What was found
AIRCRAFT WAS NOT GROUNDED: ON APPROACH, WHEN THE GEAR HANDLE WAS SELECTED DOWN, FLIGHT CREW RECEIVED THE 3 RED UNLOCKED INDICATORS BUT ACTUAL GEAR DEPLOYMENT WAS SEVERELY DELAYED, APPROXIMATELY 10 SECONDS. MAINTENANCE FOUND YELLOW HYDRAULIC QUANTITY LOW AND SERVICED IT PER AMM 12-12-29. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO FAULTS OR ISSUES NOTED.