What was found
ON APPROACH, WHEN LANDING GEAR LEVER WAS SELECTED DOWN, THERE WAS A 4 TO 5 SECOND DELAY IN EXTENSION. THE RT HYDRAULICS INDICATED ZERO THEN PRESSURIZATION RECOVERED AND THE GEAR EXTENDED. MAINTENANCE BLED HYDRAULICS, CHECKED FOR PROPER SERVICE LEVEL. R & R RT ENGINE DRIVE HYDRAULIC PUMP IAW AMM. RAN ENGINE, NO LEAKS. REPLACED HYDRAULIC FILTER. LEAK CK OK AND OPS CHECK OF LANDING GEAR. ACFT OK FOR SERVICE.