What happened
On February 4, 2023, a G1 Aviation G1 SPYL-XL-R ULS (P), registration 04IF, was conducting an instruction flight near Salignac, France. The flight, operated by the Pôle National de Vol Montagne, was traveling from Barcelonnette Saint-Pons toward Cruis Mas de Grailles. While descending near the Baume mountain at approximately 4,200 ft, the aircraft encountered aerological disturbances.
During this period, the aircraft's airspeed was recorded between 140 km/h and 170 km/h, significantly exceeding the maneuvering speed (Va) of 130 km/h. The crew heard a loud noise, and a portion of the canopy tore off. The aircraft immediately entered a right bank and subsequently entered a spin. After three full spins, the instructor deployed the airframe parachute at an altitude of approximately 1,200 ft. The aircraft descended into an olive grove, where it struck a tree. Both the pilot under instruction and the instructor survived the impact without injury.
The investigation
The BEA examined the wreckage, onboard cameras, and flight data from the Kanardia and Air Avionics computers. Analysis of the wing structure revealed significant damage, including a fracture of the right-wing front spar and distortions to the left wing. The investigation also reviewed the aircraft's technical records and weight-increase documentation.
Testing conducted by the manufacturer, G1 Aviation, in coordination with the DSAC, revealed that a wing with a single spar and 0.8 mm sheet thickness failed during a static test before reaching the required 6 g limit. The investigation also noted that the aircraft was operating near its maximum takeoff weight of 525 kg.
Findings
- The aircraft was flying at an indicated airspeed substantially higher than the maneuvering speed (Va) while encountering turbulent air.
- Structural under-dimensioning of the wings was a primary factor, as the wing's ability to withstand loads was compromised.
- The presence of lenticular clouds and strong Mistral winds indicated a high risk of severe turbulence and rotor phenomena.
- The pilot under instruction made a sudden, large control input to counteract the initial roll, which contributed to the entry into a spin.
- The structural integrity of the airframe was likely compromised by the cumulative effects of high-speed flight in rough air and the sudden control deflections.