DETECTING GEAR TOOTH CRACKS USING CEPSTRAL ANALYSIS IN GEARBOX OF HELICOPTERS

Gears are very important in the transmission of power between two shafts close together with a constant velocity ratio; search in gear damage by using vibration signals is still very attractive, because the vibration signals from gears are not easy to interpret. A failure diagnosis transmission based on Fourier analysis of the vibration signal produced from a speed reducer has shown its limits in terms of spectral resolution. For helicopter safety, early gear fault detection is important to prevent system break down and accident. Among the methods proposed in the literature, cepstral analysis has shown it efficiency. Cepstrum used to identify damage gear, it appears in the cepstrum clear peaks called rahmonic so it is easy to identify the change in the system and able to detect and foresee the development of the lateral band. This paper proposes how to detect faults in gearbox of helicopter by registration signals during flight, with spectrum analysis and cepstrum analysis. Analyzed results show that the proposed method is effective to extract modulating signal and help to detect the early gear fault.