What happened
On August 10, 2024, at approximately 18:50 UTC, an experimental Fácil MS 1/3 aircraft, registration LV-X900, was conducting a test flight at the General Rodríguez Aerodrome in Buenos Aires province. The aircraft, which was being operated for private flight testing, was performing a controlled landing when the nose gear assembly suddenly failed. The collapse caused the aircraft to skid across the runway and subsequently capsize. The impact resulted in significant damage to the nose gear, fuselage, vertical stabilizer, struts, and propeller. The pilot and one passenger, who were also the aircraft's builders, evacuated the wreckage without injuries.
The investigation
Investigators from the JST determined that the pilot and passenger had recently replaced the nose gear fork with a custom-made version. This replacement was intended to address vibrations felt during taxiing. The investigation revealed that the materials used for this new component were sourced from a local supplier without specialized aeronautical expertise, meaning the materials lacked technical traceability or aeronautical certification.
Laboratory analysis of the failed fork, constructed from carbon steel, identified a structural weakness caused by a defective welding process. The weld exhibited poor penetration and fusion, creating a localized area of reduced mechanical strength. Metallographic examination further confirmed that the thermal conditions during the welding process had led to a rapid cooling effect, resulting in a coarse grain structure in the heat-affected zone. This structural deficiency made the component susceptible to failure under a simple bending overload during the landing impact.
Additionally, the investigation established that the aircraft was not in a state of airworthiness for flight testing at the time of the accident. While the project had undergone a second intermediate inspection, it had not yet reached the required third inspection stage necessary to obtain a provisional airworthiness certificate for test flights.
Findings
- The nose gear assembly suffered a structural failure at the weld zone during touchdown.
- The replacement component was manufactured using materials lacking technical traceability or aeronautical certification.
- The welding process on the nose gear fork was defective, characterized by insufficient fusion and penetration.
- The aircraft lacked the necessary airworthiness certification required to legally conduct flight testing.
- The steel tubing used in the nose gear construction contained an undocumented structural discontinuity joined by a weld.