SYMPOSIA PAPER Published: 01 January 1989

Experiences with an Analytical Monitoring Program Designed for Commercial Flight Tests of Advanced Mil-L-23699 Turbine Fluids


Aviation turbine engine manufacturers possess different philosophies concerning the qualification of new turbine fluids for commercial aircraft. Most require a flight test employing a monitoring program that was designed to measure only basic fluid parameters such as viscosity, total acid number, etc. Warning limits for changes in these parameters were generally established from the performance characteristics of earlier generations of turbine fluids and older engine designs which imposed less operational stress upon the fluid charge. Recent flight test experience with a third generation Mil-L-23699 fluid suggests that revisions to currently recognized programs and parameter limits should be made in order to properly reflect modern engine hardware features, airline operating practices, and advanced additive behavior. It is recommended that analytical techniques such as plasma-based atomic emission spectrometry, size exclusion chromatography, gas chromatography, and thermal analysis be integrated into existing flight test programs. A “two-stage” monitoring scheme consisting of standard physical-chemical tests and these analytical techniques provided essential data about the fluid's response to thermooxidative and operational stress. Compositional information needed to detect and identify contaminants such as hydraulic and other foreign fluids was also obtained. Specific examples are cited about the diagnostic abilities of this analytically oriented monitoring program.

Author Information

Pachuta, DG
Royal Lubricants Co., Inc., E. Hanover, NJ
Thich, JA
Royal Lubricants
Knipple, RW
Royal Lubricants
Stephanic, DA
Royal Lubricants
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Developed by Committee: D02
Pages: 54–76
DOI: 10.1520/STP18691S
ISBN-EB: 978-0-8031-5082-9
ISBN-13: 978-0-8031-1252-0