Search Results

This SAE Aerospace Information Report (AIR) outlines concepts for the design and use of fault isolation equipment that have general application. The specific focus is on fault isolation of environmental control systems (ECS) in commercial transports. Presented are general fault isolation purposes, design principles, and demonstration of compliance criteria. These are followed by three design examples to aid in understanding the design principles. Future trends in built-in-test-equipment (BITE) design are discussed, some of which represent concepts already being implemented on new equipment.

This Aerospace Recommended Practice (ARP) outlines the causes and impacts of moisture and/or condensation in avionics equipment and provides recommendations for corrective and preventative action.

The fluid flow treated in this section is isothermal, subsonic, and incompressible. The effects of heat addition, work on the fluid, variation in sonic velocity, and changes in elevation are neglected. An incompressible fluid is one in which a change in pressure causes no resulting change in fluid density. The assumption that liquids are incompressible introduces no appreciable error in calculations, but the assumption that a gas is incompressible introduces an error of a magnitude that is dependent on the fluid velocity and on the loss coefficient of the particular duct section or piece of equipment. Fig. 1A-1 shows the error in pressure drop resulting from assuming that air is incompressible. With reasonably small loss coefficients and the accuracy that is usually required in most calculations, compressible fluids may be treated as incompressible for velocities less than Mach 0.2.

The recommendations of this SAE Aerospace Recommended Practice (ARP) for aircraft compartment automatic temperature control systems are primarily intended to be applicable to occupied or unoccupied compartments of civil and military aircraft.

The recommendations of this SAE Aerospace Recommended Practice (ARP) for aircraft compartment automatic temperature control systems are primarily intended to be applicable to occupied or unoccupied compartments of civil and military aircraft.

This SAE Aerospace Information Report (AIR) contains information on the thermal design requirements of airborne avionic systems used in military airborne applications. Methods are explored which are commonly used to provide thermal control of avionic systems. Both air and liquid cooled systems are discussed.

The Environmental Control Analysis SYstem (EASY) computer program is summarized in this report. Development of this computer program initially was sponsored by the U.S. Air Force Flight Dynamics Laboratory. (See References 1, 2, 3, and 4.) It provides techniques for determination of steady state and dynamic (transient) ECS performance, and of control system stability; and for synthesis of optimal ECS control systems. The program is available from the U.S. Air Force, or as a proprietary commercial version. General uses of a transient analysis computer program for ECS design and development, and general features of EASY relative to these uses, are presented. This report summarizes the nine analysis options of EASY, EASY program organization for analyzing ECS, data input to the program and resulting data output, and a discussion of EASY limitations. Appendices provide general definitions for dynamic analysis, and samples of input and output for EASY.

Like the technologies to which it contributes, the science of instrumentation seems to be expanding to unlimited proportions. In considering instrumentation techniques, primary emphasis was given in this section to the fundamentals of pressure, temperature, and flow measurement. Accent was placed on common measurement methods, such as manometers, thermocouples, and head meters, rather than on difficult and specialized techniques. Icing, humidity, velocity, and other special measurements were touched on briefly. Many of the references cited were survey articles or texts containing excellent bibliographies to assist a more detailed study where required.

The fluid flow treated in this section is isothermal, subsonic, and incompressible. The effects of heat addition, work on the fluid, variation in sonic velocity, and changes in elevation are neglected. An incompressible fluid is one in which a change in pressure causes no resulting change in fluid density. The assumption that liquids are incompressible introduces no appreciable error in calculations, but the assumption that a gas is incompressible introduces an error of a magnitude that is dependent on the fluid velocity and on the loss coefficient of the particular duct section or piece of equipment. Fig. 1A-1 shows the error in pressure drop resulting from assuming that air is incompressible. With reasonably small loss coefficients and the accuracy that is usually required in most calculations, compressible fluids may be treated as incompressible for velocities less than Mach 0.2.

This document has been declared “CANCELLED” as of January 2010. By this action, this document will remain listed in the Numerical Section of the Aerospace Standards Index.

This document has been declared “CANCELLED” as of January 2010. By this action, this document will remain listed in the Numerical Section of the Aerospace Standards Index.

This publication will discuss water carryover from the environmental control system with respect to causes and indicated corrective or preventative action. In addition, condensation on structure will be reviewed with possible preventative action described.

These recommendations cover the basic criteria for the design of aircraft cabin pressurization control systems as follows: (1) To ensure aircraft safety. (2) Physiology and limits which govern maximum permissible pressure time relations as related to aircraft passenger comfort. (3) General pressurization control system performance requirements designed to satisfy (2). (4) Technical considerations relevant to satisfying (3).

Like the technologies to which it contributes, the science of instrumentation seems to be expanding to unlimited proportions. In considering instrumentation techniques, primary emphasis was given in this section to the fundamentals of pressure, temperature, and flow measurement. Accent was placed on common measurement methods, such as manometers, thermocouples, and head meters, rather than on difficult and specialized techniques. Icing, humidity, velocity, and other special measurements were touched on briefly. Many of the references cited were survey articles or texts containing excellent bibliographies to assist a more detailed study where required.

Many different computer programs have been developed to determine performance capabilities of aircraft environmental control systems, and to calculate size and weight tradeoffs during preliminary design. Many of these computer programs are limited in scope to a particular arrangement of components for a specific application. General techniques, providing flexibility to handle varied types of ECS configurations and different requirements (i.e., during conceptual or preliminary design, development, testing, production, and operation) are designated “company proprietary” and are not available for industry-wide use. This document describes capabilities, limitations, and potentials of a particular computer program which provides a general ECS analysis capability, and is available for use in industry. This program, names AECS1, was developed under the sponsorship of the U.S. Air Force Flight Dynamics Laboratory (References 1 and 2).

The Engineering Analysis SYstem (EASY) computer program is summarized in this report. It provides techniques for analysis of steady-state and dynamic (transient) environmental control system (ECS) performance, control system stability, and for synthesis of optimal ECS. General uses of a transient analysis computer program for ECS design and development, and general features of EASY relative to these uses, are presented. This report summarizes the nine analysis options of EASY, EASY program organization for analyzing ECS, data input to the program and resulting data output, and a discussion of EASY limitations. Appendices provide general definitions for dynamic analysis, and samples of input and output for EASY.

The purpose of this document is threefold: (1) to review the problem of moisture in avionics equipment, (2) to outline methods for correcting conditions of excess moisture in existing avionics installations, and (3) to recommend design practices for new avionics cooling system installations which will minimize the adverse effects of moisture.

These recommendations are written to cover the testing of environmental control equipment, functioning as a complete and installed system in civil aircraft for the purpose of: a Demonstrating the safety of the installation and equipment. b Demonstrating proper functioning of the installation and equipment. c Demonstrating performance of the installation and equipment. d Obtaining data for future design and to aid in the analysis of in-service performance of the system and equipment.

This document supplements and in some cases supersedes the recommendations presented in ARP 85D, which refers to subsonic civil transports.

This AIR outlines concepts for the design and use of fault isolation equipment that have general application. However, the specific concern applies only to use with Environmental Control Systems in commercial transports. In particular, automatic Built In Test Equipment (BITE) with manual initiation and software programs are covered as systems already in use.