U.S. Army Second Staff and Faculty Watercraft Engineer Certification Course students Sgt. Benjamin Acevado,right, and Sgt. Adrian Orta, tighten bolts during an engine rebuild at Fort Eustis, Va., May 21, 2015. While tightening bolts, students must also check the torque value of each to ensure they reach and do not exceed an exact pressure. (U.S. Air Force photo by Staff Sgt. Natasha Stannard/Released)