Aviation industry, along with its greenhouse gas emissions, is expected to grow in the upcoming decades, requiring a substantial reduction in the environmental impact of air transport. Current research is investigating alternative energy carriers, such as hydrogen, together with increasing levels of electrification of both propulsive and secondary power systems. The introduction of these innovative technologies is accompanied by economic uncertainties. Since operating costs constitute a major portion of the total Life Cycle Cost (LCC), and maintenance is one of the largest contributors to operating costs, the capability to estimate maintenance expenditures is essential. Cost assessments are especially important during the early design phases, where design flexibility is highest and multiple configurations can still be evaluated.