Monitoring of Oscillatory Failure Cases for the Reduction of Structural Loads in an Aeroelastic Aircraft

Fachgebiet:

Betätigungssysteme und Aktuatoren

Jahr:

2008

Art der Publikation:

Paper

Schlagworte:

Oscillatory Failure Cases, Structural Loads, Monitoring System, Aeroservoelasticity

Autoren:

Helge Sachs, Udo B. Carl, F. Thielecke

Buchtitel:

26th INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES

Allocated in the field of aeroservoelasticity, the present paper deals with flight control system failures and their impact on the aeroelastic structures of large transport aircraft (AC). Oscillatory Failure Cases (OFC), occurring as control surface (CS) oscillations, represent critical design cases and they must be detected by suitable monitoring systems. However, the threshold sensibility is limited by the avoidance of false alarms and unintended system shut-downs. Successfully reducing these thresholds without favoring accidental alarms allows to decrease the level of critical failure case loads. Finally, this holds the promise of structural weight savings. Compared to the reference detection thresholds of a given sensor-based OFC monitoring system (OFC-MS), an improved model-based monitoring approach is presented, which only depends on the on-board minimum sensor equipment. The results comprise an analysis of OFC failure causes and their effect on the flexible AC structures. Moreover, the conclusion is drawn to what extent the availability of an OFC-sensitive MS allows to alleviate such adverse effects. Validation is achieved using an actuation system test rig and an aeroelastic model of a representative civil large transport AC.