WHILE TAXIING ON ICY RWY TO DEICING; FLC LOST CTL OF ACFT AND IT SKIDDED OFF THE EDGE OF THE RWY. THE ACFT WAS TAXIED ON ONLY ONE OF ITS 2 ENGS.

Narrative

TAXIING OUT ON TXWY F TOWARDS DEICING AREA ON THE E SIDE OF RWY 3C; I WAS TAXIING WITH A SINGLE ENG TO CONSERVE FUEL. THERE WERE 15 ACFT IN FRONT TO DEICE. THERE HAD BEEN SNOW AND FREEZING RAIN WHICH HAD COATED OUR ACFT WITH ICE SO WE NEEDED TO BE DEICED. THE GND CTL THEN DIRECTED US TOWARDS ANOTHER DEICING AREA SET UP ON THE E SIDE OF THE TERMINAL. UPON APPLICATION OF PWR ON THE R ENG WE STARTED TO TAXI IN A STRAIGHT LINE (47 PERCENT N1). IN ORDER TO 'SHED ICE' THERE IS A REQUIREMENT TO ATTAIN 50 PERCENT N1 ONCE EACH 30 MINS SO I GAVE THE THROTTLE ABOUT 1/2 INCH MORE FORWARD TRAVEL. THE NOSEWHEEL THEN BROKE FREE AND WE STARTED TOWARDS THE EDGE OF THE RWY. I IMMEDIATELY RETARDED THE PWR AND TRIED DIFFERENTIAL BRAKING AND STEERING WITHOUT SUCCESS. WE CAME TO A STOP IN SOME SNOW AT THE EDGE OF RWY 3C. I ASKED THE GND IF THE LIGHTS WERE ON THE PAVEMENT AND HE SAID THEY WERE ON. OUR ACR DOESN'T WANT US TRYING TO TAXI IF AN ACFT HAS LEFT THE PAVEMENT. I STARTED THE OTHER ENG AND TAXIED TOWARDS THE DEICING AREA. BECAUSE SOMEONE HAD SAID THAT I HAD LEFT THE PAVEMENT; WE RETURNED TO A GATE. THERE WAS NO DAMAGE OR EVIDENCE THAT WE HAD LEFT THE PAVEMENT. THERE WAS NO ATIS INFO ON SLIPPERY CONDITIONS.