What was found
ON FLIGHT 3314 DURING THE ON DESCENT INTO DFW OUT OF FLIGHT LEVEL 360 THE CREW NOTICED A FAINT ODOR OF BURNING /SMOLDERING RUBBER /PLASTIC IN THE COCKPIT. THE FLIGHT ATTENDANT NOTICED THE ODOR IN THE FRONT OF THE CABIN BUT NOT IN THE REAR OF CABIN. THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE NR 1 RECIRCULATION FAN. THE OPERATIONAL CHECK WAS GOOD IAW AMM 21-24-01. THE AIRCRAFT WAS RETURNED TO SERVICE.