Cleaning and control method for microorganisms in aircraft integral fuel tank, and cleaning device

Abstract

A cleaning and control method for microorganisms in an aircraft integral fuel tank. The method comprises: step 1: preparation before cleaning: discharging residual fuel in an integral fuel tank of an aircraft of this model, ventilating and exhausting the fuel tank, and enabling cleaning personnel to enter the fuel tank to remove a system pipeline in the fuel tank; step 2: inspection and troubleshooting before cleaning: before fuel tank cleaning, visually inspecting whether microorganisms and corrosion are present in the fuel tank structure, after fuel tank inspection, removing microorganisms and surface attachments, and inspecting and processing the removed pipeline in the fuel tank; step 3: cleaning of the integral fuel tank and the removed pipeline; step 4: restoration and installation of the removed pipeline in the integral fuel tank; and step 5: monitoring and prevention of fuel microorganisms in the fuel tank. In addition, a cleaning device using the method is further comprised. The technical solution is used to solve the problem of cleaning and controlling microorganisms bred in an integral fuel tank of a platform aircraft of a certain model.

Description

A method and device for cleaning and controlling microorganisms in an aircraft integral fuel tank Technical Field

[0001] The invention belongs to the field of aviation manufacturing technology assembly, and relates to a method and a cleaning device for cleaning and controlling microorganisms of an integral fuel tank of an aircraft. Background Art

[0002] A certain platform aircraft with an integral fuel tank structure repeatedly developed white flocculent microorganisms in the fuel within the tanks, exposed to the high temperatures, rain, and humidity of tropical oceans. Testing revealed these microorganisms to be a mixture of Burkholderia cepacia, Penicillium citrinum, Paecilomyces variotii, and Pseudomonas aeruginosa. These flocculent microorganisms continued to multiply and accumulate, drifting and spreading within the fuel flow. This caused blockage of the aircraft's oil filters and adhered to the fuel level and dielectric constant sensors within the tanks, triggering repeated alarms from the aircraft's EICAS system. This posed a significant risk to flight safety. Despite a simple cleanup of the tanks, the microorganisms reappeared within a week, with the clusters recurring.

[0003] Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for cleaning and controlling microorganisms in an integral fuel tank of an aircraft, which are used to remove and control the problem of microorganisms growing in the integral fuel tank of a certain type of platform aircraft.

[0005] Technical Solution

[0006] A method for cleaning and controlling microorganisms in an integral fuel tank of an aircraft, used for cleaning and controlling microorganisms in an integral fuel tank of a certain type of aircraft, comprises the following steps:

[0007] Step 1: Preparation before cleaning: drain the remaining oil in the overall fuel tank of the aircraft, ventilate the fuel tank, and the cleaning personnel enter the fuel tank and remove the system pipelines in the fuel tank;

[0008] Step 2: Inspection and troubleshooting before cleaning. Before cleaning the fuel tank, visually inspect the tank structure for microorganisms and corrosion. After inspection, remove microorganisms and surface attachments. At the same time, inspect and handle the removed pipes in the tank.

[0009] Step 3: Carry out relevant cleaning on the entire fuel tank and removed pipelines;

[0010] Step 4: Reinstall the pipelines removed from the overall fuel tank;

[0011] Step 5: Monitor and prevent fuel microorganisms in the fuel tank.

[0012] Furthermore, step one specifically includes the following steps:

[0013] 1.1) Drain the fuel from the wing's integral fuel tank and the corresponding fuel lines;

[0014] 1.2) Open the maintenance cover on the lower wing and visually inspect the remaining oil near the wing integral fuel tank opening frame. If there is excessive oil, remove it with an oil-absorbing sponge or fine flat cloth and ventilate to remove odors.

[0015] 1.3) After ensuring that the fuel tank is dry, personnel entering the tank for operation shall wear anti-static clothing and equipment. If the odor is strong, they shall use gas masks and carry explosion-proof lighting equipment when entering the tank.

[0016] 1.4) Remove the oil tank supply system accessories that are contaminated by microorganisms, including conduits, finished products, joints and seals, and keep records of the removed accessories.

[0017] Furthermore, in step 2, the fuel tank is inspected before cleaning and the fuel system pipeline is inspected before cleaning.

[0018] Before cleaning the entire tank, visually inspect the tank structure and check the surface coatings, bolts, and sealants of the structural parts in the following manner to check for microorganisms and corrosion. The inspection steps are as follows. The comparison of the inspection damage characteristics is shown in Table 1.

[0019] 2.1) Check the sealant in the overlapped area of ​​the inner surface of the upper wall panel of the fuel tank, and check whether there are any conditions shown in Table 1;

[0020] 2.2) Check the front and rear beams of the fuel tank, focusing on the upper and lower inner wall panels and the butt ribs, bolts and sealants at both ends to check for any of the conditions listed in Table 1.

[0021] 2.3) Check the upper and lower flanges, butt seam areas and rib webs of the two butt ribs of the fuel tank to see if any of the conditions listed in Table 1 exist;

[0022] 2.4) Check the inner surface of the lower wall of the fuel tank, focusing on the area around the fuel system accessories, the pollutant deposition area, and the wall overlap area

[0023] domain, etc., check whether the various conditions shown in Table 1 exist;

[0024] Table 1 Comparison table of microbial damage characteristics

[0025] The fuel system piping pre-cleaning inspection includes the following steps:

[0026] 1) Visually inspect the connections and surfaces of the removed fuel system's supply and delivery pipes, joints, seals, and finished products. Clean the pipes, joints, seals, and finished products whose connections do not affect secondary connections and whose surface coatings are not damaged;

[0027] 2) Visually inspect the outer surface of the ventilation system in the fuel tank and the pressure refueling system pipelines. If there are any microbial residues or other impurities, 100% of the pipelines should be cleaned;

[0028] 3) Remove the cables of the main finished products of the fuel system, including the separation of the cables from the finished products, including the separation of the cable plugs and sockets.

[0029] Furthermore, in step 2, the troubleshooting before cleaning includes troubleshooting the entire fuel tank, troubleshooting the fuel system pipeline,

[0030] The specific troubleshooting of the entire fuel tank is as follows: After the entire fuel tank is inspected and microorganisms and surface attachments are removed, if the damage characteristics shown in Table 1 above are found, the following treatment is performed:

[0031] 1) If the coating on the fuel tank surface is damaged, polish the damaged area and apply HY-200 oxidation liquid manually, then spray or brush a layer of S06-1010H polyurethane primer;

[0032] 2) If the rubber caps of bolts or other standard parts are damaged, remove the rubber caps and apply NJD-4 bonding primer first, then apply XM22B sealant or apply the sealing caps;

[0033] 3) If the sealant is damaged, remove the damaged area, apply NJD-4 bonding primer first, and then apply XM22B sealant or apply sealing cap;

[0034] The troubleshooting method for fuel system pipeline is as follows:

[0035] 1) Remanufacture the cables, conduits, connectors, seals and accessories that are found to be damaged;

[0036] 2) For any microbial residue or other impurities in the pipes that are not removed, wipe the surface with 180# aviation washing gasoline.

[0037] Furthermore, step three includes initial and secondary cleaning of the fuel tank and cleaning of the fuel system lines;

[0038] The steps for initial fuel tank cleaning are as follows:

[0039] 1) The person entering the fuel tank for cleaning should use a clean white fine cloth dipped in aviation kerosene RP-3 to scrub the top, side walls, and bottom of the tank. After scrubbing, visually inspect the scrubbed area and any excess material using a 5x magnifying glass.

[0040] 2) After cleaning, use a ventilator to ventilate the oil tank and apply HM504 surface protection sealing paint evenly on the cleaned parts as required;

[0041] 3) After checking the fuel tank seal and cleanliness, open the faulty fuel tank cover, ventilate the tank, and close the cover to prevent dust and excess objects from entering the tank and maintain the tank's seal;

[0042] The secondary cleaning of the fuel tank is to disassemble the entire fuel tank to the ground, hoist it onto the cleaning device and fix it, and then perform secondary pressure cleaning on the fuel tank. The operation steps are as follows:

[0043] 1) Before the secondary cleaning of the entire fuel tank, check the cleaning equipment and fuel tank rack. Use process plugs to plug all pipes that are not connected. Use copper-plated or wooden tools to install pipes and covers. Use a cloth with sewn edges to wipe off oil stains and other liquid flow marks and spots on the fuel tank and cleaning device.

[0044] 2) Position and fix the entire oil tank on the cleaning device;

[0045] 3) First connect the pressure refueling hose to the cleaning hole on the integral fuel tank, then check whether the pressure refueling hose and the integral fuel tank connection are securely fixed, and fill the integral fuel tank with nitrogen through the pressure refueling hose, maintaining the nitrogen pressure at P = 0 ~ 0.1kg / cm2 for 30 minutes;

[0046] 4) Inject cleaning fuel into the integral fuel tank, the amount to be added is as per Table 2;

[0047] Table 2 Overall oil tank cleaning oil injection table

[0048] 5) Connect the entire fuel tank to the cleaning device, and use the cleaning device to shake and clean the entire tank at an angle of ±15° and a frequency of 1 to 2 cycles per minute. During cleaning, maintain the nitrogen pressure in the fuel tank at P = (0 to 0.1) kg / cm2. If the pressure is too low, continue to add nitrogen to the tank to increase the pressure. If the pressure is too high, stop supplying nitrogen and continue cleaning the tank for 2 hours. After 2 hours, release the cleaned fuel from the oil drain port and filter it through a white silk cloth for at least 10 minutes. Visually inspect with a 5x magnifying glass. If no excess material is found after two consecutive cycles of inspection, the entire tank is considered clean. If the tank cleanliness does not meet the requirements, re-clean it for 10 minutes and re-inspect it until it passes the inspection.

[0049] During the cleaning process, when the cleaning fuel temperature reaches 50°C, stop cleaning immediately and replace the cleaning fuel in the entire fuel tank with a lower temperature cleaning fuel;

[0050] 6) Drain the cleaning fuel in the fuel tank;

[0051] 7) Pass clean and dry air through the entire fuel tank for 2 hours to keep the tank dry. After the entire fuel tank is reinstalled and docked with the fuselage, close all maintenance covers, suspend the ultraviolet lamp in the tank, and turn on the light for 24 hours for secondary sterilization.

[0052] 8) When the lighting time is up, turn off and remove the ultraviolet lamp, place activated carbon in the integral fuel tank to keep the tank dry, and remove it before the integral fuel tank is activated.

[0053] The cleaning of the entire fuel tank system pipeline includes the following steps:

[0054] 1) Tie a white silk cloth with linen thread to the catheter to be cleaned, dip it in 180# aviation washing gasoline, and repeatedly pull and clean it. After cleaning, blow the catheter dry with clean and dry compressed air;

[0055] 2) Heat the cleaned catheter in an oven at 80°C to 100°C for 1 hour;

[0056] 3) Rinse the inner cavity of the catheter with warm water at 70℃ to 80℃, wipe the inner cavity with a dry white silk cloth, and blow the catheter dry again with clean and dry compressed air;

[0057] 4) Conduct a 100% visual inspection of the inner and outer surfaces of the baked conduits and connectors;

[0058] 5) After the visual inspection is passed, all catheters are physically inspected and surface protection is done: use white gauze to wrap the catheter end and surface to prevent excess objects or dust from entering;

[0059] 6) Clean the removed seals with alcohol to ensure that the inner and outer surfaces are clean and free of impurities. After cleaning, wrap them with clean fine canvas to prevent secondary contamination.

[0060] Furthermore, step four is specifically as follows: reinstall the cleaned system pipeline into the integral fuel tank, and conduct an airtightness check on the system pipeline. After the sealing test is qualified, fill the integral fuel tank with oil through the refueling switch on the integral fuel tank. After parking for three days, test the oil tightness of the integral fuel tank and sample and test the microbial content in the fuel.

[0061] Furthermore, in step 5, the monitoring steps for the fuel microorganisms in the entire fuel tank are as follows:

[0062] 1) Before or after the flight: In conjunction with the aircraft's pre-flight and post-flight waterproofing and sedimentation operations, visually inspect the fuel cleanliness. Run the fuel pump in the entire fuel tank for 3 minutes, then take a sample for observation. If a large amount of turbid fuel is present, perform a microbial test using a test reagent.

[0063] 2) Long-term parking: If the aircraft is parked for a long time, the fuel pump in the integral tank should be run for 3 minutes every 30 days, and then the entire fuel tank should be visually inspected for cleanliness. If the inspection passes, the inspection interval will be adjusted to 2 months. If the inspection still passes after 2 months, the inspection will be adjusted to every 3 months. If the inspection fails, the inspection will be submitted to a professional testing agency for IP385 / 99 quantitative analysis.

[0064] The preventive measures for fuel microorganisms in the integral fuel tank are as follows:

[0065] Before the flight and after refueling, open the upper maintenance cover of the integral fuel tank and add the microbial removal additive PRISTTM to the fuel.

[0066] A cleaning device using the method for cleaning and controlling microorganisms in an integral fuel tank of an aircraft includes a base 10, an eccentric wheel 11, an exciter 12, a motor 2, a shock absorber 3, a vibration frame 4, a docking plate 5, a support frame 6, an electric lift 7, a hanging steel cable 8, and a dynamometer 9. The electric lift 7 is installed on the top of the support frame 6, and the electric lift 7 is connected to the dynamometer 9 through the hanging steel cable 8. The dynamometer 9 is connected to the docking plate 5 through the hanging steel cable 8. The shock absorber 3 is arranged between the base 10 and the vibration frame 4, the motor 2 is arranged on one side of the eccentric wheel 11, the output shaft of the motor 2 is connected to the center of the eccentric wheel 11, and the motor 2 drives the eccentric wheel 11 to rotate. The exciter 12 passes through the wheel surface of the eccentric wheel 11 and is connected to the vibration frame 4. The exciter 12 can drive the vibration frame 4 to vibrate periodically. A docking plate 5 is provided on the vibration frame 4. The docking plate 5 on the vibration frame 4 and the docking plate 5 on the hanging steel cable 8 are used to connect the integral fuel tank 1.

[0067] Furthermore, a universal wheel and a fixed screw rod are provided at the bottom of the support frame 6. Beneficial effects:

[0068] The present invention provides a method and device for cleaning and controlling microorganisms in an integral fuel tank of an aircraft, which can completely remove microorganisms in the integral fuel tank of a certain type of platform aircraft. The method is safe, effective, clean and thorough, with significant results and no recurrence. It solves the problem of blockage of the oil filter in the aircraft duct system, and on the other hand, adhesion to the oil level and dielectric constant sensors inside the fuel tank, thereby triggering continuous alarms in the aircraft's EICAS system, which poses a great hidden danger and threat to the aircraft's flight safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 is a schematic diagram of the overall fuel tank structure of a certain type of platform aircraft;

[0070] Among them, 1.1-front beam, 1.2-upper wall plate, 1.3-lower wall plate, 1.4-center rib, 1.5-side rib, 1.6-connecting angle material with fuselage, 1.7-rear beam, 1.8-butt rib;

[0071] Figure 2 is a partial schematic diagram of the system piping inside the overall fuel tank of a certain model platform aircraft;

[0072] Among them, 2.1-platform aircraft overall fuel tank local structure; 2.2-system piping, 2.3-local system piping finished products and accessories;

[0073] Figure 3 is a diagram of a fuel tank cleaning device for a certain type of platform aircraft;

[0074] 1-Integrated fuel tank, 2-Electric motor, 3-Shock absorber, 4-Vibration frame, 5-Docking plate, 6-Support frame, 7-Electric lift, 8-Suspension cable, 9-Dynamometer, 10-Base, 11-Eccentric wheel, 12-Vibrator;

[0075] Figure 4 is a flowchart of secondary pressure cleaning of the integral fuel tank of a certain type of platform aircraft. DETAILED DESCRIPTION

[0076] The present invention is based on a certain model platform aircraft integral fuel tank microbial cleaning and control method described in detail with reference to the accompanying drawings:

[0077] Step 1: Preparation before cleaning, follow the following operating procedures:

[0078] 1) Drain the fuel from the wing's integral fuel tank and the corresponding fuel lines;

[0079] 2) Open the maintenance cover on the lower wing and visually inspect the remaining oil near the wing's integral fuel tank opening frame. If there is excessive oil, remove it with an oil-absorbing sponge or fine flat cloth and ventilate the area to remove any odor.

[0080] 3) After ensuring that the fuel tank is dry, personnel entering the tank for operation must wear clean cotton clothes, hats, rubber shoes and other anti-static items. When the odor is strong, they must wear a gas mask and carry explosion-proof lighting equipment when entering the tank;

[0081] 4) Remove the pipes, finished products, joints, seals and other accessories of the oil supply system of the oil tank where microbial contamination occurs, and keep records of the removed pipes and finished products;

[0082] 5) Entering the fuel tank is a high-altitude operation and the space inside the tank is narrow, and the construction environment is harsh. Therefore, special attention must be paid to personnel safety during the operation. While personnel are operating inside the tank, personnel must be arranged outside the tank to accompany and provide support.

[0083] Step 2: Inspection and treatment before cleaning should be carried out according to the following operating procedures:

[0084] Before cleaning the entire tank, visually inspect the tank structure. Check the surface coatings, bolts, and sealants on the structural components as follows to check for microbial damage and corrosion. The inspection details are as follows. See Table 1 for a comparison of damage characteristics.

[0085] 1) Check the sealant in the overlapping area of ​​the inner surface of the upper wall panel of the fuel tank, and check whether there are any conditions shown in Table 1;

[0086] 2) Check the front and rear beams of the fuel tank, focusing on the upper and lower inner wall panels and the butt ribs, bolts and sealants at both ends to see if any of the conditions listed in Table 1 exist;

[0087] 3) Check the upper and lower flanges, the butt joint area and the rib web of the two butt joint ribs of the fuel tank to see if there are any of the conditions shown in Table 1;

[0088] 4) Check the inner surface of the lower wall panel of the fuel tank, focusing on the area around the fuel system accessories, the pollutant deposition area, the wall panel overlap area, etc., to check whether the various conditions shown in Table 1 exist.

[0089] Table 3 Comparison table of microbial damage characteristics

[0090] After inspection and removal of microorganisms and surface deposits, if the damage characteristics shown in Table 1 above are found in the entire fuel tank, the following treatment shall be performed:

[0091] 1) If the surface coating is damaged, polish the damaged area and then apply HY-200 oxidation liquid (anti-oxidation solvent) manually, and then brush (spray) a layer of S06-1010H polyurethane primer (anti-rust primer).

[0092] 2) If the rubber caps of bolts or other standard parts are damaged, remove the rubber caps and apply NJD-4 bonding primer (to increase the adhesion of the sealant), and then apply XM22B sealant or inject the sealing caps.

[0093] 3) If the sealant is damaged, remove the damaged area, apply NJD-4 bonding primer first, and then apply XM22B sealant or apply sealing cap.

[0094] Check the fuel system pipelines as follows:

[0095] 1) Visually inspect the connections and surfaces of the removed fuel system's supply and delivery pipes, joints, seals, and finished products. Clean the pipes, joints, seals, and finished products whose connections do not affect secondary connections and whose surface coatings are not damaged;

[0096] 2) Visually inspect the outer surface of the ventilation system in the fuel tank and the pressure refueling system pipelines. If there are any microbial residues or other impurities, 100% of the pipelines should be cleaned;

[0097] 3) The cable separation measures for the dismantled fuel system main finished products mainly include separation of the cables from the finished products, and separation of the cable plugs from the sockets.

[0098] Treatment methods for fuel system pipelines after inspection according to the above methods:

[0099] 1) Remanufacture cables, conduits, connectors, seals, accessories, etc. that are found to be damaged;

[0100] 2) For any microbial residue or other impurities in the pipes that are not removed, wipe the surface with 180# aviation washing gasoline.

[0101] Step 3: Carry out relevant cleaning on the entire fuel tank and removed pipelines.

[0102] The steps for preliminary cleaning of the entire fuel tank are as follows:

[0103] 1) The person entering the fuel tank for cleaning should use a clean white fine cloth dipped in aviation kerosene RP-3 to scrub the top, side walls, and bottom of the tank. After scrubbing, visually inspect the scrubbed area and any excess material using a 5x magnifying glass.

[0104] 2) After cleaning, use a ventilator to ventilate the oil tank and apply HM504 surface protective anti-corrosion sealing paint evenly on the cleaned parts as required;

[0105] 3) After checking the fuel tank seal and cleanliness, open the faulty fuel tank cover, ventilate the tank, and close the cover to prevent dust and excess objects from entering the tank and maintain the tank's seal;

[0106] The steps for secondary pressure cleaning of the entire fuel tank are as follows:

[0107] After the entire fuel tank is disassembled to the ground and hoisted onto the cleaning test device (see Figure 3) and fixed, the tank is subjected to secondary pressure cleaning. The cleaning process is shown in Figure 4. The main operating steps are as follows:

[0108] 1) Before cleaning the entire tank, inspect the cleaning equipment and tank rack. Any disconnected pipes should be plugged with process plugs. Use copper-plated or wooden tools to install pipes and ports. Use a sewn-edge cloth to scrub oil stains and other fluid marks and spots from workpieces and process equipment.

[0109] 2) Position and fix the integral fuel tank on the test device.

[0110] 3) First, connect the cleaning accessory hose to the cleaning hole on the integral fuel tank. Then, check that the connection between the cleaning system and the integral fuel tank is secure. Once secure, turn on the alarm system and open the nitrogen supply valve. Fill the integral fuel tank with nitrogen, maintaining the nitrogen pressure at P = 0-0.1 kg / cm² for 30 minutes.

[0111] 4) Turn on the switch that supplies the cleaning system to the integral fuel tank and inject the cleaning fuel into the integral fuel tank. Refer to Table 2 for the amount to be added. During the filling process, the system connecting pipes must be closely monitored. If oil leaks occur, immediately turn off the fuel supply and stop refueling. Once the leak has been corrected, turn on the fuel supply and resume refueling.

[0112] Table 2 Overall oil tank cleaning oil injection table

[0113] 5) Connect the entire fuel tank to the docking plate (5) in the cleaning test device, and drive the entire fuel tank through the motor (2) and the shaking controller (7, 8, 9). Use the shaking method to clean the entire fuel tank, with a shaking angle of ±15 degrees and a frequency of (1-2) cycles / minute. During cleaning, maintain the nitrogen pressure P in the fuel tank = (0-0.1) kg / cm2. When the pressure value is too low, open the nitrogen supply valve to increase the pressure. When the pressure is too high, stop supplying nitrogen and continue cleaning the fuel tank for 2 hours. After 2 hours, release the cleaned fuel at the oil drain port and filter it through white silk cloth. The filtering time is not less than 10 minutes. Visually inspect with a 5x magnifying glass. If there is no excess matter (including microorganisms) after two consecutive cycles of inspection, the entire fuel tank is judged to be clean. If the cleanliness of the fuel tank does not meet the requirements, re-clean it for 10 minutes and re-inspect it until it passes the inspection.

[0114] Note: During the cleaning process, when the cleaning fuel temperature reaches T=50℃, stop cleaning immediately and replace the cleaning fuel in the entire fuel tank with cleaning fuel with a lower temperature.

[0115] 6) Drain the cleaning fuel from the tank, turn off the fuel cleaning controller, and shake the hydraulic control. Disconnect the joints connecting the entire tank to the cleaning accessories. Close the nitrogen supply valve; do not stop the nitrogen supply before doing so. Turn off all switches on the cleaning console. After removing the cleaning accessories, plug all pipe openings and joints with plugs, wrap them with clean cotton cloth, and place them neatly.

[0116] 7) Pass clean and dry air through the entire fuel tank for 2 hours to keep the tank dry. After the entire fuel tank is reinstalled and docked with the fuselage, close all maintenance covers, suspend a medical ultraviolet lamp in the tank, and turn on the light for 24 hours for secondary sterilization.

[0117] 8) When the lighting time is up, turn off and remove the medical ultraviolet lamp. Place activated carbon in the integral fuel tank in a packaging bag to keep the tank dry and remove it before the integral fuel tank is activated.

[0118] Cleaning of the overall fuel tank system pipeline:

[0119] 1) Tie a white silk cloth with linen thread to the catheter to be cleaned, dip it in 180# aviation washing gasoline, and repeatedly pull and clean it. After cleaning, blow the catheter dry with clean and dry compressed air;

[0120] 2) Heat the twice-cleaned catheter in an oven at 80°C to 100°C for 1 hour;

[0121] 3) Rinse the inner cavity of the catheter with warm water at 70℃ to 80℃, wipe the inner cavity with a dry white silk cloth, and blow the catheter dry again with clean and dry compressed air;

[0122] 4) Conduct a 100% visual inspection of the inner and outer surfaces of the baked conduits and connectors;

[0123] 5) After the visual inspection is passed, all catheters are physically inspected and surface protection is done: use white gauze to wrap the catheter end and surface to prevent excess objects or dust from entering;

[0124] 6) Clean the removed seals with alcohol to ensure that the inner and outer surfaces are clean and free of impurities. After cleaning, wrap them with clean fine canvas to prevent secondary contamination;

[0125] Step 4: Reinstall the system pipelines that were removed from the entire fuel tank.

[0126] After cleaning, reinstall the system piping into the integral fuel tank and perform an airtightness check. Once the seal test is passed, fill the tank with oil through the refueling tap on the integral fuel tank. After three days of storage, test the tank for oil tightness and sample the fuel for microbial content.

[0127] Step 5: Monitor and prevent fuel microorganisms in the entire fuel tank.

[0128] The steps for monitoring fuel microorganisms in the entire fuel tank are as follows:

[0129] 1) Before or after flight: In conjunction with the aircraft's pre-flight and post-flight waterproofing and sedimentation operations, visually inspect the fuel cleanliness. Run the fuel pump in the entire fuel tank for 3 minutes, then take a sample for observation. If a large amount of turbid fuel is present, perform a microbiological test using the Fuelstat Resinae test kit.

[0130] 2) Long-term parking: If the aircraft is parked for an extended period, run the fuel pump for three minutes every 30 days, then visually inspect the fuel tank for cleanliness. If the inspection passes, the inspection interval will be adjusted to two months. If the inspection still passes after two months, regular inspections will be adjusted to every three months. If the inspection fails, the inspection will be submitted to a professional testing agency for IP385 / 99 quantitative analysis.

[0131] The preventive measures for fuel microorganisms in the integral fuel tank are as follows:

[0132] Before the flight and after refueling, open the upper maintenance cover of the integral fuel tank and add the microbial removal additive PRISTTM to the fuel.

[0133] The present invention also provides a cleaning device using the above-mentioned method for cleaning and controlling microorganisms in an aircraft fuel tank, comprising a base 10, an eccentric wheel 11, an exciter 12, a motor 2, a shock absorber 3, a vibration frame 4, a docking plate 5, a support frame 6, an electric lift 7, a hanging steel cable 8, and a dynamometer 9. The electric lift 7 is mounted on the top of the support frame 6, the electric lift 7 is connected to the dynamometer 9 via the hanging steel cable 8, the dynamometer 9 is connected to the docking plate 5 via the hanging steel cable 8, and the shock absorber 3 is arranged on the base 10. Between the vibration frame 4, the motor 2 is arranged on one side of the eccentric wheel 11, the output shaft of the motor 2 is connected to the center of the eccentric wheel 11, the motor 2 drives the eccentric wheel 11 to rotate, the exciter 12 passes through the wheel surface of the eccentric wheel 11, and is connected to the vibration frame 4. The exciter 12 can drive the vibration frame 4 to vibrate periodically. The vibration frame 4 is provided with a docking plate 5. The docking plate 5 on the vibration frame 4 and the docking plate 5 on the hanging steel cable 8 are used to connect the integral oil tank 1; a universal wheel and a fixed screw are provided at the bottom of the support frame 6.

[0134] The present invention can completely remove microorganisms in the entire fuel tank of a certain type of platform aircraft. The method adopted is safe, effective, clean and thorough, with significant results and no recurrence. It solves the problem of blockage of the oil filter in the aircraft duct system. On the other hand, it adheres to the oil level and dielectric constant sensors inside the fuel tank, thereby triggering continuous alarms in the aircraft EICAS system, which poses a great hidden danger and threat to the flight safety of the aircraft.

Claims

1. A method for cleaning and controlling microorganisms in an integral fuel tank of an aircraft, used for cleaning and controlling microorganisms in an integral fuel tank of a certain type of aircraft, characterized in that: The following steps are involved: Step 1: Preparation before cleaning: drain the remaining oil in the overall fuel tank of the aircraft, ventilate the fuel tank, and the cleaning personnel enter the fuel tank and remove the system pipelines in the fuel tank; Step 2: Inspection and troubleshooting before cleaning. Before cleaning the fuel tank, visually inspect the tank structure for microorganisms and corrosion. After inspection, remove microorganisms and surface attachments, and inspect and handle the removed pipes in the tank. Step 3: Carry out relevant cleaning on the entire oil tank and the removed pipelines; Step 4: Reinstall the pipelines removed from the overall oil tank; Step 5: Monitor and prevent fuel microorganisms in the fuel tank.

2. The method for cleaning and controlling microorganisms of an integral aircraft fuel tank according to claim 1, characterized in that: Step 1 specifically includes the following steps: 1.1) Drain the fuel from the wing integral fuel tank and the corresponding fuel pipeline; 1.2) Open the maintenance cover on the lower wing surface and visually check the residual oil near the wing integral oil tank frame. If there is too much residual oil, use an oil-absorbing sponge or fine flat cloth to further clean it and ventilate to remove the odor; 1.3) After the oil tank is dry, personnel entering the oil tank for operation shall wear anti-static clothing and equipment, use gas masks when the odor is strong, and carry explosion-proof lighting equipment when entering the oil tank; 1.4) Remove the accessories of the oil supply system of the oil tank that are contaminated by microorganisms, including conduits, finished products, joints and seals, and keep records of the removed accessories.

3. The method for cleaning and controlling microorganisms of an integral fuel tank of an aircraft according to claim 2, characterized in that: Step 2 includes the pre-cleaning inspection of the fuel tank and the pre-cleaning inspection of the fuel system pipeline. Before cleaning the entire fuel tank, visually inspect the fuel tank structure, check the surface coating, bolts, and sealant of the structural parts in the following manner, and check for the presence of microorganisms and corrosion. The inspection steps are as follows. The comparison of the inspection damage characteristics is shown in Table 1; 2.1) Check the sealant in the overlapping area of ​​the inner surface of the upper wall of the fuel tank and check whether there are any conditions shown in Table 1; 2.2) Check the upper and lower inner wall plates and the butt ribs, bolts and sealants at both ends of the front and rear beams of the fuel tank to see if there are any of the conditions shown in Table 1; 2.3) Check the upper and lower edge strips, the seam area and the rib web of the two butt ribs of the fuel tank to see if there are any of the conditions shown in Table 1; 2.4) Check the inner surface of the lower wall of the fuel tank, focusing on the area around the fuel system accessories, the pollutant deposition area, the wall overlap area, etc., to check whether there are any of the conditions shown in Table 1; Table 1 Comparison table of microbial damage characteristics The fuel system pipeline pre-cleaning inspection includes the following steps: 1) Visually inspect the connections and surfaces of the removed fuel system’s oil supply and delivery pipes, joints, seals and finished products. Clean the pipes, joints, seals and finished products whose connections do not affect the secondary connection and whose surface coatings are not damaged; 2) Visually inspect the outer surface of the ventilation system in the fuel tank and the pressure refueling system pipeline. If there are microbial residues or other impurities, 100% pipeline cleaning should be carried out; 3) Remove the cables of the main finished products of the fuel system, including the separation of the cables from the finished products, including the separation of the cable plugs and sockets.

4. The method for cleaning and controlling microorganisms of an integral fuel tank of an aircraft according to claim 3, characterized in that: In step 2, troubleshooting before cleaning includes troubleshooting the entire fuel tank, fuel system pipelines, The specific troubleshooting of the entire oil tank is as follows: the entire oil tank is inspected to remove microorganisms and surface attachments. If the above damage characteristics are found, it is handled as follows: 1) If the coating on the surface of the fuel tank is damaged, grind the damaged area and apply HY-200 oxidation liquid manually, then spray or brush a layer of S06-1010H polyurethane primer; 2) If the rubber caps of bolts or other standard parts are damaged, remove the rubber caps and apply NJD-4 bonding primer first, then apply XM22B sealant or injection seal caps; 3) Sealant damage: After removing the damaged part, first apply NJD-4 bonding primer, then apply XM22B sealant or apply sealing cap; The troubleshooting method for fuel system pipeline is as follows: 1) Remanufacture the cables, conduits, connectors, seals and accessories that are found to be damaged; 2) For microbial residues or other impurities in the pipelines that are not removed, wipe the surface with 180# aviation washing gasoline.

5. The method for cleaning and controlling microorganisms of an integral fuel tank of an aircraft according to claim 4, characterized in that: Step three includes initial and secondary cleaning of the fuel tank and cleaning of the fuel system pipelines; The initial cleaning steps of the fuel tank are as follows: 1) The personnel who enter the fuel tank for cleaning use a clean white fine flat cloth dipped in aviation kerosene RP-3 to scrub the top, side walls and bottom of the fuel tank. After scrubbing, visually inspect the scrubbed area and excess materials with a 5x magnifying glass; 2) After the cleaning is qualified, use a ventilator to ventilate the oil tank and evenly apply HM504 surface protection sealing paint on the cleaned parts as required; 3) After checking the sealing and cleanliness of the fuel tank, open the cover of the faulty fuel tank, ventilate the fuel tank, close the cover to prevent dust and excess objects from entering the fuel tank, and maintain the sealing of the fuel tank; The secondary cleaning of the oil tank is to disassemble the entire oil tank to the ground, hoist it to the cleaning device and fix it, and then carry out secondary pressure cleaning of the oil tank. The operation steps are as follows: 1) Before the secondary cleaning of the overall oil tank, check the cleaning equipment and oil tank rack, plug all the pipes that are not connected with process plugs, use copper-plated or wooden tools to install pipes and covers, and use cloth with sewn edges to wipe the oil stains and other liquid flow marks and spots on the oil tank and cleaning device; 2) Position and fix the integral oil tank on the cleaning device; 3) First connect the pressure refueling hose to the cleaning hole on the integral fuel tank, then check whether the pressure refueling hose and the integral fuel tank connection port are firmly fixed, fill the integral fuel tank with nitrogen through the pressure refueling hose, and maintain the nitrogen pressure at P = 0 ~ 0.1kg / cm 2 Up to 30 minutes; 4) Inject cleaning fuel into the integral fuel tank, the amount added is as shown in Table 2; Table 2 Overall oil tank cleaning oil injection table 5) Connect the whole oil tank to the cleaning device, and the cleaning device shakes the whole tank for cleaning at an angle of ±15 o , frequency 1 to 2 cycles / minute, keep the nitrogen pressure in the fuel tank P = (0 to 0.1) kg / cm during cleaning 2 When the pressure value is too low, continue to introduce nitrogen to the fuel tank for pressurization. When the pressure is too high, stop supplying nitrogen and continue cleaning the fuel tank for 2 hours. After 2 hours, release the cleaned fuel at the drain port and filter it through white silk cloth. The filtering time should be no less than 10 minutes. Visually inspect with a 5x magnifying glass. If there is no excess material after two consecutive cycles of inspection, it is determined that the entire fuel tank has been cleaned. If the cleanliness of the fuel tank does not meet the requirements, re-clean it for 10 minutes and re-inspect it until it is qualified. During the cleaning process, when the cleaning fuel temperature reaches 50°C, stop cleaning immediately and replace the cleaning fuel in the entire fuel tank with a cleaning fuel with a lower temperature; 6) Remove the cleaning fuel from the fuel tank; 7) Pass clean and dry air through the entire fuel tank for 2 hours to keep the fuel tank dry. After the entire fuel tank is reinstalled and docked with the fuselage, close all maintenance covers, suspend the ultraviolet lamp in the fuel tank, and turn on the light for 24 hours for secondary sterilization. 8) When the lighting time is up, turn off and remove the ultraviolet lamp, place activated carbon in the integral fuel tank to keep the tank dry, and remove it before the integral fuel tank is activated. The cleaning of the overall tank system pipeline includes the following steps: 1) Use linen thread to tie white silk cloth to the catheter to be cleaned, dip it in 180# aviation washing gasoline, and repeatedly pull and clean it. After cleaning, blow the catheter dry with clean and dry compressed air; 2) Heat the cleaned catheter in an oven at 80°C to 100°C for 1 hour; 3) Rinse the inner cavity of the catheter with warm water at 70℃ to 80℃, wipe the inner cavity with dry white silk cloth, and blow the catheter dry again with clean and dry compressed air; 4) Conduct 100% visual inspection on the inner and outer surfaces of the baked conduits and joints; 5) After the visual inspection is qualified, all catheters are physically inspected and surface protection is done: use white gauze to wrap the catheter end and surface to prevent excess objects or dust from entering; 6) Clean the removed seals with alcohol to ensure that the inner and outer surfaces are clean and free of impurities. After cleaning, wrap them with clean fine canvas to prevent secondary contamination.

6. The method for cleaning and controlling microorganisms of an integral fuel tank of an aircraft according to claim 5, characterized in that: Step four is as follows: install the cleaned system pipeline back into the integral fuel tank, and conduct an airtightness check on the system pipeline. After the sealing test is qualified, fill the integral fuel tank with oil through the refueling switch on the integral fuel tank. After parking for three days, test the oil tightness of the integral fuel tank and sample and test the microbial content in the fuel.

7. The method for cleaning and controlling microorganisms of an integral fuel tank of an aircraft according to claim 6, characterized in that: In step 5, the monitoring steps of fuel microorganisms in the entire fuel tank are as follows: 1) Before or after the flight: Combined with the waterproofing and sedimentation operations before and after the flight, visually check the fuel cleanliness. After running the fuel pump in the overall fuel tank for 3 minutes, take samples for observation. If there is a large amount of turbid fuel, use detection reagents for microbial detection; 2) Long-term parking: If the aircraft is parked for a long time, the fuel pump in the integral fuel tank shall be operated for 3 minutes every 30 days, and then the cleanliness of the integral fuel tank shall be visually inspected. If qualified, the inspection period shall be adjusted to 2 months. If qualified after 2 months, it shall be adjusted to regular inspection every 3 months. If unqualified, it shall be submitted to a professional testing agency for IP385 / 99 quantitative analysis; The preventive measures for fuel microorganisms in the integral fuel tank are as follows: Before the flight and after refueling, open the upper maintenance cover of the integral fuel tank and add microbial removal additives to the fuel. PRIST TM .

8. A cleaning device applied to the method for cleaning and controlling microorganisms of an integral fuel tank of an aircraft as claimed in any one of claims 1 to 7, characterized in that: It includes a base, an eccentric wheel, an exciter, an electric motor, a shock absorber, a vibration frame, a docking plate, a support frame, an electric lift, a hanging steel cable, and a dynamometer. The electric lift is installed on the top of the support frame, the electric lift is connected to the dynamometer through the hanging steel cable, the dynamometer is connected to the docking plate through the hanging steel cable, the shock absorber is arranged between the base and the vibration frame, the motor is arranged on one side of the eccentric wheel, the motor output shaft is connected to the center of the eccentric wheel, the motor drives the eccentric wheel to rotate, the exciter passes through the wheel surface of the eccentric wheel and is connected to the vibration frame, the exciter can drive the vibration frame to perform periodic vibration, a docking plate is arranged on the vibration frame, and the docking plate on the vibration frame and the docking plate on the hanging steel cable are used to connect the overall oil tank.

9. The cleaning device according to claim 7, characterized in that: A universal wheel and a fixed screw rod are arranged at the bottom of the support frame.

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