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Technical Paper

A Comparison of Fatigue Test Techniques for Gas Turbine Oils - (Report of the CRC-Aviation Bearing Fatigue Panel of the Group on Gas Turbine Lubrication)

A number of specimen life performance tests were conducted on three test lubricants selected to demonstrate their gross ranking capabilities. The results indicated that the test rigs should be used only for gross ranking. A large difference in magnitude of life values were obtained even though agreement in gross ranking was obtained by three out of the five participating laboratories. Further testing is recommended under preselected test conditions and lubricants.
Technical Paper

A Cooling System for the EAPU Shuttle Upgrade

The Shuttle orbiter currently uses hydrazine-powered APU’s for powering its hydraulic system pumps. To enhance vehicle safety and reliability, NASA is pursuing an APU upgrade where the hydrazine-powered turbine is replaced by an electric motor pump and battery power supply. This EAPU (Electric APU) upgrade presents several thermal control challenges, most notably the new requirement for moderate temperature control of high-power electronics at 132 °F (55.6 °C). This paper describes how the existing Water Spray Boiler (WSB), which currently cools the hydraulic fluid and APU lubrication oil, is being modified to provide EAPU thermal management.
Technical Paper


An important current engineering problem in the aviation field involves the providing of increasingly effective lubricating oil filtration for today's more advanced aircraft engines. The critical demands of the higher powered reciprocating engines and the new gas turbine engines, together with the strong desire to reduce aircraft operating and maintenance costs require considerable refinement and improvement in oil filtration methods. This paper discusses some recent developments in scavenge oil filtration and describes a basic, new filter design.
Technical Paper

A History of Aircraft Piston Engine Lubricants

This paper is a review of the literature covering the history of the use of lubricants. The uses of oils derived from animals, vegetables and minerals are placed in perspective from ancient times to the Wright Brothers' flight in 1903. After that period, the discussion is confined largely to the lubrication of aircraft piston engines. The paper attempts to explain the preference for castor oil in European and British engines and the more general, but by no means exclusive, use of petroleum-based mineral oils in the United States. The British Air Ministry, in 1929, reached a decision to abandon castor oil due to availability and cost of petroleum-based oils. The simultaneous U.S. Army Air Corps recognition of the advantages of the very flat viscosity-temperature curve of Pennsylvania oils for hot running engines and for cold starting led to the world-wide use of these lubricating oils.
Technical Paper

A Look at Some Lubricating Oil Specifications and Approvals

Specifications describing performance characteristics for lubricating oils are examined. The author describes the engine performance requirements, and physical and chemical tests required by the military and by the leading automobile manufacturers. Specifications for passenger car automatic transmission fluids are also examined, as are synthetic aircraft lubricants for commercial and military use.
Technical Paper

A Look at the MIL-L-23699 (WEP) Lubricants

Laboratory, component, and engine tests have been conducted by the General Electric Co. to evaluate the various lubricant properties important to the J79 jet engine. Such properties as elastomer volume swell, oxidation-corrosion, coking characteristics, and lubricity were evaluated. The effects of these various properties on engine performance and how the laboratory results relate to the component results and engine test results are discussed.

A Methodology for Quantifying the Performance of an Engine Monitoring System

The purpose of this SAE Aerospace Information Report (AIR) is to present a quantitative approach for evaluating the performance and capabilities of an Engine Monitoring System (EMS). The value of such a methodology is in providing a systematic means to accomplish the following: 1 Determine the impact of an EMS on key engine supportability indices such as Fault Detection Rate, Fault Isolation Rate, Mean Time to Diagnose, In-flight Shutdowns (IFSD), Mission Aborts, and Unscheduled Engine Removals (UERs). 2 Facilitate trade studies during the design process in order to compare performance versus cost for various EMS design strategies, and 3 Define a “common language” for specifying EMS requirements and the design features of an EMS in order to reduce ambiguity and, therefore, enhance consistency between specification and implementation.
Technical Paper

A New Apparatus to Evaluate Lubricants for Space Applications - The Spiral Orbit Tribometer (SOT)

Lubricants used in space mechanisms must be thoroughly tested prior to their selection for critical applications. Traditionally, two types of tests have been used: accelerated and full-scale. Accelerated tests are rapid, economical, and provide useful information for gross screening of candidate lubricants. Although full-scale tests are more believable because they mimic actual spacecraft conditions, they are expensive and time consuming. The spiral orbit tribometer compromises between the two extremes. It rapidly determines the rate of tribochemically induced lubricant consumption, which leads to finite test times, under realistic rolling/pivoting conditions that occur in angular contact bearings.
Technical Paper

A New Laboratory Method of Evaluating Ring-Sticking Tendencies of Aircraft Oils

CONTINUOUS increase in the power output of aircraft engines introduces from time to time lubricating problems including excessive wear and scuffing, excessive oxidation of the oil, and ring sticking. The one problem of ring sticking was chosen and the discussion is limited to the testing of lubricating oils to compare their abilities to prevent this type of failure. Although the best answer as to the ring-sticking tendencies of a lubricant rests with the full-scale engine in service, a simple test is needed during the development period. The development work which led up to the selection of an L-head CFR engine for a ring-sticking test is discussed. Various criteria used for detecting incipient ring sticking are mentioned and a method for direct measurement of incipient ring sticking is described.
Technical Paper

A New Servovalve Concept - The Ball Valve

The new type of fluid device described in this paper is closely analogous to a vacuum tube cathode follower amplifier. It provides an output pressure equal to an input control pressure, but with a high input impedance and low output impedance providing a power gain. A string of balls moving in response to pressures acting on the ball surfaces provides the basic valve action. Because of its structure and the use of balls as the control elements, this device is relatively easy to manufacture, does not require a lubricating fluid and can be operated at high temperatures.

A Review of Literature on the Relationship Between Gas Turbine Engine Lubricants and Aircraft Cabin Air Quality

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 world1-4. 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.
Technical Paper

A Study of High Temperature Fuels and Lubricants on Supersonic Aircraft/Engine System Performance

An evaluation of the influence of two classes of fuels and four types of lubricants on supersonic military interceptor aircraft performance at the airframe subsystem and engine component level is presented. Engine cycles representative of anticipated technology levels in the 1980 time period are analyzed to determine interceptor performance as a function of fuel and lubricant properties and temperature limitations. The relative allotment of available fuel heat sink between engine and airframe is also investigated to determine the primary factors affected by fuel interface temperature and to provide meaningful design guidance for future system applications. The results indicate that with an integrated systems approach to the management of the aircraft and engine system heat loads, JP type fuels and type 2 (MIL-L-27502) lubricants will meet the minimum requirements for advanced military systems.
Technical Paper

A Study of the Potential Benefits Associated with the Development of a Dedicated Helicopter Transmission Lubricant

A common oil is now used in both the engines and transmissions of virtually all U.S. military helicopters. While this provides significant logistic advantages, these advantages are attained only by compromising the optimization of the oil for either system. This paper summarizes the results of two studies undertaken to determine what benefits would accrue through the development of a special oil tailored specifically to meet the unique requirements of high-speed, heavily loaded helicopter transmission systems. These studies, conducted independently by two major helicopter manufacturers under the direction of the Naval Air Propulsion Center, addressed specific problem areas as related to typical production aircraft in order to reach well-documented conclusions. In addition, the effect of the availability of such a special gearbox lubricant on the development of other advanced-technology components was evaluated and documented.


This report summarizes data and background relative to age control of specific classes of those nitrile type synthetic elastomers used in sealing devices which are resistant to petroleum base hydraulic fluids, lubricating oils and aircraft fuels. This includes, but is not limited to, those nitrile (NBR or BUNA-N) elastomers specifically covered by Section I of MIL-STD-1523.