What was found
AIRCRAFT WAS GROUNDED: AT FL240 ON DEPARTURE RECEIVED ECAM MESSAGE HYDRAULIC GREEN RESERVOIR LOW LEVEL FOLLOWED BY SEVERAL ASSOCIATED HYDRAULIC MESSAGES. COMPLETED ECAM PROCEDURES AND LOWERED THE GEAR MANUALLY. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO DFW WHERE IT LANDED SAFELY AND TAXIED TO THE GATE WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND THE LEFT ENGINE HYDRAULIC PRESSURE LINE IN THE LEFT PYLON BLOWN AND LEAKING. REPLACED PRESSURE LINE AND ACCOMPLISHED A SATISFACTORY LEAK / OPERATIONAL CHECK PER AMM 29-11-49.