Black Tank Flush Accident

[ppkemper]

After negligently leaving the black tank flush water hose on and forgetting about it, I heard a loud structural steel-frame crash while I was inside located in the general area of the black tank. It sounded just like the expanded black water tank popped/busted a retainer strap which banged against the steel framework of the 2015 Surveyor Cadet 30 feet trailer.
No water sprayed anywhere, but the black water tank valve was under a lot of pressure when I opened it.
Everything seems normal now.

Can anyone help me figure out what may have happened to the steel framework of the trailer, and what risks I may have just continuing to use the trailer normally?

Thanks.

[2015 Flagstaff 21DS]

Don't know what may have broken but it sounds like you have a secondary issue. The black tank vent should have relieved the internal pressure in the tank. If the tank actually filled to overflowing the water should have gone up the stack and flowed down off the roof.

[DDC]

Check the roof vent, I did the same thing a few years ago and because of the tank expansion it pushed the vent pipe up and broke the vent off. Very loud bang.