Hydrogen is an energy vector identified as a promising candidate to replace fossil fuel on aircraft, used in a gaseous or cryogenic liquid form, either through direct combustion or through reaction in fuel cells. Hydrogen comes with intrinsic properties that lead to hazards and safety risks. The objective of this work, conducted under the Clean Aviation CONCERTO research project, is to perform a regulatory gap analysis and a risk assessment to prepare future rulemaking activities for the timely certification of hydrogen-powered aircraft. The existing EASA certification regulation will be evaluated to determine its relevancy for hydrogen aircraft architecture and the adaptations that will be needed. Firstly, a synthesis of hazards is determined from hydrogen properties and related research. Through a proposed methodology, a gap analysis is then conducted to cross-evaluate hydrogen hazards, generic concepts of hydrogen aircraft and existing certification regulations. The preliminary results of this analysis show that multiple requirements related to fire protection and cabin safety/emergency evacuation are affected due to the flammability properties of hydrogen. It can be concluded that hydrogen hazards challenge some existing certification assumptions, and that further regulatory evolutions will be needed, with a still on-going analysis that raises significant gaps in existing requirements and means of compliance.