A worker checks landing gear on a C-21 during a phase inspection Sept. 15, 2010, at Scott Air Force Base, Ill. The phase inspections are done on aircraft after they reach flying milestones to ensure the aircraft remain in top condition. (U.S. Air Force photo/Staff Sgt. Brian J. Valencia) Photo essay: C-21 undergoes phase inspection by Staff Sgts. Brian J. Valencia and Ryan Crane 375th Air Mobility Wing Public Affairs 10/5/2010 - SCOTT AIR FORCE BASE, Ill. (AFNS)  -- Contractors with DynCorp International work on phase inspections for the C-21 here Sept. 15. The inspections are done after the aircraft reaches flying milestones to ensure that it remains in tip-top shape. View the slideshow.