DIESEL DUTY U.S. Marine Corps Gunnery Sgt. Marcus S. McCollum, foreground, watches as fellow U.S. Marines refuel a British Sea King MK4 helicopter with diesel in Helmand province, Afghanistan, Dec. 11, 2013. McCollum is a crew chief assigned to Marine Heavy Helicopter Squadron 462. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 835455-P-XMS70-181.jpg Photo Gallery