Fresh water Tank Collapse

[rjohnsonnm]

I just recently filled my FW tank to capacity to give it a good flush (I normally keep it about 1/3 for weight considerations). I heard a strange thump and when I looked under the trailer I saw a big bulge in the plastic/rubber underbelly. When my RV repair guy opened up the bottom he found that the tank had fallen down and was resting on the underbelly. The tank had been supported by a 1/4 in. piece of plywood and the edges were only overlapping the frame by about 1 in of the plywood. There was nothing else holding tank in place. The weight of the full tank apparently caused the plywood to sag and then it came off the frame. He welded in a couple of metal braces and replaced the 1/4 in. plywood with 3/4 in. What an amazingly bad piece of engineering by Doubletree (or perhaps an installer). Has anybody had a problem like that?
Ron