[avs733]

What matters isn’t the size of the gap, what matters is the size of the gap relative to the size of the gap it was designed for.

If I design a 10” Diam part to be assembled to another with a .001” gap, then a .010 gap is huge. If it’s a 10’ part that has the same tolerance, a 0.01” gap is still huge.

Tolerances aren’t arbitrary, they are analyzed and the issue is you generally don’t k ow what happens accurately if those tolerance limits are violated.

As for the mechanism, you need to worry not just about a single cycle load to failure, you need to also worry about shortened fatigue life (I,e, failure after many cycles - but many less cycles than predicted). Overall, load transfer is highly complicated in thin skin structures and that the gap is small doesn’t mean that a change in that gap crosses a small change in load