The present invention relates to a device which allows joining torsion boxes of aircraft structures, particularly of structures carrying fuel therein, such that fuel leaks during the operative life of the aircraft are prevented.
A torsion box consists of two skins which are applied to a central or inner material (core), generally a mesh or a grid of the same type. The torsion box functions similarly to a beam, although it is considerably lighter than a solid beam of the same size, without losing much strength. Torsion boxes are used in building fuselages or aircraft structures, particularly in wings and in vertical and horizontal stabilizers.
Joining the torsion boxes of those elements of the aircraft carrying fuel therein has a number of problems with respect to leaks. Leaks usually occur when joining torsion boxes both in the rear part of the joint and in the front part thereof. These leaks occur due to the geometry itself of the parts forming the mentioned boxes, since these parts generate cavities or gaps when they are joined, these cavities serving as a path for the fuel housed inside said boxes.
There are several defined problematic areas and these leak problems are solved today with a methodology prone to improvement. Today, this type of leak is handled in several ways; one of them consists of flooding the area in which there are cavities or gaps of a material acting as a sealant. Another one of the known solutions consists of using a part with a special design which covers most of the possible surface in which the cavities or gaps exist, such that the amount of sealant material which is necessary to apply is slightly reduced. In both cases, the leak is dealt with at the end of its path and with rather ineffective methods, since the application of a large amount of sealant material causes it to crack over time, which causes the occurrence of new leak paths for the fuel.
In addition to the sealant cracking, as can be seen in the previous example, the parts with a special design are secured to the structure of the torsion box only by means of the grip of the sealant material itself. Due to the operative life itself of the aircraft, which is subjected to loads and vibrations, this solution generates a number of problems during the maintenance of the aircraft, it even being necessary to remove all the sealant material applied and again installing new parts again embedded in a large amount of sealant material in the event that the original material is cracked and the sealing part is loose. This solution therefore presents a number of problems with respect to costs and times.
Sealing devices are known, such as the one described in document U.S. Pat. No. 6,073,889 for example, which improve the aerodynamics of the aircraft, preventing jumps in the external airflow in contact with the surface of the airplane (increasing the aerodynamic efficiency of the airplane). However, devices intended for sealing fuel leaks of an aircraft are not known.
The present invention offers a solution to the previously mentioned problems.
Thus, the invention develops a device for joining torsion boxes of aircraft structures, said structures carrying fuel therein, said devices preventing fuel leaks during the entire operative life of the aircraft. Thus, the device of the invention comprises three sides, said device being placed in the inner part of the joint of the torsion boxes, said device furthermore being installed during the step of the process of assembling the torsion boxes, and in a permanent manner, thus preventing future problems in the service life of the aircraft.
One of the essential features of the device of the invention for joining torsion boxes is the fact that it is a non-structural component of the mentioned joint, which allows assuring perfect sealing of said joint. The device of the invention is non-structural because it does not withstand the loads existing in the mentioned structure. One way to make the device not withstand stresses is by making the borehole in which the rivet for securing the mentioned device to the other parts is arranged slightly larger than the diameter of said rivet. The structural parts of the joint of torsion boxes of structures of the aircraft must withstand high loads or forces to which these structures are subjected, so they require a perfect support between the sides forming them with the adjacent parts. Achieving this perfect support with parts having three sides is very complex. Since the device of the invention is not structural, the support of the mentioned device does not have to be perfect, there being able to be small allowances between its three sides and the adjacent parts, it only being necessary to cover these minimum allowances with sealant material to assure a perfect sealing during the entire useful service life of the aircraft.
Other features and advantages of the present invention will be understood from the following detailed description of its object in relation to the attached drawings.
The present invention develops a device 1 for joining torsion boxes 5, 6 of aircraft structures, said structures carrying fuel therein, said devices 1 preventing fuel leaks during the entire operative life of the aircraft. The device 1 comprises three sides, 2, 3 and 4 (shown in detail in
The concept used until now in joining torsion boxes of aircraft is shown in
The new concept of the device 1 of the invention consists of attacking the fuel leak from its start, i.e., from inside the torsion box, 5 or 6, making a device 1 designed with three sides, 2, 3 and 4, said device 1 being installed in the process of assembling the torsion boxes 5 and 6. Said device 1 is fixed to the joint of the boxes 5 and 6 such that it is completely impossible for it to become detached therefrom, thus preventing future problems in the service life of the aircraft.
The mentioned device 1 is installed inside the joint of torsion boxes 5 and 6, unlike the known sealing parts 8, which are installed from the outside of the mentioned boxes, 5 and 6. Furthermore, as a result of the three-sided geometry of the device 1, perfect sealing of the existing cavities or gaps 7 is assured.
The device 1 of the invention is permanently joined to the torsion boxes 5 and 6 preferably by means of the use of rivets. The device 1 is thus joined for life to the structure, improving the sealing concept in the structure itself, since it is joined from inside the torsion boxes 5 and 6, and uses a minimum amount of sealant material, which is a considerable savings in curing time and material of the structure comprising the mentioned torsion boxes 5 and 6. In addition, as a result of the three-dimensional geometry itself of the device 1, said device is able to cover the gaps or cavities 7 existing in the previous structures (
The device 1 of the invention is a non-structural device because it does not withstand the loads existing in the joint of the torsion boxes 5, 6 of the structure of the aircraft. The device 1 is thus joined in a permanent manner to the torsion boxes 5 and 6 preferably by means of the use of rivets, such that in order for the device 1 to not withstand stresses, the boreholes in which the rivets for securing the device 1 to the torsion boxes 5, 6 are arranged are somewhat larger than the diameters of the mentioned rivets.
Those modifications comprised within the scope defined by the following claims can be introduced in the preferred embodiment described above.
Number | Date | Country | Kind |
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200901269 | May 2009 | ES | national |