What happened
On 13 January 2008, during a celebration at the Moorsele airfield, a demonstration flight was performed in a DPM Aquilair Swing 582, registration OO-F23. Following an initial successful flight, a second flight was conducted with a passenger on board. During this second sortie, the aircraft performed several maneuvers, including a go-around and a climb to approximately 1,200 feet.
While flying in a downwind position, the pilot initiated a stall maneuver. This maneuver involved a dive at full throttle to gain speed, followed by a steep climb. Witnesses observed the aircraft reaching a nearly vertical pitch angle. This maneuver triggered a tumbling motion, where the aircraft rotated rapidly around its pitch axis. The intense forces generated during this rotation caused the wing structure to fail, and the aircraft fell vertically to the ground. The impact resulted in two fatalities.
The investigation
Investigators examined the wreckage and found significant structural damage consistent with high-stress loads. The wing's leading edge tubes and keel tube were fractured, and the basebar was bent and partially disconnected. The investigation confirmed that there were no signs of structural failure prior to the accident.
Analysis of the pilot's credentials revealed that while he held a valid medical certificate, he was operating under a Training Authorization. Under the specific privileges of this authorization, carrying a passenger is not permitted. Additionally, the aircraft's manual prohibits acrobatic maneuvers and limits the pitch angle to 60 degrees.
Findings
- The primary cause of the loss of control and subsequent tumble was the initiation of a stall maneuver at a high pitch angle, which pushed the aircraft beyond its flight envelope limits.
- A contributing factor was the pilot's limited recent experience with this specific aircraft, having flown only 10 hours on the type in the preceding six months.
- Meteorological conditions at the time included wind peaks of approximately 20 knots in nearby areas, meaning a wind gust could have potentially shifted the aircraft off-balance during the critical maneuver.