Identifying enhancement potentials of actuation systems using a criticality index

Abstract

The potential benefits of multifunctionality drives the design of flight control systems today. For instance, the flaps of the A350XWB used in providing high lift, are additionally used for span-wise lift distribution to reduce wing loads. Hence, the underlying control surface actuation systems must be designed to accomodate these new and future functionalities. Because of the high complexity of these safety-critical systems this poses many challenges, which may cause certain conceptual drawbacks go unmitigated by the designer. Thus, incurring costly design changes later in the design process or in the worst case catastrophic failures in different operational phases. In order to identify potential weakness of the system architectures early in the design process, this study proposes the use of the Criticality Index (CI) within the design structure matrix framework as a method to analyse the functional model during concept development. Using the Functional Hazard Index and the Failure Propagation Index as inputs, the CI quantifies the failure impact of subsystem functions on the overall architecture. To demonstarate its applicability, the method is used to identify enhancement opportunities for two actuation system architectures.