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It discusses the design choices and engineering trade-offs available to the system designer in the efficient selection and application of Last-Chance filters in contrast to main or primary system filters.

This test describes a self-checking procedure for the determination of particulate contaminant five microns or greater in size in hydraulic fluids by the particle count method. A maximum variation of two to one (±33% of the average of two runs) in results should be expected for replicate counts on the same sample, providing that the procedure is followed closely and the precautions presented on pages 10 and 11 of the procedure, regarding manipulation, check samples and self-checking aspects, are observed.

This test describes a self-checking procedure for the determination of particulate contaminant five microns or greater in size in air by the particle count method. A maximum variation of two to one (±33% of the average of two runs) in results should be expected for replicate counts on the same sample, providing that the procedure is followed closely and the precautions presented regarding check samples and self-checking aspects are observed.

This ARP describes procedure for determining the counting and sizing accuracy for an automatic liquid-borne particle counter (APC). This procedure is used in conjunction with a suspension of precisely sized spherical particles.

This aerospace recommended practice describes procedures for establishing a calibration curve for use with an automatic liquidborne particle counter (APC) and verifying the sizing and counting accuracy of the instrument.

This report presents data on hydraulic fluids which are of interest to detail designers of hydraulic systems and components for military flight vehicles. The data pertain to fluids conforming to specifications MIL-H-5606, MIL-H-8446, MIL-H-27601, and MIL-H-83282.

This report describes a mathematical model which can be used to analyze particle count data. Particle counts which fit the model can be graphically displayed. converted from one counting size-frequency range to another, and extrapolated to estimate counts beyond the measured range. Derivation, applications and calculations are described.

This Aerospace Recommended Practice covers the calibration and verification of automatic liquid-borne particle counter for the determination of the concentration by number and size distribution of particles in aerospace liquids. This method is intended for the standardization of automatic liquid-borne particle counting instrumentation.

This document discusses the relative merits of the physical and chemical properties of hydraulic fluids in relation to the aerospace hydraulic system design, and the related materials compatibility. The discussion in this report applies both to hydrocarbon and phosphate ester based aircraft hydraulic fluids. In some cases, numerical limits are suggested, but, in general, the significance and effect of a property is noted qualitatively.

This document discusses the relative merits of the physical and chemical properties of hydraulic fluids in relation to the aerospace hydraulic system design, and the related materials compatibility. The discussion in this report applies both to hydrocarbon and phosphate ester based aircraft hydraulic fluids. In some cases, numerical limits are suggested, but, in general, the significance and effect of a property is noted qualitatively.

This document discusses the relative merits of the physical and chemical properties of hydraulic fluids in relation to the aerospace hydraulic system design, and the related materials compatibility. The discussion in this report applies both to hydrocarbon and phosphate ester based aircraft hydraulic fluids. In some cases, numerical limits are suggested, but, in general, the significance and effect of a property is noted qualitatively.

This document discusses the relative merits of the properties of hydrocarbon-based hydraulic fluid in relation to the fluid formulation, aerospace hydraulic system design and the related materials compatibility. In some cases, numerical limits are suggested, but, in general, the effect of a property is noted qualitatively. The properties of the fluid must be considered in the design of a hydraulic system, but it is possible to design a system to be less sensitive, or more robust, to a particular fluid property. For this reason, the property of the hydraulic fluid must be weighed for each individual hydraulic system, taking into account the system's basic design, function and environment, as well as the fluid toxicity and disposal issues. Besides the hydraulic system itself, ground handling and servicing needs of the system must also be considered. The only absolute characteristic of a hydraulic fluid is that it be a liquid throughout the range of use.

This document discusses the relative merits of the properties of hydrocarbon-based hydraulic fluid in relation to the fluid formulation, aerospace hydraulic system design and the related materials compatibility. In some cases, numerical limits are suggested, but, in general, the effect of a property is noted qualitatively. The properties of the fluid must be considered in the design of a hydraulic system, but it is possible to design a system to be less sensitive, or more robust, to a particular fluid property. For this reason, the property of the hydraulic fluid must be weighed for each individual hydraulic system, taking into account the system's basic design, function and environment, as well as the fluid toxicity and disposal issues. Besides the hydraulic system itself, ground handling and servicing needs of the system must also be considered. The only absolute characteristic of a hydraulic fluid is that it be a liquid throughout the range of use.

This report discusses the characteristics of hydraulic fluids and evaluates their importance, not only from the standpoint of fluid formulation, but also in their effect on aero-space hydraulic system design and the materials used in the components of the system. In some cases numerical parameter limits are suggested, but, in general, the effect of a parameter is the basic consideration. Not only must the characteristics of the fluid be considered in the design of a hydraulic system in which it is to be used, but also the characteristics of the system will affect the extent of the importance of the various characteristics of the fluid. In each individual system, as it employs a fluid, the characteristics of the fluid must be assessed with their immediate import and weighed in considering their effects on the system design requirements based upon the variables of system environment, function and basic design.

This SAE Aerospace Information Report (AIR) provides technical information to assist the development of specific cleaning methods for those filter elements which are designated as "cleanable" and cannot be cleaned by simple and obvious procedures.

This SAE Aerospace Information Report (AIR) provides technical information to assist the development of specific cleaning methods for filter elements. Consideration is limited to filter elements which are designated as "cleanable" (not "disposable"), but which cannot be cleaned by simple and obvious procedures. Cleaning methods developed according to this report should be evaluated by the methods of ARP725. Satisfactory cleaning methods can be developed for most "cleanable" filter elements. Technical or economic feasibility of the cleaning method may be limited, however, by incompatibility of filter-element construction materials, by mechanical weakness or lack of corrosion resistance to withstand repeated or continued cleaning, or by the presence of unusually tenacious contamination. These factors must be considered when selecting approaches to the development of specific methods.

This specification establishes the requirements for phosphate ester hydraulic fluids for use in aircraft systems where fire resistance is required.

This document establishes the requirements for physical and chemical properties and the minimum tests to evaluate suitability of phosphate ester hydraulic fluids for use in aircraft systems where fire resistance is required. Additional tests may be specified by procuring agencies to demonstrate compliance with specific requirements.