Eileen Frock, the 570th Aircraft Maintenance Squadron operations officer, briefs Air Force Chief of Staff Gen. Mark A. Welsh III on an F-35 Lightning II replacement modification at Hill Air Force Base, Utah, Oct. 15, 2015. The part depicted, a root rib, was removed from an F-35 airframe, and a stronger replacement was added, extending the aircraft’s service life. During his visit, Welsh received an overview of Ogden Air Logistics Complex facilities and operations. (U.S. Air Force photo/R. Nial Bradshaw)