What was found
DURING FLIGHT 2745 THE F/A REPORTED A RUMBLE SOUND FROM FLOOR FOLLOWED BY AN ELECTRICAL SMELL. AC RETURNED TO GATE. MAINTENANCE RAN SUPPLEMENTAL AC FOR AWHILE, NO RUMBLING OR FUMES NOTED. OPS CHECK GOOD. RAN RECIRC FAN ON BOTH SETTINGS, NO DISCREPANCY, NO RUMBLING NOTED FOR THE DURATION OF ALL. OPS CHECK GOOD.