AN ACR CL65 FLC EXPERIENCES SEVERAL EPISODES OF ANTI-ICE DUCT LEAK DISPLAYS WHILE ON APCH TO THE ARPT. THE CREW BLAMES THESE DISPLAYS AND A CHANGE OF RWYS AS THE CAUSE FOR THEIR LNDG WITHOUT A CLRNC.

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WE REQUESTED AND WERE TOLD TO EXPECT RWY 19R IN ICT. WE WERE THEN VECTORED TO RWY 19L. DURING RESOLUTION OF THE CONFUSION REGARDING RWYS; WE RECEIVED A TRIPLE CHIME MASTER WARNING AND AN ANTI-ICE DUCT LEAK MESSAGE. AS I RAN THE CHKLIST FOR THIS ITEM; THE CAPT REQUESTED RWY 19R AND WE BEGAN TO SIDESTEP. WE WERE NOW AT OR BELOW 2000 FT MSL. WHILE COMPLETING THE CHKLIST ITEMS THE WARNING DISAPPEARED (CLRED FROM THE EICAS). NO EMER WAS DECLARED AS THE MESSAGE WAS GONE. ON SHORT FINAL; PRIOR TO CONTACTING TWR (SWITCHED ON A 3 MI FINAL) WE RECEIVED THE ANTI-ICE DUCT MESSAGE AGAIN. I CHKED THE 'ANTI-ICE PAGE' ON ED-2 (EICAS DISPLAY 2) WHICH INDICATED A LEAK IN THE L WING. DUE TO THE SERIOUS NATURE OF THIS TYPE OF WARNING AND THE IMMINENT LNDG; THE LNDG WAS COMPLETED. AT THAT TIME TWR NOTIFIED US WE DID NOT HAVE A LNDG CLRNC. UPON EXPLANATION OF OUR SIT AND OUR FEELING IMMEDIATE ACTION WAS REQUIRED; THE TWR CTLR ACKNOWLEDGED HIS UNDERSTANDING. DUE TO THE RECEIPT OF SUCH A SERIOUS WARNING AT SUCH A CRITICAL PHASE OF FLT COUPLED WITH BEING ALIGNED WITH THE WRONG RWY BY THE CTLR; THE CONFUSION WHICH RESULTED LED TO LNDG WITHOUT CLRNC. ALSO; THERE WAS NO OTHER TFC IN THE AREA AND THE CTLR WAS AWARE OF THE HDOF; HE COULD HAVE CALLED US. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR SAID THAT THIS WAS A NIGHT FLT AT THE END OF A LONG DAY IN A CL65. THE EARLY PART OF THIS SCHEDULE HAD CONSISTED OF EARLY MORNING FLTS AND THE FLC WAS TIRED. THE CTLR WANTED THEM TO USE RWY 19L; BUT DID NOT SEEM TO HAVE ANY TFC SO THEY STARTED TO SWITCH THE RADIOS AND APCH INFO WHEN THE EICAS MESSAGE FIRST APPEARED. THE CAPT DECIDED TO USE THE LONG RWY AND INFORMED THE CTLR. THE CTLR SEEMED TO BE UPSET AND ALLEGEDLY WAS VERY RUDE. THE FLC DECIDED TO USE THE LONGER RWY BECAUSE OF A HIGHER THAN NORMAL APCH SPD DUE TO WT AND BECAUSE OF SNOW ON THE RWY. AFTER LNDG THE FLC TALKED TO THE ATCT LCL CTLR WHO SAID THAT HE WAS NOT CONCERNED ABOUT THE LACK OF A LNDG CLRNC AND UNDERSTOOD HOW THIS COULD HAPPEN. THE DUCT LEAK WARNING WAS CAUSED BY A FAULTY SENSOR IN THE PRESSURIZATION SYS.