Health assessment of planetary gearboxes for gas-turbine engines under operating conditions

The study demonstrates that for assessing the condition of aircraft gas-turbine engine gearboxes during on-site operation, the most effective method is analyzing speed signals from standard onboard tachometers on their input and output shafts. The use of these signals, compared to vibration signals, significantly reduces the time and material costs of developing the corresponding methods. In this case, signals are analyzed in a frequency range of no more than 100 Hz, which significantly reduces the requirements for the facilities used. As an example, the problem under consideration was solved relative to the differential gearbox of one of the turboprop engines with two coaxial propellers. Several potential diagnostic indicators based on the frequency parameters of narrow-band processes of the analyzed signals are considered. The selection of the most helpful diagnostic indicator is substantiated, and recommendations for the establishment of its basic level (reference value) are formulated. An example of one of the potential options for assessing the amount of wear on gearbox teeth under operating conditions is presented. The work does not require highly qualified personnel and can be provided, if the appropriate methodology is available, by the airfield service personnel.