Dear TEDSKI -
You think they put the lines separately in 747s (for the 4 systems...?)
And that was the reason JAL 123 went down... at least UA crew did save many people lives by attempting to control the aircraft, and landing it at Sioux City... with the JAL plane, they did not...
What can happen to a DC-10 can happen (again) - including 747s and many other "all hydraulic airplanes"... at least in the Caravelle and the Comet, which are mid-1950 designs, if the 4 hydraulic systems were lost, they could go through the floor of the cabin to the reservoirs, and fill them with Coca Cola, strained tea, water or milk - in emergency...
They dont say if milk must be low fat...