Combining on-site and on-line voltammetric analyses to better understand the different degradation mechanisms of industrial lubricants and equipment - Part I: Joint Strike Fighter Engine©

This paper presents research to develop, optimize and evaluate on-line oil condition monitoring (OCM) sensors for the lubrication system of the Joint Strike Fighter engine. The capabilities of the OCM sensors to detect accelerated oxidation, engine fires and contamination by other commercial fluids were evaluated using laboratory tests and a seeded fault engine test. The laboratory results indicate that voltammetric OCM sensors located in the liquid and vapor phases of lubricant systems could detect oil fires within seconds of fire initiation and could detect contamination by commercial hydraulic fluid, coolant and ground equipment lubricants above 1% within minutes of contaminant addition. The laboratory results indicated that only the OCM sensor located in the vapor phase had potential for detecting fuel leaks. The seeded fault engine test results indicate that on-line voltammetric OCM sensors, regardless of location, detected accelerated oxidative degradation of the oil in agreement with the offline analytical techniques. The seeded fault engine test results also indicate that the liquid OCM sensor outputs should be recorded at two or more selected engine speeds to minimize any oil formulation effects on the performance of the OCM sensors. The results also indicate that the on-site RULER instrument could be used to detect the initiation of accelerated oil oxidation prior to detection by the on-line OCM sensors or other offline analytical techniques. Due to the success of the laboratory and seeded fault engine tests, the voltammetric OCM sensors have been selected for further evaluation on the Joint Strike Fighter engine program.