The ATSB is reminding pilots of the dangers of aerodynamic stall, after a student pilot and instructor were killed after their aircraft collided with terrain.
The accident occurred on 9 November 2012 near Lismore Airport, New South Wales where the student and instructor were conducting circuit training flights in a SOCATA TB 20. The ATSB found that while making a left turn in the circuit, an aerodynamic stall occurred, resulting in a significant left-wing low and nose-down attitude in close proximity to the terrain. The aircraft collided with terrain in a paddock, about 3 km south of Lismore Airport. Both occupants received fatal injuries and the aircraft was destroyed by the impact and an intense fuel-fed, post-impact fire.
...the aircraft stalled at such a low altitude that they were unable to recover fully to controlled flight before the aircraft collided with terrain.
Either because of insufficient warning or lack of time to react, the instructor was unable to prevent the stall from occurring. Although it appeared that a stall recovery was commenced, the aircraft stalled at such a low altitude that they were unable to recover fully to controlled flight before the aircraft collided with terrain.
The ATSB also found that the aircraft’s engine contained crankcase through bolts from a different engine manufacturer that were installed in the engine prior to the aircraft’s importation into Australia and were probably unapproved for use in that engine. Although these bolts did not contribute to the accident, their installation meant that the continued safe operation of the engine could not be assured.
The accident highlights the need for pilots to minimise the risk of aerodynamic stall, particularly when in proximity to the ground, such as during take-off and landing.
In addition, aircraft owners and maintainers should ensure that all parts fitted to their aircraft are appropriately approved for the application.
Read the full ATSB investigation report, AO-2012-149