 19 July 2011, a PZL-Mielec M18A Turbine Dromader aircraft, registered VH-FOZ, impacted terrain on a cotton station about 23 km west-south-west of Dirranbandi, Queensland while conducting a spraying flight. The pilot was fatally injured and the aircraft was destroyed by impact forces.

What the ATSB found
The ATSB found that, for reasons that could not be determined with certainty, the aircraft departed from controlled flight during a turn at low altitude and the pilot was unable to recover before impacting the ground.

The ATSB also identified a significant safety issue affecting the safety of future spraying operations in turbine Dromader aircraft: the potential for the aircraft's centre of gravity to vary significantly depending on the weight in the aircraft's chemical/spray tank and exceed the forward and aft limits during a flight. This safety issue was unlikely to have contributed to the accident as the aircraft was probably within the approved weight and balance limits at the time of the accident.

Moreover, although also not found to have contributed to the accident, there was an increased risk to the flight from the aircraft's operation, at times, in excess of its published airspeed and angle of bank limitations.

What has been done as a result
During the investigation, the Australian Transport Safety Bureau worked with the Civil Aviation Safety Authority (CASA) and the Aerial Agricultural Association of Australia to address the risk to turbine Dromader aircraft of the potential for excessive movement of the aircraft's centre of gravity as the contents of the aircraft's chemical/spray tank are dumped or dispensed.

CASA and the owner/developer of the approval for operations at weights of up to 6,600 kg, which had effect during the flight, took action to improve operator and pilot understanding of the issue. In addition, the owner/developer indicated that the design would be reviewed to address any excessive centre of gravity variations.

Safety message
Although it was not contributory in this instance, the ATSB highlights the importance of pilots maintaining their aircraft's weight and balance within limits throughout a flight, and of understanding the implications of changing weight and balance. Similarly, the ATSB reaffirms the importance of being familiar with and adhering to aircraft operational limitations.