What was found
C HYD QTY EICAS MSG, TURNED INTO A C HYD FLUID TOTAL LOSS. CREW TURNED CENTER PUMPS OFF TO SEE IF FLUID WOULD STILL BE LOST. THE FLUID QTY CONTINUED TO GO DOWN. THIS STARTED ABOUT 75 MILES FROM SDF. FOUND NR 9 SPOILER FILTER PLUG O-RING BLOWN, SEE IPC 27-61-02 AS PER MM 27-91-02-4. REMOVED PLUG AND REPLACED O-RING AND TIGHTENED, LEAK CHECKS OK. RAN ALL FH. CONTROLS THROUGH SEVERAL TIMES.