The ENGIRO contribution to the E‑SATstart consortium focused on the systematic assessment and optimisation of electric propulsion systems for future regional air transport. Central to the work was the development of a comprehensive failure‑mode and effects analysis (FMEA) for the electric drive chain, the construction of ageing models for critical components such as seals, bearings and winding insulation, and the formulation of a maintenance strategy based on quantified load distributions. To validate the models, a dedicated test rig was assembled in collaboration with the Institute for Electrical Machines (IEM). The rig enabled the measurement of electrical stresses, partial‑discharge inception voltages and bearing currents under realistic operating conditions, which were then compared with the life‑time predictions derived from the simulation framework.
The technical effort began with a detailed quantification of the mechanical and electrical loads experienced by each motor component. Equivalent load values were calculated and used to drive the ageing models. For the 97 kW M97‑250‑90‑43 motor, already under flight testing on an amphibious aircraft, the analysis confirmed that the current design margins were sufficient for the projected duty cycle. In parallel, a smaller 260 W‑25011 prototype was selected for extensive simulation and measurement campaigns. This motor can operate at up to 850 Vdc and 6 000 rpm, making it suitable for rapid‑take‑off and low‑noise flight profiles. Simulation results for this unit demonstrated that the parasitic currents induced by the motor’s electrical coupling remain below the thresholds identified in the FMEA, provided that the insulation system meets the specified breakdown voltage criteria.
A key outcome of the study was the determination of the required partial‑discharge inception voltage for a 400 V system. The analysis showed that an over‑voltage factor (OVF) of 1.1 can be achieved without phase isolation, whereas an OVF of 2.0 requires both an improved impregnation resin and dedicated phase isolation. These findings directly informed the design of the motor’s insulation and the selection of suitable materials for the stator and rotor windings. The measurement campaign, which employed both sinusoidal 50‑Hz excitation and specialized test equipment from Schleich and Stahl, revealed a moderate spread in the results, underscoring the importance of accounting for cable length and voltage variations in the predictive models.
Beyond the technical validation, the ENGIRO team produced an analysis tool that integrates the load calculations, ageing predictions and maintenance schedules. This tool is intended to support the design phase of future electric motors and to provide a basis for certification documentation under the EASA CS‑23 framework. The work also contributed to the broader E‑SATstart objective of developing a silent, low‑cost air taxi that can operate from existing regional airfields. By ensuring that the electric drive chain meets stringent reliability and safety requirements, the ENGIRO contribution helped to advance the consortium’s goal of a commercially viable, environmentally friendly regional air transport solution.
The project ran from early 2020 until the end of October 2022, with the ENGIRO work package (2.3) spanning the entire duration. The consortium comprised ENGIRO, the Institute for Electrical Machines (IEM), and several other partners from industry and academia. Funding was provided by the German Federal Ministry for Economic Affairs and Climate Action (BMWi) for the HyFly initiative and by the European Regional Development Fund (EFRE.NRW) for the E‑SAT‑Electromotorenproduktion programme. Through this collaboration, ENGIRO leveraged its experience in compact, high‑performance electric motors for aviation to deliver a robust, data‑driven maintenance framework and a validated simulation methodology that support the certification and operational readiness of next‑generation electric aircraft.