U.S. Air Force crew chiefs muscle an engine into position for installation in an F-16. U.S. Air Force crew chiefs muscle an engine into position for installation in an F-16 Fighting Falcon on April 7, 1999, at Aviano Air Base, Italy. These crew chiefs from the 23rd Fighter Squadron, Spangdahlem Air Base, Germany, are keeping pace with the maintenance associated with the increased operating tempo of NATO Operation Allied Force. Operation Allied Force is the air operation against targets in the Federal Republic of Yugoslavia. SHARE IMAGE: Download Image: Full Size (0.07 MB) Photo By: VIRIN: 345096-E-VMC43-344.jpg Photo Gallery