What was found
SDF TO IAH. DURING CRUISE FLIGHT CREW RECEIVED A "STEERING INOP" CAS MESSAGE. CREW RAN APPROPRIATE CHECKLIST AND SPOKE TO DISPATCH AND MAINTENANCE CONTROL ABOUT THE SITUATION. IAH OPERATIONS WAS CONTACTED TO HAVE A TUG STANDING-BY NEAR THE RUNWAY IF A TOW BACK TO GATE WAS REQUIRED. ATC WAS INFORMED OF THE SITUATION AND THE LONGEST AVAILABLE RUNWAY WAS REQUESTED, BUT THAT THERE WAS NO NEED TO DECLARE AND EMERGENCY. ATC APPROVED RUNWAY 27 AND DECLARED AN EMERGENCY FOR THE CREW. PASSENGERS WERE BRIEFED OF THE SITUATION. THE AIRCRAFT LANDED WITHOUT INCIDENT AND WAS ABLE TO TAXI CLEAR OF THE RUNWAY. THE AIRCRAFT WAS TOWED BACK TO GATE TO PREVENT ANY POSSIBLE FURTHER DAMAGE OR PROBLEMS ASSOCIATED WITH TAXING BACK TO GATE. MAINTENANCE TROUBLESHOT THE NOSE WHEEL STEERING SYSTEM AND FOUND THE LT NOSE STEERING RVDT WAS BAD. THE RVDT WAS REPLACED AND THE STEERING SYSTEM OPS CHECKED GOOD.