What was found
MECHANICAL DISCREPANCY: THE PILOT REPORTED WHILE ON DESCENT INTO KCVG THAT BOTH LEFT AND RIGHT “HYDRAULIC PRESSURE” WARNING LIGHT ANNUNCIATORS ILLUMINATED. THE PILOT FOLLOWING PROCEDURES IN THE QRH PERFORMED MANUAL LANDING GEAR EXTENSION UNTIL A “THREE GREEN” GEAR DOWN LOCKED INDICATION WAS RECEIVED. THE PILOT NOTIFIED ATC FOR VECTORS TO COMPLETE CHECK LIST ITEMS AND LANDED WITHOUT INCIDENT IN KCVG AND TAXIED TO PARKING. MAINTENANCE CORRECTIVE ACTION: MAINTENANCE CLEANED AND INSPECTED THE HYDRAULIC SYSTEM. THEN REMOVED AND REPLACED WITH SERVICEABLE UNIT A CHAFFED HYDRAULIC LINE GOING TO THE HYDRAULIC POWER PACK, P\N 27-81032-225. MAINTENANCE ALSO REMOVED AND REPLACED BOTH LEFT AND RIGHT ENGINE DRIVEN HYDRAULIC PUMPS WITH SERVICEABLE UNITS. INSPECTED HYDRAULIC SYSTEM FOR CONTAMINANTS AND SERVICED WITH HYDRAULIC FLUID AND PERFORMED GROUND RUNS AND LEAK CHECKS, OPERATION OF THE HYDRAULIC SYSTEM WAS NORMAL.