Külper, NilsNilsKülperHillig, DennisDennisHilligBröhan, JasminJasminBröhanThielecke, FrankFrankThieleckeStigge, LukasLukasStigge2026-01-212026-01-212025-10-2511th IEEE International Symposium on Systems Engineering, ISSE 2025https://hdl.handle.net/11420/60946Developing complex, hydrogen-powered aircraft and their on-board systems is challenging due to a vast design space, limited knowledge, and high uncertainties. Hence, the risk of undetected errors introduced during conceptual design increases. To address this, a method for early model-based functional integration testing as an integrated part of systems architecting is proposed. It includes simulation-based testing of functional behavior under nominal and off-nominal conditions based on executable architecture models, enabling the discovery of design errors and the down-selection of large design spaces. The method is demonstrated on a fuel cell-powered propulsion unit of a novel hydrogen-powered concept aircraft, showing its value for complex, novel systems in off-design conditions.enAircraftMBSESystems ArchitectingFunctional BehaviorTestingTechnology::600: TechnologyConference Paper10.1109/isse65546.2025.11370079Conference Paper