What happened
On January 17, 2023, a Beechcraft C-90, registration N9VC, was performing a private flight from Yariguíes Airport (SKEJ) to Palonegro International Airport (SKBG). The flight crew, consisting of a pilot in command, an observer pilot, and one passenger, arrived at the airport under visual flight conditions.
Upon landing on runway 35, the aircraft initially maintained a stable touchdown and successfully traveled approximately 364 meters with the landing gear fully extended. However, during the deceleration phase, the left main landing gear suddenly collapsed, followed 0.76 seconds later by the collapse of the right main landing gear. While the nose gear remained extended, the failure caused the aircraft to scrape the runway surface for an additional 1,114 meters before coming to a final stop near taxiway Charlie.
The three occupants evacuated the aircraft on their own and were reported to be uninjured.
The investigation
The GRIAA investigation focused on the mechanical failure of the landing gear components. Physical examination of the aircraft revealed significant damage to the lower fuselage, including friction damage to the tail cone, antenna assemblies (transponder, VHF, and DME), and the elevator cable pulley support. The investigation also noted cracks in the right main landing gear door and displacement of the landing gear torsion tubes.
Technical analysis of the landing gear actuators was conducted by the manufacturer in the presence of FAA personnel. The examination of the fractured components revealed that the failures occurred at the rivet holes used to secure the actuators to the airframe. The fracture surfaces showed evidence of overload, characterized by a combination of tensile and shear stresses, but no signs of material fatigue (such as beach marks) were identified. The investigation ruled out the possibility that the gear was in a state of transition (retracting) at the moment of touchdown, as the aircraft had operated normally on all three wheels for several seconds prior to the collapse.
Findings
- The primary cause of the accident was the retraction of both main landing gears during the landing roll and deceleration.
- This retraction was triggered by the fracture of the rivet holes securing the actuators to the airframe due to undetermined stresses that exceeded the material's strength.
- The aircraft's maintenance was up to date, and the crew followed all established procedures and checklists.
- Meteorological conditions were optimal for visual flight.