As aircrafts move toward electrification with the research and development of hybrid-electric powertrains, the focus has begun to shift to the reliability challenges of electronic devices subject to flight. Electronic components in aircraft applications are subject to two main sources of failure inducing stresses: the thermomechanical stresses that develop due to unequal coefficients of thermal expansion of different materials used in the components, and the stresses developing due to shocks and vibrations during flight as well as landing and takeoff. While the challenge of dealing with CTE mismatches is applicable to electronic devices in general, the ambient conditions surrounding the aircraft in flight, combined with weight and space constrains add significant logistical issues to any cooling mechanism. This paper will focus on the environmental influence on the thermal dissipation profile that will ultimately lead to CTE failures. The push toward more-electric-aircraft (MEA) increases the need to further advance the power and versatility of electronic cooling systems to adequately manage high density power modules, which until recently were not highly incorporated in aviation systems. Environmental conditions will play a large role in the design space and limitations of potential cooling solutions and will dictate the effectiveness of current thermal management systems. In arising scenarios where high-density electronics cannot be contained within a pressurized and temperature-controlled cabin, drastic pressure and temperature swings, facilitated by the external environment, will lead to an extra source of fluctuating stress on the cooling system. This is likely to be a prevalent factor in hybrid-electric and all-electric powertrains as requiring environmental controlled spaces for major components could be limited. This can easily be seen in current attempts to examine and redesign local cooling systems for electric motors in aviation. Representing just one of the major cooling requirements on an electric aircraft, motor cooling systems demonstrate the universal cooling problems limiting all aspects of the powertrains system. This paper aims to define the impact of the changing environment, through a flight profile of an aircraft, on high density electronic cooling systems by assessing the potential system stressors that significantly impact performance, efficiency, and reliability of the cooling systems. It will also utilize local cooling efforts for motors to relate the general problems to applicable design considerations that must be understood to further the performance capability of the overall propulsion system.

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