I used to fly 727 freighters. We had one bird that used B hydraulics to actuate the main deck cargo door. On a turn in STL, the second officer went to open the cargo door and one of the hydraulic lines ruptured, completely depleting the B system. And the door was still closed and latched. Contract maintainence, on the advice of MX control, emptied the ULD in the forward position and used the crash axe to hack a big enough hole in the can so they could crawl through and see WTF was going on with the cargo door/hydraulics.