The aircraft power and thermal management system (PTMS) developed by Honeywell combines the functions of an auxiliary power unit (APU), emergency power unit (EPU), environmental control system (ECS), and thermal management system (TMS) in one integrated system. For the F-35 aircraft this approach resulted in a substantial reduction in overall aircraft size and weight as compared to configurations using separate “federated” secondary power systems. Future aircraft incorporating the new more electric architecture (MEA) and energy efficient aircraft (EEA) initiatives are likely to benefit from this integrated approach as well, but they are also likely to require increased electric power generation capability, greater cooling capacity and higher operating efficiency. Further, these aircraft will likely require an adaptive power and thermal management system (APTMS) which can be reconfigured to optimize operation for various flight conditions, diverse missions and for use on a variety of platforms. To provide for these future aircraft needs the incorporation of new technologies and architectures, further integration with other aircraft systems and more advanced control and protection algorithms are considered.