I'm not trying to defend the owner by any means, but there is a logical explaination for this tragedy..
Fruehauf in my opinion was a very good, quality built product. The use of ProPar axles with their standard, same-sized inner & outer wheel bearings, the square axle tube configuration, etc. made for a good vehicle.
However, their bathtub design was a great idea in terms of materials sliding out faster than a square-cornered box, but once the (aluminum especially,) floors showed signs of abrasion on top of the strenthening ribs, or between them, this was a severe weak point to say the least. It's kind of like a "unibody" design in layman's terms, and again, it comes down to having enough COMMON SENSE to visually inspect these weak points and determine whether or not it's safe to flip the PTO in one more time or not.
I had a friend years ago who experienced the same thing, and so from that point all of us who owned dump trailers and triaxles with bathtub or 1/2 round designed bodies kept a watchful eye on things.
It happens to the best of them.
A trucking company in Ct. I know has a few awesome looking Peterbilts all tricked out, pulling dump trailers and a couple pushout trailers that primarily haul scrap metals.
One day in the landfill, dumping the first load with a brand new Alumatec 1/2 round trailer (a trailer in excess of $40,000.00,) and a beautiful Pete daycab, the piston got to the second stage, snapped in half, sending it down through the middle of the cab, and the trailer with 25 tons crashing back down. Demolished the truck, demolished the trailer. So it goes without saying...you just never know.