What happened
On June 15, 2019, a Cessna 185F, registration HK-1654G, operated by Paracaidismo de Colombia, was performing a scheduled skydiving flight at Santiago Vila Airport in Flandes, Tolima. During the takeoff roll, at a speed of approximately 40 knots, the pilot noted a leftward deviation and applied right rudder to correct the aircraft's path.
During this correction, a loud noise and significant vibration were felt on the right side of the aircraft. The aircraft abruptly veered to the right, causing the right main landing gear to exit the runway surface. As the pilot attempted to correct the trajectory, the right main gear suffered a structural failure and detached from the airframe. The right wing subsequently impacted the asphalt runway, causing the aircraft to rotate 180 degrees before coming to a stop.
Following the impact, the pilot immediately shut off the fuel selector and deactivated the magnetos. Although a fuel leak was observed from the right wing, no fire occurred. All 6 occupants (the pilot and five passengers) evacuated the aircraft safely and sustained no injuries.
The investigation
The GRIAA investigation focused on the structural integrity of the landing gear components and maintenance practices. Investigators performed fractography and hardness testing on the components involved. The examination revealed that the axial nut (P/N S1117-24) holding the wheel on the right gear had undergone a ductile fracture.
Technical analysis indicated that the failure was driven by cyclic overstressing of the nut. The investigation also scrutinized the manufacturer's maintenance manual, noting that it lacked specific torque values for this particular part and did not establish a life-limit or non-destructive testing (NDT) procedure for these nuts. Furthermore, the investigation looked into maintenance practices regarding wheel removal and installation, as well as the operator's risk management protocols.