It happened during the Predators first playoff series. I've often told people about it. I just stumbled on the crappy video i shot on my old Sony Clie PDA back in the day.
The fan/motor system fell off the Flying Tiger (blimp/balloon) while it was over the ice. Since that is the main ballast to an otherwise very light balloon, it shot to the rafters and stayed there for the rest of the game.
I have yet to find any mention of it online anywhere.
It happened on April 11th, 2004 at the Preds very first home playoff game ever. Not a very auspicious beginning.