Aircraft fuel pressure indication system

Abstract

This invention discloses an aircraft fuel pressure indication system. The aircraft fuel pressure indication system includes: a fuel pressure measuring device installed inside the aircraft's fuel tank, the fuel pressure measuring device including a mechanical interface, an electrical interface, and a capacitive pressure sensor; a pressure-conducting line for transmitting fuel from the fuel pump outlet or refueling shut-off valve to the fuel pressure measuring device; and a fuel pressure measuring cable passing through the wall of the fuel tank for transmitting the fuel pressure signal measured by the capacitive pressure sensor of the fuel pressure measuring device to a fuel signal processor located outside the fuel tank.

Description

Technical Field

[0001] This invention belongs to the field of aircraft design, and in particular relates to an aircraft fuel pressure indication system. Background Technology

[0002] Aircraft fuel indication systems typically include fuel quantity indication, fuel temperature indication, and fuel pressure indication. The fuel pressure indication system functions to provide the host computer with fuel pressure signals from the outlets of all fuel pumps on board, indicating the operating status of each fuel pump to the pilot; it can also provide fuel pressure signals from the refueling lines of each fuel tank, indicating the on / off status of the refueling shut-off valves of each fuel tank to maintenance personnel.

[0003] An aircraft fuel pressure indication system typically consists of a fuel pump pressure signaler, a refueling shut-off valve pressure signaler and necessary pressure signaler mounting brackets, pressure measurement lines and necessary line clamps and brackets, as well as a host computer for processing the pressure signaler signals. Traditional aircraft pressure signalers generally use mechanical pressure signalers, which sense changes in fuel pressure through internal elastic springs.

[0004] Because the pressure signaler is electrically connected to the fuel system or avionics system, it is generally installed outside the fuel tank to prevent the cables from introducing an ignition source into the fuel tank. These pressure signalers are typically located in the main landing nacelle and on the leading and trailing edges of the wings. The fuel pump is installed inside the aircraft fuel tank, and a fuel pressure tapping line usually runs from the fuel pump outlet, connecting to one end of a frame connector on the aircraft fuel tank structure. The fuel pressure signaler is installed outside the fuel tank at the other end of the frame connector. Similarly, a fuel pressure tapping line usually runs from the refueling shut-off valve located inside the fuel tank, connecting to the pressure signaler via a frame connector.

[0005] In this type of solution, the installation of the pressure signaler requires various structural supports and components, increasing the aircraft's weight and creating numerous structural openings that affect structural strength. Furthermore, moisture and impurities in the fuel may deposit and accumulate at the pressure sensor's measurement port, affecting the accuracy of the pressure signaler's measurements and consequently impacting aircraft dispatch.

[0006] Therefore, there is a need in the art for an improved aircraft fuel pressure indication system. Summary of the Invention

[0007] This invention provides an aircraft fuel pressure indication system for monitoring and transmitting the pressure status of the aircraft fuel pump outlet and the refueling shut-off valve outlet.

[0008] In one embodiment, a capacitive fuel pressure sensor is used instead of a traditional mechanical pressure signaler. By installing the capacitive fuel pressure sensor inside the fuel tank, the impact of rotor explosion can be avoided, and there is no need to drill a frame hole in the structure, thus avoiding fuel leakage problems caused by insufficient sealing.

[0009] In a preferred embodiment, the pressure sensor integrates an electrical interface and a mechanical interface for connecting to the pressure tapping line. During installation, the mechanical interface end that is adapted to the pressure tapping line is positioned "high" to prevent the impact of water in the fuel freezing or impurities accumulating in cold environments on pressure measurement. At the same time, it ensures that condensate at the electrical interface can flow down the cable, preventing it from accumulating at the electrical interface and affecting signal transmission.

[0010] In a preferred embodiment, the excitation and feedback cables of the capacitive fuel pressure sensor reuse the fuel quantity measurement cable design. This eliminates the need for additional R&D costs for ignition source protection of the cables inside the fuel tank; it allows the sharing of a shielding layer with the fuel quantity measurement cable, reducing the added weight due to the additional shielding layer; and the cable installation path is the same as the fuel quantity measurement cable, eliminating the need for additional wiring channels.

[0011] In one embodiment of the present invention, an aircraft fuel pressure indication system is provided, comprising: a fuel pressure measuring device installed in the aircraft's fuel tank, the fuel pressure measuring device including a mechanical interface, an electrical interface, and a capacitive pressure sensor; a pressure tapping line, a first end of which is located at the fuel pump outlet of the fuel tank or on a refueling shut-off valve, and a second end of which is connected to the mechanical interface of the fuel pressure measuring device for transmitting fuel from the fuel pump outlet or the refueling shut-off valve to the fuel pressure measuring device; and a fuel pressure measuring cable, the fuel pressure measuring cable being connected to the electrical interface of the fuel pressure measuring device and passing through the wall of the fuel tank for transmitting the fuel pressure signal measured by the capacitive pressure sensor of the fuel pressure measuring device to a fuel signal processor located outside the fuel tank.

[0012] On one hand, the mechanical interface includes a pipe thread interface for adapting and connecting to the pressure-feeding pipeline.

[0013] On one hand, the fuel pressure measuring device is mounted on a rib on the inner wall of the fuel tank via a bracket.

[0014] On one hand, the fuel pressure measuring device is located above the pressure tapping line, and the electrical interface is higher than the mechanical interface and the pressure tapping line.

[0015] On one hand, the fuel pressure measuring cable passes through a frame hole on the fuel tank to reach the outside of the fuel tank.

[0016] On one hand, the fuel pressure measuring cable and the fuel quantity measuring cable share the same through-frame hole.

[0017] In one aspect, the fuel pressure measurement cable includes an excitation cable and a feedback cable for the capacitive pressure sensor.

[0018] In one aspect, the fuel signal processor includes a fuel remote data concentrator (FRDC) that converts the fuel pressure signal measured by the capacitive pressure sensor from an analog quantity to a digital quantity and transmits the digital fuel pressure signal to a fuel quality control (FQC) computer, which determines that the measured fuel pressure signal is a high-pressure / low-pressure discrete quantity.

[0019] On one hand, the fuel computer sends the high / low pressure discrete values ​​of the fuel pump to the avionics system.

[0020] On one hand, the fuel computer determines the high / low pressure discrepancy of the fuel cut-off valve and determines whether the fuel pressure of the fuel cut-off valve is normal based on the high / low pressure discrepancy. If the fuel pressure of the fuel cut-off valve is abnormal, the FQC generates a fuel alarm signal and provides the fuel filler / discharge control panel (RDCP) with the fuel alarm signal. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the architecture of a fuel pressure indicating system according to an embodiment of the present invention.

[0022] Figure 2 This is the signal transmission path of a fuel pressure indicating system according to an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of a fuel pressure measuring device according to an embodiment of the present invention.

[0024] Figure 4 This is an assembly diagram of a fuel pressure measuring device according to an embodiment of the present invention. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but this should not be construed as limiting the scope of protection of the present invention.

[0026] Aircraft typically have one or more fuel tanks to store enough fuel to meet their flight requirements; these include fuselage tanks and wing tanks. Each tank may be equipped with one or more fuel pumps to transfer fuel from the tank to the engine. Larger tanks are usually equipped with multiple fuel pumps, and aircraft fuel systems are typically designed with redundancy, so that even if one fuel pump fails, the others can continue to operate, ensuring a normal fuel supply to the engine.

[0027] Engines require stable fuel pressure to operate normally. Low fuel pressure can lead to insufficient fuel supply, reduced engine power, or even stalling. Therefore, each fuel tank's fuel pump is equipped with a fuel pressure sensor to monitor its operation. Measuring fuel pressure allows for timely detection of issues such as whether the fuel pump is functioning properly or whether there are blockages in the fuel lines. If the fuel pressure is below the normal range, it may indicate a fuel pump malfunction or insufficient fuel. A sudden increase in fuel pressure may indicate a blockage in the fuel lines, preventing proper fuel flow; in this case, immediate inspection and repair are necessary.

[0028] In addition, the aircraft is equipped with a refueling shut-off valve to control the flow of fuel into the fuel tank. During refueling, when the fuel level in the tank reaches a predetermined level, the refueling shut-off valve automatically closes, stopping the flow of fuel into the tank and thus preventing fuel spillage. Each fuel tank may have an independent refueling shut-off valve, and the refueling shut-off valve is equipped with a fuel pressure sensor to monitor its status.

[0029] Figure 1 This is a schematic diagram of the architecture of a fuel pressure indicating system according to an embodiment of the present invention. Figure 1 Three fuel tanks 110, 120, and 130 are shown. By way of example and not limitation, fuel tank 120 may be a fuselage fuel tank, and fuel tanks 110 and 130 may be wing fuel tanks. In other embodiments, different numbers or locations of fuel tanks may be included. Each fuel tank may have one or more fuel pumps 112, such as DC or AC fuel pumps, for delivering fuel from the tank to the engine or auxiliary power unit. Additionally, each fuel tank may have a fuel cut-off valve 114 for controlling fuel inflow into the tank.

[0030] In one embodiment of the present invention, each fuel pump or fuel cut-off valve may be equipped with a capacitive pressure sensor 116 for monitoring the fuel pressure status at the corresponding fuel pump or fuel cut-off valve. The capacitive pressure sensor 116 may be installed in a fuel pressure measuring device, which can be mounted inside the fuel tank via a bracket. A capacitive pressure sensor is a pressure sensor that uses a capacitive sensing element to convert the measured pressure into an electrical output that is related to it. It typically uses a metal thin film or a metal-plated thin film as one electrode of a capacitor. When the film senses pressure and deforms, the capacitance between the film and the fixed electrode changes, outputting an electrical signal that is related to the voltage.

[0031] According to one embodiment of the present invention, the fuel pump outlet pressure and the refueling shut-off valve outlet pressure are both measured using a capacitive fuel pressure sensor. The capacitive fuel pressure sensor is mounted on the rib inside the fuel tank via a mounting bracket, near the corresponding fuel pump / refueling shut-off valve mounting position.

[0032] The fuel pressure indication system may also include a fuel pressure measurement cable 118, which passes through a through-hole on the fuel tank to the outside of the tank, for transmitting the fuel pressure signal measured by the capacitive pressure sensor 116 to a fuel signal processor located outside the fuel tank, such as a fuel remote data concentrator (FRDC). Although Figure 1 The diagram shows multiple separate fuel pressure measuring cables 118 for a single fuel tank; however, it should be understood that the individual fuel pressure measuring cables 118 for the same fuel tank can reach the outside of the fuel tank via the same fuel tank through-frame hole.

[0033] In one embodiment, the fuel pressure measurement cable 118 can share a through-hole with the fuel quantity measurement cable. In aircraft fuel monitoring, capacitive sensors are typically used to measure fuel level, and the fuel volume and quantity are calculated based on the fuel tank shape and density. The capacitive sensor for fuel quantity measurement is installed inside the fuel tank and transmits the measured fuel quantity signal to a signal processing device outside the fuel tank via the fuel quantity measurement cable. The fuel quantity measurement cable passes through a through-hole on the fuel tank to reach a fuel remote data concentrator (FRDC) outside the tank. The aircraft fuel pressure indication system described in this invention can reuse existing fuel measurement cables, fuel remote data concentrators, fuel computers, and their communication lines in fuel quantity indication systems, without requiring additional new equipment.

[0034] The fuel pressure signal is transmitted via the fuel pressure measurement cable to the FRDC for data processing before being sent to the FQC. The FQC then sends the fuel pump pressure signal to the avionics system for fuel pump status determination. The refueling pressure signal is used to determine the refueling function status within the system. In other words, the refueling status can be determined within the FQC, and a refueling alarm signal can be sent to the fuel dispensing control panel (RDCP) if the refueling function is malfunctioning.

[0035] Compared to existing fuel pressure signalers installed outside the fuel tank, the fuel pressure indication solution provided by this invention installs a capacitive fuel pressure sensor inside the fuel tank, eliminating the need to divert fuel to the outside of the tank, thus avoiding the impact of rotor explosion. Furthermore, it eliminates the need for frame holes in the structure, preventing oil leakage problems caused by insufficient sealing.

[0036] In a preferred embodiment, the fuel pressure measuring cable reuses the design of the fuel quantity measuring cable, eliminating the need for additional R&D costs for ignition source protection of the cable inside the fuel tank; it can share the same shielding layer as the fuel quantity measuring cable, reducing the weight added by adding a new shielding layer; the cable installation path is the same as the fuel quantity measuring cable, eliminating the need for additional wiring channels.

[0037] In addition, the capacitive fuel pressure sensor can be mounted on the ribs inside the fuel tank via a bracket, reducing the number of structural openings through the frame, significantly reducing the number of parts required for pressure sensor installation, simplifying the installation process, and reducing system weight.

[0038] Figure 2 This is the signal transmission path of a fuel pressure indicating system according to an embodiment of the present invention.

[0039] FRDC 202 provides excitation to the capacitive fuel pressure sensor 201 and receives the signal fed back from the pressure sensor. The fuel pressure measurement cable includes an excitation cable and a feedback cable for the capacitive pressure sensor. The fuel pressure measurement cable can be the same type as the fuel quantity measurement cable, featuring a shielding layer and abrasion-resistant braided sleeve. To reduce cable installation steps and development costs, it can be a branch of the original fuel measurement cable.

[0040] The FRDC 202 can provide an excitation signal, such as a triangular wave or square wave, to the capacitive pressure sensor 201 via an excitation cable. The thin-film electrode of the capacitive pressure sensor 201 deforms under fuel pressure, causing a change in capacitance between the thin-film electrode and the fixed electrode, thereby outputting an electrical signal that is related to the fuel pressure (i.e., the detected fuel pressure signal). The detected fuel pressure signal is an analog quantity, which is transmitted to the FRDC 202 via a feedback cable in the fuel pressure measurement cable.

[0041] FRDC 202 converts the fuel pressure signal measured by the capacitive pressure sensor from an analog signal to a digital signal and transmits the digital fuel pressure signal to the fuel quality control (FQC) 203. FQC 203 determines the current outlet pressure as a high / low pressure discrete value (high pressure = GND, low pressure = OPEN) based on the design characteristics of the fuel pump / fuel cut-off valve outlet pressure, and sends the high / low pressure discrete value (OPEN / GND) of the fuel pump to the avionics system 204. The avionics system 204 can further send the high / low pressure discrete value (OPEN / GND) of the fuel pump to the target system 205.

[0042] For example, target system 205 can be an alarm system. The alarm system combines the fuel pump control command signal and the pressure signal at the fuel pump outlet to determine the fuel pump fault status (e.g., the command is "start pump", but the pressure signal is "low pressure"). When the fuel pump fails, a PUMP FAULT warning is displayed on the cockpit display.

[0043] The FQC 203 determines the high / low pressure discrepancy of the fuel cut-off valve and whether the fuel pressure at the fuel cut-off valve is normal. If the fuel pressure at the fuel cut-off valve is abnormal, such as low pressure detected when the fuel cut-off valve is open or high pressure detected when the fuel cut-off valve is closed, the FQC 203 generates a fuel alarm signal and provides the fuel filler / discharge control panel (RDCP).

[0044] In one embodiment, when the fuel pump switch is pressed, the fuel pump starts, and high-pressure fuel is conducted to the fuel pressure sensor via the fuel pressure tapping line. The fuel pressure sensor detects the high-pressure fuel and outputs a corresponding electrical signal to the avionics system, indicating to the pilot that the fuel pump is currently on. Conversely, if the fuel pump fails to start due to a malfunction or other reason after the fuel pump switch is pressed, and the fuel pressure sensor detects low pressure at the fuel pump outlet, the host computer (e.g., an alarm system) determines that the fuel pump is faulty and sends a low-pressure fuel pump alarm signal to the cockpit. At the same time, the alarm light corresponding to the fuel pump switch on the top control panel of the cockpit fuel tank will also illuminate, reminding the pilot that the fuel pump has malfunctioned and that appropriate action must be taken according to the flight manual.

[0045] In one embodiment, when maintenance personnel open the fuel cut-off valve by operating the pressure refueling switch via the fuel refueling control panel, the connected fuel pressure sensor detects high fuel pressure and sends a signal to the host computer (e.g., FQC) indicating that the fuel cut-off valve is open. Conversely, if the fuel cut-off valve fails to open after the pressure refueling switch is opened, and the fuel pressure sensor detects low pressure at the fuel cut-off valve outlet, the FQC will send an alarm signal to the fuel refueling control panel (RDCP), indicating to maintenance personnel that the current fuel cut-off valve is malfunctioning.

[0046] Figure 3 This is a schematic diagram of a fuel pressure measuring device according to an embodiment of the present invention. In one embodiment, the pressure sensor may integrate an electrical interface and a mechanical interface as a fuel pressure measuring device. There are various types of capacitive pressure sensors, commonly including single-capacitive pressure sensors and differential-capacitive pressure sensors, which can be selected according to the actual project requirements. Figure 3 View (a) shows a side view of a fuel pressure measuring device, and view (b) shows a top view of the fuel pressure measuring device.

[0047] As shown in the figure, the fuel pressure measuring device may include a mechanical interface 302, one or more device end retaining rings 303 and 304, a fuse hole 305, an electrical interface 306, and a capacitive pressure sensor 310, etc.

[0048] The fuel pressure measuring device may have a hollow structure (e.g., a hollow tubular structure), and the capacitive pressure sensor 310 may be located on the wall surrounding the hollow structure, such as on the inner wall of the tubular structure. The mechanical interface 302 of the fuel pressure measuring device (e.g., a threaded pipe interface) is adapted to the pressure tapping line of the fuel pump / fuel shut-off valve, allowing fuel to enter the fuel pressure measuring device from the opening end 301 via the pressure tapping line and contact the capacitive pressure sensor 310, enabling the capacitive pressure sensor 310 to measure the fuel pressure.

[0049] The electrical interface 306 of the fuel pressure measuring device is the signal transmission port of the capacitive pressure sensor 310. It is connected to the FRDC via a fuel pressure measuring cable and is used to receive the excitation signal applied to the capacitive pressure sensor 310 from the FRDC and to transmit the fuel pressure signal detected by the capacitive pressure sensor 310 to the FRDC.

[0050] One or more device-end retaining rings 303 and 304 can clamp the main body of the fuel pressure measuring device. The retaining ring 303 is connected to a bracket 308 via a fastener, and the bracket 308 is fixed to a structural rib on the inner wall of the fuel tank via the fastener. Similarly, the device-end retaining ring 304 can be connected to a structural rib inside the fuel tank via a bracket. Thus, the fuel pressure measuring device can be fixed to the inner wall of the fuel tank. Furthermore, the capacitive pressure sensor may have a fuse hole 305 for securing a fuse.

[0051] Figure 4 This is an assembly diagram of a fuel pressure measuring device according to an embodiment of the present invention.

[0052] The fuel pressure measuring device can be connected to one end of the pressure tapping line 404 via an interface thread. The other end of the pressure tapping line 404 is located at the fuel pump outlet or on the fuel cut-off valve, used to conduct fuel from the fuel pump outlet or fuel cut-off valve to the fuel pressure measuring device. The fuel pressure measuring device can be secured to the structural ribs inside the fuel tank via one or more retainers 304 and fasteners 405 (e.g., screws). The fuel pressure measuring cable 402 is connected to the FDRC outside the fuel tank via a through-hole in the fuel tank (e.g., the same through-hole used for the fuel quantity measuring cable), transmitting the fuel pressure signal to the FDRC.

[0053] The design of the mechanical interface (e.g., threaded interface) and electrical interface (e.g., interface with fuel pressure measuring cable 402) of the fuel pressure measuring device should ensure that when the fuel pressure measuring device is installed at a certain angle, the electrical interface is protected from water contamination, while the mechanical interface end is positioned as a "high point" to prevent water freezing or impurity accumulation from affecting the measurement. For example, if the mechanical interface end of the fuel pressure measuring device is higher than the pressure tapping line 404, it can prevent moisture and impurities in the fuel from depositing and accumulating at the pressure sensor measurement port, ensuring the accuracy of the pressure signal measurement.

[0054] Pressure sensors should avoid being installed at a "low point," meaning that the connection between the fuel pump / fuel shut-off valve outlet and the pressure sensor measuring end should ideally be at the highest point, while the fuel pump / fuel shut-off valve outlet should be at the lowest point. This ensures that water or impurities do not accumulate at the pressure sensor measuring end, affecting the accuracy of the pressure signal and misleading pilots or ground crew. However, due to space constraints in the installation area, traditional mechanical pressure signal installations often fail to meet this requirement.

[0055] The aircraft capacitive fuel pressure indication system proposed in this invention uses a capacitive fuel sensor to measure the outlet pressure of the fuel pump and the outlet pressure of the refueling shut-off valve. By installing the capacitive fuel pressure sensor inside the fuel tank, the impact of rotor explosion can be avoided, and there is no need to drill through-holes in the structure, thus avoiding fuel leakage problems caused by insufficient sealing. During installation, the mechanical interface of the fuel pressure sensor is positioned "high" relative to the pressure tapping line, which can prevent the impact of water in the fuel freezing or impurities accumulating in cold environments on the pressure measurement. At the same time, it can ensure that condensate at the electrical interface can flow down along the cable, preventing it from accumulating at the electrical interface and affecting signal transmission. The fuel pressure measurement cable of this invention can reuse the design of the fuel quantity measurement cable (e.g., having a common cable type, shielding layer, and installation path), eliminating the need for additional R&D costs for ignition source protection of cables inside the fuel tank, and eliminating the need to add through-holes and wiring channels to the fuel tank.

[0056] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the scope of protection of the present invention.

[0057] The various steps and modules of the methods and apparatus described above can be implemented in hardware, software, or a combination thereof. If implemented in hardware, the various illustrative steps, modules, and circuits described in connection with this disclosure can be implemented or executed using a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic components, hardware components, or any combination thereof. A general-purpose processor can be a processor, microprocessor, controller, microcontroller, or state machine, etc. If implemented in software, the various illustrative steps and modules described in connection with this disclosure can be stored as one or more instructions or codes on a computer-readable medium or transmitted. Software modules implementing the various operations of this disclosure can reside in a storage medium, such as RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, removable disk, CD-ROM, cloud storage, etc. The storage medium can be coupled to a processor so that the processor can read and write information from / to the storage medium and execute the corresponding program modules to implement the various steps of this disclosure.

[0058] It should also be noted that these embodiments may be described as processes depicted as flowcharts, flow diagrams, structure diagrams, or block diagrams. Although a flowchart may describe the operations as a sequential process, many of these operations can be executed in parallel or concurrently. Furthermore, the order of these operations can be rearranged.

[0059] The directional terms used in the description of this application, such as "front, back, up, down, left, right", "horizontal, vertical, horizontal", "top, bottom", "inner, outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application.

[0060] Furthermore, it should be noted that the use of sequential terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this application.

[0061] The disclosed methods, apparatuses, and systems should not be limited in any way. Rather, this disclosure covers all novel and non-obvious features and aspects of the various disclosed embodiments (individually and in various combinations and sub-combinations of each other). The disclosed methods, apparatuses, and systems are not limited to any particular aspect or feature or combination thereof, and no disclosed embodiment is required to have any one or more specific advantages or to solve any particular or all technical problems.

Claims

1. An aircraft fuel pressure indication system, characterized in that, include: A fuel pressure measuring device installed inside the aircraft's fuel tank, the fuel pressure measuring device including a mechanical interface, an electrical interface, and a capacitive pressure sensor, the fuel pressure measuring device being mounted on a rib plate on the inner wall of the fuel tank via a bracket; A pressure-sensing line, the first end of which is located at the fuel pump outlet of the fuel tank or on the fuel cut-off valve, and the second end of which is connected to the mechanical interface of the fuel pressure measuring device, for transmitting fuel from the fuel pump outlet or the fuel cut-off valve to the fuel pressure measuring device; as well as A fuel pressure measurement cable, which connects to the electrical interface of the fuel pressure measurement device and passes through the wall of the fuel tank, is used to transmit the fuel pressure signal measured by the capacitive pressure sensor of the fuel pressure measurement device to a fuel signal processor located outside the fuel tank. The fuel pressure measuring device is located above the pressure tapping line, and the electrical interface is higher than the mechanical interface and the pressure tapping line.

2. The aircraft fuel pressure indication system as described in claim 1, characterized in that, The mechanical interface includes a pipe thread interface for adapting and connecting to the pressure-feeding pipe.

3. The aircraft fuel pressure indication system as described in claim 1, characterized in that, The fuel pressure measuring cable passes through the frame hole on the fuel tank to reach the outside of the fuel tank.

4. The aircraft fuel pressure indication system as described in claim 3, characterized in that, The fuel pressure measuring cable and the fuel quantity measuring cable share the same through-frame hole.

5. The aircraft fuel pressure indication system as described in claim 1, characterized in that, The fuel pressure measurement cable includes an excitation cable and a feedback cable for the capacitive pressure sensor.

6. The aircraft fuel pressure indication system as described in claim 1, characterized in that, The fuel signal processor includes a fuel remote data concentrator (FRDC), which converts the fuel pressure signal measured by the capacitive pressure sensor from an analog quantity to a digital quantity, and transmits the digital fuel pressure signal to the fuel quality computer (FQC). The fuel quality computer determines that the measured fuel pressure signal is a high-pressure / low-pressure discrete quantity.

7. The aircraft fuel pressure indication system as described in claim 6, characterized in that, The fuel computer sends the high / low pressure discrete values ​​of the fuel pump to the avionics system.

8. The aircraft fuel pressure indication system as described in claim 6, characterized in that, The fuel computer determines the high / low pressure discrepancy of the fuel cut-off valve and determines whether the fuel pressure of the fuel cut-off valve is normal based on the high / low pressure discrepancy. If the fuel pressure of the fuel cut-off valve is abnormal, the FQC generates a fuel alarm signal and provides the fuel filling / discharging control panel (RDCP) to the fuel filling / discharging control panel.

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