Lubricant and Lubricant Additive Degradation: Implications for Cabin Air Quality

The composition and decomposition chemistry of the lubricants used in commercial aircraft was described. The common reactions of ester base stocks include hydrolysis and oxidation which results in the formation of aldehydes, anhydrides and a new set of organic acids. This explains why there is an increase in the number of compounds in the lubricant upon use. The chemistry of phosphate ester additives was also described along with the reasons for their continued use. High temperatures can result in isomerization of the cresol along with hydrolysis and addition reactions leading to a wide range of phosphate ester products. The implications of lubricant degradation on cabin air quality is also considered.