Lightning protection of digital automatic control system of aircraft engine with composite nacelle

Abstract

FIELD: lightning protection of a gas turbine engine.SUBSTANCE: lightning protection of the digital automatic control system of an aircraft engine (1) includes standard metallization jumpers, with the help of which the body of the electronic regulator (2) of the engine is connected through metallization terminals to the body of the engine. The design of each channel of the electronic engine controller (2) contains built-in protection against impulse surge voltages induced by lightning in the electrical communication lines of the electronic controller (2). The electronic controller (2) contains electrical connectors that ensure the attenuation of electromagnetic influence on the electrical communication lines of the electronic controller.EFFECT: reliability and efficiency of the digital system are increased.4 cl, 6 dwg

Description

[0001] The invention relates to aircraft engine building and can be used to protect the electronic digital automatic control system of a gas turbine engine (GTE) from the effects of lightning, static electricity, and electrical switching interference.

[0002] As is well known, a direct lightning strike on an aircraft causes an electric current of up to 200,000 amperes or more to flow through its structural elements, which can cause instantaneous heating and a through-flashover of the aircraft's airframe, resulting in the failure of electronic and radio equipment. Furthermore, a lightning strike generates a strong electromagnetic field and subsequently induces voltages in the onboard electrical wiring, which can lead to the failure of the digital engine control system and, consequently, to a change in jet thrust. Therefore, according to airworthiness regulations, all transport aircraft must have lightning protection to prevent emergency and catastrophic situations.

[0003] The problem of lightning resistance and electromagnetic interference immunity of digital aircraft engine control systems is complicated by the widespread use of polymer composite material (PCM) nacelles in modern turbomachines. In some designs, lightning protection for these nacelles is provided by perforated foils or expanded metal meshes. A characteristic feature of such meshes is a high percentage of open area, which can reach values ​​of approximately 84%. This reduces the electromagnetic interference immunity of the power plant when exposed to external electromagnetic pulses from lightning strikes or high-intensity external electromagnetic fields (L / HIRF – Lightning / High-intensity Radiated Field) from radio transmitters, radars, and other electronic equipment.

[0004] Lightning resistance and electromagnetic interference immunity are especially important for turbomachines in which the electronic engine governor (EGV) is mounted directly on the engine's outer casing beneath the composite nacelle, and the EEG itself is the primary component of a fully automatic electronic control system (FADEC). Failure of such an EEG, which lacks a backup hydromechanical governor, effectively results in engine shutdown in flight.

[0005] In connection with the above, lightning protection of an electronic digital automatic control system of an aircraft engine with a composite nacelle is a substantial technical problem and is the subject of the present invention.

[0006] A device for active protection of an aircraft against lightning strike is known (RU 2395434, IPC B64D 45 / 00, published on 27.07.2010), comprising a lightning rod made in the form of a target - a lightning rod or a group of lightning rods built into the aircraft body and providing attraction of a lightning charge due to local ionization of air. There is also an electric resonant LC filter, the input of which is connected to the output of the lightning rod or the common output of the group of lightning rods, and the output is connected to ground on the aircraft body. The electric resonant LC filter consists of a capacitor and a choke. The choke is made with a low-impedance winding, a diode bridge is connected in parallel to its output, the diagonal of which includes a high-capacity capacitor - an energy storage device for lightning charges.

[0007] The main disadvantages of this alternative include the complexity of the design and reduced efficiency of the LC filter at lightning pulse frequencies that differ from the filter settings. Furthermore, the implementation of this alternative increases the engine's weight, compromises the integrity (strength) of the engine nacelle, and creates flow turbulence due to the location of the target—the lightning rod or group of targets—on the outer edge of the engine nacelle.

[0008] Methods and systems for active protection against lightning strikes on aircraft are known, according to a patent (US 10457413 (B2) - 2019-10-29). The protection system comprises a sensor for measuring the electric field strength E near the aircraft, a capacitor charged by the charge induced by a thunderstorm front, and a processor interacting with the sensor. Based on information from the sensor indicating that the electric field strength E or its derivative E meets a threshold value, a signal from the processor automatically discharges the capacitor to generate a high-voltage pulse (streamer) from the aircraft. The polarity of the pulse is opposite to that of the thunderstorm front. The counter-pulse is directed to connect with lightning far from the aircraft.

[0009] The patent's drawbacks include its complexity and the need to develop a specialized, autonomous digital system. There are risks of system ineffectiveness during an intercepted lightning strike, when the aircraft's flight path already intersects with existing lightning; or during dynamic events during multiple direct or glancing strikes on the engine nacelle. Furthermore, the presence of a trigger electrode on the nacelle in the direct strike zone may negatively impact airflow conditions, as the trigger electrode effectively acts as a flow turbulator.

[0010] A gas turbine engine with lightning protection is known (US10549865 (B2) - 2020-02-04). The engine design includes a conductive rod that passes through the outer casing of the engine directly into the engine path, wherein the first end of the conductive rod is electrically connected to the engine shaft, and the second end of the conductive rod is electrically connected to at least one mounting pad (engine mounting pylon). Thus, lightning protection is ensured by routing the lightning current along the conductive rod, bypassing the rotating elements of the bearings located on the engine shaft, or by distributing the lightning current among several bearings simultaneously. In addition, routing the lightning current is ensured, bypassing the digital engine control system.

[0011] The disadvantages of the analogue include its inability to counter the effects of electromagnetic fields in the electrical communication lines of a digital FADEC type system, including the on-board +28 V power lines.

[0012] A lightning protection device is known for an electronic unit installed under an aerodynamic fairing of an aircraft according to the application (US2011 / 0259999 (A1) 10 / 27 / 2011).

[0013] The device comprises an electrically conductive mounting plate located on the outer side of the aerodynamic fairing's carbon fiber panel. The device also has an electrically conductive backplate located on the inner side of the carbon fiber panel and electrically connected to the mounting plate. A first set of fasteners (screws) for the electronic unit connects the unit to the backplate. Electrical current generated by a lightning strike is conducted with low resistance from the electronic unit through the backplate and mounting plate to the aircraft body.

[0014] From the description of the invention, it follows that on the top sheet of the carbon fiber panel of the aerodynamic fairing, it is possible to place a metal wire mesh, for example, made of bronze, or metal foil to protect the panel from the effects of a direct lightning strike or induced electromagnetic field.

[0015] The main disadvantage of the analog is that lightning protection of the electronic unit and its electrical wiring from lightning-induced overvoltages U in the electrical communication lines of the electronic unit is not shown.

[0016] A number of patents related to the protection of electronic aviation devices from lightning-induced surges are taken into account (GB 2484737 (A) ― 2012-04-25, EP 232 6005 (A1) -2011-05-25, US 8922961 (B2) - 2014-12-30, US 11095113 (B2) -2021-08-17). However, these methods and devices are quite complex, require the use of high-speed switching equipment, solid-state power controllers, which can lead to a significant increase in cost, while in some cases short-term equipment shutdowns are allowed, which is not always acceptable for aircraft engine thrust control systems. Another drawback of such patents is the lack of data on the level of parried impulse interference U.

[0017] The above review of the state of the art demonstrates that existing active lightning protection systems for aircraft can be ineffective for digital automatic control systems of turbomachinery, while passive lightning protection systems are often very limited in scope and aimed at eliminating specific lightning impacts. Therefore, for practical use in modern turbomachinery, lightning protection for digital automatic control systems must be comprehensive and multifunctional.

[0018] The prototype chosen was the lightning protection system for the electronic automatic control system of the PS-90A aircraft engine, equipped with a nacelle whose movable cowl flaps and thrust reverser components are made of polymer composite materials. This lightning protection system protects the dual-channel RED-90 type electronic governor from direct lightning strikes using a solid metal air intake fairing (an aluminum alloy nacelle component). Furthermore, the electronic governor housing itself is also made of aluminum alloy and is electrically connected to the engine housing via a metallization terminal using a single standard metallization jumper in accordance with OST 1 11303-73.The electronic governor's electrical communication lines are made of BIFEZ cables, consisting of two or three BIF-type wires twisted together at 30-40 mm pitch and enclosed in a shielding braid that protects the communication lines from external electromagnetic influences and provides a protective sheath against mechanical damage. Low-voltage wiring harnesses are routed separately from the power harnesses and high-voltage lines. The low-voltage wiring of the electronic engine governor, part of the electronic automatic control system, is connected to sensors, units, components, and aircraft electronic devices using electrical connectors such as the SNC23 and other connectors.

[0019] During flight, the electronic governor's integrated control system continuously monitors the operation of the electronic automatic control system (primary automation) and, in the event of a lightning strike that results in the failure of both channels of the electronic governor, can disconnect the electronic governor from the control circuit, switching to the backup hydromechanical automation. If the lightning strike does not result in the complete inoperability of the electronic governor, the pilot can restore engine control from the primary automation by switching the +27 V power supply to the electronic governor ("Aircraft Engine PS-90A" edited by A.A. Inozemtsev, Moscow, Libra-K, 2007, pp. 197-198, p. 300). In addition, the engine casing is securely connected to the aircraft's metallization, through which electrical dischargers (lightning rods) ensure the discharge of induced electrical charges into the atmosphere.

[0020] The disadvantages of the prototype include:

[0021] 1. Risk of abnormal changes in engine operating mode. Lightning-induced high-voltage pulses can penetrate the electronic governor, causing failure of its power supply components and / or digital microprocessors. Such interference can also be transmitted to the electronic governor via power lines, sensor wiring, alarms, and / or actuator circuits, causing failure of the governor's input / output modules and / or unauthorized changes in engine operating mode.

[0022] 2. Increased risk of electronic governor failure in the event of a direct lightning strike. This deficiency is due to the RED-90 unit being located near the air intake, i.e., in the maximum lightning hazard zone 1A. If struck by lightning with a high or exceeding the standard electromagnetic field, this could result in complete failure of the electronic governor in flight.

[0023] 3. Increased weight and dimensions of the electronic controller due to the use of large-sized electronic components for protection against external electrical influences in the power supply and input / output boards of the electronic controller.

[0024] 4. Reduced reliability of the metallization of the electronic regulator using only one metallization terminal and one standard metallization jumper.

[0025] 5. Insufficient noise immunity of the electrical communication lines of the electronic controller.

[0026] The technical problem, the solution of which is provided by the implementation of the proposed invention, and which cannot be ensured by using the prototype, is the insufficient fault tolerance of the operation of the digital automatic control system of an aircraft engine when exposed to transient processes caused by lightning, as well as during direct lightning strikes on an engine equipped with a composite nacelle with a non-continuous lightning protection coating.

[0027] The technical objective of the proposed invention is to ensure reliable and efficient operation of a digital automatic control system for an aircraft engine by increasing the fault tolerance and noise immunity of the electronic controller included in the digital automatic control system for an aircraft engine when lightning strikes the aircraft and its power plants.

[0028] The technical problem is solved due to the fact that lightning protection of the digital automatic control system of an aircraft engine equipped with a nacelle made of polymer composite materials, providing that the body of the electronic regulator with a two-channel structure is made of a metal alloy and is electrically connected to the engine body through a metallization terminal using a standard metallization jumper, the electrical communication lines of the electronic regulator are made of shielded twisted (with a certain pitch) pairs of wires placed in a common shielding braid, while the electrical communication lines of the electronic regulator are connected with sensors, blocks and units of the aircraft engine, other on-board electronic devices using electrical connectors, according to the invention, in the design of each channel of the electronic engine regulator, a built-in protection against impulse overvoltage U is additionally introduced,induced by lightning in the electrical communication lines of the electronic controller, in addition, the electronic controller is placed on the engine housing outside the maximum lightning hazard zone; in addition, a second metallization terminal and a second metallization jumper are additionally introduced into the design of the electronic controller, connecting the housing of the electronic controller to the engine housing; in addition, electrical connectors are introduced into the design of the electronic controller, ensuring the attenuation of the electromagnetic impact on electrical communication lines by an amount from 65 to 90 dB in the frequency range from 100 to 1000 MHz.

[0029] The present invention also provides that the built-in protection against surge voltage introduced into the design of each channel of the electronic regulator is a complex of semiconductor voltage limiters up to 70 kW in the power supply unit of each channel of the electronic regulator, a complex of filters-limiters of current and voltage levels of signals arriving at the input converters of each channel of the electronic regulator and a complex of power limiters of voltages up to 5 kW arising in the electrical communication lines of the output converters of each channel of the electronic regulator with the actuators of the digital automatic control system, wherein the common wires of the filters-limiters, the power supplies of each channel of the electronic regulator are combined with the corresponding metallization terminal connected to the motor housing through the corresponding metallization jumper.

[0030] In addition, the total contact resistance between the body of the electronic engine controller and the body of the engine itself is no more than 1000 μOhm due to the use of two standard metallization jumpers according to OST 1 11303-73.

[0031] Furthermore, sealed connectors of the SNC156 type are used as electrical connectors, allowing for direct mounting on a printed circuit board. This design solution allows for a compact layout of communication lines on the printed circuit board, divided into modules, which in turn reduces the size and weight of the electronic controller.

[0032] In addition, the built-in protection introduced into the design of the electronic motor controller ensures trouble-free operation of the electronic controller when exposed to a lightning-induced surge voltage U up to 1500...1700 V.

[0033] Fig. 1 shows a general view of the engine with the main elements of the digital automatic control system. Category of the area for placing the electronic engine controller on the engine.

[0034] Fig. 2 shows a block diagram of a digital ACS.

[0035] Fig. 3 shows the principles of lightning protection of the electronic controller.

[0036] Fig. 4 shows the locations of the metallization terminals on the electronic regulator body.

[0037] Fig. 5 shows the flow of currents from the induced voltage from the electronic regulator housing to the engine housing. through the first metallization terminal.

[0038] Fig. 6 shows the flow of currents from the induced voltage from the electronic regulator housing to the engine housing. through the second metallization terminal.

[0039] Figure 1 shows a general view of the engine with the main components of the digital automatic control system. To better understand the approximate placement of the digital control system components on the engine body, the right movable nacelle door is not shown. Figure 1 also shows pre-determined experimental lightning hazard zones 1A and 1C, according to aviation regulations and airworthiness standards.

[0040] Aircraft Engine 1 – Any known type of aircraft gas turbine engine. However, the use of a high-bypass turbofan engine (HBJT) is preferred, as it is the most modern and commercially successful type of gas turbine engine for subsonic mainline aviation.

[0041] Aircraft engine 1 is equipped with a polymer composite nacelle with a lightning-proof coating.

[0042] Typically, an aircraft engine nacelle consists of four main components: the air intake, the nacelle cowlings, the thrust reverser, and the outer nozzle. The thrust reverser can be combined with the outer nozzle.

[0043] Various metal meshes, perforated foils made of copper, aluminum, and other metals and alloys can be used as the conductive layer of the nacelle's lightning protection coating. Typically, the lightning protection layer is connected to the engine / aircraft metallization with a minimum (standardized) contact resistance value in accordance with aviation regulations and airworthiness standards. The lightning protection coating of engine nacelle 1 can be implemented, for example, according to patent type RU 2842497, IPC B32B 7 / 025, B32B 27 / 38, B32B 15 / 092, H05F 1 / 02, published 06 / 27 / 2025.

[0044] Also, in accordance with the requirements of OST 1 00738 “Metalization of engines”, all metal parts of the engine structure, as well as fuel and oil pipelines, fuel supply and ignition units, shielding surfaces of wires and devices, etc., are subjected to metallization of engine 1.

[0045] The composition of the engine nacelle's lightning protection coating and the metallization scheme for the engine's pipelines and components are not the subject of the invention. Those skilled in the art understand that these can be of various designs, subject to compliance with aircraft manufacturer requirements and airworthiness standards.

[0046] Electronic engine governor 2 is the central device of the FADEC (Full Authority Digital Engine Control system) digital engine control system.

[0047] Functionally, the electronic engine controller, in Anglo-Saxon terminology referred to as the EEC - Electronic Engine Control or ECU - Electronic Control Unit, provides full engine control, starting from starting, maintaining the engine's operating modes and ending with its shutdown.

[0048] Electronic controller 2 is a specialized two-channel digital computer equipped with input / output devices for receiving input information and generating control and information signals according to specified operating algorithms to ensure the required level of thrust and fuel efficiency of the gas turbine engine.

[0049] Engine experts understand that the electronic governor of a modern dual-circuit engine interacts with a significantly larger number of electrical sensors. Specifically, the electronic governor, using its input converters, receives and processes signals from sensors for parameters such as temperature and air inlet pressure (Tvh). * and Rvh * , position of the compressor inlet guide vane L вна , air pressure behind the compressor Рк * , temperature of gases behind the turbine Tt, rotation speed of the fan rotor n в and the rotation frequency of the high-pressure rotor n вд , position of the engine control lever L руд and others.

[0050] Based on input information and in accordance with specified operating algorithms, electronic controller 2 generates control signals for the fuel-regulating equipment, such as fuel dispenser 3, to create the desired operating mode of gas turbine engine 1, including its jet thrust and fuel consumption Gt. The total number of output control commands from electronic controller 2 may exceed 20 units.

[0051] The electronic controller receives and transmits digital code information in digital code in accordance with GOST 18977-79, RTM 1495-75 with amendment 3 or its Western equivalent ARINC-429.

[0052] For reliability, the electronic controller 2 includes at least two control channels identical in function and structure – the main channel 2.1 and the backup channel 2.2. Typically, the main channel 2.1 of the electronic controller controls the engine, while the other – the backup channel (2.2) – is in a loaded reserve, i.e., electrically powered, performs the necessary calculations, but does not send control signals to the actuators of the automatic control system.

[0053] Typically, for reliable operation of a dual-channel electronic regulator, a double set of sensors (one set per regulator channel) and / or sensors with duplicated sensitive elements are used.

[0054] Electronic controller 2 has a built-in control system that provides protection against a number of failures that may occur when lightning strikes the sensors, actuators, and their communication lines.

[0055] A distinctive design feature of the 2-channel electronic regulator is the built-in protection against lightning-induced surge voltages (U) in each channel. The regulator's resistance to lightning-induced transients complies with Category B4 of Section 22.0 of KT-160G, meaning that reliable operation of the electronic regulator is ensured in accordance with the specified requirements at a maximum surge voltage (U) of up to 1500 V.

[0056] Additional protection against induced voltages is provided by the presence of two metallization terminals and two metallization jumpers connecting the body of the electronic regulator and its internal components with the motor body, and ensuring the total transition resistance of the metallization of the regulator body with the motor body of no more than 1000 μOhm and the use of noise-proof, sealed electrical connectors of the SNC156 type in the electronic regulator.

[0057] The locations of the metallization terminals on the electronic regulator body are shown in Figure 4. The flow of static currents from the induced voltage through the metallization jumpers is demonstrated in Figures 5 and 6.

[0058] Protection of the input electrical circuits of the electronic regulator power supply is provided by power semiconductor voltage limiters up to 70 kW.

[0059] Protection of the input converters of the electronic regulator is provided by voltage limiting filters up to 10 V, including resistors, capacitors and zener diodes.

[0060] Protection of the output converters of the electronic regulator is provided by power (up to 5 kW) semiconductor voltage limiters, including limiters integrated into the control modules of power discrete output signals.

[0061] All electronic components of the filter-limiters used are of Russian production (commercially produced resistors, capacitors, diodes, zener diodes).

[0062] Surge protectors (in combination with communication line screens) reduce the magnitude of lightning-induced voltage pulses to a level safe for input converters (10 V).

[0063] The applied types of power (semiconductor) voltage limiters are Russian-made, specifically designed for the PD-14 electronic engine regulator: the KR243A and KR1204A9 limiters, and the unpackaged limiter for the M16-5-1 power modules. The internal electrical circuit of the KR and M16 limiters is not the subject of this invention.

[0064] The limiters ensure the reduction of the magnitude of voltage pulses caused by lightning to a level safe for the protected elements of the regulator (16 V for information exchange channels, 100 V for output discrete signal generators and the power supply), thereby preventing their damage.

[0065] Integration of limiters into discrete output signal control modules provides a significant (up to 2 times) reduction in the volume occupied by the limiters and, accordingly, their total weight due to the large number of discrete output signals - more than 20 in each channel of the electronic controller.

[0066] The common wires of the filter-limiters, power supplies of both channels of the electronic regulator are combined with two metallization terminals connected to the engine body through two standard metallization jumpers in order to ensure a single potential in the regulator.

[0067] Thus, the present invention provides protection of the electronic engine controller from the possible penetration of electrical interference of varying power, caused by lightning, along all electrical communication lines of the electronic controller, namely:

[0068] - via +28 volt power supply lines of the electronic regulator;

[0069] - via communication lines that ensure the transmission of output signals from sensors to the electronic controller (to its input converters),

[0070] - via communication lines that provide reception of information from on-board systems (in digital code) to the electronic controller;

[0071] - via communication lines that ensure the transmission of output control actions of the electronic controller to the actuators of the digital ACS (to dispenser 3) and its output information signals to the on-board systems (in digital code).

[0072] The block diagram of the digital control system, including a two-channel electronic controller 2, is shown in Fig. 2. The principles of lightning protection of the electronic controller 2 are illustrated in Fig. 3.

[0073] According to the results of high-voltage tests of the aircraft model For the MS-21 engine nacelle, lightning-struck zones were identified. Statistics established that the initial strike area of ​​the lightning leader, and therefore the most lightning-hazardous zone (1A), is the engine air intake area. This zone is characterized by lightning impact with a current of 200 kA and a transferred charge Q of 39 C, according to Section 23.0 of the "Qualification Requirements of the Interstate Aviation Committee KT-160G. Operating and Environmental Conditions for Onboard Aviation Equipment." According to the invention, electronic controller 2 is located outside the most lightning-hazardous zone (1A), and specifically, the controller is placed in lightning-hazardous zone (1C), where there is a high probability of displacement of a subsequent low-amplitude return lightning strike and a low probability of channel binding. This technical solution is illustrated in Fig. 1.

[0074] Block 3 – Fuel Meter. This hydromechanical fuel metering unit ensures the required fuel flow rate G т Into the combustion chamber of gas turbine engine 1 via a control electrical signal from electronic regulator 2. Unit 3 is referred to in Western literature as a fuel metering unit (FMU) or a hydromechanical unit (HMU). Unit 3 is designed to control the position of the compressor's inlet guide vane (IGV) blades. However, experts know that compressor mechanization, and the IGV in particular, can be controlled using pneumatic control and / or an electric drive.

[0075] Electrical communication lines 4 - engine wiring that provides electrical communication of the electronic governor 2 with the sensors, units and assemblies of the engine 1, as well as with aircraft electronic devices, for example, with the thrust control computer system, the integrated engine parameter signaling system in the cockpit (not shown).

[0076] The advantages of the digital engine control system wiring harness design 1 compared to the prototype include its high noise immunity and lightning resistance. The wiring harnesses for engine 1 utilize electrical connectors with a high noise immunity level of 65 to 90 dB in the frequency range of 100 to 1000 MHz.

[0077] The best implementation of noise immunity of electrical connectors is the use of sealed electrical connectors of domestic production type SNC156.

[0078] Thus, the electric charge generated on the interference-protective sheath of electrical communication lines as a result of induced voltage from lightning current flowing through the engine housings and nacelle flows through interference-resistant electrical connectors to the electronic unit housings and further to the engine housing thanks to metallization jumpers in accordance with OST 1 11303-73, made of tinned copper braid with an electrical resistance of less than 2000 μOhm. For the electronic engine governor—a critical electronic unit of a digital FADEC system—two metallization jumpers are used (installed) through two metallization terminals located on opposite sides of the electronic unit to ensure redundancy and improve the reliability of static charge removal from the electronic governor housing. The locations of the metallization terminals on the electronic governor housing are shown in Figure 4.

[0079] The flow of static currents from induced voltage from the housing of the electronic unit of a digital FADEC system through the metallization jumpers is shown in Figures 5 and 6.

[0080] As in the prototype, the low-voltage wiring of the electronic regulator 2 is laid separately from the power harnesses and high-voltage lines of the engine 1.

[0081] Thus, the claimed invention actually implements a two-stage circuit for suppressing induced voltage from an external electromagnetic field, the first stage being the attenuation of interference in the electrical wiring, the second stage being the final suppression of interference in the input-output devices of the electronic engine controller.

[0082] It should be emphasized that this technical solution also reliably protects the electronic engine controller from the effects of static electricity, as well as from the effects of electrical switching interference that occurs when high-current loads or powerful electric generators located on the engine drive box are turned on or off.

[0083] The claimed invention is implemented in the automatic control and fuel supply system of the advanced PD-14 aircraft engine developed by UEC-Aviadvigatel JSC, Russian Federation. The functional operability of the claimed invention was successfully verified on an MS-21 long-haul aircraft during ground high-voltage tests simulating the indirect effects of lightning. The engine's electronic governor was also successfully tested for lightning resistance in accordance with Section 22.0 of the "Qualification Requirements of the Interstate Aviation Committee KT-160G. Operating and Environmental Conditions for Onboard Aviation Equipment." The electronic governor's test results yielded no comments, including those obtained under the influence of voltage pulses in communication and power lines up to 1500 volts.

[0084] The reliability and resistance of the claimed lightning protection method to the impact of climatic factors, various force and thermal effects, has also been successfully confirmed as part of an aircraft engine of the PD-14 type under the conditions of bench tests and flights of MS-21 aircraft.

[0085] The proposed invention with the above-mentioned distinctive features and in combination with known features makes it possible to reliably ensure lightning resistance of the digital automatic control system of an aircraft engine with a nacelle made of polymer composite materials in accordance with the requirements of aviation regulations AP-25, qualification requirements KT-160G.

Claims

1. Lightning protection for a digital automatic control system of an aircraft engine equipped with a nacelle made of polymer composite materials, which provides that the housing of an electronic engine controller containing at least two control channels is made of a metal alloy and is electrically connected through a first metallization terminal to the engine housing using a first standard metallization jumper, the electrical communication lines of the electronic engine controller are made of shielded twisted wires twisted together with a certain pitch, in addition, the electrical communication lines of the electronic engine controller are connected with sensors, blocks and units of the engine, as well as on-board electronic devices using electrical connectors, characterized in that the design of each channel of the electronic engine controller additionally contains built-in protection against impulse overvoltage U,induced by lightning in the electrical communication lines of the electronic regulator, in addition, the electronic regulator is located on the engine housing outside the maximum lightning-hazardous zone, while the design of the electronic regulator additionally contains a second metallization terminal connecting the housing of the electronic regulator to the engine housing through a second metallization jumper, in addition, the design of the electronic regulator contains electrical connectors that ensure attenuation of the electromagnetic impact on the electrical communication lines of the electronic regulator by an amount from 65 to 90 dB in the frequency range from 100 to 1000 MHz.

2. Lightning protection of a digital automatic control system of an aircraft engine according to paragraph 1, characterized in that the built-in protection against impulse voltage surges is a set of semiconductor voltage limiters of up to 70 kW in the power supply unit of each channel of the electronic regulator, a set of filters and limiters of current and voltage levels of signals of up to 10 V, arriving at the input converters of each channel of the electronic regulator, and a set of power limiters of voltages of up to 5 kW, arising in the electrical communication lines of the output converters of each channel of the electronic regulator with the actuators of the digital automatic control system, wherein the common wires of the filters and limiters, the power supplies of each channel of the electronic regulator are combined with the corresponding metallization terminal, connected to the engine housing through the corresponding metallization jumper.

3. Lightning protection of a digital automatic control system of an aircraft engine according to paragraph 1, characterized in that the total contact resistance between the body of the electronic regulator and the body of the engine through two standard metallization jumpers does not exceed 1000 μOhm.

4. Lightning protection of a digital automatic control system of an aircraft engine according to paragraph 1, characterized in that interference-proof, sealed connectors СНЦ156 are used as electrical connectors.

Images