Marines perform maintenance on an MV-22B Osprey aircraft in a hangar at Camp Bastion.
Marines from Marine Medium Tiltrotor Squadron 264 perform maintenance on an MV-22B Osprey aircraft in a hangar at Camp Bastion, Afghanistan, on June 16, 2011. In 2007 the Osprey began replacing the CH-46 Sea Knight helicopter, which had been in service since 1962.