What happened
On July 25, 2018, a Siren C30S glider, registration F-CDAL, was performing a local flight under tow from the Argenton-sur-Creuse airfield. While flying near the commune of Mosnay, the tow plane pilot signaled the presence of an updraft by wing rocking. In response, the glider pilot initiated a climbing left-hand turn and activated the release mechanism to disconnect from the tow cable.
During this maneuver, the glider experienced a structural failure and broke apart in flight. The pilot, who remained attached to the seat and several aircraft components, managed to deploy a parachute. The pilot sustained one slight injury upon impact with the ground. The wreckage was distributed across several hectares near Le Coudray.
The investigation
The BEA examined the wreckage and the flight sequence to determine the cause of the structural failure. Investigators found the glider's fuselage had suffered two primary longitudinal fractures extending from the nose to the rear wing spar. The central wing spar attachment showed evidence of deformation through flexion and torsion. The investigation established that the separation between the wing and the fuselage originated at the forward spar, where small bonding surfaces were present.
Physical evidence showed the tow cable had broken near its connection to the glider, though the release ring and cable fuses were not recovered from the site. The investigation also reviewed the pilot's experience, noting that while the pilot was an experienced glider pilot, they had only performed their first flight on this specific aircraft type the previous day.
Findings
- The release maneuver was performed before the cable had been successfully released.
- This sequence placed the glider in a high position relative to the tow plane, creating excessive tension on the tow cable.
- The combination of high cable tension and the aerodynamic forces generated by the improper release maneuver caused the in-flight breakup of the aircraft.
- The pilot's limited experience with this specific aircraft model may have contributed to the inappropriate maneuver.