What happened
On 13 May 2009, an amateur-built, float-equipped Aventurier with registration C-GZIR departed Lac Prinzèles, Quebec, for a local fishing flight under visual flight rules. Shortly after takeoff, while traveling south, the aircraft turned east toward Lac au Mirage. At approximately 12:15, a loud impact was heard. The aircraft subsequently crashed and was discovered floating upside down on the water's surface. The accident resulted in two fatalities.
The investigation
The investigation examined the structural integrity of the aircraft, which was constructed using parts from a previously damaged ultralight model. While the pilot was highly experienced with nearly 4,500 flying hours, the investigation focused on the aircraft's airworthiness and recent modifications.
Investigators found that the aircraft's wings had been extended by 30 inches without consultation with aviation specialists or notification to Transport Canada. Furthermore, while an initial inspection by the Minister's Delegate - Recreational Aviation (MD-RA) had identified flight control anomalies, there was no formal follow-up to verify that the builder had actually corrected these issues. The investigation also noted that the wing materials used were originally specified for much lighter ultralight aircraft, rather than the heavier 2,200-pound maximum takeoff weight of this specific aircraft.
Findings
- The right wing failed in flight because it had not been reinforced to handle the increased stresses caused by the unauthorized 30-inch extensions.
- The wing extensions created a bending load at the strut attachment point that was 4.6 times higher than the force experienced during normal level flight.
- The structural strength of the wings was compromised because the aluminum thickness matched original ultralight specifications, which were insufficient for an aircraft of this weight.
- The lack of dimpling on the rear spar holes reduced the overall rigidity and strength of the wing structure.
- The pilot performed major structural modifications without engineering expertise or regulatory approval.
Safety action
Following the investigation, the TSB issued an Aviation Advisory to Transport Canada. The advisory recommended that the regulator inform owners and builders of the significant risks associated with installing ultralight-designed wings on heavier amateur-built aircraft. It also emphasized the necessity of notifying the Minister regarding major modifications and the dangers of performing such work without competent engineering oversight.