Belite, a company that folded (and just renamed themselves) after a certain number of crashes of their experimental ultralights, sold my dad a plane where the AOA sensor was malfunctioning, the propeller hit the ground if there was someone in the plane, and one wing side was longer than the other. By a visible amount. My dad broke a set of propellers and they sent him a new set with 3" cut off each blade. i have those in my shed.

I'm no aerospace engineer or anything, but that plane shouldn't have been able to stay in the air.

and, lo, it didn't, the motorcycle engine used as the prime mover sputtered out at 200' AGL and since it's not a glider (and i don't even think it can glide), it crashed straight into the ground.

Fly an ultralight if you want, just be aware that people will think very poorly of you.