What was found
AIRCRAFT ROLLS SHARPLY TO THE LEFT WHEN SLAT EXTENDED. A LOUD BANG WAS HEARD AFTER 5 DEGREES OF FLAP SELECTED AND ROLLING MOVEMENT STOPPED. THERE WERE NO ABNORMAL ANNUNCIATOR INDICATIONS. THE FLIGHT LANDED SAFELY AT DTW. MAINTENANCE STATED THAT SLAT EXTENSION APPEARED NORMAL BUT SLAT RETRACTION WAS SLOW AND JERKY. ALL TRACKS AND TRACK DOORS ARE NORMAL. ALIGNMENT CHECK APPEARS NORMAL. THE RIGHT T-DUCT BINDS ON RETRACTION AND THE INBOARD RIGHT SLAT SEAL WAS FOUND TO BE BADLY DAMAGED AND WAS REPLACED. THE AIRCRAFT RETURNED TO SERVICE.