Auxiliary Power Unit - System Essentials

Paper presents functions and maintenance procedures of auxiliary power unit. Auxiliary power unit is used as a source of electrical power on the ground and it can be also used in the event of dissipation of an engine generator. An electrical system is essential component of the most simplistic aircraft designs. System complexity and capacity varies between different types of engines. Auxiliary power unit is also designed to provide bleed air by diverting some compressor discharge air from the path to the combustor and into the airplane duct system.