To conceive and assess engines with minimum global warming impact and lowest cost of ownership in a variety of emission legislation scenarios, emissions taxation policies, fiscal and Air Traffic Management environments, a Techno-economic and Environmental Risk Assessment model is needed. This paper presents an approach to estimate the cost of maintenance and the direct operating costs of turbofan engines of equivalent thrust rating, both for long and short range applications, as well as for typical long and short range aircraft. The economic model is composed of three modules: a lifing module, an economic module and a risk module. The lifing module estimates the life of the high pressure turbine disk and blades through the analysis of creep and fatigue over a full working cycle of the engine. The economic module uses the time between overhauls together with the cost of labour and the cost of the engine (needed to determine the cost of spare parts) to estimate the cost of maintenance of the engine. The risk module uses the Monte Carlo method with a Gaussian distribution to study the impact of the variations in some parameters on the net present cost (NPC) of operation. The accuracy of the economic model in DOC estimation is good (within about 15%) and so can be adapted for use in the cost analysis of future types of engines, such as ultra high bypass ratio turbofans, with little modifications. The equations that constitute the economic model are under a confidentiality agreement of the European project VITAL and can not be divulgated.

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