What happened
On September 19, 2021, an Aero Boero AB180, registration LV-JYF, was performing a glider towing operation at the San Andrés de Giles Aerodrome in Buenos Aires province. During the landing phase under visual flight conditions, the aircraft experienced a significant mechanical failure. As the pilot attempted to correct the aircraft's attitude following a bounce upon touchdown, the right main landing gear wheel detached from the assembly. The detached component dragged for approximately 20 meters before digging into the grass runway, causing the aircraft to capsize. The impact resulted in substantial damage to the fuselage, wings, propeller, and engine, though the pilot escaped with only one minor injury.
The investigation
The investigation focused on the structural integrity of the landing gear assembly. Investigators examined the wreckage and identified a fissure in the support for the right main gear axle. Metallurgical analysis revealed that the failure was driven by a progressive fatigue mechanism. The study found that the material's granular structure had been altered due to heat exposure near the weld points, and significant welding defects, specifically lack of penetration, were present. These defects created stress concentration zones within the component. While the pilot's credentials and the aircraft's maintenance records were all in compliance with regulations, the investigation noted that the existing maintenance manual lacked effective inspection items to detect this specific type of progressive fatigue failure.
Findings
- The right main landing gear assembly failed during the landing sequence, leading to the aircraft's excursion and capsize.
- The primary cause was material fatigue that had progressed undetected by previous inspections.
- Manufacturing quality control issues were evident, specifically regarding improper heat treatment near welds and defective weld penetration.
- The investigation identified that these manufacturing defects acted as stress concentrators, making the component susceptible to failure even under normal design loads.