Results from a New Separation Algorithm for Planetary Gear System Vibration Measurements

Results are presented from a new algorithm developed for separating the vibration signals from a planetary gear system into separate signals attributable to each planet gear. From the separate signals, time synchronous average signals are produced for each planet gear and for the sun gear meshing with each planet gear. Assessments of the individual planet and sun gears can be made from these new vibration signals. These new separated signals match very well with noise-free synthetic data with and without characteristics indicative of faults. In a 3planet system, distortions planted in synthetic signals are easily distinguished over a wide range of signal-to-noise (S/N) values. In an 8-planet system, distortions are easily detected for high S/N with degradation at low S/N. Spectra from separated signals from vibration measurements made in flight on the transmissions of OH-58C and AH1S helicopters are consistent with what would be expected based upon the transmission geometries.