<Tr> <Th> Number built </Th> <Td> 131 (C - 5A: 81, C - 5B: 50) </Td> </Tr> <Tr> <Th> Unit cost </Th> <Td> C - 5A: US $224.29 million (2016) C - 5B: US $262.75 million (2016) C - 5C: US $129.17 million (2016) C - 5M: US $100.37 million (2016) </Td> </Tr> <P> The Lockheed C - 5 Galaxy is a large military transport aircraft originally designed and built by Lockheed, and now maintained and upgraded by its successor, Lockheed Martin . It provides the United States Air Force (USAF) with a heavy intercontinental - range strategic airlift capability, one that can carry outsize and oversize loads, including all air - certifiable cargo . The Galaxy has many similarities to its smaller Lockheed C - 141 Starlifter predecessor, and the later Boeing C - 17 Globemaster III . The C - 5 is among the largest military aircraft in the world . </P> <P> The C - 5 Galaxy's development was complicated, including significant cost overruns, and Lockheed suffered significant financial difficulties . Shortly after entering service, cracks in the wings of many aircraft were discovered and the C - 5 fleet was restricted in capability until corrective work was completed . The C - 5M Super Galaxy is an upgraded version with new engines and modernized avionics designed to extend its service life beyond 2040 . </P>

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