What happened
On January 20, 2012, a Beechcraft F33A, registration PT-LNH, was performing a private transport flight from Campo Verde, Mato Grosso, to Rondonópolis, Mato Grosso. The flight, operated under visual flight rules (VFR), carried a pilot and three passengers.
Upon landing on runway 20 at Rondonópolis Aerodrome (SWRD), the pilot confirmed the landing gear was down and locked via cockpit indications. Immediately after the tires contacted the ground, the occupants felt abnormal vibrations. Approximately 45 meters after the touchdown point, the right main landing gear retracted. This caused the right wingtip to strike the ground, forcing the aircraft to veer to the right. The aircraft traveled about 100 meters along the runway before rotating 90 degrees and coming to a stop approximately 30 meters beyond the right edge of the runway.
All four occupants escaped the aircraft without injury, though the aircraft sustained light damage.
The investigation
CENIPA investigators faced significant challenges during the investigation. The incident was not reported to the regional investigation office (SERIPA VI) until five days after the occurrence. Furthermore, the aircraft was removed from the scene without authorization, and the landing gear had been handled by third parties before investigators could examine it. Upon locating the aircraft in a maintenance hangar, investigators found the damaged gear had been manipulated, with iron bars and ropes used to force the gear into the down position.
Technical examination of the landing gear mechanism revealed that the rod of the right main landing gear actuation mechanism had broken due to overload. Physical evidence, including a 90-degree bend in the rod extremity and specific fracture angles, confirmed the high-stress event. While the braking system, tire pressure, and directional controls were found to be in normal working order, the investigation could not definitively pinpoint the exact trigger for the retraction due to the lack of scene preservation.