First application and feedback on preliminary aircraft safety assessment

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Deport, S.
Bailly, S.
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The X4 is the future Airbus Helicopters modern rotorcraft. It will embed the most modern technologies, including Integrated Modular Avionic (IMA). This creates interdependencies between systems, as functions are no longer supported by a single system. This was already the case for Airbus Helicopters’ previous development, and the need for an efficient methodology appears obvious with the growth in complexity of X4. Therefore, the work in progress in the frame of ARP4761a/ED135a appears to be an opportunity to improve the process. Airbus Helicopters see foremost in the new activity of Preliminary Aircraft Safety Assessment a powerful way to enhance the management of helicopter systems interdependencies. In the frame of its new medium class helicopter certification, Airbus Helicopters will perform this new activity. In spite of the fact that the development of ARP4761a/ED135a is still in progress, Airbus Helicopters decided to apply this methodology believing that safety benefit can be found. By performing a PASA and allocating safety objectives to each system safety analysis, interdependencies are no longer a risk but are anticipated and under control. The functional interdependency diagrams capitalize on knowledge of system functionality. As an umbrella analysis, the PASA process ensures higher consistency between systems safety analysis throughout the helicopter development. The PASA is an iterative process. The PASA should start early in the development. Nevertheless, the proposed helicopter architectures shall have sufficient maturity to reduce iterations. By contrast, starting the analysis late will decrease PASA benefits. PASA will be re-applied on future developments, it has been identified that appropriate tools can help to save time and improve efficiency.