Wings arn't designed to take a point load at the wing tips.
I am sure G or IM have the proper data but i would have thought as an ex structural engineer.
The design is for a force loading over the length of the wing design so even if you don't take into account the washout as you get near the tips you can simplifiy that to a point halfway between the support and wing tip. In actual fact it will be alot closer to the support which makes matters worse the nearer the support it is.
Now the support will act as a pivot point so the moment applied from one side with counteract the moment from the other. So in flight the moment acting on the pivot point will be reduced.
By point loading the tip you have doubled the moment acting on the pivot point (in real life it will be more). Yep great the plane is rated at 3g so that not a problem but then you don't have is the balancing moment from lift from the other side of the pivot point. Then the bit of wing inside the pivot point is subject to a negative moment 3 times as a guess more than its designed for which is of course -1g. Then the wing mountings are also getting 3 times more in the wrong direction as well.
Metal doesn't just break when you hit its limit. It has a linear load profile up unto its yield point. Which means it will go back to where it started when the load is taken off, then a nonlinear responce until it fails.
Stress
It could very well be the metal has deformed but not to notice. So what you might say.
Then we get into strain hardening.
Work hardening - Wikipedia, the free encyclopedia
Again so what.
Different strength metals next to each other act as a stress concentrator which means that it acts as a focal point for fatigue cracks to occur.
I reckon it could be a time bomb, it might also not be picked up in a normal inspection unless the engineer knows the history and is looking for it. Until some one sits down and runs the numbers nobody will know. And you certainly wouldn't know with a quick walk round.
Quite alot of industrial failures are caused by none designed loads which have occured while in transport. In fact one of my collegues from my degree course all he does is design loading jigs for transport. And unless the transport jig is certified by DMV etc the equipement ain't allowed to be used.
Now I haven't practised as an engineer for quite some time and I don't have a FEA package to play with or a copy of Roarks. So if this thinking is a pile of poo please correct it.
O and I haven't even started on a point load in the laterial direction