What happened
On November 14, 2016, a Beechcraft F33A, registration PT-OMK, departed from Fazenda Bandeirantes in Aquidauana, Mato Grosso, bound for the Estância Santa Maria Aerodrome in Campo Grande. The flight, operated for private purposes, carried a pilot and two passengers.
During the final approach, the pilot confirmed that the landing gear position indicators showed green lights, signifying that the gear was down and locked. Following a three-point landing, the aircraft suddenly veered to the right. This maneuver was caused by the spontaneous retraction of the right main landing gear, which forced the aircraft off the side of the runway. The aircraft sustained substantial damage, though all three occupants escaped without injury.
The investigation
The investigation conducted by SERIPA IV examined the aircraft's mechanical condition and the circumstances of the landing. Investigators noted that the aircraft's maintenance logs for the airframe, engine, and propeller were technically outdated due to missing signatures and hour entries. Furthermore, the aircraft was removed from the scene by the operator before investigators could perform a field examination.
Subsequent inspections at a certified maintenance facility revealed that a specific component of the landing gear assembly, the BRAZE ASSY ROD RH (part number 35-815125-604), exhibited deformations consistent with structural overload. This rod is a critical part of the interconnected system responsible for the extension, retraction, and locking of the landing gear.
Findings
- The pilot was properly rated and held a valid medical certificate.
- The landing gear indicators correctly showed the gear as down and locked prior to touchdown.
- The excessive force applied to the right landing gear strut during the three-point landing caused the deformation of the BRAZE ASSY ROD.
- This structural deformation led to the failure of the locking mechanism, resulting in the retraction of the right gear and the subsequent runway excursion.