As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK. 'A' HYDRAULIC SYSTEM LIGHT ILLUMINATED ON TAKEOFF. A SYSTEM HYDRAULIC QUANTITY DROPPED TO 1/3 AIR RETURN TO GSO, TURNED 'A' SYSTEM HYDRAULIC PUMP OFF TO PREVENT FURTHER LOSS OF FLUID. REMOVED AND REPLACED NR 1 ENGINE ENGINE DRIVEN PUMP IAW AMM.