Tech. Sgt. Chris Tanksley, left, observes as Airman Daniel Barcea, a 362nd Training Squadron crew chief apprentice course student, performs a nitrogen servicing procedure on an A-10 Thunderbolt II hydraulic reservoir accumulator at Sheppard Air Force Base, Texas, Sept. 20, 2018. The test ensures the aircraft is able to maintain pressure in its hydraulic system. Barcea and his class are scheduled to graduate Oct. 31. (U.S. Air Force photo by John Ingle)