What was found
EMERGENCY LANDING - ACFT LOST TREAD FROM 1 OF THE LT MAIN TIRES ON TAKEOFF. FLIGHT CONTINUED AND WHILE ENROUTE, CREW REPORTED LOSS OF YELLOW HYD SYS. AN EMERGENCY WAS DECLARED, ACFT LANDED WITHOUT INCIDENT AND TAXIIED TO GATE. MAINTENANCE DETERMINED TREAD LOSS FROM THE NR 2 MLG TIRE CAUSED DAMAGE TO THE FLAPS, HYDRAULIC LINES AND UNDERSIDE OF WING. REPLACED NR 1 AND NR 2 MLG TIRES, HYDRAULIC PRESSURE AND RETURN LINE, AND REPAIRED DAMAGE TO WING / FLAPS.