 Both unmanned K-MAX helicopters in use by the Marine Corps returned to the U.S. in May 2014, when the Corps determined that they were no longer needed to support missions in Afghanistan.After deploying in December 2011, originally planned for six months, they stayed for almost three years and lifted 2,250 tons of cargo.The aircraft were sent to Lockheed's Owego facility in New York, while the service contemplated the possibility of turning the unmanned K-MAX from a proof-of-concept project into a program of record.