I have a Citabria, a modern version of the old airknocker. Once I lost a wheel when the axle busted off the plate that is bolted to the gear leg. I hated myself until we looked at the failed part. There was a crack in the weld and the axle had rusted totaly through. Due to mine and and others failing they had to come out with a one piece axle and mounting plate. I had a blind date with me. A friend of mine had fixed me up with his boss. I think he quit his job shortly after that!
This was back around 1978? I had the plane totally restored a little over a year ago. Due to other factors I need to sell it but haven't brought myself to do it yet.
The first picture is waay back then, the 2nd is lately.