A two-hangar complex at Mitchell International Airport will become one of 12 U-S maintenance bases for SkyWest Airlines.  The property was previously used by Midwest Airlines, but has been sitting vacant.  The 190-thousand-square-foot space will be the airline’s largest maintenance base and will replace a smaller one.  At least 25 new jobs will be added to the 75 maintenance workers already on staff.  SkyWest says it will run 24 hours-a-day and will be able to service up to 12 aircraft at a time.