What was found
AIRCRAFT WAS GROUNDED: LEFT WING FUEL TANK OVERFLOW ECAM MESSAGE, AN EMERGENCY WAS DECLARED, AND THE AIRCRAFT RETURNED TO CLT WHERE IT LANDED SAFELY WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED CLACK VALVE 214QM (AND) CLACK VALVE 216QM (AALA202110219658) AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.