What happened
On May 29, 2004, at 13:50, a Cessna 206 Stationair 6, registered F-BMCQ, was taxiing toward the holding point for runway 26 at Arcachon Aerodrome. The aircraft, operated by a local club, was engaged in skydiving operations with a pilot and five passengers on board. During a left turn while taxiing, the aircraft suddenly slumped to the right side and came to a halt a few meters later. The pilot and all five passengers were able to evacuate the aircraft without injury. The incident caused damage to the right aileron and the tail section.
The investigation
The investigation focused on the structural failure of the right main landing gear leg, which features a blade-shaped design. Examination of the fracture surface revealed that the failure was caused by a metal fatigue crack. This crack originated on the lower face of the blade, an area subjected to tensile stresses during taxiing and landing operations. The crack began at a site where the metal surface had been corroded and worn. This surface degradation was caused by repeated friction between the landing gear blade and the aircraft fuselage, which had stripped away the protective paint.
At the time of the accident, the landing gear leg had completed 1,680 flight hours and approximately 4,200 landings since its last major inspection. During that previous major inspection, both landing gear blades had been removed and inspected, but no anomalies were detected at that time.
Findings
- The primary cause of the failure was a fatigue crack originating from a surface area weakened by corrosion and wear.
- The wear was driven by continuous friction between the landing gear component and the airframe.
- The existing maintenance program, which required inspections every 100 flight hours or annually, was insufficient to detect the surface degradation caused by the friction between the blade and the fuselage.