A B-1B undergoes a major isochronal inspection March 27, 2014, at Dyess Air Force Base, Texas. The B-1B is inspected twice during an 1,800 day period. A minor inspection is performed during the first 900 days and a major inspection is performed at the 1,800 day mark to check for damage and structural weaknesses. (U.S. Air Force photo by Airman 1st Class Alexander Guerrero/Released)