The pilot thought he struck a pothole while landing the Baby Great Lakes on the grass runway at the airport in Castroville, Texas.
During the landing, the airplane caught on fire and was destroyed. The pilot sustained thermal injuries and was hospitalized for an extended period of time.
Post-accident examination revealed the right main landing gear axle had fractured during the landing and the landing gear leg punctured the fuel tank, which likely contributed to the post-impact fire.
Metallurgical examination revealed a series of ratchet marks consistent with multiple fatigue crack initiation points joining into a single larger crack on the right main landing gear axle. The fatigue crack extended across about 30% of the cross section of the tube before final failure due to overstress. The locations of the fatigue initiation points were consistent with the cyclic bending forces that would have been applied to this section of the landing gear under normal landing and takeoff conditions.
Probable Cause: The failure of the right main landing gear axle due to multiple fatigue crack initiation points joining into a single larger crack.
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This April 2024 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
I would only wonder if these cracks would have been visible during a pre-flight inspection or a maintenance inspection. I suspect it helps if one is very familiar with the plane they are flying.