Checking the oil
Airman 1st Class Patrick Monroe, a crew chief assigned to the Air Force Reserve 931st Aircraft Maintenance Squadron adds oil to one of the engines of a KC-135 Stratotanker on the flight line at McConnell Air Force Base, Kan., Oct. 22, 2012. The aircraft had just returned from an overseas flight. Along with numerous other tasks, maintainers check the oil in each of the four engines on the Stratotankers after every flight and service the oil levels whenever necessary. The KC-135 provides the core aerial refueling capability for the U.S. Air Force, and has been performing in this role for more than 50 years. (U.S. Air Force photo by 1st Lt. Zach Anderson)