Towards A Regulation Based Functional Hazard Assessment for Safety & Certification Requirements of Hydrogen-Hybrid eVTOLs

The multitude of new eVTOL projects provides not only revolutionary configurations, but also the chance to consider cleaner energy sources for providing power. At the same time, regulations for these systems have not been defined in detail. Nevertheless, the use of classical safety assessment standards could assist in preliminary safety & reliability investigations. This work describes an approach to be used to facilitate the creation of functional safety requirements for hydrogen-hybrid architectures for eVTOLs. In a first step, we present an overview of current EU safety regulations to introduce the accepted Target Level of Safety (TLS) which is then followed by a systematic method to describe how a Functional Hazard Assessment (FHA) can be tailored for both manned and unmanned use cases. We apply this process to the power systems of two different VTOL case studies (manned VTOL & UAV), discuss examples of the created FHAs and comment on the shortcomings and benefits of this method.