Safety Critical Design of Flight Control System Architectures - Potential Safety Aspects for a Triple Split Aileron for the Project WISDOM

Abstract

As part of the WISDOM (Wing Integrated Systems Demonstration On Mechatronic Rig) project the German Aerospace Center (DLR) - in cooperation with Liebherr Aerospace, FFT Produktionssysteme, TU Berlin and Diehl Aerospace - is developing a demonstrator test rig for future control surface actuation systems. The control surface actuation system is intended as a potential part of future flight control systems. The conceptual design of the underlying flight control system architecture is performed according to design processes for safety critical systems to support the concepts viability for potential real life application. The flight control system is assumed to fulfil traditional flight control functions in addition to innovative gust load alleviation and flutter suppression functions using a set of three ailerons per wing. The aircraft used as conceptual baseline is an A320-like low to mid-range commercial passenger aircraft. The design focus lies on realising the necessary reliability of the considered flight control functions while accommodating project specific technology innovations within the flight control system. The analysis processes are based on ARP4761. A potentially viable architecture concept has been identified that incorporates a triplex electrical power supply and simplex control surface actuation. Central challenges and requirements towards a multitude of components and peripheral systems could be identified. These will be presented and discussed after presenting the design process and the resulting architecture. The paper is comprised of four sections. The first introduces central concepts and definitions necessary, such as safety processes and considered actuation technologies. The second addresses the detailed aircraft configuration, the control surface layout, functional allocation and description of the relevant flight control functions. The third section describes the applied design and analysis workflow. Established methods from ARP4761 have been adapted to be used within a model-based systems engineering (MBSE) model and enable side-by-side consideration of system design and safety analysis in a shared model. The fourth and final section presents and discusses the results of the performed design process. These include the resulting flight control system architecture, identified central technology requirements for and a collection of technological challenges that arose from the safety analyses and design iterations.