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Standard

Contamination Classification for Hydraulic Fluids

2022-11-22
CURRENT
AS4059G
This SAE Aerospace Standard (AS) defines contamination classes and levels for particulate contamination of hydraulic fluids and includes methods of reporting related data (Appendix A).
Standard

Bubble-Point Test Method

2022-09-30
CURRENT
ARP901B
This test method describes a procedure for measuring the largest pore or hole in a filter or similar fluid-permeable porous structure. A standard referee test method for precise determination or resolution of disputes is specified. A simpler inspection test procedure for quality assurance “go-no-go” measurement is also given. Bubble-point testing physics, analysis of bubble-point test data, and correlation with other methods of pore size determination are separately discussed in the appendix.
Standard

Fluid Properties

2021-07-20
CURRENT
AIR1116C
This report summarizes data relative to liquid fluids and their properties which are of interest to Aerospace Fluid Power technologists.
Standard

Fire Resistant Phosphate Ester Hydraulic Fluid for Aircraft

2021-07-20
WIP
AS1241E
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 the qualifying agency to demonstrate compliance with their specific requirements. The "qualifying agency" will be defined herein to be the airframe manufacturer submitting certification approval for use of the fluid in a specific model airplane. Fluids meeting the requirements of this specification may be approved by a qualifying agency for use on specific airplane models. Data used to show compliance to this specification can be used by the qualifying agency to show compliance to the applicable regulations for the appropriate certifying authority; e.g., FAA, EASA, etc.
Standard

Methods, Locations and Criteria for System Sampling and Measuring the Solid Particle Contamination of Hydraulic Fluids

2021-05-06
CURRENT
ARP5376C
This Aerospace Recommended Practice (ARP) provides: Recommended methods for cleaning sample bottles, when used, and the solvents to be applied and how these solvents should be prepared. Recommendations for three measuring methods for determining the level of solid particle contamination of hydraulic fluids used in aerospace hydraulics. Recommendations for the selection of the sampling point, sampling method, and the sampling frequency.
Standard

Liquid Filter Ratings, Parameters and Tests

2021-04-29
CURRENT
AIR887C
This SAE Aerospace Information Report (AIR) identifies and explains the meaning of various ratings and terms used to describe the physical characteristics of liquid filter elements. The significance of various filter parameters is discussed. In addition, a number of filter test methods are briefly described. This AIR and the data presented are only applicable where the system liquid wets the filter elements.
Standard

Degradation Limits of MIL-PRF-5606, MIL-PRF-83282, and MIL-PRF-87257 Hydraulic Fluids Used in Hydraulic Test Stands

2020-10-14
CURRENT
AIR810E
This SAE Aerospace Information Report (AIR) presents data on normally accepted changes in physical properties and contamination levels for MIL-PRF-5606, MIL-PRF-83282, and MIL-PRF-87257 hydraulic fluids used in hydraulic test stands. This information is of importance to all users of hydraulic test stands to assure the performance data obtained on these test stands for specific components will not be adversely affected by excessive changes in fluid properties or contamination levels.
Standard

Filter Element Cleaning Methods

2020-10-09
CURRENT
AIR787B
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.
Standard

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

2020-05-05
CURRENT
ARP599D
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

Aerospace Fluid Power - Contamination Classification for Hydraulic Fluids

2020-05-05
HISTORICAL
AS4059F
This SAE Aerospace Standard (AS) defines contamination classes and levels for particulate contamination of hydraulic fluids and includes methods of reporting related data (Appendix A). The contamination levels selected are based on the widely accepted NAS 1638 cleanliness classes. The conversion from NAS 1638 cleanliness class specifications to AS4059 class specifications is defined. The comparison of the NAS 1638 classes to AS4059 classes and levels is provided and are defined and the differences explained (Appendix B). NAS 1638 classes based on weight of particles are not applicable to these classes and are not included. A contamination code has been added to describe the contamination levels of the fluid at the specified particle size ranges.
Standard

Methods for Evaluating Cryogenic Filters

2019-12-03
CURRENT
ARP900C
The purpose of this document is to present test methods that can be utilized to evaluate the filtration and operating characteristics of filters that will be utilized in a cryogenic system. The methods presented herein are intended to supplement standard filter testing specifications to allow evaluation of filter performance characteristics in areas that could be affected by extreme low temperatures.
Standard

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

Aerospace Fluid Power - Waste Reduction Practices for Used Phosphate Ester Aviation Hydraulic Fluid

2019-08-22
CURRENT
AIR5277B
This SAE Aerospace Information Report (AIR) covers the generation of used phosphate ester aviation hydraulic fluid (AS1241) that is deemed waste because it does not meet in-service limits for use in aircraft. This document also lists the relevant United States Environmental Protection Agency (U.S. EPA) regulations on used hydraulic fluid that are in force at the time of this report's publication. Regulations of other countries as well as those for states and municipalities should be consulted prior to initiating any of the waste disposal recommendations listed here.
Standard

Aerospace Hydraulic Fluids Physical Properties

2018-08-16
CURRENT
AIR1362D
This SAE Aerospace Information Report (AIR) presents data on hydraulic fluids which are of interest to detail designers of hydraulic systems and components for aerospace flight vehicles. The data pertains to fluids conforming to the following specifications: MIL-PRF-5606 MIL-H-8446 MIL-PRF-27601 (canceled) MIL-PRF-27601 has been canceled without replacement and the data presented herein is for information purposes only. MIL-PRF-83282 MIL-H-53119 MIL-PRF-87257 AS1241 Type IV, Classes 1 and 2, and Type V
Standard

Aerospace - Evaluation of Particulate Contamination in Hydraulic Fluid - Membrane Procedure

2018-08-13
CURRENT
ARP4285A
This SAE Aerospace Recommended Practice (ARP) establishes a method for evaluating the particulate matter extracted from the working fluid of a hydraulic system or component using a membrane. The amount of particulate matter deposited on the membrane due to filtering a given quantity of fluid is visually compared against a standard membrane in order to provide an indication of the cleanliness level of the fluid.
Standard

Air in Aircraft Hydraulic Systems

2018-01-19
CURRENT
AIR5829
This SAE Aerospace Information Report (AIR) discusses the forms that air may take in aircraft hydraulic systems. Further, the effects of the various air forms on system operation are addressed. Recommended system design to prevent air effects and maintenance procedures to prevent and remove air are provided. Nitrogen leakage from accumulators is also a source of gas in hydraulic systems and may compose a portion of the “air” in the hydraulic system. The term “air” in this report does not differentiate between a gas composed strictly of normal atmospheric air or one that includes a mixture of additional nitrogen as well. The discussions of the report apply equally with any proportions of atmospheric air and nitrogen in the system.
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