What happened
On April 1, 2019, a Cessna 150L, registration LV-CRR, was performing a local flight for pilot re-adaptation when it experienced a landing gear failure at Morón Airport, Buenos Aires. The flight, operated by a private owner for flight instruction, departed at 13:40 UTC. After approximately 80 minutes of flight in visual meteorological conditions, the aircraft was landing on runway 02 at 14:54 UTC. During the landing roll, the left main landing gear wheel detached from the assembly. The aircraft slid approximately 50 meters along the runway before coming to a stop at the intersection of the runway and taxiway Foxtrot. Both the flight instructor and the student pilot evacuated the aircraft without injury.
The investigation
Investigators examined the left main landing gear assembly and found that the wheel had separated from the hub. The investigation revealed that three bolts located in the threaded section of the hub had broken, while an additional three bolts were missing entirely. A search of the runway by airport ground personnel failed to locate the missing hardware. /nLaboratory analysis of the wheel hub and brake assembly showed no evidence of overheating or sudden braking forces that would suggest a caliper failure. Microscopic inspection of the bolts remaining in positions A, D, and E revealed surface roughness consistent with a tensile overload. Furthermore, the threads at position B had been stripped, leaving only 9 mm of engagement at the time of the failure.
Records indicated the aircraft had undergone a 100-hour inspection just two days prior to the incident; however, the maintenance workshop did not provide the specific work order for this inspection. While the crew performed a pre-flight inspection, investigators noted that visual inspections are often unable to verify the proper torque of landing gear bolts.
Findings
- The left main landing gear wheel assembly collapsed due to a mechanical overload on the remaining bolts.
- The bolts in positions A, D, and E fractured because they were subjected to stresses exceeding the material's strength limits.
- The missing bolts (positions C and F) likely detached due to operational vibrations, potentially caused by insufficient torque during assembly.
- There was no documented evidence of recent tire replacements or specific landing gear maintenance in the aircraft's history.
- The investigation could not confirm the exact assembly method or the specific work performed during the recent 100-hour inspection due to a lack of documentation from the maintenance facility.