Fuel Management System
The AMETEK Sensors and Fluid Management Systems team boasts nearly four decades of expertise in aircraft-level sensing systems. Over the years, we've successfully developed, certified, and manufactured fuel gauging systems for aircraft with fuel capacities spanning from less than 5000 pounds to over 150,000 pounds. Our comprehensive fluid gauging product line encompasses signal conditioners, fuel management units, indicators, refuel control panels, low-level sensors, and active capacitance probes tailored for both conductive and non-conductive fluids, including aviation fuel, potable water, and hydraulic fluids. Currently, we produce upwards of 5000 fuel probes annually. Our fluid gauging systems find application across a wide spectrum, including business jets, military transports, UAVs, and helicopters and the probes leverage proven technology, materials, and manufacturing processes to ensure reliability. Our fuel probe has 470,000 operating hours, and our FQSC has 32,700 operating hours.
Fuel Probe
Active fuel probes seamlessly integrate advanced signal processing electronics into the capacitance sensor, enabling precise measurement while immune to common gauging system issues. These probes interface with the FQSC using a DC current signal ranging from 1.0mA to 2.0mA, with each probe having its dedicated signal. This robust signal is highly resistant to electromagnetic interference (EMI) and lightning-induced transients, while maintaining low power levels to mitigate explosion hazards. In essence, this system is explosion proof. AMETEK's DC current interface offers key advantages, including robust signal resilience against EMI, immunity to ground potential variation, resistance to wire harness stray capacitance, individual probe signals facilitating built-in testing, and simple troubleshooting without the need for specialized equipment; a basic digital multimeter is sufficient for probe interface diagnostics.
Mechanical Design
Our fuel probes consist of concentric tubes that form the capacitance sensing elements. At the top of the probe is a sealed housing for the electronic circuits, and the tubes themselves are constructed of precision-drawn aluminum tubing. To ensure protection inside the probe, we use a chemical conversion coating providing corrosion protection, an insulating endcap which supports the inner electrode at the lower end, and a hermetic electrical connector that is mounted to the underside of the electronics housing. The nameplate information and serial number are permanently marked by laser engraving on the top of the electronics housing. Our fuel probe also reduces the possibility of “bridging” by contaminants such as microbial growth in the fuel.
Mounting
Along with reliability, our probes are designed for efficiency. A customer has the option to choose between two mounting options, fixed brackets, or fixed bushings which are inserted into spring clips that can be installed seamlessly. Our fuel probes are customizable to fit each tank, minimizing the amount of ungaugable fuel but if needed AMETEK SFMS includes the option to provide a tank study to help design the system, in which we can simulate various pitch and roll conditions to ensure accuracy. For probes up to 40 inches only two attachment points are required.
Electrical Design
Due to their placement in challenging environments and difficult-to-reach positions, AMETEK has engineered fuel probes with a streamlined design, minimizing electronic components to enhance reliability. The probes exclude ASICs, hybrids, programmable devices, or software, opting for simplicity. Electrical inputs are effectively shielded against electromagnetic interference and lightning-induced transients for optimal performance.
Our probes use AMETEK’s proprietary capacitance measurement technology, offering better performance than the typical high impedance capacitance bridge or timing circuits. This technology has been proven in over 10-million-unit flight hours and can be used with all types of fuels, even SAFs.
The capacitance measurement circuit regulates the output current according to the measured capacitance. The signal is a DC current that flows through the FQSC, through the probe, back to the FQSC and out to the return in which the signal current provides the operating power for the probe. The probes are fully calibrated at the factory and can be interchangeable with other probes of the same part number.
Fuel Quantity Signal Conditioner (FQSC)
The Fuel Quantity Signal Conditioner (FQSC) serves as a crucial component within the aircraft's fuel management system. It receives input signals from active fuel probes situated within the tanks, processes these signals to determine the fuel contents accurately, and then transmits the data via ARINC-429 digital data bus outputs, which are then interpreted by the Air Vehicle Computer. Notably, the FQSC operates with two independent processing channels to enhance reliability and redundancy.
Functionally, the FQSC performs several key tasks. Firstly, it supplies DC excitation to the fuel probes and regulates current, voltage, and stored energy within the in-tank wiring to prevent potential issues. It also receives signals from the probes and incorporates built-in-test (BIT) capabilities to identify any faults, including open or out-of-range signals from the probes or internal malfunctions within the FQSC itself. Additionally, the FQSC employs filtering mechanisms to mitigate the effects of fuel movement or sloshing during aircraft maneuvers, ensuring more stable and accurate readings. Overall, the FQSC plays a critical role in maintaining precise fuel management and ensuring the safety and efficiency of aircraft operations.
In essence, the AMETEK Sensors and Fluid Management Systems team stands at the forefront of innovation, reliability, and efficiency in aircraft-level sensing systems. With nearly four decades of expertise, we have meticulously developed, certified, and manufactured fuel gauging systems that set the industry standard. Our comprehensive fluid gauging product line, tailored for a diverse range of fluids and aircraft types, reflects our commitment to precision engineering and unwavering reliability. From active capacitance probes to sophisticated Fuel Quantity Signal Conditioners, every component embodies our dedication to excellence. With millions of flight hours behind us and a steadfast focus on simplicity, resilience, and accuracy, AMETEK SFMS continues to shape the future of aviation technology, ensuring safer, more efficient skies for all.
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