A simplified automated approach for a preliminary safetyassessment of distributed electric and hybrid propulsionsystems

Abstract

The environmental impact of disruptive aircraft and propulsion system architectures are investigated in many studies. Different energy generation and storage paths, in conjunction with the distributed propulsion systems are evaluated. The complexity of those hybrid powertrains increases significantly. As, the safety impact on aircraft level is not always obvious it has to be analyzed 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 combinations of single and multiple failures are identified and a combined failure rate is derived. As the suitability of a component failure rate is suitable depends on the analysis of its intended function. Therefore, the component failure impact has to be evaluated on aircraft level. A selection of metrics for top-level-aircraft functions, as introduced by Jézégou is used to implement an impact driven analysis for each relevant failure case. The impact on aircraft level is calculated using handbook methods. 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 configurations used for the assessment exemplarily were developed within the GNOSIS project. Results show the necessity for a reevaluation of either the architecture or the component failure rate. The method allows an early detection of configuration specific shortcomings of complex hybrid powertrain architectures, for the chosen metrics, already in a preliminary aircraft design stage.