A Comprehensive Simulation Approach for Maintenance Costs of Future Aircraft Engines Using the Example of Hybrid-Electric Propulsion

Abstract With the forthcoming introduction of novel propulsion systems into the aviation sector, there is a need for adapted prediction methods for Maintenance, Repair & Overhaul (MRO). This study presents a holistic approach, covering aircraft mission analysis, operating simulation of the propulsion system, modular degradation progression, and condition-based maintenance cost estimation. The model is applied to a turbofan engine with 1 MW and 2 MW parallel-electric hybridization as an example, where peak-shaving at takeoff and climb causes a considerable change of the typical load profile of turbofan engines. With regard to statistic data of operational parameters, atmospheric data as well as reference data of degradation and costs of conventional turbofan engines from literature, the model simulates a reduced exhaust gas temperature degradation rate of 2.1 K/1000EFC and more stable maintenance costs. The deceleration of degradation is found to be dominated by reduced thermal loading of the hot section of the engine. Thereby, operational severity does not scale linearly with the degree in hybridization. Simulating full mission profiles proofs to be vital, as the critical operating point can shift from takeoff into the climb phase. Being adaptable to other airframes and novel propulsion systems, the approach provides a high degree of flexibility and may be useful to simulate operational severity and MRO with low computational effort, where no field data is yet available.