What happened
On October 16, 2022, at approximately 19:20 UTC, a Tecnam P92 Echo MKII, registration LV-S114, was performing a recreational VFR flight from Chascomús to Morón, Argentina. During the landing phase at Morón Aerodrome, the aircraft's left main landing gear failed, causing the plane to veer off the runway. The aircraft sustained significant damage to the fuselage, empennage, and landing gear, though the engine and propeller remained intact. The two occupants—the pilot and one passenger—sustained no injuries.
The investigation
The Argentine Transportation Safety Board (JST) examined the wreckage and conducted metallurgical testing on the landing gear components. Investigators focused on the threaded bolt used to secure the main landing gear assembly. Laboratory analysis, including scanning electron microscopy, revealed that the bolt had suffered from a progressive fatigue mechanism.
While the investigation noted that the pilot performed the approach at a slightly higher speed than usual, the fracture analysis indicated the failure was ductile and that the gear was not subjected to loads exceeding its design limits. The investigation also found that the aircraft's maintenance records were up to date and complied with manufacturer requirements. However, the existing maintenance manual did not provide specific inspection tasks capable of detecting microscopic fatigue cracks within the complex geometry of the bolt's threaded area.
Findings
- The primary cause of the accident was the failure of the left main landing gear assembly due to the weakening of a securing bolt.
- The failure was driven by a fatigue mechanism within the bolt.
- The maintenance manual lacked specific procedures for detecting progressive fatigue cracks in the landing gear attachment bolts.
- Meteorological conditions and operational parameters (such as weight and speed) were not contributing factors to the structural failure.