Abstract: An Aircraft Ground Power Unit (“AGPU”) is a mobile vehicle, preferably self-propelled, on which is mounted an enclosure. Within the enclosure are a number of subsystems, each of which provides a service required by a stationary aircraft for servicing and diagnostic testing prior to flight. Such services include electrical power, hydraulic power, engine-start capability (bleed-air), conditioned air (hot or cold) for the aircraft's equipment recesses or interior, and nitrogen to inflate struts and operate power tools. The control, status, configuration, and automation of all of the subsystems contained within the enclosure are consolidated under computer control. The enclosure and the subsystems contained therein can be readily mounted on and dismounted from the vehicle.