Detecting Shaft Misallignment in Gearbox of Helicopter Using Average Synchronous Analysis

This paper deals with signal processing techniques for non-destructive fault detection on gearbox of helicopter by using time synchronous averaging. Time synchronous averaging is a signal processing technique that is used to extract repetitive signals from additive noise. This process requires an accurate measurement of the repetitive frequency of the desired signal or a signal that is synchronous with the desired signal. The raw data is then divided up into segments of equal length blocks related to the synchronous signal and averaged together. When sufficient averages are taken, the random noise is canceled, leaving an improved estimate of the desired signal. Time synchronous averaging is a feature extraction technique that have been used successively to gearbox condition monitoring. Index Term-time synchronous averaging, misalignment, diagnosis, cepstrum, spectrum.