A comparative study of helicopter planetary bearing diagnosis with vibration and acoustic emission data

Planetary bearings inside a helicopter main gearbox (MGB) are key components, successful diagnosis of planetary bearing defects benefits helicopter maintenance, reducing accidents rate and increasing aircraft flightworthiness. Most widely adopted methods for bearing fault diagnosis are envelope analysis and kurtogram; both have achieved many successes in practical application. However, diagnosis of faulty planetary bearing inside a MGB can be more complicated for reasons such as extremely strong operating noise, overwhelming gear meshes and so on. In this paper, acoustic emission (AE) data was recorded in comparison with traditional vibration data from test rig built using commercial helicopter gearbox with seeded defects, diagnosis of vibration data and AE data is performed using kurtogram and envelope analysis, results showed that AE signals are more sensitive to excitations from defects and suffer less from background noises.