What happened
On 22 June 2019, a Zenair CH-601-XL ultralight aircraft was performing a non-commercial cross-country flight from Maillen to Pont-à-Celles/Buzet. During the final landing approach to runway 3/33, the aircraft experienced a sudden loss of control. Witnesses observed the aircraft pitch up abruptly and veer to the right before entering a stall and a right-wing spin at a very low altitude. The aircraft impacted the ground approximately 515 meters ahead of the runway threshold. The two fatalities occurred as a result of the impact, which also left the aircraft totally destroyed. Although observers noted the activation of the emergency ballistic parachute recovery system, the deployment failed to prevent the accident.
The investigation
The AAIU(Be) conducted an extended investigation involving international partners, including the Canadian TSB, the Czech Air Accident Investigation Institute, and the US NTSB. Investigators examined the aircraft's wreckage and analyzed the installation of the BRS Aerospace ballistic parachute system. The inquiry focused on the technical configuration of the parachute harnesses and the manufacturer's installation instructions. The investigation also reviewed the flight path, meteorological conditions, and the aircraft's technical maintenance history.
Findings
Technical analysis revealed that the emergency parachute system was improperly installed. Specifically, the manufacturer, Czech Aircraft Works sro, had attempted to adapt a rear-cockpit installation design for a front-cockpit configuration without adequate technical guidelines. This resulted in the rear harness being routed through an unauthorized cut-out in the fuselage near the canopy hinge bolt. This improper harness routing caused the harness to be too short and concentrated all deployment loads on a single point of the airframe. This configuration likely prevented the parachute from deploying as intended and could have induced the unexpected pitch and roll movements seen during the accident. Additionally, the investigation noted the aircraft lacked a stall warning system and was operating in a crosswind on an upslope runway.
Safety action
Following the investigation, the AAIU(Be) issued safety recommendation BE-2022-02 to Zenair Ltd, requesting more detailed technical documentation and imagery for harness installation to prevent future errors. Furthermore, the AAIU(Be) released Technical Safety Note 2020-1, urging owners of similar Zenair Zodiac aircraft to verify the integrity of their parachute system installations. The authority also encouraged the ultralight community to implement stall warning systems to mitigate risks during low-altitude maneuvers.