There are some parts that’ll cause the plane to fail in obvious ways, like the fuel tanks and engines. The tricky thing is that there are parts that’ll work with holes in them for a bit, but eventually if enough holes get punched in them they’ll fail under load, causing the plane to crash.
Or, there are events that’ll cause the parts, say a wing, to fall off, and then the pilot will fly it home still despite the manufacturer swearing that their plane can’t fly without a wing[0]. Aerodynamics are hard.
0: https://theaviationist.com/2014/09/15/f-15-lands-with-one-wi...
