Vibration detection of local gear damage by advanced demodulation and residual techniques

Damage detection in a gearbox is reported based on analysis of vibration signals measured on a running aircraft engine on a test bed. The experiment was stopped due to material being found on the magnetic chip detectors in the oil system. Subsequent inspection found a significant damage to a bevel gear inside the drive train system. Three damage detection techniques are applied to the vibration signals: advanced demodulation, advanced residual technique, and the classical residual technique. Fault indicators are defined from each technique and trended over time. Results show that these techniques have the ability to provide early damage detection; however, with some noticeable difference in their feature evolution. The advantages of the techniques are compared and discussed.