What was found
CLIMBING APPROX FL180 GREEN SYS QTY WENT TO 0 RETURNED TO DEPARTURE FOR EMERGENCY LANDING, AFTER GEAR EXTENDED VIA GRAVITY EXTENSION AND AT 2000 GREEN QTY RETURNED TO NORMAL. TAXIED CLEAR OF RWY. VERIFIED GREEN SYSTEM HYDRAULIC QTY. WAS NOT DEPLETED COMPLETLY IT WAS STILL WELL ABOVE RED DOT. FOUND HYDRAULIC FLUID LEAKING OUT OF THE NR 2 ENGINE COWLING. FOUND OUTLET LINE OF GREEN SYSTEM HYDRAULIC PUMP LEAKING,REMOVED AND REPLACED O-RING AND BACK-UP O-RING ON LINE REF. A300-600 AMM 29-11- 32-04-01, BLED SYSTEM AND OPERATED FLIGHT CONTROLS THROUGH SEVERAL TIMES. NO LEAKS WERE NOTED.FREE FALL SYSTEM RETURNED TO NORMAL CONFIGURATION REF. AMM 32-33-00-02. RAN NR 2 ENGINE VERIFIED GREEN SYSTEM HYDRAULIC QTY NORMAL WITH NO DISCREPANCIES NOTED,A/C IS OK FOR CONTINUE SERVICE.