LTT JET SKIDS OFF END OF RWY AFTER MAKING A DOWNWIND LNDG IN HVY RAIN; IN A NIGHT OP.

Narrative

DURING OUR DSCNT INTO SPRINGFIELD; MO; WE RECEIVED THE ATIS AND UNDERSTOOD THERE WERE TSTMS IN THE AREA AND 3 MI VISIBILITY. THE ACTIVE RWY WAS 20 WITH A VOR APCH. SINCE THERE WAS A 9 KT TAILWIND; WE REQUESTED RWY 2. THE TWR TOLD US 'UNABLE; RWY 2 LOC; OTS.' DURING OUR APCH FOR RWY 20 WE WERE ABLE TO IDENT THE APCH LIGHTS 3 MI OUT. AS WE CAME OVER THE THRESHOLD; THE RAIN STARTED COMING DOWN HEAVIER. WHEN I STARTED MY FLARE I LOST MY HORIZ VISIBILITY; BUT HAD MY VERT VISIBILITY. ONCE I STARTED BRAKING WE WERE INSTANTLY HYDROPLANING. IT TOOK A FEW SECONDS TO REALIZE WE WERE NOT DECELERATING DUE TO POOR FORWARD VISIBILITY. I THEN COMMANDED THE FO TO PULL THE DRAG CHUTE. UNFORTUNATELY THERE WAS A MECHANICAL PROB AND THE CHUTE NEVER DEPLOYED; IT JUST RELEASED ITSELF FROM THE ACFT. I HAD NO REVERSERS BECAUSE THE COMPANY ELECTS TO OPERATE THE ACFT WITH THE REVERSERS PINNED. I HAD THE CHOICE OF MAKING A TOUCH-AND-GO BEFORE DEPLOYING THE DRAG CHUTE BUT I FELT PULLING THE CHUTE IS THE BEST SOLUTION WHEN YOU CANNOT SEE FAR ENOUGH DOWN THE RWY TO SEE HOW MUCH YOU HAVE LEFT IN ORDER TO MAKE A SAFE GAR. SINCE THE DRAG CHUTE FAILED WE SKIDDED OFF THE RWY ABOUT 25 FT. THE NOSE GEAR COLLAPSED AND NO ONE WAS HURT. SUPPLEMENTAL INFORMATION FROM ACN 243483: I ARMED AND DEPLOYED THE DRAG CHUTE; BUT THE ACFT DID NOT SLOW DOWN. IT WAS LATER DISCOVERED THAT THE DRAG CHUTE WAS NOT PROPERLY ATTACHED TO THE ACFT; THUS WHEN DEPLOYED IT SIMPLY FELL TO THE RWY.