The MD 500 was developed from the Hughes 500, a civilian version of the US Army's OH-6A Cayuse/Loach. The series currently includes the MD 500E, MD 520N, and MD 530F. The successful Hughes 500/MD 500 series began life in response to a U.S. Army requirement for a Light Observation Helicopter (LOH). Hughes' Model 369 won the contest against competition from Bell and Hiller. The subsequent OH-6 Cayuse first flew in February 1963. The 500 series design features shock-absorbing landing skid struts, a turboshaft engine mounted at a 45-degree angle toward the rear of the cabin pod, a fuel tank cell under the floor and the battery in the nose. The engine exhaust port is located at the end of the cabin pod underneath the tailboom. It has a short-diameter main rotor system and a short tail, giving it agile control response and is less susceptible to weather-cocking. Manufactured under licence by Breda Nardi Costruzioni Aeronautiche SpA as the Breda Nardi NH-500D. For more details of the civilian version, click here. For details of the military MD 500 Defender, click here. Specifications below are for the 500C variant.