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This SAE Aerospace Recommended Practice (ARP) provides guidelines for specifying Linear Variable Differential Transformers (LVDTs) and Rotary Variable Differential Transformers (RVDTs). Information on the application, operation, design, and construction of LVDTs and RVDTs is also provided.

This aerospace recommended practice provides a framework and suggested procedures or values for requirements for the design, performance, and test of hydraulically powered servoactuators for use in aircraft flight control systems. The original version of this document was intended for military usage: consequently, the requirements still often reflect such use. However, the basic requirements of this ARP may and should be applicable to commercial usage as well, provided that appropriate considerations are given for the applicable FAR/JAR 25 regulations, hydraulic fluids, and environmental conditions.

This SAE Aerospace Information Report (AIR) includes all missile and launch vehicle actuation systems, including electrohydraulic, electropneumatic, and electromechanical types. The data for many systems are not complete. As more information becomes available, periodic updates will be issued to complete existing data sheets and to add new ones. An index by type of vehicle and by type of actuation system is included. The actual data sheets in the body of the report are organized in alphabetical order.

There is a need to guide component designers and system integrators in the development of specifications for Synchro/Resolvers that are used for positional measurement in aerospace applications. This document addresses that need.

This Aerospace Recommend Practice (ARP) offers guidelines for the development of hydraulic actuation system models and simulation. Guidance is provided in the process of specifying, developing, and validating the models.

This recommended practice is intended as a guide for the specification of electrohydraulic mechanical feedback servoactuators used for position control. It provides performance definitions and capabilities that are specific to mechanical-feedback servoactuators and different from those applicable to electrical-feedback servoactuators.

This SAE Aerospace Recommended Practice (ARP) is intended as a guide to aid in the specification and testing of Direct Drive Servovalves, but does not include the associated electronic controller. The recommendations contained in this ARP are primarily confined to the input and output characteristics of Direct Drive Servovalves (DDV). The only exception to this approach involves the definition and specification of chip shear force, which is not typically measurable by nondestructive external testing. The information presented should be useful in standardizing the terminology, the specification of physical and performance parameters, and the test procedures used in conjunction with these components. Direct drive servovalves are of two basic types: open loop and closed loop. In the case of open loop direct drive servovalves, the significant input is the motor current as is the case with electrohydraulic servovalves covered in ARP490.

This Aerospace Recommended Practice (ARP) offers guidelines for specifying servoloop pressure feedback transducers for use in hydraulic actuation for servosystems.

This SAE Aerospace Recommended Practice (ARP) provides guidance in the design, development, qualification test, process control and production acceptance test for flight critical control valve (FCCV) design used in military flight control servoactuators where loss of single valve control could cause a catastrophic failure resulting in death, permanent total disability, and/or financial loss exceeding a defined contractual limit. The FCCV, which is one element of a flight control actuator servo control loop, is a variable position control valve which modulates fluid into and out of the servoactuator power stage cylinders. The FCCV may be mechanically driven by either a mechanical flight control system as shown in Figure 1 or hydraulically driven from electro-hydraulic servo valve (EHSV) modulation control flow as shown in Figure 2. This type of control valve is not an EHSV or a direct drive valve (DDV). The FCCV is used in military hydraulic systems which conform to AS5440.

This SAE Aerospace Recommended Practice (ARP) describes the design conditions under which tests should be conducted to demonstrate satisfactory performance of a flight critical servo-actuator under the maximum allowable particulate contamination in the associated airplane hydraulic system. Additionally, this document also describes the recommended tests and the required acceptance criteria.

This SAE Aerospace Recommended Practice (ARP) provides definitions and background information regarding the physical performance and testing of electrohydraulic flow control and pressure control servovalves. This ARP also provides extensive guidance for the preparation of procurement specifications and for functional testing. NOTE: An example of a procurement specification is provided as Appendix A.

This SAE Aerospace Information Report (AIR) defines the materials, strength and finishes utilized in current linear hydraulic flight control actuators. To keep the information at a relevant minimum, only cylinders (barrels), glands and pistons are listed. Also identified are the reasons for the material selection and any pertinent comments. All data were collected from the respective suppliers.

Various gas systems are classified in a broad sense, component operation is described in moderate detail, pertinent design parameters are discussed, and possible modes for system operation are listed.

Gas, for the purpose of this ARP, shall be defined as the gaseous product(s) resulting from the decomposition, dissociation, or combustion of liquid or solid mono or bi-propellants. Where other gases such as heated N2, H2, H2O (steam), etc., which may have similar physical and/or chemical properties as the defined "gas", are used to effect testing economics, they may he considered as being included in this ARP.

This SAE Aerospace Recommended Practice (ARP) provides guidance in the design, development, qualification test, process control and production acceptance test for flight critical control valve (FCCV) design used in military flight control servoactuators where loss of single valve control could cause a catastrophic failure resulting in death, permanent total disability, and/or financial loss exceeding a defined contractual limit. The FCCV, which is one element of a flight control actuator servo control loop, is a variable position control valve which modulates fluid into and out of the servoactuator power stage cylinders. The FCCV may be mechanically driven by either a mechanical flight control system as shown in FIGURE 1 or hydraulically driven from electro-hydraulic servo valve (EHSV) modulation control flow as shown in FIGURE 2. This type of control valve is not an EHSV or a direct drive valve (DDV). The FCCV is used in military hydraulic systems which conform to AS5440.

This SAE Aerospace Recommended Practice (ARP) is intended as a guide to aid in the specification and testing of Direct Drive Servovalves, but does not include the associated electronic controller. The recommendations contained in this ARP are primarily confined to the input and output characteristics of Direct Drive Servovalves (DDV). The only exception to this approach involves the definition and specification of chip shear force, which is not typically measurable by nondestructive external testing. The information presented should be useful in standardizing the terminology, the specification of physical and performance parameters, and the test procedures used in conjunction with these components. Direct drive servovalves are of two basic types: open loop and closed loop. In the case of open loop direct drive servovalves, the significant input is the motor current as is the case with electrohydraulic servovalves covered in ARP490.

The scope of this document includes all missile and launch vehicle actuation systems, including electrohydraulic, electropneumatic, and electromechanical types. The data for many systems are not complete. As more information becomes available, periodic updates will be issued to complete existing data sheets and to add new ones. An index by type of vehicle and by type of actuation system is included. The actual data sheets in the body of the report are organized in alphabetical order.

Various gas systems are classified in a broad sense, component operation is described in moderate detail, pertinent design parameters are discussed, and possible modes for system operation are listed.

Gas, for the purpose of this ARP, shall be defined as the gaseous product(s) resulting from the decomposition, dissociation, or combustion of liquid, or solid mono or bi-propellants. Where other gases such as heated N2, H2, H2O (steam), etc., which may have similar physical and/or chemical properties as the defined "gas", are used to effect testing economies, they may be considered as being included in this ARP.

This SAE Aerospace Recommended Practice (ARP) provides definitions and background information for understanding the physical performance, and test procedures of electrohydraulic flow control servovalves. The recommendations are confined to interface definition and input/output characteristics. This ARP does not restrict or attempt to define the internal characteristics of servovalves. As such, the recommendations are equally applicable to valves having different internal functioning, different ratings, different physical size, and valves used with different fluids. In certain instances, standards for valve design are recommended for the purpose of interchangeability, as for example, valve polarity, mounting bolt and fluid port locations. The ARP provides extensive guidance for the preparation of Procurement Specifications and for functional testing. A sample Procurement Specification is provided in Appendix A. The primary focus of this ARP is on four-way valves.