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Importance of Physical and Chemical Properties of Aircraft Hydraulic Fluids

2019-10-02
CURRENT
AIR81E
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.
Standard

Importance of Physical and Chemical Properties of Aircraft Hydraulic Fluids

2016-04-20
HISTORICAL
AIR81D
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.
Standard

Aerospace - Chlorinated Solvent Contamination of MIL-H-5606/MIL-H-83282 Vehicle Hydraulic Systems

2013-06-18
CURRENT
AIR4713A
Although there is controversy regarding the chemical form of chlorine and its relation to harmful effects in the hydraulic fluid (i.e., chloride ions versus organic chloro-compounds versus total chlorine in all forms), it is generally agreed that total chlorine content should be measured and controlled. In the near future, the ban on the manufacture of chlorinated solvents, out of concern for depletion of the ozone layer, may in itself diminish or eliminate chlorine contamination related aircraft malfunctions. It is generally accepted that hydraulic fluid contamination should be held to a minimum under all conditions. The benefits of low contamination levels are improved performance, lower maintenance due to lower wear, corrosion and erosion, longer fluid life, longer component life, etc. Contaminants can be classified into two general types: those that are insoluble and those that are soluble in the hydraulic fluid.
Standard

Fine Wire Mesh for Filter Elements

2012-09-24
CURRENT
AIR888C
This SAE Aerospace Information Report (AIR) discusses the terminology, types, method of manufacture and chemistry of the fine wire meshes used for filtration of hydraulic, lubrication fuel systems, and similar applications. Information contained herein may be used for quality assurance testing to insure that a high performance filter grade wire mesh is acceptable for use in an aerospace application.
Standard

HYDRAULIC FLUID CHARACTERISTICS

2011-08-10
HISTORICAL
AIR81
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.
Standard

RECOMMENDED STANDARD FOR AEROSPACE FILTER ELEMENT FINE WIRE MESH

2011-02-11
HISTORICAL
AIR888
This AIR discusses the nature, method of manufacture and chemistry of fine wire meshes of the type used for filtration and similar applications, and how this information may be utilized in setting up a quality control program to insure reliability of meshes used for such applications.
Standard

Importance of Physical and Chemical Properties of Aircraft Hydraulic Fluids

2011-02-08
HISTORICAL
AIR81C
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.
Standard

Fine Wire Mesh for Filter Elements

2002-11-14
HISTORICAL
AIR888B
This SAE Aerospace Information Report (AIR) discusses the terminology, types, method of manufacture and chemistry of the fine wire meshes used for filtration of hydraulic, lubrication fuel systems, and similar applications. Information contained herein may be used for quality assurance testing to insure that a high performance filter grade wire mesh is acceptable for use in an aerospace application.
Standard

Aerospace - Chlorinated Solvent Contamination of MIL-H-5606/MIL-H-83282 Vehicle Hydraulic Systems

2002-08-08
HISTORICAL
AIR4713
Although there is controversy regarding the chemical form of chlorine and its relation to harmful effects in the hydraulic fluid (i.e., chloride ions versus organic chloro-compounds versus total chlorine in all forms), it is generally agreed that total chlorine content should be measured and controlled. In the near future, the ban on the manufacture of chlorinated solvents, out of concern for depletion of the ozone layer, may in itself diminish or eliminate chlorine contamination related aircraft malfunctions. It is generally accepted that hydraulic fluid contamination should be held to a minimum under all conditions. The benefits of low contamination levels are improved performance, lower maintenance due to lower wear, corrosion and erosion, longer fluid life, longer component life, etc. Contaminants can be classified into two general types: those that are insoluble and those that are soluble in the hydraulic fluid.
Standard

Aerospace - Dynamic Test Method for Determining the Relative Degree of Cleanliness of the Downstream Side of Filter Elements

2002-05-21
HISTORICAL
ARP599C
This SAE Aerospace Recommended Practice (ARP) describes a procedure for determining the insoluble contamination level of the downstream side of filter elements. Results of this procedure represent the particulate released from the tested filter element under the prevailing conditions of the test. The results may be used for comparative evaluation of the effectiveness of various cleaning methods or the cleanliness of elements after cleaning or as received from manufacturers.
Standard

Hydrocarbon-Based Hydraulic Fluid Properties

2000-12-01
HISTORICAL
AIR81B
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.
Standard

AEROSPACE - DYNAMIC TEST METHOD FOR DETERMINING THE RELATIVE DEGREE OF CLEANLINESS OF THE DOWNSTREAM SIDE OF FILTER ELEMENTS

1996-05-01
HISTORICAL
ARP599B
This SAE Aerospace Recommended Practice (ARP) describes a procedure for determining the insoluble contamination level of the downstream side of filter elements. Results of this procedure represent the particulate released from the tested filter element under the prevailing conditions of the test. The results may be used for comparative evaluation of the effectiveness of various cleaning methods or the cleanliness of elements after cleaning or as received from manufacturers.
Standard

A DYNAMIC TEST METHOD FOR DETERMINING THE DEGREE OF CLEANLINESS OF THE DOWNSTREAM SIDE OF FILTER ELEMENTS

1996-05-01
HISTORICAL
ARP599
This test method describes a procedure for determining the insoluble contamination level of the downstream side of filter elements. Results of this procedure are intended to be used only for evaluation of the effectiveness of various cleaning treatments, or cleanliness of element as received from manufacturers. The data obtained by this procedure do not necessarily indicate, qualitatively or quantitatively, the contamination which may be released by a filter element into a fluid during service use. Because of the wide variety of conditions which may exist in service applications, it is recommended that the user design and conduct his own particular service performance test. (See paragraph 10.1).
Standard

AEROSPACE-CLEANLINESS CLASSIFICATION FOR HYDRAULIC FLUIDS

1990-03-30
HISTORICAL
AS4059A
This SAE Aerospace Standard defines cleanliness levels for particulate contamination of hydraulic fluids and includes methods of reporting data relating to the contamination levels. The contamination levels selected are an extension and simplification of the widely accepted NAS 1638.
Standard

FINE WIRE MESH FOR FILTER ELEMENTS

1989-05-30
HISTORICAL
AIR888A
This AIR discusses the terminology, types, method of manufacture and chemistry of the fine wire meshes used for filtration of hydraulic, lubrication, fuel systems and similar applications. Information contained herein may be used for quality assurance testing to insure that a high performance filter grade wire mesh is acceptable for use in an aerospace application.
Standard

AEROSPACE-CLEANLINESS CLASSIFICATION FOR HYDRAULIC FLUIDS

1988-06-14
HISTORICAL
AS4059
This SAE Aerospace Standard defines cleanliness levels for particulate contamination of hydraulic fluids and includes methods of reporting data relating to the contamination levels. The contamination levels selected are an extension and simplification of the widely accepted NAS 1638.
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