Fault detection of bearing defects for ballscrew based electro-mechanical actuators

Electro-mechanical actuators (EMAs) are considered a promising energy-efficient technology for actuating flight controls of future aircrafts. When it comes to aerospace systems, the EMAs degradation should be checked in regular maintenance events or through condition-based maintenance. Ball bearings have a significant failure rate for flight control EMAs and they are usually monitored by vibration noise. A challenge for detecting bearing faults, using state-of-the-art industrial methods, is the presence of a ballscrew mechanism that produces a nominal vibration noise similar to that of faulty bearings. No prior research has investigated this problem. This paper explores vibration noises generated from a set of healthy and faulty bearings included in a typical ballscrew EMA. In addition, a method is introduced for evaluating fault diagnosis performance for different time and frequency vibration features. The technique has been validated on an EMA actuator at the German Aerospace Center (DLR)