What happened
On August 5, 2019, a Cessna 210D, registration LV-INT, departed from the Avellaneda Aerodrome in Santa Fe, Argentina, for a local general aviation flight. During the initial climb, the pilot attempted to retract the landing gear, but the right main gear remained in a transition position. Following established flight manual procedures, the pilot climbed to 1,000 feet and attempted to manually extend the gear using the cockpit's manual hydraulic pump.
Despite these efforts, the right main gear failed to lock into place. After 30 minutes of flight, the pilot prepared for an emergency landing on runway 11. Upon touchdown, the right main gear collapsed into a transition state, causing the aircraft to strike the ground with the right wingtip and the right horizontal stabilizer. The aircraft slid approximately 50 meters before coming to a stop. The pilot and passenger were uninjured, though the aircraft sustained minor damage to the right wing, right horizontal stabilizer, and right main gear.
The investigation
The investigation focused on the landing gear retraction system. While the hydraulic power pack and the rest of the hydraulic circuit showed no leaks or malfunctions, testing confirmed that the right main gear consistently remained in a transition position during extension attempts.
Upon disassembly of the right main gear hydraulic actuator, investigators discovered that the actuator shaft was fractured. The fracture was the result of a crack that had propagated through the shaft due to cyclic loading. The crack originated from a stress concentrator located in the center hole of the shaft and spread toward the outer edge, gradually reducing the component's structural integrity until it could no longer withstand operational stresses.
Findings
- The right main landing gear remained in a transition position during the emergency landing.
- The primary cause of the failure was a fractured actuator shaft.
- The fracture resulted from a crack propagating from a stress concentrator within the shaft's central hole due to cyclic operational loads.
- The failure occurred under normal service conditions and was not detectable through the manufacturer's recommended visual inspection methods.