Robust Detection of Oscillatory and Transient Aircraft Actuation System Failures Using Analytical Redundancy

System failures represent critical design cases for the development of an actuation control system and its integration in the surrounding structures of any new aircraft. With the focus on oscillatory and transient actuation system failures, this paper presents a method that uses analytical redundancy for the robust detection of such failure cases with minimum sensor equipment. Additional background information is given about the causes for the occurrence of such flight control system failures. Particular focus is here on failures leading to control surface oscillations, so-called Oscillatory Failure Cases (OFCs). Compared to classical signal-based concepts, the benefits of the proposed model-based detection approach are lowered detection amplitudes and reduced detection times. This allows for a considerable reduction in the corresponding failure case load levels that can determine the dimensioning of the airframe structure. Validation of the detection device is achieved by means of hardware-in-the-loop (HIL) testing using a representative primary flight control actuation system.