INTEGRAL PART U.S. Air Force Staff Sgt. Tony Simper prepares to spur gear the drum exit unit of an F-16 Fighting Falcon aircraft gun system at Aviano Air Base, Italy, Feb. 6, 2007. Simper is an aircraft armament system journeyman with the 31st Maintenance Squadron. SHARE: Download: Full Size (0.04 MB) Credit: VIRIN: 335599-Z-PGS51-740.jpg Photo Gallery