What was found
AIR TURNBACK, 'A' SYSTEM HYDRAULIC QUANTITY LIGHT CAME ON AFTER TAKEOFF. QUANTITY DROPPED TO LESS THAN 1.5 GALLONS. ON APPROACH, WITH GEAR AND FLAPS DOWN, QUANTITY CAME BACK TO R/F LINE. CHECKED FOR VISIBLE LEAKS, NO LEAKS NOTED. SERVICED HYDRAULIC SYSTEM WITH 3.5 QUARTS, OPS CHECK NORMAL. REPLACED 'A' SYSTEM TRANSMITTER PER CARD R429001, OPS AND LEAK CHECK GOOD. REPLACED HYDRAULIC QUANTITY INDICATOR, GROUND CHECK GOOD.