What was found
ORD - FLT 1966 - AFTER TAKEOFF ORD, FLIGHT CREW TURNED ON WING ANTI-ICE AND HEARD A LOUD BANG FOLLOWED BY VIBRATION. AIRCRAFT RETURNED TO ORD AND LANDED WITHOUT INCIDENT. CHECK OF AIRCRAFT REVEALED TWO SUPPLY DUCTS RUPTURED. AIRCRAFT MAINTENANCE REPLACED RUPTURED SUPPLY DUCTS AND AS A PRECAUTION, REPLACED ENGINE BLEED AIR SHUT-OFF VALVE. SYSTEM GROUND AND LEAKED CHECKED NORMAL OPERATION. (X)