On 9 November 2012, a student and instructor departed Gold Coast Airport, Queensland for a training flight in a SOCATA TB 20, registered VH-HBB, to Lismore Airport, New South Wales. This included circuit training as part of the student’s conversion to the aircraft type. On their fifth circuit, and while making a left turn from downwind to base, the aircraft aerodynamically stalled and the left wing dropped steeply. A recovery was commenced, but the aircraft collided with terrain in a paddock to the east of the Bruxner Highway, 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.
What the ATSB found
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 instructor was unable to prevent the stall from occurring due to either insufficient warning or available time to react. Although it appeared that a stall recovery was commenced, the aircraft stalled at an altitude from which they were unable to fully recover to controlled flight before the aircraft collided with the 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. The use of unapproved parts means that aircraft safety cannot be assured.