What happened
On February 23, 2008, an Aero Boero AB-115, registration PP-GCN, was performing a local flight instruction mission at the Pelotas Aerodrome (SBPK) in Rio Grande do Sul, Brazil. The flight, operated by Aeroclube de Pelotas, involved an instructor and a student pilot conducting touch-and-go training.
During the second landing of the mission, the aircraft was on its landing roll when the right main landing gear wheel detached from the assembly. The loss of the wheel caused the aircraft to veer toward the right side of the runway, with the landing gear strut dragging along the pavement until the aircraft came to a complete stop. The detached wheel traveled approximately fifty meters from the aircraft. Both occupants of the Aero Boered AB-115 were uninjured, and the aircraft sustained light damage.
The investigation
CENIPA investigators examined the aircraft and the detached component to determine the cause of the failure. The investigation focused on the axle of the right main landing gear wheel, which had been installed since the aircraft's manufacture and had only 4.9 flight hours remaining before its next scheduled inspection.
Technical analysis of the axle was conducted by the Institute of Aeronautics and Space (IAE). The metallurgical examination revealed that the fracture originated in the weld region, characterized by intergranular fracture, before progressing through the base material via cleavage. This pattern indicated material embrittlement caused by an improper welding process, which had created a coarse and heterogeneous microstructure with degraded mechanical properties.
Findings
- The detachment of the wheel was caused by the breakage of the axle securing it to the landing gear strut.
- The fracture was driven by material embrittlement resulting from an inadequate welding process.
- While the component was part of the original manufacturing, it remains undetermined if the defect originated during initial production or through an undocumented repair, as maintenance records showed no welding services performed on the part.
- All pilot certifications, aircraft airworthiness documentation, and weight and balance limits were in compliance at the time of the occurrence.