Integration of a Model-based System Engineering Framework with Safety Assessment for Early Design Phases: A Case Study for Hydrogen-based Aircraft Fuel System Architecting

Novel hydrogen-based aircraft concepts pose significant challenges for the system development process. This paper proposes a generic, adaptable, and multidisciplinary framework for integrated model-based systems engineering (MBSE) and model-based safety assessment (MBSA) for the conceptual design of complex systems. The framework employs a multi-granularity, modelcentric approach, whereby the architectural specification is utilized for design as well as query purposes as part of a qualitative and quantitative, graphbased preliminary safety assessment. For the qualitative assessment, design and safety rules based on existing standards and best practices are formalized in the model and applied to a graph-based architecture representation. Consequently, the remaining architectures are quantitatively assessed using automated fault trees. This safety-integrated approach is applied to the conceptual design of a liquid hydrogen fuel system architecture as a novel, uncertain, and complex system with many unknown system interrelations. This paper illustrates the potential of a combined MBSE-MBSA framework to streamline complex, early-stage system design and demonstrates that all qualitatively down-selected hydrogen system architecture variants also satisfy quantitative assessment. Furthermore, it is shown that the design space of novel systems is also constrained by safety and certification requirements, significantly reducing the number of actual feasible solutions.