`Tree stand aluminum turnbuckle lawsuit`

Cast aluminum turnbuckle from a hunting tree stand fractured; plaintiff's expert magnified four pores to basketball size in SEM imagery. Tom's "four ping-pong balls on a desk" analogy at trial conveyed the actual ~2% area loss to the jury. The turnbuckle was also bent — failure cause was bending overload, not porosity. Used to illustrate (a) the proportional strength-loss relationship for porosity in aluminum, (b) how to explain microstructural scale to lay audiences.

One time I had a guy who was in a tree stand somewhere near White Plains, New York — that's where the trial was. It was a cast aluminum turnbuckle that was one of the things holding this tree stand. A tree stand is where some guy's going to go out there with a bow and arrow or a rifle and shoot little deers, shoot Bambi. He sits in the tree freezing in the fall just so he can shoot Bambi, okay. So this guy fell from the tree stand, hurt himself, and the turnbuckle was broken. Someone looked on the fracture surface and they found four pores. Whew — I should be concerned, I guess.

Forensic case used to illustrate that small amounts of porosity (four or five pores under half a millimeter in a cast aluminum turnbuckle) are not the cause of failure. Tom on the witness stand uses a five-ping-pong-balls-on-a-table analogy to convey the porosity fraction. The actual failure cause was overloading from improper climbing.

I had a case once where a guy fell out of a tree stand. In fact I had a number of cases where people fell out of a tree stand, but this one was a cast aluminum turnbuckle. I think this was a homemade tree stand. They took an x-ray of it, and there were four or five little pores — little pores, less than half a millimeter, in this whole little turnbuckle. I was on the witness stand in White Plains, New York, trying to explain how little this porosity was. I think I ripped a piece of paper to show them a brittle material — and aluminum is not a brittle material, it's ductile, particularly this type of casting. The witness box had a little table, about four feet by three feet, in front of my chair. I said it'd be the equivalent of having five ping-pong balls on the table. I'd done the calculation: the porosity and the area of the little turnbuckle. The reason the turnbuckle broke was not anything defective about the turnbuckle — it's because if you overload things they sometimes break. The guy had been climbing improperly.