Building Quality & Realistic Models Since 1969 The MD Helicopters MD 500 series is an American family of light utility civilian and military helicopters. 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 Hughes Helicopters, Inc, Model 500 went into commercial production in 1969 after 8 years of development which began with the OH6A CAYUSE military scout version. The Model 500 C, certified in 1972, quickly established a reputation as economical and productive for use as a multi-purpose business helicopter. In December 1976, The Huges Model 500D was certified by the FAA, replacing the 500C on the company's production line.