What was found
ON SELECTION OF LANDING GEAR DOWN, HYDRAULIC LIGHT ILLUMINATED. MAIN HYDRAULIC PRESSURE INDICATED 0 PSI. ONLY NOSE LANDING GEAR SHOWED DOWN & LOCKED, 1 GREEN, CREW DECIDED NOT TO LAND IN ARUBA (TNCA) & RETURN TO MAINTENANCE BASE - CURACAO (TNCC). PERFORMED INSPECTION OF THE HYDRAULIC SYSTEM IAW AMM 29-00-00. PERFORMED OPS CHECK OF THE MOTOR-DRIVEN PUMP IAW AMM 29-10-10-05-P1. PERFORMED FUNCTIONAL TEST OF THE EXTENSION AND RETRACTION OF LANDING GEARS IAW AMM 32-30-00-05 SATISFACTORY. AS PRECAUTION THE HYDRAULIC MOTOR PUMP WAS REPLACED IAW AMM 29-10-10-04.