Detection of on-aircraft fatigue cracks in a UH-60A planet carrier using spectral averaging.

In this paper, a new method for planet carrier fatigue crack detection is presented. This method begins by time synchronously resampling vibration signals to segment the signals according to shaft crossing times, such that an even number of data points are obtained to compute a spectral average. Then, the result is used to extract features and evaluate numerous condition indicators (CIs) for planet carrier fatigue crack detection. The methodology is validated using data from a number of US Army UH-60A Black Hawk helicopter main transmissions. The results are presented using vibration measurements of faulted and unfaulted transmissions over low-torque levels in on-aircraft conditions