An Air Wisconsin Canadair CRJ-200 on behalf of United, registration N464AW performing flight UA-3749 from Huntsville,AL to Chicago O'Hare,IL (USA), was on approach to Chicago's runway 10C when the crew initiated a go around due to an unsafe gear indication, the right main gear did not extend and they were restricted to 200 KIAS or less. The aircraft climbed back to 5000 feet and entered a hold while the crew was working the checklists. The aircraft subsequently landed safely on runway 10C about 20 minutes after the go around.
The occurrence aircraft is still on the ground in Chicago 11 hours after landing.