David W. Johnson

[18] Enghardt L, Zhang Y, Neise W. Experimental Verification of a Radial Mode Analysis Technique Using Wall‐Flush Mounted Sensors. Journal of The Acoustical Society of

[19] Sijtsma P, Zillmann J. In‐Duct and Far‐Field Mode Detection Techniques. In: Proceed‐ ings of the 13th AIAA/CEAS Aeroacoustic Conference, Rome, Italy; May 21‐23; 2007.

[20] Taddei F, De Lucia M, Cinelli C, Schipani C. Experimental Investigation of Low Pressure Turbine Noise: Radial Mode Analysis for Swirling Flows. In: Proceedings of 12th International Symposium on Unsteady Aerodynamics, Aeroacoustics & Aeroe‐

[21] Lengani D, Santner C, Spataro R, Paradiso B, Göttlich E. Experimental Investigation of the Unsteady Flow Field Downstream of a Counter‐Rotating Two‐Spool Turbine Rig. In: Proceedings of the ASME Turbo Expo, Copenhagen, Denmark; June 11‐15; 2012.

[22] Spataro R, Göttlich E, Lengani D, Faustmann C, Heitmeir F. Development of a Turning Mid Turbine Frame with Embedded Design‐Part I: Design and Steady Measurements. In: Proceedings of the ASME Turbo Expo, San Antonio, Texas, United States of America;

[23] Spataro R, Göttlich E, Lengani D, Faustmann C, Heitmeir F. Development of a Turning Mid Turbine Frame with Embedded Design‐Part II: Unsteady Measurments. In: Proceedings of the ASME Turbo Expo, San Antonio, Texas, United States of America;

[24] Schennach O, Pecnik R, Paradiso B, Göttlich E, Marn A, Woisetschläger J. The Effect of Vane Clocking on the Unsteady Flow Field in a One‐and‐a‐Half Stage Transonic Turbine. Journal of Turbomachinery. 2008;130:031022-1 – 031022-8. DOI:

America. 1999;105(2):1186–1187. DOI: 10.1121/1.425598

lasticity of Turbomachines, London, United Kingdom; 2009.

DOI: 10.2514/MAERO07

34 Recent Progress in Some Aircraft Technologies

DOI: 10.1115/GT2012‐68583

10.1115/1.2777199

June 3‐7; 2013. DOI: 10.1115/GT2013‐95279

June 3‐7; 2013. DOI: 10.1115/GT2013‐95280

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/62394

#### **Abstract**

The lubricant systems used in turbine engine applications are discussed with respect to the particular problems associated with aircraft applications. After initially describing the relevant specifications, the typical basestocks are described along with some common degradation schemes. The additive systems, including antioxidants, anti-foaming agents, and anti-wear additives needed to achieve the typical specifications, are described along with their mechanism of action and degradation mechanisms. The methods used for the monitoring of lubricant health, including in-line and offline methods, are also dis‐ cussed. Finally, future changes in specifications, basestocks, and additives are dis‐ cussed with respect to new, high-performance bearing materials.

**Keywords:** synthetic lubricants, anti-oxidants, phosphate esters, condition monitor‐ ing, tribology, lubricant additives
