Comparison of Direct Operating Cost and Life Cycle Cost-Benefit Methods in Aircraft Technology Assessment

Abstract

Estimating the direct operating costs (DOC) is a common way to assess new technologies and aircraft designs. In aircraft technology assessment, a variety of DOC methods (i.e. sets of equations relating known aircraft parameters with operating costs) find their application, yet the explanation of choice is usually omitted. Alternatively, life cycle based models can be used, which incorporate the technologys' impact throughout all life phases. However, their usage is less common. The objective of this paper is to analyze the effort and effectiveness of DOC methods compared to the life cycle cost-benefit model developed by DLR. To do so, the first part of the paper deals with the differences of selected DOC models applied on hybrid laminar flow control (HLFC) as a use case. Effort and extent are investigated and sensitivities regarding key parameters (i.e. fuel price and system mass change) are analyzed. In the second part, the life cycle based model is presented and applied on the same aircraft to assess HLFC. After the results in terms of Net Present Value and Internal Rate of Return, the impact on total operating costs as well as on line and base maintenance are shown. Furthermore, sensitivity studies regarding uncertainties are performed, which give a full picture of the economical impact to be expected by applying laminar flow control. While all models yield an economical benefit, the different DOC methods show considerable variations in their results. The life cycle based method requires more detailed information, but provide a detailed breakdown of the economic impact of HLFC.