There are no other controlls except rudder and elevator on the tail. This of course is speculation, but....since that model blimp uses cables and pullies attached to the surface, I have seen what happens when, if unchecked, your pressure gets too low, the tail will start to sag. when that happens the cables can become loose or detached. nothing you can do at that point. if you fly from hot to cold, or high to low, this can happen without opening the vent behind the engine to fill the ballonet with more air to keep the ships shape in check. I dont see any other way you could loose controll of the airship.
I have flown with this pilot around 70 hours, in a simillar airship. thats all i will say about that.