What happened
On August 2, 2011, an instructor and a student pilot were conducting a training flight at the Saint-Girons Antichan aerodrome. The flight was part of a training program for a microlight pilot license. After a successful pre-flight inspection, the Humbert Tetras, registration 31-GK, departed from runway 34. The flight consisted of circuit patterns followed by local flight maneuvers.
During the first touch-and-go, the instructor noted that the wind was light and aligned with the runway. The approach speed was stabilized between 80 and 85 km/h. Upon touchdown, the student pilot maintained back-pressure on the control stick, resulting in a firm landing. Shortly after contact with the runway, the aircraft began to veer toward the right. Although the instructor attempted to correct the deviation, the left rudder pedal proved ineffective. The instructor determined that a go-around was not possible and continued to observe the aircraft's trajectory. The left wing appeared to lift slightly before dropping, causing the aircraft to enter a ground loop. The aircraft eventually came to a stop perpendicular to the runway direction. Following the event, the crew shut down the engine and fuel supply before exiting the aircraft.
The investigation
The investigation focused on the mechanical integrity of the aircraft and the control systems. Investigators examined the landing gear and the wing structure, which sustained damage. Specifically, the left main landing gear was destroyed and forced underneath the fuselage, and approximately one-third of the left wing, starting from the wingtip, was damaged.
Technical inspections of the 31-GK revealed no malfunctions in the rudder control linkage, the steering system, or the braking system. The instructor reported that there were no jams in the controls and no evidence of the student pilot applying the brakes or rudder during the excursion. The student pilot also confirmed they did not use the rudder pedals during the incident.
Findings
- The primary cause of the accident was a late correction of a trajectory deviation during the landing roll.
- The resulting ground loop placed excessive lateral loads on the left landing gear, leading to its structural failure.
- No mechanical anomalies or failures in the control systems were identified prior to the event.