5.1 Aircraft turbine lubricants, upon standing at low temperatures for prolonged periods of time, may show an increase in kinematic viscosity. This increase may cause lubrication problems in aircraft engines. Thus, this test method is used to ensure that the kinematic viscosity does not exceed the maximum kinematic viscosity in certain specifications for aircraft turbine lubricants.

1.1 This test method covers the determination of the kinematic viscosity of aircraft turbine lubricants at low temperature, and the percent change of viscosity after a 3 h and a 72 h standing period at low temperature.

1.1.1 The range of kinematic viscosities covered by this test method is from 7700 mm²/s to 14 000 mm²/s at –40 °C and from 7000 mm²/s to 17 500 mm²/s at –51 °C. The precision has only been determined for those materials, kinematic viscosity ranges, and temperatures as shown in the precision section. Kinematic viscosities and percent change of viscosity may be measured and reported at other temperatures and other thermal soak period intervals as agreed by the contracting parties.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.2.1 The SI unit used in this test method for Kinematic Viscosity is mm²/s. For user reference, 1 mm²/s = 10^-6 m²/s = 1 cSt.

1.3 Warning—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Use caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.