GB2549516A

GB2549516A - A method and apparatus for determining the displacement of an aerodynamic seal for an aircraft

Info

Publication number: GB2549516A
Application number: GB1606904.9A
Authority: GB
Inventors: Ibrahim Yasser; Vitale Nicholas; Jaggard Phillip; Morgan Angus; Folkard Christian
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2016-04-20
Filing date: 2016-04-20
Publication date: 2017-10-25

Abstract

The method comprises arranging an aerodynamic seal 20 on a testing apparatus 40 and disposing an expandable bladder 51 at the internal side 34 of the seal. The expandable bladder or balloon is inflated to act on the internal side of a displaceable portion 25 of the seal. The amount of displacement is then measured in response to the action of the expandable bladder. The seal may be a root fillet fairing seal between an aeroplane wing and fuselage. The displacement of the seal may be determined by measuring the deflection of a predetermined point or array of points on the external surface of the seal. A distance indicator 71 such a dial gauge or laser scanner may be used to measure the displacement of the seal. The pressure applied to the expandable bladder may be monitored and a pressure differential to which the seal will be exposed during operation of the aircraft may be applied. A fluid may be fed into the bladder to fill it up.

Description

A method and apparatus for determining the displacement of an aerodynamic seal for an aircraft

FIELD OF THE INVENTION

[01] The present invention relates to a method for determining the displacement of an aerodynamic seal for an aircraft. The present invention also relates to an apparatus for determining the displacement of an aerodynamic seal for an aircraft.

BACKGROUND OF THE INVENTION

[02] Seals are used extensively for mechanical operations of aircraft. Aerodynamic seals are typically exposed to form a sealing operation between an internal space of the aircraft and external to the aircraft. As such, an aerodynamic seal has an internal side and an external side. At least part of the external side is typically exposed to an airflow over the aircraft.

[03] During operation, aerodynamic seals may experience a variety of conditions. Generally, during operation a pressure differential may be formed across the seal, that is a difference in pressure between the external side and an internal side of the seal. Such a pressure differential may cause an outward suction due to a pressure reduction on the external side of the seal which may be brought about by the movement of air over the seal.

[04] Aerodynamic seals are typically formed from a deformable material and so a pressure differential across the seal can cause the seal to deform. Such deformation includes ballooning. Should the seal balloon outwards, then it is possible that such ballooning may impact the aerodynamic performance of the seal, may have a negative influence on the seals operational integrity, or may restrict movement of a movable element on an aircraft such as a control surface of the aircraft.

[05] It is therefore beneficial to have an understanding of the behaviour of an aerodynamic seal during operation. However, replicating such high speed, hostile environments can be expensive and difficult to achieve. Furthermore, seals generally behave non-linearly when subjected to a pressure differential and so it can be difficult to model and predict the behaviour of such an aerodynamic seal.

[06] One known method for determining the behaviour of an aerodynamic seal during operation is to use computer modelling. However, such an approach is highly analytical and may result in some inaccuracy. Another method is to conduct field testing, that is to test the seal during normal operation of an aircraft. However such an approach is expensive, and is often hard to implement.

SUMMARY OF THE INVENTION

[07] According to a first aspect of the invention, there is provided a method for determining the displacement of an aerodynamic seal for an aircraft, the aerodynamic seal having a displaceable portion which is configured to be exposed, during operation of the aircraft, to a pressure differential across the displaceable portion between an internal side and an external side, the method comprising arranging the aerodynamic seal on a testing apparatus, disposing an expandable bladder at the internal side of the displaceable portion, expanding the expandable bladder to act on the internal side of the displaceable portion and displace the displaceable portion, and determining a displacement of the displaceable portion in response to the action of the expandable bladder.

[08] Therefore, it is possible to easily and reliably determine a displacement, and in particular a deformation, of the seal that will occur during operation of an aircraft.

[09] The displaceable portion may be a deformable portion such that expanding the expandable bladder to act on the internal side of the deformable portion causes the deformable portion to distend.

[10] Determining a displacement of the displaceable portion may comprise determining a deformation of the deformable portion in response to the action of the expandable bladder.

[11] The method may further comprise determining the displacementof the displaceable portion by measuring the deflection of the displaceable portion between a neutral condition and a displaced condition in response to the action of the expandable bladder.

[12] The method may further comprise the deflection of the displaceable portion being determined by measuring on the external side of the displaceable portion.

[13] The external side of the displaceable portion may comprise an external surface. Displacement of the displaceable portion may be determined by measuring the deflection of at least one predetermined point on the external surface.

[14] The method may further comprise measuring the displacement of the aerodynamic seal at an array of predetermined points on the external surface.

[15] The method may further comprise using a distance indicator to determine the displacement of the displaceable portion.

[16] The distance indicator may be a dial gauge.

[17] The method may further comprise using laser scanning to determine the displacement of the displaceable portion.

[18] The method may further comprise using a mounting device to restrict movement of the seal.

[19] The seal may be slidably mountable to the mounting device.

[20] The seal may be fixably mountable to the mounting device.

[21] The method may further comprise disposing a restriction member adjacent to the expandable bladder to restrict expansion of the expandable bladder.

[22] The method may further comprise monitoring a pressure applied to the expandable bladder to determine a predetermined pressure acting on the displaceable portion.

[23] The method may further comprise applying a predetermined pressure to the expandable bladder to apply a predetermined pressure differential on the displaceable portion.

[24] The method may further comprise determining a pressure differential to which the displaceable portion will be exposed between the internal side and the external side, during operation of the aircraft, and applying a predetermined pressure to the expandable bladder based on the determined pressure differential.

[25] The method may further comprise feeding a fluid into the expandable bladder to expand the expandable bladder.

[26] The fluid may be a gas.

[27] The method may further comprise arranging the expandable bladder to cover the internal side of the displaceable portion.

[28] The method may further comprise determining the displacement of an aerodynamic seal for an aircraft which has at least part of the external side of the displaceable portion exposable to airflow over the aircraft during operation of the aircraft.

[29] The method may be conducted away from the aircraft.

[30] According to another aspect of the present invention, there is provided a testing apparatus for determining the displacement of an aerodynamic seal for an aircraft, the aerodynamic seal, during operation of the aircraft, being configured to be exposed to a pressure differential across the displaceable portion between an internal side and an external side, the testing apparatus comprising a mounting device for mounting the aerodynamic seal, an expandable bladder configured to be disposed at the internal side of the displaceable portion and to act on the internal side to displace the displaceable portion, and a measurement device configured to determine a displacement of the displaceable portion in response to the expandable bladder acting on the displaceable portion.

[31] The displaceable portion may be a deformable portion such that expanding the expandable bladder to act on the internal side of the deformable portion causes the deformable portion to distend.

[32] The measurement device may be configured to measure the deflection of the displaceable portion between a neutral condition and a displaced condition in response to the action of the expandable bladder on the displaceable portion.

[33] The measurement device may be configured to measure the deflection of the external side of the displaceable portion.

[34] The measurement device may be configured to measure the displacement of the displaceable portion at an array of predetermined points across the displaceable portion.

[35] The measurement device may be a distance indicator, for example a dial gauge.

[36] The measurement device may be a laser scanner.

[37] The mounting device may comprise a restriction member configured to restrict expansion of the expandable bladder.

[38] The testing apparatus may further comprise a pressure gauge for monitoring a pressure applied to the expandable bladder.

[39] The testing apparatus may further comprise a fluid pump configured to apply a pressure to the expandable bladder.

[40] The expandable bladder may be configured to cover the internal side of the displaceable portion.

[41] According to another aspect of the present invention, there is provided testing kit comprising the testing apparatus as recited in any of one of claims 19 to 28, and an aerodynamic seal.

BRIEF DESCRIPTION OF THE DRAWINGS

[42] Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 shows an aircraft with an aerodynamic seal;

Fig. 2 shows part of an outer portion of the aircraft shown in Fig. 1 with an aerodynamic seal;

Fig. 3 shows an outer side of the seal shown in Fig. 2;

Fig. 4 shows an inner side of the seal shown in Fig. 3;

Fig. 5 shows a schematic cross-sectional view of the aerodynamic seal shown is Figs. 3 and 4 mounted to part of the aircraft in Fig. 1;

Fig. 6 shows a schematic cross-sectional view of the aerodynamic seal shown in Fig. 5 with a testing apparatus for determining the deformation of the aerodynamic seal, with the aerodynamic seal in a neutral condition;

Fig. 7 shows a cross sectional schematic view of the aerodynamic seal and the testing apparatus shown in Fig. 6 with the aerodynamic seal in a deformed condition;

Fig. 8 shows the aerodynamic seal of Figs. 3 and 4 with part of the testing apparatus for determining the deformation of the aerodynamic seal shown in Figs. 6 and 7;

Fig. 9 is a flow diagram of a method for determining the deformation of the aerodynamic seal for an aircraft;

Fig. 10 shows a cross-sectional schematic view of another aerodynamic seal and testing apparatus arrangement with the seal in a neutral condition; and

Fig. 11 shows a cross-sectional schematic view of the aerodynamic seal and the testing apparatus arrangement of Fig. 10 in a displaced condition. DETAILED DESCRIPTION OE EMBODIMENT(S) [43] Referring to Eig. 1, an aircraft 10 is shown. The aircraft 10 has a fuselage 11 and wings 12. The wings 12 extend from the fuselage 11. An engine 13 is mounted to each wing 12.

[44] A root fillet seal 20 is shown in Fig. 1. The seal 20 is disposed at a juncture of the wing 12 with the fuselage 11. The seal 20 is disposed at the leading edge 14 of the wing 12. The seal 20 is mounted to the forward root fillet fairing 15, forming an external part of the aircraft 10.

[45] The root fillet seal 20 is an aerodynamic seal. Aerodynamic seals are exposed to the external environment of an aircraft. Generally, at least part of an aerodynamic seal is exposed to airflow over the aircraft 10 during operation.

[46] Although the below described embodiments will be described with respect to one type of aerodynamic seal - the root fillet seal 20 - it will be understood that alternative types of aerodynamic seal may be used with the method and apparatus described herein. Other applicable types of aerodynamic seal include a flap track aperture flap seal and a wing leading edge cable seal.

[47] Aerodynamic seals are, during operation, subjected to a pressure differential across them. That is, a pressure differential is formed between one side of the seal and another side of the seal. Typically, a low, or lower, pressure is applied at an external side of the seal, with a high, or higher, pressure applied at an internal side of the aerodynamic seal.

[48] Referring to Figs. 3 to 5, the root fillet seal 20 is shown. Description of an apparatus and method for use with an aerodynamic seal will be described in general with reference to the root fillet seal 20 shown in the Figures.

[49] The root fillet seal 20 has a generally U-shape. The seal 20 has a main part 21 and a flange 22. The main part 21 is formed with a panel section and the flange 22 extends inwardly from the peripheral edge 23 of the main part 21. The flange 22 has a locating face 24. The locating face 24 seals again with fuselage 11. That is, the locating face 24 of the flange 22 seals against part of the aircraft 10.

[50] The seal 20 has a deformable portion 25. The deformable portion 25 acts as a displaceable portion. The deformable portion 25 is formed by a section of reduced thickness of the seal 20. However, the deformable portion of an aerodynamic seal may be formed by other means, for example by use of alternative or multiple materials. Alternatively, the deformable portion of an aerodynamic seal may be the entire aerodynamic seal. The deformable portion 25 may be formed from two or more regions of the seal 20.

[51] The deformable portion 25 acts as a displaceable portion. That is, at least part of the seal is movable between different operating conditions. In the present embodiment, part of the seal 20 is deformable, that is the deformable portion 25 is displaced during operation due to deformation of the deformable portion 25. In an alternative arrangement, the seal 20 may be displaced by movement of the seal 20, with or without deformation of the deformable portion 25. That is, displacement of the seal 20 or part of the seal 20 may occur without deformation of a deformable portion.

[52] The deformable portion 25 of the seal 20 is formed in the main part 21 of the seal 20. Therefore, a region of the seal 20 is deformation and is defined by the deformable portion 25 the seal is formed from a deformable and resilient material. Such materials include rubber.

[53] The seal 20 also has a rigid portion 29. The rigid portion 29 adds rigidity to the seal 20. The rigid portion 29 may be formed from two or more regions of the seal 20.

[54] A reinforcement element 26 is disposed in part of the main part 21 to prevent deformation of the seal 20 in that region. A flange reinforcement element 27 is disposed in a region of the flange to increase the rigidity of the flange 22. The rigid portion 29 comprises the reinforcement element 26 and flange reinforcement element 27.

[55] Referring to Fig. 5, the seal 20 is shown mounted with respect to the fuselage 11 and the wing 12. The flange 22 abuts against the fuselage 11 and a distal edge 28 of the main part 21 of the seal 20 abuts against the wing 12. As such, a sealed cavity 30 is defined by the seal 20. The seal cavity 30 is defined between the seal 20, the fuselage 11 and the wing 12.

[56] The seal 20 has an outer side 31 and an inner side 32. The peripheral edge 23 of the main part 21 extends along the fuselage 11. The distal edge 28 of the main part 21 of the seal 20 extends along the wing 12. The peripheral edges of the outer side 31 of the seal 20 are defined by the peripheral edge 23 and the distal edge 28. The inner side 32 of the seal 20 opposes the outer side 31.

[57] The deformable portion 25 of the seal is formed in the main part 21 of the seal 20. The deformable portion 25 is formed by a section of reduced thickness of the main part 21. The deformable portion 25 is formed between the outer side 31 and the inner side 32 of the seal 20.

[58] The deformable portion 25 has an external surface 33 and an internal surface 34. An external side of the deformable portion 25 comprises the external surface 33. An internal side of the deformable portion 25 comprises the internal surface 33. The external surface 33 forms part of the outer side 31 of the seal 20. The internal surface 34 forms part of the inner side 32 of the seal 20. The external surface 33 is exposable to atmospheric pressure during operation such that a pressure differential is formed between the exposed external surface 33 and the internal surface 34.

[59] With the root fillet seal 20, the deformable portion 25 is substantially U-shaped in plan view, and substantially follows the path and shape of the peripheral edge 23 of the main part 21. The deformable portion 25 defines an elongate curved shape. However, it will be understood that the shape and path of the deformable portion of an aerodynamic seal is dependent on the shape and function of the aerodynamic seal and its mounted position on the aircraft 10.

[60] The reinforcement element 26 and flange reinforcement element 27 provide rigidity to the seal 20 outside the area of the deformable portion 25. In embodiments, one or both of the reinforcement element 26 and flange reinforcement element 27 may be omitted. Again, the shape and position of the rigid portion is dependent on the type of aerodynamic seal. Furthermore, the rigid portion may be defined by a section of increased thickness of the aerodynamic seal.

[61] A testing apparatus 40 for determining the deformation of an aerodynamic seal, such as the root fillet seal 20, is shown in Fig.6 and Fig.7. The testing apparatus 40 comprises of an expansion device 50, a mounting device 60 and a measurement device 70.

[62] The expansion device 50 comprises an expandable bladder 51 and a pump 52. The pump 52 is configured to expand the bladder 51. The pump 52 may also contract the bladder 51.

[63] The expansion device 50 includes a connection arrangement 53 for fluidly communicating the pump 52 with the expandable bladder 51. A pressure gauge 54 is arranged to determine the fluid pressure applied to the expandable bladder 51.

[64] The expandable bladder 51 is formed from a deformable material, such as rubber. The bladder 51 is also resilient. The shape of the bladder 51 is configured to at least substantially correspond to the shape of the deformable portion 25 of the seal 20. The bladder 51 is configured to cover the area of the seal 20 to be deformed. For the root fillet seal 20, for example, the expandable bladder 51 is an elongate tube as shown in Fig. 8. However, it will be understood that the shape of the expandable bladder is dependent on the shape of the deformable portion of the aerodynamic seal to be tested.

[65] The expandable bladder 51 is configured to cover the internal surface 34 of the deformable portion 25, when the expandable bladder 51 is expanded. The expandable bladder 51 is configured to act on the internal surface 34 to provide an urging force corresponding to a pressure differential across the deformable portion 25 between the exposed external surface 23 and the internal surface 34. However, it will be understood that the urging force is applied due to a change in the pressure acting on the internal surface 34 of the formal portion 25 when using the testing apparatus 40 as opposed to a change in the pressure acting on the exposed surface 33 of the deformable portion 25 when the seal 20 is in operation.

[66] The expandable bladder 51 is fluidly connected to the pump 52 by the connection arrangement 53. The pressure gauge 54 is connected to determine the fluid pressure acting in the expandable bladder 51. The pressure gauge may be in line with the pump 52 or, for example, at an opposing end of the expandable bladder 51 to the pump 52. The pump 52 is a fluid pump. The expandable bladder 51 in the present embodiment is inflated by means of a gas, such as atmospheric air being fed into the expandable bladder by the fluid pump 52. However, it will be understood that a liquid may alternatively be used to expand the bladder 51.

[67] It will be understood that alternative means of expanding the expandable bladder 51 may be used. For example, an alternative pressurised gas supply, such as gas stored in a pressurised tank, may be used.

[68] The testing apparatus 40 comprises the mounting device 60. The mounting device 60 is configured to represent a part of the aircraft to which the seal 20 is mounted. The mounting device 60 comprises a base 61 to which the sealed 20 is fixedly mounted. The mounting device 60 also includes a restriction member 62. The restriction member 62 is mountable in the space defined by the sealed cavity 30 when the seal is mounted to the aircraft 10 to restrict the direction of expansion of the expandable bladder 51. The base 61 and restriction member 62 may be integrally formed. The restriction member 62 minimises the size of expandable bladder 51 required for use in the testing apparatus 40. The restriction member 62 is received substantially in the space defined by the sealed cavity outside of the area defined by the internal surface 54 of the deformable portion 25.

[69] The base 61 and the restriction member 62 are formed from a rigid material such as a rigid plastic or wood.

[70] The testing apparatus 40 also includes the measurement device 70. The measurement device 70 is configured to determine the deformation of the seal in response to the action of the expandable bladder 51. In particular, the measurement device 70 is configured to determine the deflection of the external surface 33 of the deformable portion 25. By using the testing apparatus 40 including the expandable bladder 51 it is possible to easily determine the deflection of the external surface 33 of the deformable portion 25 as it is not covered by testing apparatus. Measurement device 70 includes a distance indicator 71, such as a dial gauge. The measurement device 70 also includes a support frame 72 for the distance indicator 71. The support frame 72 is configured to mount the distance indicator 71 relative to the seal 20. This allowed reliable and repeated measurement readings to be taken of the deflection of the deformable portion 25 of the seal 20. The measurement device 70 is mounted to the mounting device 60 or is in fixed relationship to the mounting device 60 to enable repeated and reliable measurements to be taken.

[71] Although, in the present embodiment, the measurement device 70 is a distance indicator 71, it will be understood that alternative measurement devices may be used. For example, the measurement device 70 may be a laser scanner which is used to obtain measurements of the deflection of the external surface 33 of the deformable portion 25.

[72] A method of using the testing apparatus 40 will now be described with reference to the Figures, and in particular with reference to Fig. 9 which shows a flow diagram of the method steps. Although, one series of method steps is described herein, it will be understood that the order of the method steps may be altered, or method steps may be omitted. Alternatively, further method steps may be introduced.

[73] At step 101, the expandable bladder 51 is inserted or disposed adjacent to the deformable portion 25 of the seal 20. The expandable bladder 51 is based approximate to the internal surface 34 to the deformable portion 25 so that is extends along and adjacent to the internal surface 34.

[74] At step 102, the seal 20 is mounted to the mounting device 60. With the seal 20 described herein the flange 22 in mounted to the base 61. The restriction member 62 is placed in the space defining the cavity 30 so is to restrict expansion of the expandable bladder 51. This is done by restricting the space in which the expandable bladder 51 is able to expand. The restriction member 62 retains the expandable bladder 51 in the correct position. That is, aligned with the internal surface 34 of the deformable portion 25 of the seal 20.

[75] At step 103, the expandable bladder 51 is connected to the remainder of the expansion device 50. The expandable bladder 51 is connected to the pump 52 and the pressure gauge 54 by the connection arrangement 53. The expandable bladder 51 may be integrally formed with the remainder of the expansion device 50 in which case this step may be omitted.

[76] At step 104, the pressure differential that will occur across the seal 20 between the sealed cavity 30 and external to the seal 20 is determined. The pressure differential acting across the deformable portion 25 is therefore determined. A simple analysis method may be used to determine the pressure differential experienced by the seal 20 in operation. Such analysis may be used to identify one or more areas on the seal 20 that would be likely to deform. The pressure differential may be determined, for example, by measuring the fluid pressures acting on an aircraft in operation, or by computer modelling. Once the desired pressure differential acting across the seal 20 to be tested has been determined, at step 105 is it possible to determine the fluid pressure to be imparted on the bladder corresponding to the pressure differential that will act across the seal 20 in operation.

[77] At step 106, the neutral condition of the seal 20 is measured. The neutral condition in this embodiment is a condition in which the seal is in an undeformed position. As such, no pressure differential is applied across the deformable portion 25 of the seal 20. However, if a pressure differential is applied across the seal in the neutral condition during operation of the seal 20, then this can be taken into account. The neutral condition is shown in Fig. 6.

[78] In the neutral condition the measurement device 70 is used to undertake measurements to act as a baseline. The measurement device 70 is positioned relative to the external surface 33 of the deformable portion 25. The position of the deformable portion 25 is determined at one or more predetermined points. The position of the deformable portion 25 may be determined at an array of predetermined points. The predetermined points of the array are spaced from each other. This helps to build a model of the deformable portion 25 in the neutral condition. The measurement device 70 may be moved on the support frame 72 to measure different predetermined points.

[79] At step 107, the pump 52, acting as a pressurised fluid supply, is actuated. The pump 52 is fluidly connected to the expandable bladder 51, and so the expandable bladder 51 expands. The expandable bladder 51 expands in the available space in the sealed cavity 30.

[80] As the expandable bladder 51 expands, a contact surface 55 of the expandable bladder 51 acts against the deformable portion 25. The expandable bladder 51 urges the deformable portion 25 to deform outwardly. In effect, a pressure differential is formed across the deformable portion 25 of the seal 20 between the external side 31 and the internal side 32.

[81] The fluid pressure in the expandable bladder 51 is increased until the desired fluid pressure in the expandable bladder 51 is achieved. The fluid pressure is determined by reference to the pressure gauge 54. At this stage, the desired pressure differential should be acting across the deformable portion 25. As such, the deformable portion 25 will have deformed, that is displaced. The deformed condition, that is displaced condition, is shown in Fig. 7. It will be understood that different pressure differentials may be applied, and therefore different deformed conditions may result.

[82] As a result of the pressure differential applied across the deformable portion 25 by the expandable bladder 51, the deformable portion 25 will be distending outwardly.

[83] At step 108, the deformed condition of the seal 20 is measured. The deformed condition in this embodiment is a condition in which the seal is in the deformed position as a result of the pressure differential applied across the deformable portion 25 by the expandable bladder 51.

[84] In the deformed condition the measurement device 70 is used to undertake measurements to determine the displacement of the deformable portion 25. The measurement device 70 is positioned relative to the external surface 33 of the deformable portion 25. The position of the deformable portion 25 in the deformed condition is determined at one or more predetermined points. The position of the deformable portion 25 may be determined at an array of predetermined points. The predetermined points of the array are spaced from each other. This helps to build a model of the deformable portion 25 in the deformed condition. The measurement device 70 may be moved on the support frame 72 to measure different predetermined points.

[85] At step 109, the deformation of the seal 20 between the neutral condition, as determined at step 106, and the deformed condition, as determined at step 108, are compared to determine the deformation of the seal 20 in dependence on the predetermined pressure differential. Such determination shows the displacement of the deformable portion 25 of the seal 20. As such, the extent of the ballooning of the seal 20 during operation may be determined.

[86] Such a method of testing and the accompanying apparatus allows for the deformation of the seal 20 to be easily and reliable determined. By placing the pressure differential generating apparatus on the internal side of the seal 20 it is possible to easily measure the deformation of the seal, without the apparatus causing an obstruction. In particular, it provides a straightforward method of determining the displacement of the external side of the seal. This helps enable an improved understanding of the behaviour of the seal and the impact on wing and control surface performance.

[87] It will be understood that in an additional step, the pressure differential across the seal 20 may be removed and the measurement device used to undertake measurements to determine the displacement of the deformable portion 25 in this condition relative to the neutral condition and/or the deformed condition.

[88] It will be understood that other environmental conditions may be taken into account, or altered, in addition to a pressure differential being applied across the seal 20. For example, the temperature of the seal, or on one or both sides of the seal 20, may be adjusted. As such, the behaviour of the seal 20 in response to a pressure differential in combination with a temperature variation may be determined and modelled.

[89] In the above described embodiments, the deformation of the seal is determined between the seal in a neutral, undeformed, condition in which the expandable bladder is not acting on the seal, and a deformed condition, in which the expandable bladder is acting on the seal. However, it will be understood that the neutral condition may be a first deformed condition, in which the expandable bladder is acting on the seal in response to a first pressure being applied, and the deformed condition may be a second deformed condition, in which the expandable bladder is acting on the seal in response to a second pressure being applied.

[90] In the above described embodiments, the seal 20 is fixedly mounted to the mounting device 60. However, in an alternative embodiment, the seal 20 is movable, for example slidable, relative to the mounting device 60. Such an arrangement is shown in Figs. 11 and 12. In such an arrangement, the base 61 forms a seal receiving cavity 63 in which the seal 20 is received. The peripheral edge 23 of the main part 21 of the seal 20 locates against an inner surface 65 of the base 61. A chamber 66 is defined between the base 61 and the seal 20. The expandable bladder 51 is disposed in the chamber 66. When the expandable bladder 51 is expanded, the bladder 51 acts on the seal 20 to distend the deformable portion 25. The deformable portion 25 moves in the chamber 66 by sliding relative to the base 61. Therefore, the displacement of the deformable portion 25 is caused by the deformation of the deformable portion 25 and by the seal sliding relative to the base 61.

[91] It will be understood that in an alternative arrangement and/or condition, the deformable portion acting as a displaceable portion does not deform, and that all displacement is caused by the seal sliding relative to the base 61.

[92] It will be understood that in some conditions applied to the seal 20 that the seal may not deform in response to the pressure differential applied to it by the expandable bladder 51. For example, the pressure differential applied by the expandable bladder 51 may not be sufficient to overcome the rigidity of the deformable portion 25. As such, in these conditions, the deformed condition will be a condition in which there is no deflection of the deformable portion 25.

[93] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A method for determining the displacement of an aerodynamic seal for an aircraft, the aerodynamic seal having a displaceable portion which is configured to be exposed, during operation of the aircraft, to a pressure differential across the displaceable portion between an internal side and an external side, the method comprising: arranging the aerodynamic seal on a testing apparatus, disposing an expandable bladder at the internal side of the displaceable portion, expanding the expandable bladder to act on the internal side of the displaceable portion and displace the displaceable portion, and determining a displacement of the displaceable portion in response to the action of the expandable bladder.

2. The method according to claim 1, wherein the displaceable portion is a deformable portion such that expanding the expandable bladder to act on the internal side of the deformable portion causes the deformable portion to distend.

3. The method according to claim 2, wherein determining a displacement of the displaceable portion comprises determining a deformation of the deformable portion in response to the action of the expandable bladder.

4. The method according to any one of claims 1 to 3, further comprising determining the displacement of the displaceable portion by measuring the deflection of the displaceable portion between a neutral condition and a displaced condition in response to the action of the expandable bladder.

5. The method according to claim 4, wherein the deflection of the displaceable portion is determined by measuring on the external side of the displaceable portion.

6. The method according to claim 5, wherein the external side of the displaceable portion comprises an external surface, and displacement of the displaceable portion is determined by measuring the deflection of at least one predetermined point on the external surface.

7. The method according to claim 6, further comprising measuring the displacement of the aerodynamic seal at an array of predetermined points on the external surface.

8. The method according to any one of the preceding claims, further comprising using a distance indicator to determine the displacement of the displaceable portion.

9. The method according to claim 7, wherein the distance indicator is a dial gauge.

10. The method according to any one of the preceding claims, further comprising using laser scanning to determine the displacement of the displaceable portion.

11. The method according to any one of the preceding claims, further comprising using a mounting device to restrict movement of the seal.

12. The method according to claim 11, wherein the seal is slidably mountable to the mounting device.

13. The method according to claim 11, wherein the seal is fixably mountable to the mounting device.

14. The method according to any one of the preceding claims, further comprising disposing a restriction member adjacent to the expandable bladder to restrict expansion of the expandable bladder.

15. The method according to any one of the preceding claims, further comprising monitoring a pressure applied to the expandable bladder to determine a predetermined pressure acting on the displaceable portion.

16. The method according to any one of the preceding claims, further comprising applying a predetermined pressure to the expandable bladder to apply a predetermined pressure differential on the displaceable portion.

17. The method according to claim 16, further comprising determining a pressure differential to which the displaceable portion will be exposed between the internal side and the external side, during operation of the aircraft, and applying a predetermined pressure to the expandable bladder based on the determined pressure differential.

18. The method according to any one of the preceding claims, further comprising feeding a fluid into the expandable bladder to expand the expandable bladder.

19. The method according to any one of the preceding claims, further comprising arranging the expandable bladder to cover the internal side of the deformable portion.

20. The method according to any one of the preceding claims, further comprising determining the displacement of an aerodynamic seal for an aircraft which has at least part of the external side of the displaceable portion exposable to airflow over the aircraft during operation of the aircraft.

21. The method according to any one of the preceding claims, wherein the method is conducted away from the aircraft.

22. A testing apparatus for determining the displacement of an aerodynamic seal for an aircraft, the aerodynamic seal, during operation of the aircraft, being configured to be exposed to a pressure differential across the displaceable portion between an internal side and an external side, the testing apparatus comprising: a mounting device for mounting the aerodynamic seal. an expandable bladder configured to be disposed at the internal side of the displaceable portion and to act on the internal side to displace the displaceable portion, and a measurement device configured to determine the displacement of the displaceable portion in response to the expandable bladder acting on the displaceable portion.

23. The testing apparatus according to claim 22, wherein the displaceable portion is a deformable portion such that expanding the expandable bladder to act on the internal side of the deformable portion causes the deformable portion to distend.

24. The testing apparatus according to claim 22 or claim 24, wherein the measurement device is configured to measure the deflection of the displaceable portion between a neutral condition and a displaced condition in response to the action of the expandable bladder on the displaceable portion.

25. The testing apparatus according to claim 24, wherein the measurement device is configured to measure the deflection of the external side of the displaceable portion.

26. The testing apparatus according to claim 25, wherein the measurement device is configured to measure the displacement of the deformable portion at an array of predetermined points across the displaceable portion.

27. The testing apparatus according to any one of claims 23 to 26, wherein the measurement device is a distance indicator.

28. The testing apparatus according to any one of claims 22 to 27, wherein the mounting device comprises a restriction member configured to restrict expansion of the displaceable bladder.

29. The testing apparatus according to any one of claims 22 to 28, further comprising a pressure gauge for monitoring a pressure applied to the expandable bladder.

30. The testing apparatus according to any one of claims 22 to 29, further comprising a fluid pump configured to apply a pressure to the expandable bladder.

31. The testing apparatus according to any one of claims 22 to 30, wherein the expandable bladder is configured to cover the internal side of the displaceable portion.

32. A testing kit comprising the testing apparatus according to any of one of claims 22 to 31, and an aerodynamic seal.