After that experience in Sioux City, certain modifications were made to the MD-11 hydraulic system 3. MD-11 has 3 hydraulic systems and in case of system 1 and 3 failure, there is an electrically operated shutoff valve and some special features in the system 3 supply line to keep some hydraulic power to the flight controls. However, if a break occur in hydraulic system 3 aft of the bulkhead (for example: a catastrophic failure of number 2 engine), the shutoff valve will close, preserving hydraulic fluid and pressure forward of the bulkhead. But, with dual failure of hydraulic system 1 and 2 and a limited system 3 the MD-11 will lose rudder, elevators, flaps and spoilers (except one panel on each wing) control. Only aileron control will remain and pitch attitude is controlled by thrust.
This maneuver can be made during simulator training but it’s decidedly hard to keep the airplane flying.
Bkmk