What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED INBOUND INTO CLT DUE TO THE FLIGHT CREW REPORTING LOW FREQUENCY VIBRATION AND NOISE FROM UNDER FLIGHT DECK LAST HALF OF FLIGHT. 30 MIN OUT WENT SILENT, MOMENTARILY FUME SMELL AND VENT EXTRACT FAULT. FUMES QUICKLY DISSIPATED AFTER EXTRACT TO OVERIDE PER ECAM. THE AIRCRAFT LANDED SAFELY AT CLT WITHOUT FURTHER INCIDENT. MAINTENANCE ACCOMPLISHED JC 26L00021001, FOUND EXTRACT FAN 18HQ CAUSE OF ODOR. REPLACED EXTRACT FAN 18HQ PER AMM 21-26-51 AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.