An Approach to the Investigation of Oscillatory Failure Cases In Electro-Hydraulic Actuation Systems


Hydraulische Energieversorgung





Art der Publikation:



Primary Flight Control System, Electro-Hydraulic Servo Actuator (EHSA), Oscillatory Failure Case (OFC), Failure Detection and Identification (FDI), Output Observer, Monitor System, Electronic Flight Control Signal (EFCS), Hardware-In-T


Helge Sachs, Udo B. Carl, F. Thielecke


Recent Advances in Aerospace Actuation Systems and Components, Toulouse, France

The occurrence of actuator failures in primary flight control (PFC) systems such as powered runaway, jamming, or the oscillation of control surfaces, the latter also known as Oscillatory Failure Cases (OFC), leads to a severe performance deterioration of the actuation system. Malfunctioning of the PFC, as classified in JAR/FAR 25.671c (Federal Aviation Administration - FAA 1994, Joint Aviation Authorities - JAA 1997), represents critical design cases in the development of fault tolerant actuation systems. Beyond a potential loss of control, surface oscillations have a tremendous impact on the structural loads of a flexible aircraft (A/C). The approach to this problem presented hereafter incorporates both an analysis of the failure causes which can trigger OFC, and suitable means for their detection.