FLC OF B727 IS REQUESTED BY MECH TO EXTEND FLAPS TO 30 DEGS. FO QUERIES MECH TO ASSURE HE WANTS FLAPS EXTENDED AND THEN DOES SO. HE IS LATER INFORMED THAT THE FLAPS HIT A SVC TRACTOR PARKED UNDER THE TRAILING EDGE OF THE WING. ACFT TAKEN OTS.

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LOCATION: DFW. UPON ARRIVING AT THE ACFT; 2 MAINT PERSONNEL WERE IN THE COCKPIT WORKING ON A REPEAT WRITE- UP ON THE OUTBOARD FLAPS. AFTER SOME DISCUSSION ON THE PROB; BOTH MAINT PERSONNEL LEFT THE COCKPIT. THE FO THEN GOT INTO HIS SEAT TO START HIS DUTIES. SHORTLY 1 MAINT PERSONNEL CAME BACK INTO THE COCKPIT AND ASKED FOR THE FLAPS TO BE LOWERED TO 30 DEGS. THE FO RESPONDED WITH 'YOU WANT ME TO LOWER THE FLAPS TO 30 DEGS?' MAINT ACKNOWLEDGED WITH A YES AND LEFT THE COCKPIT. FO THEN MOVED THE FLAP HANDLE TO 30 DEGS. AFTER A BRIEF TIME; THE FO RECEIVED A VISUAL SIGNAL TO RAISE THE FLAPS AND HE DID. AFTER ANOTHER BRIEF PERIOD OF TIME; MAINT APPEARED AT THE COCKPIT DOOR AND STATED THAT THE R OUTBOARD FLAPS HAD COME IN CONTACT WITH A FLEET SVC TRACTOR PARKED UNDER THE TRAILING EDGE OF THE WING. THE FO THOUGHT THE AREA HAD BEEN CLRED BY THE OTHER MAINT PERSONNEL. I WAS SEATED ON THE JUMP SEAT AND HEARD THE EXCHANGE AND THOUGHT ALSO THE AREA HAD BEEN CLRED. ACFT WAS TAKEN OTS. LESSON LEARNED: RECEIVE VERBAL CONFIRMATION THAT THE AREA IS CLR BEFORE ANY LEVER OR SWITCH IS MOVED.