The Application of Multifactorial Diagnostic Criteria for Early Vibration Diagnostics of Aircraft Gas Turbine Engine Bearings

Abstract

The paper proposes basic approaches and results of working out and application of early vibration diagnostics of gas turbine engine bearings using multifactorial diagnostic criteria.
Fatigue spalling, not detected at an early stage on working surfaces of ring raceways and rollers of a turbine bearing subsequently leads to its failure and considerable expenses for regenerative engine repairing. Thus the regular alarm system detecting debris presence in oil due to insufficient sensitivity and selectivity gives an alarm signal too late, at a high stage of damage that excludes the possibility of malfunction elimination without the engine withdrawing from the operation. The vibrations generated by a bearing at its work in the aircraft GTE structure, mostly, have a very low intensity in relation to the noise level and consequently, for working out of an early and reliable diagnostics, it is necessary on the one hand, to take measures in decreasing the levels of external and internal noise, on the other hand, to develop reliable diagnostic criteria on the basis of multifactorial models, allowing to minimize a zone of uncertainty of diagnostic parameters, to lift their diagnostic sensitivity by taking into account various influencing additional parameters such as shaft speed, ambient temperature, etc.