B190 FLT CREW EXPERIENCE TXWY EXCURSION DUE TO ICING CONDITIONS.

Narrative

AFTER LNDG IN DODGE CITY; KS; ON RWY 32; WE BEGAN OUR TAXI TO THE RAMP AREA ON TXWY A. BRAKING ACTION HAD BEEN RPTED AS POOR ON THE TXWYS AND I WAS TAXIING SLOWLY WITH THE PROPS FULL FORWARD TO ALLOW THE USE OF REVERSE IF NECESSARY. I STARTED AN INITIAL R TURN INTO THE RAMP AND NOTICED THE NOSEWHEEL WAS NOT COMPLYING WITH THE INTENDED TURN. I USED REVERSE TO BRING THE ACFT SAFELY TO A STOP. A SECOND ATTEMPT TO MAKE THE TURN WAS MADE USING DIFFERENTIAL PWR FROM THE L ENG. AS THE ACFT BEGAN TO MOVE; THE TURN WAS AGAIN NOT BEING COMPLETED. ICE UNDERNEATH PACKED SNOW PREVENTED THE ACFT FROM STOPPING DESPITE USING BOTH REVERSE THRUST AND FULL BRAKES. THE ACFT SKIDDED AHEAD AND THE L MAIN GEAR DROPPED OFF OF THE TXWY; THUS CLIPPING A TXWY LIGHT WITH THE L PROP. THE ACFT CONTINUED FORWARD BACK ONTO THE RAMP AREA AND I WAS ABLE TO GUIDE IT INTO THE PARKING AREA 30 FT FROM WHERE IT SLID OFF THE CEMENT. BOTH ENGS WERE THEN IMMEDIATELY SHUT DOWN. I SUBSEQUENTLY DOWNGRADED THE BRAKING ACTION FOR THE TXWYS AND RAMP AREA TO NIL. STRONG WINDS CAUSING SNOW TO DIMINISH THE AVAILABLE AREA TO ENTER THE RAMP; AS WELL AS MASK THE SEVERITY OF THE UNDERLYING ICE WERE SUBSTANTIAL FACTORS TODAY. AS WELL; I FELT THE BRAKING ACTION RPT WAS CLRLY INACCURATE AS I WATCHED SEVERAL PEOPLE NEARLY FALL ON THE RAMP; INCLUDING MYSELF; AFTER WE HAD PARKED AT THE GATE. SUPPLEMENTAL INFO FROM ACN 574958: WE CONTINUED TO THE RAMP. ON MY POSTFLT INSPECTION IS WHEN I NOTICED THE DAMAGE TO THE L PROP. AS WE INSPECTED THE RAMP THERE WAS A SHEET OF ICE UNDERNEATH THE PACKED SNOW WHICH I FEEL WAS THE CAUSE OF THE INCIDENT.