SCOTT AIR FORCE BASE, Ill. - Staff Sgt.Cari Perez, a crew chief with the 126th Aircraft Maintenance Squadron, replaces an engine cover on a KC-135E Stratotanker as it completes a 60 day regular maintenance cycle. The 126 AMS is a part of the 126th Air Refueling Wing, Illinois Air National Guard, located at Scott Air Force Base, Ill. (U.S. Air Force photo by Master Sgt. Ken Stephens) (Released)