Development of health features and automatic fault diagnosis methods for primary flight control actuators

Daniele Bruno

Development of health features and automatic fault diagnosis methods for primary flight control actuators.

Rel. Massimo Sorli, Giovanni Jacazio. Politecnico di Torino, Master of science program in Mechanical Engineering, 2018

Abstract

As the leading technology employed in primary flight controls, Electro-Hydraulic Servo Actuators (EHSA) have been the focus of several studies in the aviation industry, particularly in the field of fault diagnosis. The established testing procedures at Maintenance, Repair and Overhaul (MRO) companies are manual, time-consuming and do not guarantee an optimal condition-based maintenance. This thesis stems from a research project developed at Lufthansa Technik, with the purpose to automatize and improve the accuracy of the diagnostic procedures. The proposed approach consists in commanding the servoactuators with a modular test signal, which reproduces the tests from the component manuals. In addition, the signal contains a series of original test sequences, created to assess the state of two critical subassemblies: the servovalve and the recentering device.

To elaborate the response of degraded units, an automatic feature extraction algorithm was implemented, which applies a statistical technique known as change points detection to achieve a high reliability