This Recommended Practice outlines the electrical performance characteristics for a continuous duty, diesel or gasoline engine driven brushless alternator unit for supplying 409-Hertz electrical power to commercial transport aircraft. It is intended to assist the airlines in standardizing recommendations for various sizes and configurations of equipment and it is a guide for the preparation of detailed specifications. The unit is primarily intended to supply power to the aircraft during passenger loading and unloading, and during servicing operations. The combination of the equipment specified herein and the interconnecting cables(s) between the 400-Hertz alternator and the aircraft shall provide power characteristics at the aircraft receptacle which meet MIL-STD-704 requirements for Category "B" equipment. Other limits which are necessary to meet specific conditions must be specified by the purchaser.