Staff Sgt. Tiffany Fairbanks, 302nd Maintenance Squadron fuel systems specialist, applies grease to a personnel door opening of an auxiliary fuel cell belonging to a C-130 aircraft July 11, 2020, at Peterson Air Force Base, Colorado. The grease is necessary to fit a flexible rubber ring into a small track inside of the doorway, creating an airtight seal when the doorway cover is secured onto the fuel cell. (U.S. Air Force photo by Staff Sgt. Justin Norton)