What was found
AFTER DEPARTING, GREEN HYD QTY BEGAN TO SLOWLY DECREASE. ON RETURN, QTY DECREASED TO RED DOT ON QTY GAUGE. ECAM DISPLAY CONFIRMED LOW QTY . FOLLOWED ECAM AND QRH AND PERFORMED GRAVITY EXTENSION OF LANDING GEAR. AFTER GEAR WAS EXTENDED, HYD QTY ROSE BACK INTO THE MIDDLE OF GREEN ARC. AFTER ARRIVAL FOUND GREEN SYS HYD QTY BACK IN ARC UPPER HAT. RESET GEAR EXTENSION IAW AMM 32-33-00-02. GREEN SYS HYD DE-PRESSURIZED AND GREEN RESERVOIR DE-PRESSURIZED IAW 29-10-00-03 AND 29-14-00-03 . PRESSURIZED GREEN HYD RESERVE BACK TO 45 PSI. GREEN HYD SYS SERVICED TO TOP OF ARC IAW AMM 12-12-29-00. VISUALLY INSPECTION OF MAIN WHEEL WELL AREA, NOSE WHEEL WELL AREA WITH HYD SYS PRESSURIZED. NO LEAKS FOUND, RAN BOTH ENGINES AND OPERATED ALL FLT CONTROL SURFACES SEVERAL TIMES FOR COMPLETE 35 MINS OF ENG RUN DURATION. PRESSURE FOR ALL 3 HYD SYS SUSTAINED NORMAL AND NO ABNORMAL PARAMETERS. WITH HYD SYS PRESSURIZED, PERFORMED WHEEL WELL INSPECTION, FLAP SLAT IN DOWN POSITION , NO LEAKS FOUND. AFTER ENG SHUTDOWN INSPECTION THE FLEX HOSE REPLACED EARLIER IAW 29-02/1097, NO LEAK IN THE AREA. ALL 3 HYD SYS QTY NORMAL AFTER ENG SHUTDOWN. VERIFIED RESERVOIR RETURN FILTER AND EDP FILTERS NOT POPPED. ALL NORMAL CONDITION AND ACFT IS RELEASED TO SERVICE.