Moral of the story, dont trust your life on Carbon Fiber. I dont think you can do non destructive testing on a 5 inch thick carbon fiber pressure hull. Multiple layers? I wonder how it is built, honeycombs? That thick, to many variables to do an adequate NDT inspection. At that depth, the hull has got to be squeezed inward by inches.
Something like that, with hindsight, you dont trust other's lives with it. And you certainly dont use it over and over and over.
I wonder how many dives the sub made.
Best to stick with HY-80, HY-100, HY-120 carbon steel, I imagine steel is much more flexible than Carbon fiber, returning to it's orginal shape sort of like a rubber band. Elasticity would be the word.