Development of a Laboratory Apparatus to Study the Thermal Degradation Behavior of Commercial Jet Engine Oils

Abstract

Air quality on airplanes is a key priority of the Federal Aviation Association (FAA). It is suspected that, although rare, oil leaks in the engine can potentially allow contaminants into the air supply that is provided to the passengers in the cabin. Reliable and validated commercial sensors would enable the air quality on the airplane to be monitored. Before sensors can be utilized on airplanes a better understanding of the degradation behavior of jet engine oils is needed. Although a few previous studies have reported on the reaction products produced during thermal degradation of oil, the experimental set-ups used exhibited limited flexibility. Current technology, such as thermogravimetric analysis (TGA), can provide the precise data and information needed for understanding the thermal degradation behavior of jet engine oil, but such laboratory instruments are expensive, can only evaluate small sample sizes, and constrain the possible experimental protocols. The laboratory apparatus described in this thesis performs the same functions as a TGA but it is reasonably inexpensive, accommodates samples up to 2 g, and provides considerable flexibility in designing experimental protocols. The thermal degradation system consists of a microbalance, a cylindrical furnace, and a crucible to hold the sample. The system can be easily interfaced with other laboratory equipment such as custom sensor chambers or a Fourier Transform Infrared Spectrometer (FTIR). The modes of heat transfer of the thermal degradation system are characterized in this paper. Additionally, preliminary results of the thermal degradation behavior of Mobil Jet Oil II are reported.