AN ACR MLG RAN OFF THE TXWY AFTER LOSING ALL HYD PWR.

Narrative

UPON ARR IN STL ALL HYD PRESSURES WERE NORMAL AND QUANTITIES WERE APPROX 12-13 QUARTS. LNDG GEAR AND FLAPS EXTENDED NORMALLY. IT WAS MY APCH AND LNDG. BOTH REVERSERS OPERATED NORMALLY. I DECELERATED THE ACFT AND BROUGHT BOTH REVERSERS TO FORWARD IDLE AT 80 KTS. AT 90 KTS I STARTED BRAKING AND BRAKING WAS NORMAL. AT JUST UNDER 80 KTS; THE CAPT TOOK THE ACFT AND SLOWED TO 5-10 KTS. AS HE STARTED TURNING OFF RWY 30R ONTO TXWY B; ABOUT 1/2 WAY THROUGH THE TURN; I NOTICED HE WAS HAVING A HARD TIME TURNING THE NOSEWHEEL STEERING. WE WERE NOW HEADED AT A 45 DEG ANGLE OFF THE RWY. AT THIS TIME EVERYTHING ON THE ACFT APPEARED NORMAL. THE CAPT USED 2 HANDS ON THE STEERING AND FULL L RUDDER TO KEEP FROM GOING OFF THE TXWY. WE HAD MADE THE TURN ONTO TXWY B NOW AND AT THIS TIME WE NOTICED WE HAD NO HYD PRESSURE IN EITHER SYS. BOTH QUANTITY GAUGES WERE OFF SCALE HIGH. WE ARE NOW STILL ROLLING AND HEADED OFF TXWY B AT A 45 DEG ANGLE TO THE L. WITH NO BRAKES; THE CAPT ELECTED TO TRY REVERSE THRUST BUT NEITHER REVERSER OPENED. WE DEPARTED THE TXWY AND WENT INTO THE GRASS. WE SHUT DOWN BOTH ENGS AND THE CAPT NOTIFIED EMER EQUIP AND TOLD THE PAX TO FOLLOW THE DIRECTIONS OF THE FLT ATTENDANTS. I NOTIFIED THE COMPANY AND MAINT AND RAN THE AFTER LNDG CHKLIST. MAINT PUSHED US BACK ONTO THE TXWY AND TOWED US INTO THE GATE. NONE OF THE PAX WERE INJURED AND THERE WAS NO DAMAGE TO THE ACFT. PRELIMINARY INVESTIGATIONS INDICATED A CRACK IN THE TRANSFER PUMP CASE WHICH CAUSED BOTH SYS TO DUMP DIRECTLY TO THE RESERVOIRS CAUSING BOTH SYS TO FOAM UP. IT SEEMS TO ME THAT THERE MUST BE A DESIGN FLAW IN THIS SYS FOR SOMETHING LIKE THIS TO HAPPEN. THESE WERE SUPPOSED TO BE 2 INDEPENDENT SYS. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: THE RPTR STATES THAT HE HAS HEARD OF NO OTHER INCIDENTS OF THIS TYPE. HIS ACR; THE FAA; NTSB; AND THE MANUFACTURER ARE ALL WORKING ON A SOLUTION TO A 'PROB THAT CANNOT HAPPEN;' BUT DID. THE ACR AND PLT'S UNION PUT OUT A BULLETIN TO WARN ALL PLTS OF THIS POSSIBILITY. THERE WAS NO FLUID LOST OVERBOARD; BOTH FLUID GAUGES READ FULL WHEN THE ACFT CAME TO REST. THERE WAS NO CRACK IN THE CASE OF THE TRANSFER PUMP; BUT SOME KIND OF INTERNAL FAILURE THAT ALLOWED THE PUMPS TO CIRCULATE FLUID THROUGH THE TANKS WITHOUT PRODUCING ANY PRESSURE AND THEREFORE PWR. THE RPTR STATES THAT HE NOW HAS BEEN INFORMED THAT IF HE HAD TURNED OFF THE TRANSFER PUMP ELECTRICALLY; OP WOULD HAVE RETURNED TO NORMAL.