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The test method describes the procedure for determination of the total acid number (TAN) of new and degraded polyol ester and diester-based gas turbine lubricants by the potentiometric titration technique. The method was validated to cover an acidity range of 0.05 to 6.0 mg KOH g-1. The method may also be suitable for the determination of acidities outside of this range and for other classes of lubricants.

The high-temperature deposition test (HTDT) method is designed to evaluate the deposition and degradation characteristics of turbine lubricants when stressed under mixed-phase flow conditions found in certain parts of aviation gas turbine engines. This method is applicable to lubricants that form deposits in the range of 0.1 to 100 mg during the course of a test.

This method is designed to evaluate the micropitting performance of currently available and future aviation turbine oil formulations. Drawing on previously performed tests documented in AIR6989, the method comprises of three rings rotating against a rotating central roller configuration using the standard, commercially available PCS Instruments Micropitting Rig (MPR). A test profile has been developed between industry and academia that relies on standard, commercially available test specimens.

The document is a recommended guide for evaluating new or replacement test methods. It considers applicability, suitability, accessibility, and return on effort. Particular emphasis should be placed on completing the “strategy definition” portion of this document (Stage 2), to capture all relevant process stages and complete in a recognizable order for any specific development project. The overall process should: 1 address the rationale behind testing; 2 result in a thorough review of whether a test is fit for purpose; 3 act as a pathway for vetting if a test should be added to AS5780. If, in any project, this process is not an exact fit, users should feel free to adjust, as necessary. The process provides the following stages:

The intent of this SAE Aerospace Information Report (AIR) is to summarize and review the E34 committee’s efforts to educate the aerospace propulsion lubrication community on the science of micropitting, its consequences, and the various tribology evaluation methods that can be employed under aviation related conditions to differentiate formulation related aggravating factors.

The lubricant performance capability for aero propulsion drive systems is derived from the physical properties of the oil and the chemical attributes associated with the oil formulation. All properties, such as viscosity, pressure-viscosity coefficient and full-film traction coefficient are inherent properties of the lubricating fluid. Chemical attributes are critical for the formation of protective boundary lubricating films on the surfaces to prevent wear and scuffing. To assure performance and to provide needed information for engineering design, test methodologies for at least five oil properties or attributes are being addressed: (1) pressure-viscosity coefficient, (2) full-film traction coefficient, (3) scuffing resistance, (4) wear resistance, and (5) micropitting propensity. While viscosity versus temperature data are readily available, the above five properties or attributes must be measured under relevant conditions for aero propulsion hardware systems.

This test method provides procedures for exposing specimens of elastomer materials (AS 568-214 size O-rings) representative of those used in gas turbine engines to lubricants or reference fluids under defined time and temperature conditions. This test includes both suspended and compressed O-rings. Resultant changes in the O-ring’s physical properties (tensile strength, elongation, hardness, mass, volume, and compression set) are measured to determine the amount of deterioration of the elastomer.

This test method is designed to simulate the synergistic combinations of oil flow, temperature cycling, hot spots, and tribology that would typically be found in a gas turbine engine. The method is intended to quantitatively characterize changes in four basic oil properties that are brought about by exposure to the afore mentioned simulated turbine engine environment: the tendency of aviation lubricants to form coke deposits, viscosity changes, total acid number changes (TAN), and oil consumption.

There has been a recent upsurge in interest from the media concerning the quality of the environment within aircraft cabins and cockpits especially in the commercial world. This has included (although by no means been limited to) the air quality, with particular reference to the alleged effects of contamination from the aircraft turbine lubricant. Possible exposure to 'organophosphates' (OPs) from the oil has raised special concerns from cabin crew. Such is the concern that government organisations around the world, including Australia, USA and UK, have set up committees to investigate the cabin air quality issue. Concern was also voiced in the aviation lubricants world at the way in which OP additives in turbine lubricants were being blamed in some reports for the symptoms being experienced by air crew and passengers. SAE Committee E-34 therefore decided that it should gather as much available information on the subject as possible.

This AIR describes the current scientific and engineering principles of gas turbine lubricant performance testing per AS5780 and identifies gaps in our understanding of the technology to help the continuous improvement of this specification.

This method is intended to evaluate the thermal and oxidative stability of synthetic, ester-based aviation lubricants under defined conditions of time and temperature. This method is applicable to lubricants meeting the compositional and performance requirements of AS5780.

The lubricant performance capability for aero propulsion drive systems is derived from the physical properties of the oil and performance attributes associated with the chemical properties of the oil. Physical properties, such as viscosity, pressure-viscosity coefficient and full-film traction coefficient are inherent properties of the lubricating fluid. Chemical attributes are critical for the formation of protective boundary lubricating films on the surfaces to prevent wear and scuffing. These attributes are also associated with surface initiated fatigue (micropitting). To assure performance and to provide required information for engineering design, methodology for at least five oil properties are being studied: (1) pressure-viscosity coefficient, (2) full-film traction coefficient, (3) scuffing resistance, (4) wear resistance, and (5) micropitting propensity.

This method is used for determining the volume swelling effect of aero-derived gas turbine engine lubricants on elastomeric materials. It provides insight into the expected performance of a candidate lubricants impact upon elastomer swell and provides data to determine if the candidate lubricant meets specification requirements. This ARP is based upon Federal Standard 791, Method 3604.

The intent is to provide a reference which explains the types of possible changes to AS5780 products and provide appropriate context to the QPG. All product change requests to the QPG will be evaluated on their merits recognizing the content of this AIR is guidance only.

This method is designed to evaluate the coking propensity of synthetic ester-based aviation lubricants under two phase air-oil mist conditions as found in certain parts of a gas turbine engine, for instance, bearing chamber vent lines. Based on the results from round robin data in 2008-2009 from four laboratories, this method is currently intended to provide a comparison between lubricants as a research tool; it is not currently a satisfactory pass/fail test. At this juncture a reference oil may improve reproducibility (precision between laboratories); a formal precision statement will be given when there is satisfactory data and an agreed on, suitable reference oil if applicable.

Employing ‘ball-on-cylinder’ philosophy, a non-rotating steel ball is held in a vertically mounted chuck and using an applied load is forced against an axially mounted steel cylinder. The test cylinder is rotated at a fixed speed while being partially immersed in a lubricant reservoir. This maintains the cylinder in a wet condition and continuously transports a lubricating film of test fluid to the ball and cylinder interface. The diameter of the wear scar generated on the test ball is used as a measure of the fluid’s lubricating properties. The apparatus can be used, by adjusting the operating conditions, to reproduce two different wear mechanisms; mild and severe wear, the ALTE therefore has the ability to assess a lubricant’s performance in that regard.

This test method provides procedures for exposing specimens of elastomer material (slab form) representative to those used in gas turbine engines to aviation lubricants under extended duration and engine relevant thermal conditions. For AS5780 requirements the time is at least 1800 hours and temperatures are 100 °C to 160 °C. Positive volume change is an indication of specimen swell and subsequent negative volume change is an indication of specimen deterioration, both properties are important in the evaluation of the compatibility of the lubricant with elastomers used in the construction of the gas turbine.

This specification defines basic physical, chemical, and performance limits for 5 cSt grades of gas turbine engine lubricating oils used in aero and aero-derived marine and industrial applications, along with standard test methods and requirements for laboratories performing them. It also defines the quality control requirements to assure batch conformance and materials traceability, and the procedures to manage and communicate changes in oil formulation and brand. This specification invokes the Performance Review Institute (PRI) product qualification process. Requests for submittal information may be made to the PRI at the address in Appendix D Section D.2, referencing this specification. Products qualified to this specification are listed on a Qualified Products List (QPL) managed by the PRI. Additional tests and evaluations may be required by individual equipment builders before an oil is approved for use in their equipment.

This specification defines basic physical, chemical, and performance limits for 5 cSt grades of gas turbine engine lubricating oils used in aero and aero-derived marine and industrial applications, along with standard test methods and requirements for laboratories performing them. It also defines the quality control requirements to assure batch conformance and materials traceability, and the procedures to manage and communicate changes in oil formulation and brand. This specification invokes the Performance Review Institute (PRI) product qualification process. Requests for submittal information may be made to the PRI at the address in Appendix D Section D.2, referencing this specification. Products qualified to this specification are listed on a Qualified Products List (QPL) managed by the PRI. Additional tests and evaluations may be required by individual equipment builders before an oil is approved for use in their equipment.

The lubricant performance capability for aero propulsion drive systems is derived from the physical properties of the oil and performance attributes associated with the chemical properties of the oil. Physical properties, such as viscosity, pressure-viscosity coefficient and full-film traction coefficient are inherent properties of the lubricating fluid. Chemical attributes are critical for the formation of protective boundary lubricating films on the surfaces to prevent wear and scuffing. These attributes are also associated with surface initiated fatigue (micropitting). To assure performance and to provide required information for engineering design, methodology for at least five oil properties are being studied: (1) pressure-viscosity coefficient, (2) full-film traction coefficient, (3) scuffing resistance, (4) wear resistance; and (5) micropitting propensity.