Flying electric: A comparative analysis of spare part demands and material cost for all-electric, hybrid-electric, and conventional aircraft propulsion systems

The aviation industry is driven by its pursuit of a cleaner and more sustainable ecosystem while continually growing in passenger volume and emissions on a global level. While current aero-engines have already reached their limits in terms of efficiency optimization, revolutionary drivetrain technologies such as battery-powered propulsion systems promise to significantly reduce emissions. However, besides the technological challenges such as low gravimetric energy densities for battery storage systems, a potential adoption of these technologies is further hampered by uncertainties about operational availability and maintenance costs. Therefore, with this work, we address parts of that knowledge gap by quantifying the expected changes in material costs and part replacements for the maintenance of battery-powered All-Electric Aircraft (AEA) and Hybrid-Electric Aircraft (HEA) propulsion systems. For this purpose, we establish a cost estimation method, which is based on expected reliability metrics for the corresponding drivetrain components and resulting spare part demand. Special focus is given to design and operating recommendations for the battery storage unit through the application of a degradation model. As a consequence, we can identify appropriate over-sizing ratios and operating temperatures to optimize the resulting maintenance costs of the battery system. By carrying out a comparative analysis with a conventional propulsion system, we can observe an expected increase in maintenance-related material costs of 163 % for AEA and 26 % for HEA configurations, respectively. Therefore, with the results from this study being fed-back to early design iterations, we can support the development of technically-feasible and economically-sustainable electric aircraft design concepts.