What was found
AFTER TAKEOFF, AND CLIMBING THROUGH FL310, CREW DISCOVERED GEAR UNLOCK ANNUNCIATION FOLLOWED BY HYD PRESS ON. RAN APPROPRIATE AFM CHECKLIST AND DETERMINED ONE GEAR FELL OUT OF WELL. CYCLED GEAR TO DOWN AND LOCK WITH (3) GREENS DIVERTED BACK TO ICT LANDED WITHOUT INCIDENT. ON SITE MAINTENANCE FOUND LANDING GEAR EMERGENCY EXTENSION CABLE RIGGING TO BE TOO TIGHT. RERIGGED EMERGENCY GEAR CABLES AND OPS CHECKED SATISFACTORY, RETURNED AIRCRAFT TO SERVICE.