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This report is intended to identify the various errors typically encountered in capacitance fuel quantity measurement systems. In addition to identification of error sources, it describes the basic factors which cause the errors. When coupled with appraisals of the relative costs of minimizing the errors, this knowledge will furnish a tool with which to optimize gauging system accuracy, and thus, to obtain the optimum overall system within the constraints imposed by both design and budgetary considerations. Since the subject of fuel measurement accuracy using capacitance based sensing is quite complex, no attempt is made herein to present a fully-comprehensive evaluation of all factors affecting gauging system accuracy. Rather, the major contributors to gauging system inaccuracy are discussed and emphasis is given to simplicity and clarity, somewhat at the expense of completeness. An overview of capacitive fuel gauging operation can be found in AIR5691.

This SAE Aerospace Information Report (AIR) is a compilation of engineering references and data useful to the technical community that can be used to ensure fuel system compatibility with composite structure. This AIR is not a complete detailed design guide and is not intended to satisfy all potential fuel system applications. Extensive research, design, and development are required for each individual application.

Ice formation in aircraft fuel systems results from the presence of dissolved and undissolved water in the fuel. Dissolved water or water in solution with hydrocarbon fuels constitutes a relatively small part of the total water potential in a particular system with the quantity dissolved being primarily dependent on the fuel temperature and the water solubility characteristics of the fuel. One condition of undissolved water is entrained water such as water particles suspended in the fuel as a result of mechanical agitation of free water or conversion of dissolved water through temperature reduction. Another condition of undissolved water is free water which may be introduced as a result of refueling or the settling of entrained water which collects at the bottom of a fuel tank in easily detectable quantities separated by a continuous interface from the fuel above. Water may also be introduced as a result of condensation from air entering a fuel tank through the vent system.

This document suggests and summarizes points that should be considered with respect to the formation of ice in aircraft fuel systems. These summaries represent a cross-section of the opinions of fuel system designers and users.

Ice formation in aircraft fuel systems results from the presence of dissolved and undissolved water in the fuel. Dissolved water or water in solution with hydrocarbon fuels constitutes a relatively small part of the total water potential in a particular system with the quantity dissolved being primarily dependent on the fuel temperature and the water solubility characteristics of the fuel. One condition of undissolved water is entrained water, such as water particles suspended in the fuel as a result of mechanical agitation of free water or conversion of dissolved water through temperature reduction. This can be considered as analogous to an emulsion state. Another condition of undissolved water is free water which may be introduced as a result of refueling or the settling of entrained water which collects at the bottom of a fuel tank in easily detectable quantities separated by a continuous interface from the fuel above.

The test procedure applies to the refueling manifold system connecting the receiver aircraft fuel tanks to the refueling source fuel pump(s) for both ground and aerial refueling. The test procedure is intended to verify that the limit value for surge pressure specified for the receiver fuel system is not exceeded when refueling from a refueling source which meets the requirements of AS 1284 (reference 2). This recommended practice is not directly applicable to surge pressure developed during operation of an aircraft fuel system, such as initiating or stopping engine fuel feed or fuel transfer within an aircraft, or the pressure surge produced when the fuel pumps are first started to fill an empty fuel manifold.

The test procedure applies to the refueling manifold system connecting the receiver aircraft fuel tanks to the refueling source fuel pump(s) for both ground and aerial refueling. The test procedure is intended to verify that the limit value for surge pressure specified for the receiver fuel system is not exceeded when refueling from a refueling source which meets the requirements of AS1284 (reference 2). This recommended practice is not directly applicable to surge pressure developed during operation of an aircraft fuel system, such as initiating or stopping engine fuel feed or fuel transfer within an aircraft, or the pressure surge produced when the fuel pumps are first started to fill an empty fuel manifold.

The test procedure applies to the refueling manifold system connectingn the receiver aircraft fuel tanks to the refueling source fuel pump(s) for both ground and aerial refueling. The test procedure is intended to verify that the limit value for surge pressure specified for the receiver fuel system is not exceeded when refueling from a refueling source which meets the requirements of AS1284 (reference 2). This recommended practice is not directly applicable to surge pressure developed during operation of an aircraft fuel system, such as initiating or stopping engine fuel feed or fuel transfer within an aircraft, or the pressure surge produced when the fuel pumps are first started to fill an empty fuel manifold.

This SAE Aerospace Specification (AS) is applicable to all aircraft. This AS defines the minimum design and operating requirements for the aircraft refueling interface. These requirements establish the minimum criteria for the aircraft design that provides practical standardized refueling system requirements, provides minimum standardized criteria for the operation and performance of any aircraft refueling equipment, and establishes an integrated minimum performance for aircraft refueling operations. This standardization provides the minimum design criteria to assure full compatibility between the aircraft refueling system connection point(s), aircraft operating characteristics, and the design and operation of ground based aircraft refueling equipment in all steady state and dynamic refueling and defueling conditions. The criteria that shall be used to test the operation and performance of the aircraft refueling system and equipment are also specified.

This SAE Aerospace Information Report (AIR) is limited to the subject of aircraft fuel system plumbing systems and the questions concerning the requirements for electrical bonding of the various components of the system as related to Static Electric Charges, Electromagnectic Interference (EMI) and Lightning Strikes (Direct and Indirect Effects)

This SAE Aerospace Information Report (AIR) is limited to the subject of aircraft fuel systems and the questions concerning the requirements for electrical bonding of the various components of the system as related to Static Electric Charges, Fault Current, Electromagnetic Interference (EMI) and Lightning Strikes (Direct and Indirect Effects). This AIR contains engineering guidelines for the design, installation, testing (measurement) and inspection of electrical bonds.

This document establishes requirements, test procedures, and acceptance criteria for the fire testing of fluid handling components and materials used in aircraft fluid systems. It is applicable to fluid handling components other than those prescribed by AS1055 (e.g., hoses, tube assemblies, coils, fittings). It also is applicable to materials, wiring, and components such as reservoirs, valves, gearboxes, pumps, filter assemblies, accumulators, fluid-cooled electrical/electronic components, in-flight fluid system instrumentation, hydromechanical controls, actuators, heat exchangers, and manifolds. These components may be used in fuel, lubrication, hydraulic, or pneumatic systems.

It is intended to provide capacitance gaging system "specifiers" with the necessary tools to make value judgements concerning the various errors typically encountered in systems of this type. Thus, in addition to merely identifying the error-causes, descriptions are given concerning the basic factors from which these error-causes derive. This knowledge, when complemented with appraisals of the relative costs of minimizing the error-causes, will furnish the system specifier with a powerful tool with which to optimize gaging system accuracy, and thus, to obtain the "best possible" overall system within the constraints imposed by both design and budgetary considerations. Since the subject of capacitance gaging accuracy is quite extensive, and in some instances very complex, no attempt is made herein to present an all-inclusive and fully comprehensive evaluation of the subject. Rather, the major contributors to gaging system inaccuracy are discussed.

A fuel level control valve/system controls the quantity of fuel in a tank being filled or emptied on the aircraft. This document provides a general familiarization with these mechanisms (e.g., forms they take, functions, system design considerations). This document provides the aircraft fuel system designer with information about these mechanisms/devices, so that he can prescribe the types of level control valves/systems which are best suited for his particular fuel system configuration. The scope has been expanded as different aircraft manufacturers may use different type of fuel system architectures. Their refueling and defueling systems may take different configurations, may require different types of fuel control valves and may require different types of interface with the onboard Fuel Measurement System. They must also limit pressure surges and be compatible with ground refueling equipment which have varying surge potentials and create surges.

A fuel level control valve/system controls the quantity of fuel in a tank being filled or emptied. This document provides a general familiarization with these mechanisms (e.g. forms they take, functions, system design considerations). This document provides the aircraft fuel system designer with information about these mechanisms/devices, so that he can prescribe the types of level control valves/systems which are best suited for his particular fuel system configuration.

This report is intended to identify the various existing technologies used for a fuel level sensing system. In addition to sensing technologies, it describes the basic architecture of fuel level sensing systems and their association with fuel gauging system to increase integrity of fuel measurement and management. As the fuel level sensing system is generally based on electrical components within fuel tanks, a specific focus is made on fuel tank explosion safety protection. An overview of the capacitive fuel gauging operation can be found in AIR5691.

This document describes the requirements for air vehicle fuel, vent, and propulsion fuel system functional components.

This document describes the requirements for air vehicle fuel, vent, and propulsion fuel system functional components.