An Advanced Concept Ejection Seat (ACES II) from a B-1 is maintained in the egress shop at Ellsworth Air Force Base, S.D., Dec. 13, 2017. To ensure the system is ready at all times, egress technicians perform maintenance regularly, conducting a full diagnostic inspection of the system, checking for any broken components and swapping out any time-changeable items that have expired. (U.S. Air Force photo by Airman 1st Class Donald C. Knechtel)