Improved process for decontaminating an aircraft tank

Abstract

Improved method for depolluting an aircraft tank The invention relates to a method for depolluting an aircraft tank comprising a flexible bladder (12) housed in a chamber (14) formed in a structure of said aircraft, and an absorbent material (21) provided between said bladder (12) and said chamber (14), the chamber (14) comprises at least one drainage inlet (22) and is equipped with a fluid connection interface (10) to the bladder (12), characterized in that it consists of depolluting fuel from said chamber (14) by implementing the following steps: - from the fluid connection interface (10), injecting heated air into the bladder (12); - from the drainage inlet (22), purging the air contained in said chamber (14) until the bladder (12) expands and the absorbent material (21) is compressed by the bladder (12) against the walls of said chamber (14). Abstract figure: Fig.2

Description

Title of the invention: Improved method for decontaminating an aircraft tank

[0001] The present invention relates to a method for decontaminating an aircraft tank, in particular a method particularly suitable for rapidly decontaminating a chamber of an aircraft tank.

[0002] The decontamination caused by a leak from an aircraft tank requires a good knowledge of the structure of the aircraft. Both from the outside and from the inside of the aircraft, certain current decontamination methods require as much skill as the repair operations of said tanks.

[0003] Some aircraft tanks may be in the form of a flexible bladder made of rubber, neoprene, or other material, arranged in a cavity in the structure of the aircraft or in a part of the aircraft, inside the wings or in the hold for example.

[0004] In order to evacuate any leakage flows, the structure containing said flexible reservoir is generally provided with at least one drainage outlet. Said structure also comprises an air intake to compensate for the consumption and the reduction in volume of the bladder.

[0005] Furthermore, the flexible bladder is surrounded by an absorbent material generally made of polymer foam or similar. The absorbent material mainly prevents the bladder from being damaged against the walls of the tank. In this way, when a fuel leak occurs at the bladder, the flow circulates in the absorbent material arranged between said bladder and the structure up to the level of the outlet of the drainage socket, where said leak flow is easily identifiable.

[0006] If the leak is detected, it remains very difficult to decontaminate the tank without removing the bladder from the aircraft structure. Indeed, in order to decontaminate an aircraft tank, it is necessary to completely extract said bladder from the aircraft structure and then remove the absorbent material from the tank for cleaning or replacement. This complete extraction requires disassembly and reassembly of all the internal connections with the bladder. Indeed, the bladder includes numerous fluid connections and numerous mechanical connections in order to be held in place. These are therefore long and tedious operations that affect the operational availability of the aircraft and considerably increase the cost of maintenance operations.

[0007] Furthermore, when it is extracted or replaced in the structure of the aircraft, said flexible bladder is subjected to mechanical stresses likely to damage it. Frequently, simply extracting the bladder or the absorbent material damages them. and it is necessary to replace them, which leads to much higher maintenance costs.

[0008] The invention aims to overcome at least one of the drawbacks cited by proposing to simplify the decontamination of an aircraft tank.

[0009] To this end, the invention relates to a method for depolluting an aircraft tank comprising a flexible bladder housed in a chamber provided in a structure of said aircraft, and an absorbent material provided between said bladder and said chamber, the chamber comprises at least one drainage inlet and is equipped with a fluidic connection interface to the bladder, remarkable in that it consists of depolluting said chamber with fuel by implementing the following steps:

[0010] - from the fluid connection interface, inject heated air into the bladder;

[0011] - from the drainage outlet, purge the air contained in said chamber until expansion of the volume of the bladder and compression of the absorbent material by the bladder against the walls of said chamber.

[0012] The combination of a step of injecting air into the flexible bladder and a step of purging air from the chamber makes it possible to extract the fuel trapped in the absorbent material from the tank and to dry this absorbent material.

[0013] The injection of heated air into the bladder has the effect of increasing the temperature of the absorbent material by heat transfer from the wall of the bladder. Such an increase in temperature promotes the extraction of fuel from the absorbent material. For example, when the fuel is kerosene, the injection of heated air above about 40°C allows its evaporation.

[0014] Purging the chamber allows the expansion of the bladder to be accompanied until the absorbent material is compressed.

[0015] According to one embodiment of the invention, the method comprises the following step consisting of:

[0016] - from the fluidic connection interface, inject heated air into the material absorbent prior to and / or simultaneously with the injection of heated air into the bladder.

[0017] The injection of heated air into the absorbent material has the effect of facilitating the extraction of the fuel retained by it.

[0018] According to one embodiment of the invention, the method comprises the following steps consisting of:

[0019] - using a pressure sensor, monitoring the pressure in said bladder;

[0020] - using a temperature sensor, control the air temperature in said bladder.

[0021] Monitoring the pressure and temperature in the bladder ensures that the pressure and temperature of the air in the bladder are within value ranges not contraindicated at the risk of deterioration of the bladder.

[0022] According to one embodiment of the invention, the method comprises the following step consisting of, using a fuel separator, separating the liquid fuel from the air loaded with fuel vapor.

[0023] Thus, once the air has been purged from the chamber, it is planned to separate the liquid fuel from the air loaded with fuel vapor, with a view to its analysis.

[0024] According to one embodiment of the invention, the method comprises the following step consisting of, using a fuel pollution analyzer, analyzing the air loaded with fuel vapor to determine a pollution level.

[0025] The air loaded with fuel vapor supplied by the separator is advantageously directed towards a pollution diagnostic device comprising a fuel pollution analyzer.

[0026] According to one embodiment of the invention, the steps of the method are repeated for a predetermined number of cycles until a predetermined decontamination level is reached.

[0027] The predetermined decontamination level corresponding to a threshold value in ppm units below which the tank is considered sufficiently decontaminated.

[0028] According to one embodiment of the invention, the method comprises the following step consisting of:

[0029] - cooling at least the fluid connection interface by injecting cold air into the bladder and / or in the absorbent material.

[0030] Cooling the elements involved in implementing the process has the advantage of making them quickly manipulable at the end of the decontamination operation.

[0031] The invention also relates to a system for depolluting an aircraft tank capable of implementing the depolluting method described above, remarkable in that it comprises:

[0032] - a fluid connection interface comprising a main air inlet configured to receive the heated air and a main air outlet configured to be fluidically connected to a flexible bladder of the aircraft tank;

[0033] - air suction means configured to be fluidically connected to a socket tank drainage.

[0034] The air suction means are advantageously integrated into the fuel separator. The separator thus makes it possible both to purge the air in the chamber and to separate the liquid fuel from the air loaded with fuel vapor.

[0035] According to one embodiment of the invention, the pollution control system comprises a pollution diagnostic device configured to be fluidically connected to the fuel separator.

[0036] According to one embodiment of the invention, the fluidic connection interface includes a secondary air inlet configured to receive the heated air and at least one secondary air outlet configured to be fluidically connected to the absorbent material comprised between the bladder and the reservoir chamber.

[0037] According to one embodiment of the invention, the fluid connection interface comprises removable sealed connection means of the latter to the reservoir.

[0038] Other characteristics and advantages of the invention will appear on reading the non-limiting description which follows and the appended figures.

[0039] [Fig.l] represents a schematic view of an aircraft tank equipped with a flexible bladder.

[0040] [Fig.2] represents a perspective view of the decontamination system according to the invention implementing the method of the invention.

[0041] [Fig. 3] represents a perspective view of a fluid connection interface intended to equip the aircraft tank.

[0042] [Fig. 4] represents an enlarged view of the tank of [Fig. 1] without connectors.

[0043] As represented in [Fig. 1], an aircraft tank 10 comprising a flexible bladder 12 housed in a chamber 14 formed in a structure of an aircraft. The flexible bladder 12 is intended to store fuel, here kerosene, for the needs of the aircraft.

[0044] Said flexible bladder 12 is held in the chamber 14 by several connections (not shown) connecting it to the structure of the aircraft, an interstitial space 20 being provided between said bladder 12 and said chamber 14. This interstitial space 20 comprises an absorbent material 21 surrounding the flexible bladder 12 to allow the absorption of fuel which may escape from the bladder 12. The chamber 14 comprises at least one drainage inlet 22 allowing the evacuation of any fuel flows which may escape from the bladder 12.

[0045] The chamber 14 forms a substantially closed volume whose sealing depends mainly on the sealing of the structure of the aircraft.

[0046] A chamber 14 may be located in different parts of the structure of the aircraft, such as for example inside a wing or a hold, and it comprises at least one access opening 24 closed by an inspection hatch for carrying out various checks and repairs, in particular during maintenance operations.

[0047] Referring to [Fig. 2], there is shown a cutaway view of the tank 10 of an aircraft connected to a pollution control system of an aircraft tank 10, comprising a fuel separator 26 fluidly connected to the drainage inlet 22 of the aircraft tank 10 and a pollution control device 28 comprising a fuel pollution analyzer and fluidly connected to the fuel separator 26.

[0048] The fuel separator 26 advantageously incorporates suction means provided for purging the air contained in the chamber forming the tank.

[0049] The method for decontaminating an aircraft tank 10 according to the invention will now be described according to a preferred embodiment with reference indifferently to FIGS. 1 to 3.

[0050] In order to allow the decontamination of the tank 10 without extraction of the flexible bladder 12 and the absorbent material 21 from the structure of the aircraft, the decontamination method according to the invention implements the following steps in an automated manner:

[0051] injecting heated air into the bladder 12;

[0052] purge the air contained in the chamber 14 until the bladder 12 expands and the absorbent material 21 is compressed by the bladder 12 against the walls of said chamber 14.

[0053] The heated air is injected into the bladder 12 from a fluid connection interface 30 which comprises a main air inlet 30A formed by a pneumatic valve and configured to receive the heated air and distribute it into the bladder via a main air outlet connected to the bladder 12 in a sealed manner.

[0054] The air contained in the chamber 14 is purged from the drainage outlet 22 giving access to the interstitial space 20 comprising the absorbent material 21 arranged between the bladder 12 and the chamber 14, this has the effect of increasing the volume of the bladder 12 in the chamber 14 caused by the purging of the chamber 14.

[0055] The expansion of the bladder has the effect of compressing the absorbent material 21 against the walls of the chamber 14, the fuel that it retains is then directed towards a leak point formed by the drainage outlet 22.

[0056] Purging the air in the chamber from the drainage port 22 allows the volume of the chamber 14 to be released and ensures the expansion of the bladder 12.

[0057] The air purged by the drainage inlet 22 is advantageously sucked in by the air suction means included in the fuel separator 26 and allows suction by the Venturi effect. The separator 26 is itself supplied by the pollution control device 28 designed to be connected to an air compressor 25. Thus, the purged air passes first through the drainage inlet 22, then through the fuel separator 26, before reaching the pollution control device 28. It will be noted, however, that the air purged from the chamber 14 passes into the separator where it retains the liquid fuel sucked from the chamber in a tank provided for this purpose and redirects the air loaded with fuel vapor to the pollution control device 28.

[0058] The chamber 14 is then gradually emptied of its air contained in the interstitial space 20.

[0059] It will be understood that the air purged in the chamber 14 corresponds to the air contained in the interstitial space 20, of course in the case where the bladder 12 does not include a defect which could make it permeable to gases.

[0060] The air purged from chamber 14 filtered from liquid fuel and charged with vapor of fuel is then directed to the pollution control device 28 for analysis.

[0061] After analysis, the air loaded with fuel vapor can be discharged through an exhaust outlet of the pollution control device 28.

[0062] For this purpose, the pollution control device 28 comprises a fuel pollution analyzer capable of determining the content of polluting particles (ppm) contained in the air to be analyzed.

[0063] The fuel pollution analyzer is advantageously formed by an infrared fuel sensor capable of measuring the pollution level of the air it receives.

[0064] Measuring the level of pollution in the air loaded with fuel vapor provides the maintenance operator with an indication of the need to repeat the depollution process.

[0065] The method described above can advantageously be repeated automatically until a predetermined pollution level representative of sufficient decontamination of the chamber is measured.

[0066] In addition to the method of the invention, it is possible to provide for the injection of heated air into the interstitial space 20 comprising the absorbent material 21 prior to and / or simultaneously with the injection of the heated air into the bladder 12.

[0067] The heated air is injected into the interstitial space 20 from a secondary air inlet 30B that the fluid connection interface 30 comprises and distributed into the interstitial space 20 from a plurality of secondary air outlets 30C that the fluid connection interface 30 comprises.

[0068] The injection of heated air into the interstitial space 20 distinctly from that provided in the bladder 12 advantageously allows preheating of the absorbent material 21 prior to its compression. Of course, the injection of heated air into the interstitial space 20 can be simultaneous with the injection of heated air into the bladder 12.

[0069] The fluid connection interface 30 will now be further described with reference to [Fig. 3].

[0070] The fluid connection interface 30 comprises removable sealed connection means for connecting it to the reservoir 10.

[0071] To implement the method of the invention, the inspection hatch is removed to allow access to the opening 24 of the chamber 14.

[0072] A fixing ring 32 of the interface to the reservoir 10 is inserted into the chamber 14 and arranged between the chamber 14 and the bladder 12. A seal 34 is then placed outside the reservoir 10 to ensure sealing between the reservoir 10 and the fixing ring 32. A series of fixing screws is also provided to secure the fixing ring 32 and the seal 34 to the reservoir 10.

[0073] A fluid connection box 36 of the interface 30 then covers an opening 32A of the fixing ring 32.

[0074] In addition to the main and secondary air inlets and outlets 30A, 30B, 30C, the fluid connection box 36 comprises inlets for measuring the pressure 30D and the temperature 30E of the air contained in said bladder. A temperature sensor and a pressure sensor are provided for monitoring the temperature and pressure of the air in the bladder 12.

[0075] The fluidic connection interface 30 also comprises an input 30F for measuring the pressure of the air contained in the interstitial space 20 from which a pressure sensor arranged to extend into the interstitial space 20 is connected.

[0076] Furthermore, the fluid connection housing 36 comprises a degassing outlet 30G provided in the event of overpressure in the bladder 12.

[0077] The reservoir 10 and the elements necessary for carrying out the method can be made available for rapid disassembly by cooling at least the fluidic connection interface 30 by injecting cold air into the bladder 12 and / or into the absorbent material 21.

[0078] It can therefore be seen that the method for decontaminating the tank 10 which has just been described makes it possible to decontaminate the tank 10 of the aircraft without dismantling the flexible bladder 12 and the absorbent material 21. Advantageously compared to the methods of the prior art, said method for decontaminating the tank 10 can be carried out in just a few hours, which has a significant impact on the availability of the aircraft.

[0079] Generally, particularly on combat aircraft, the space available in the structure of the aircraft is used to the maximum and consequently, accessibility to the interior of the structure of the aircraft is limited to components requiring regular maintenance. By allowing decontamination without disassembly, the method according to the invention is likely to allow a simplification of the design of the structure of the aircraft at the level of the chamber(s) provided to receive a tank bladder by limiting the number of accesses necessary for maintenance of the aircraft.

[0080] The invention also covers the application of the present decontamination method to other tanks or devices comprising a flexible bladder housed in a volume similar to a chamber.

[0081] Obviously, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the different characteristics, forms, variants and embodiments of the invention can be associated with each other in various combinations insofar as they are not incompatible or mutually exclusive. In particular, all the variants and embodiments described above can be combined with each other.

Claims

Claims

1. Method for depolluting an aircraft tank (10) comprising a flexible bladder (12) housed in a chamber (14) formed in a structure of said aircraft, and an absorbent material (21) provided between said bladder (12) and said chamber (14), the chamber (14) comprises at least one drainage inlet (22) and is equipped with a fluid connection interface (30) to the bladder (12), characterized in that it consists of depolluting fuel from said chamber (14) by implementing the following steps: - from the fluid connection interface (30), injecting heated air into the bladder (12); - from the drainage inlet (22), purging the air contained in said chamber (14) until the volume of the bladder (12) expands and the absorbent material (21) is compressed by the bladder (12) against the walls of said chamber (14).

2. Pollution control method according to claim 1, characterized in that it comprises the following step consisting of: - from the fluid connection interface (30), injecting heated air into the absorbent material (21) prior to and / or simultaneously with the injection of the heated air into the bladder (12).

3. Pollution control method according to claim 1, characterized in that it comprises the following steps consisting of: - using a pressure sensor, controlling the pressure in said bladder (12); - using a temperature sensor, controlling the temperature of the air in said bladder (12).

4. Pollution control method according to claim 1, characterized in that it comprises the following step consisting of, using a fuel separator (26), separating the liquid fuel from the air loaded with fuel vapor.

5. Pollution control method according to claim 4, characterized in that it comprises the following step consisting of, using a fuel pollution analyzer, analyzing the air loaded with fuel vapor to determine a pollution level.

6. A decontamination method according to claim 1, characterized in that the steps of the method are repeated for a predetermined number of cycles until a predetermined decontamination level is reached.

7. Decontamination method according to claim 1, characterized in that the method comprises the following step consisting of: - cooling at least the fluidic connection interface (30) by injecting cold air into the bladder (12) and / or into the absorbent material (21).

8. Fuel depollution system for an aircraft tank (10) comprising a flexible bladder (12) housed in a chamber (14) provided in a structure of said aircraft, and an absorbent material (21) provided between said bladder (12) and said chamber (14), the chamber (14) comprises at least one drainage inlet (22), wherein said depollution system is capable of implementing the method according to any one of the preceding claims and it comprises: - a fluid connection interface (30) comprising a main air inlet (30A) connected to a heated air injection means and configured to receive the heated air, and a main air outlet configured to be fluidically connected to the flexible bladder (12) of the aircraft tank (10); - air suction means configured to be fluidically connected to the drainage inlet (22) of the tank (10).

9. Pollution control system according to claim 8, characterized in that the fluid connection interface (10) comprises a secondary air inlet (30B) configured to receive the heated air and at least one secondary air outlet (30C) configured to be fluidically connected to the absorbent material (21) between the bladder (12) and the chamber (14) of the tank (10).

10. Pollution control system according to claim 8, characterized in that the fluid connection interface (10) comprises removable sealed connection means of the latter to the tank (10).

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