DC8 FLT CREW HAS HYD FAILURE AND DEPARTS THE RWY WHILE TAXIING AT MSP.

Narrative

WHILE TAXIING ONTO RWY 30L; ATTEMPT TO TURN ACFT ONTO CTRLINE BECAME DIFFICULT WITH NOSEWHEEL STEERING. ACFT SEEMED TO BE SKIDDING ON THE ICE. AFT CTR OF GRAVITY OF 30.9% WAS PERCEIVED AS REASON FOR POOR STEERING RESULT. DIFFERENTIAL THRUST AND BRAKING WAS USED TO LINE UP ON CTRLINE. NOSEWHEEL WAS STILL NOT EFFECTIVE. CREW ELECTED NOT TO TAKE OFF. ATTEMPT TO TURN OFF ON NEXT TXWY PROVED DIFFICULT. WITH POOR CTL AND OTHER COMMERCIAL ACFT NEARBY; WE ELECTED TO PROCEED DOWN RWY 30L AND TURN OFF ON RWY 22. TURN WAS ACCOMPLISHED WITH DIFFERENTIAL THRUST AND BRAKING. AFTER CLR OF RWY 30L; FE NOTICED THAT WE HAD LOST HYD QUANTITY AND PRESSURE. ATTEMPT WAS MADE TO STOP USING BRAKE ACCUMULATORS WITH NO RESULTS. ENG REVERSERS WERE DEPLOYED YET NO REVERSE THRUST WAS OBTAINED. PLANE CONTINUED DOWN THE SNOW COVERED RWY (WITH QUARTERING TAILWIND AT 350 DEGS AT 11 KTS). AS ACFT DRIFTED SLOWLY OFF CTRLINE TO EDGE OF RWY (APPROX 3-5 KTS); ATTEMPT WAS MADE TO STOW #1 AND #2 REVERSER SO ENGS #1 AND #2 COULD BE RUN UP TO STOP DRIFT OFF OF RWY. REVERSERS WOULD NOT STOW. EMER AIR BRAKE DEPLOYED BUT ACFT STILL CONTINUED TO DEPART RWY INTO ADJACENT FIELD. NO DAMAGE TO ACFT OR INJURY TO CREW MEMBERS. MAINT DISCOVERED BROKEN HYD LINE TO NOSEWHEEL STEERING.