A simplified automated approach for a preliminary safety assessment of distributed electric and hybrid propulsion systems

Abstract

AbstractTo reduce the environmental impact of future aircraft, the usage of disruptive hybrid electric propulsion systems, in conjunction with distributed propulsion systems, is envisioned. The complexity of those novel powertrain concepts increases significantly. Besides nominal system characteristics, this particularly applies for off-nominal behaviour and consequences. As the safety impact on aircraft level is not always obvious, the suitability of a given component failure rate has to be analysed already in a preliminary design stage. Within this work, a method shall be introduced that allows a simplified automated safety assessment of any powertrain architecture. All relevant combinations of single and multiple failures are identified and a combined failure rate is derived. Thereafter, the impact of single and multiple component failures is evaluated on aircraft level. A selection of metrics for top-level-aircraft functions is used to implement an impact-driven analysis for each relevant failure case. The metrics used assess the adverse effects on climb performance, lateral controllability and range degradation. For all failure combinations, these effects can be validated against requirements imposed on the configuration. The possibility to formulate failure rate-related requirements follows the idea to target an equivalent level of safety compared to existing regulations, independently of the nature of the failure scenario. Results of this study show the necessity for a reevaluation of the configurations assessed, either regarding their architecture or the assumed component failure rate. The method allows an early detection of configuration-specific shortcomings of complex powertrain architectures already in a preliminary aircraft design stage.