Isochronal Inspection
Tech. Sgt Mathia Renken, 28th Maintenance Squadron metals technology craftsman, replaces a keylocking thread insert on an B-1B engine during an isochronal inspection at Ellsworth Air Force Base, S.D., Feb. 8, 2012. These thread inserts strengthen and secure operation critical aircraft parts, which must be taken out for inspection and reinstalled once the inspection is complete. (U.S. Air Force photo by Airman Alystria Maurer/Released)