An aircraft accessory system includes an aircraft engine powered direct air turbine driven accessory and an air turbine drivingly directly connected by an air turbine shaft to the accessory. The air turbine includes a variable geometry turbine nozzle in selectable direct flow communication with at least two compressed engine air sources. The two compressed engine air sources may be an HPC interstage bleed and an HPC compressor discharge stage bleed. The variable geometry turbine nozzle may be in selectable direct flow communication with a third compressed engine air source such as a bypass duct or an engine inlet duct. The air turbine includes a turbine exit which may be in selectable direct flow communication with at least two relatively lower pressure engine air sinks. The air sinks may be located in the aft end of a bypass duct and in a divergent section of the exhaust nozzle.