SF340 FLT CREW SLIDES OFF SNOW COVERED RWY AT JHW; RESULTING IN ACFT DAMAGE.

Narrative

I WAS CAPT ON ACR X ENRTE FROM BFD TO JHW. I REVIEWED THE CURRENT WX; NOTAMS; AND ARPT CONDITIONS FOR OUR RTE OF FLT AND FOUND THAT WE REQUIRED AN ALTERNATE ARPT. I CALLED DISPATCH AND SPOKE WITH MY DISPATCHER MR X AND REQUESTED AN ALTERNATE BECAUSE WE REQUIRED ONE DUE TO THE FORECAST AT OUR DEST. HE SENT A NEW FLT RELEASE WITH AN ALTERNATE OF PIT. I REVIEWED THE NEW RELEASE AND FOUND ALL WX; NOTAMS; AND ARPT CONDITIONS TO BE GOOD AND WE WERE READY TO DEPART FOR JHW. JHW WX WAS INITIALLY RPTED BY ATIS AT XA47Z; WINDS 230 DEGS AT 7 KTS; VISIBILITY 10 SM; LIGHT SNOW; BROKEN CLOUDS AT 6500 FT; TEMP 03 DEGS C; DEWPOINT -06 DEGS C; ALTIMETER 29.76. WHILE ENRTE TO JHW I NOTICED THE WX TO BE LOWER THAN WHAT THE ATIS WAS RPTING. I CONTACTED UNICOM AT JHW AND REQUESTED A NEW ATIS. AT XB37Z THE WX WAS UPDATED TO WINDS 310 DEGS AT 17 KTS GUSTING TO 27 KTS; VISIBILITY 3/4 SM; LIGHT SNOW; OVCST CLOUDS AT 200 FT; TEMP 01 DEGS C; DEWPOINT -03 DEGS C; ALTIMETER 29.82. I FOUND THE WX TO BE MEET THE MINIMUM REQUIREMENTS TO ALLOW US TO COMMENCE THE APCH. BRAKING ACTION AT JHW WAS RPTED AS FAIR TO GOOD AND THIS ALLOWED US A MAX XWIND COMPONENT OF 25 KTS. OUR XWIND COMPONENT WAS 23 KTS SO WE WERE WITHIN LIMITS. WE FLEW A STABILIZED ILS APCH TO RWY 25 AND HAD VISUAL CONTACT WITH THE RWY AT 400 FT AGL. WE TOUCHED DOWN IN THE CTR OF THE RWY; AT A VREF OF 118 KIAS; IN THE TOUCHDOWN ZONE AT 1250 FT FROM THE APCH END OF THE RWY. DUE TO XWIND AND SLIPPERY RWY CONDITIONS THAT WERE WORSE THAN ADVERTISED WE SLID OFF THE DOWNWIND SIDE OF THE RWY. THE L MAIN WHEELS WERE OFF THE RWY AND THE L PROP IMPACTED 1 RWY EDGE LIGHT. AFTER ADDING PWR AND REGAINING DIRECTIONAL CTL OF THE ACFT ON THE CTR OF THE RWY I STOPPED THE ACFT ON THE RWY AND LOOKED OUT MY WINDOW TO CHK FOR DAMAGE. I NOTICED A VIBRATION COMING FROM THE L ENG AND DID NOT WANT TO CAUSE ANY FURTHER DAMAGE TO THE ACFT SO I COMMANDED THE FO TO SHUT DOWN THE #1 ENG. I THEN TAXIED THE ACFT VERY SLOWLY TO THE TERMINAL RAMP. I WOULD HAVE RPTED THE BRAKING ACTION AS POOR TO NIL; MUCH WORSE THAN WHAT WAS EXPECTED AND RPTED AT THE TIME. AFTER EXITING THE RWY AND COMPLETING THE AFTER LNDG CHKLIST I NOTIFIED THE CABIN AND ASKED THE FLT ATTENDANT IF EVERYONE WAS ALRIGHT AND SHE TOLD ME YES. WE DEPLANED THE ACFT; DID A POSTFLT INSPECTION OF THE ACFT AND LOGGED THE PROPER ENTRIES IN THE ACFT MAINT LOGBOOK. THERE WERE NO INJURIES TO PAX OR CREW AND NO DAMAGE TO THE ACFT OTHER THAN 2 BLADES ON THE #1 ENG PROP AND A CRACKED NAV LIGHT COVER. SUPPLEMENTAL INFO FROM ACN 688587: THE FIELD CONDITION WAS RPTED AS FAIR TO GOOD BRAKING ACTION WITH THIN LOOSE SNOW.