What was found
WHILE ON CLIMB OUT, THE FLIGHT CREW NOTICED A LOSS OF THE A SYS HYD QTY, THE CREW DECLARED AN EMER & THEY RETURNED BACK. FLIGHT CREW EXECUTED THE APPROPRIATE CHECKLISTS & BURNED OFF ENOUGH FUEL TO MEET THE LANDING WEIGHT. WHEN THEY LANDED THE A SYS HYD QTY WAS INDICATING 5 PERCENT, & THE EMER BRAKES WERE UTILIZED. FOUND A FAILED A SYS HYD RESERVOIR, PN 9914454-3. THE RESERVOIR WAS REPLACED WITH AN OVERHAULED UNIT, BLEED, LEAK & OPERATIONAL CHECKS PERFORMED, WITH NO DEFECTS NOTED. A SATISFACTORY CONFIDENCE FLIGHT WAS ACCOMPLISHED & THE ACFT WAS RETURNED TO SERVICE.