Water tank fell out.

Had the exact thing happen to me. Just pulling into our driveway from a two hour drive. Tank partially slid out from resting on top of the axles. I normally let tank drain on the way home but when I opened up the petcock leaving the dump station I noticed the water flow was not normal. Should have been my first clue as the tank had already shifted position causing the drain hose to kink. No real damage other than some scuffs on the tank corners. I didn't want to tackle the repair so took it into the dealer (mine is also a Keystone). I bought a new tank because I was concerned about the heavy scuff from road rash and they put in some extra reinforcement. Extremely poor welds and I may have helped it along by possibly pressurizing the tank somewhat by my filling technique. Sorta glad it happened because it was something I always worried about knowing how poor some of the welds I have seen on these frames. I always fill up at home before a trip. I think it cost about $900 which included the tank @ $ 275, reinforcement, labor and a new piece of coroplast on the bottom.