Conducting maintenance

U.S. Air Force Senior Airman Mathew Harrington, a precision measurement equipment laboratory journeyman with the 57th Maintenance Squadron, conducts maintenance on a 53-plugin unit, used to calibrate an oscilloscope, at Nellis Air Force Base, Nev., April 5, 2011. (DoD photo by Senior Airman Michael Charles, U.S. Air Force/Released)