U.S. Army Sgts. Michael Marshall, left, and Issac Johnson, both with Charlie Company, 3rd Battalion, 8th Aviation Brigade Task Force Corsair Medical Evacuation Detachment, conduct a preflight inspection on a UH-60 Black Hawk helicopter Nov. 29, 2009, at Forward Operating Base Wolverine, Zabul, Afghanistan. U.S. Air Force photo by Tech. Sgt. Efren Lopez/Released.