DOOR FAIRING FOR AN AIRCRAFT LANDING GEAR LEG

Abstract

A door fairing for a retractable landing gear leg of an aircraft is disclosed having an outer member which covers a portion of a landing gear bay of the aircraft when the landing gear leg is retracted. An inner member of the door fairing is coupled to the outer member via a number of configurable couplings which allow adjustment of the position of the outer member with respect to the inner member. The inner member has mounting points for mounting the door fairing to the landing gear leg. Prior to fitting the door fairing at the aircraft, measured or derived dimensional parameters of the landing gear bay are used to adjust the configurable couplings such that the door fairing is preconfigured to fit the landing gear bay of the aircraft.

Claims

1. A door fairing for attachment to a retractable landing gear leg of an aircraft, the door fairing comprising: an outer member for providing a door for an orifice of the aircraft when the retractable landing gear leg is in a retracted position; an inner member coupled to the outer member via a plurality of configurable couplings, the door fairing having at least one mounting device for mounting the inner member to the retractable landing gear leg; wherein the plurality of configurable couplings facilitate adjustment of the position of the outer member with respect to the inner member in dependence upon at least one dimensional parameter of the aircraft such that the door fairing is pre-configurable with respect to the orifice prior to being attached to the retractable landing gear leg.

2. The door fairing according to claim 1, wherein said at least one mounting device comprises a plurality of mounting arms, which are separate from the plurality of configurable couplings.

3. The door fairing according to claim 2, wherein the plurality of configurable couplings comprise at least five configurable couplings.

4. The door fairing according to claim 1, wherein the plurality of configurable couplings comprise: at least one coupling which allows for adjustment of the position of the outer member relative to the inner member in a first direction which has a component perpendicular to the outer surface of the outer member; at least one coupling which allows for adjustment of the position of the outer member relative to the inner member in a second direction which has a component perpendicular to the outer surface of the outer member; and at least one coupling which allows for adjustment of the position of the outer member relative to the inner member in a third direction which is both non-parallel to the first direction and non-parallel to the second direction.

5. A retractable landing gear leg of an aircraft comprising the door fairing according to claim 1.

6. A kit comprising a jig and the door fairing according to claim 1, wherein adjustment of the position of the outer member with respect to the inner member is arranged to be performed with the door fairing mounted on the jig.

7. The kit according to claim 6, wherein the jig has at least one element arranged in dependence upon said at least one dimensional parameter such that the door fairing is configured with reference to said at least one element of the jig.

8. A method of fitting a door fairing to a retractable landing gear leg of an aircraft, the door fairing being configured such that immediately before a step of fitting it to the landing gear it has at least one adjustable dimension that can be configured to compensate for variations, from one aircraft of a given design to another, that arise as a result of dimensional tolerances which affect the fit of the door fairing with the aircraft when the landing gear leg is retracted, the method comprising: prior to fitting the door fairing to the retractable landing gear leg of the aircraft, configuring at least one dimension of the door fairing in dependence upon at least one dimensional parameter of the aircraft so that the door fairing is pre-configured to fit an orifice of the aircraft when the landing gear leg is retracted; and then fitting the door fairing to the retractable landing gear leg of the aircraft.

9. The method according to claim 8, wherein the door fairing includes an outer member and an inner member coupled to the inner member via a plurality of configurable couplings arranged to facilitate adjustment of the position of the outer member with respect to the inner member; wherein the step of configuring at least one dimension of the door fairing comprises adjusting one or more of the plurality of configurable couplings.

10. The method according to claim 8, wherein the step of configuring at least one dimension of the door fairing is performed with the door fairing mounted on a jig.

11. The method according to claim 10, wherein the step of configuring at least one dimension of the door fairing includes using at least one guide element attached to the jig, said at least one element being positioned in dependence upon said at least one dimensional parameter such that the door fairing is configured with reference to the guide element.

12. The method according to claim 10, wherein the step of configuring at least one dimension of the door fairing includes using an optical guidance device to determine a target position for the door fairing in dependence upon said at least one dimensional parameter.

13. The method according to claim 8, wherein said at least one dimensional parameter includes a measurement taken at the aircraft.

14. The method according to claim 8, wherein said at least one dimensional parameter includes a parameter derived from statistical analysis of a series of dimensional parameters corresponding to a plurality of different aircraft.

15. The method according to claim 8, wherein said at least one dimensional parameter comprises at least four dimensional parameters.

16. An aircraft comprising the door fairing as claimed in claim 1.

Description

DESCRIPTION OF THE DRAWINGS

[0032] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

[0033] FIGS. 1a and 1b show a prior art arrangement of an aircraft with retractable landing gear;

[0034] FIG. 2 shows an aircraft landing gear door fairing;

[0035] FIG. 3 show a landing gear door fairing according to a first embodiment of the invention;

[0036] FIG. 4 shows the landing gear door fairing of FIG. 3 fitted to a landing gear leg;

[0037] FIG. 5 shows the arrangement of FIG. 4 in an alternative aspect;

[0038] FIG. 6 shows in plan view the landing gear door fairing of FIG. 3 and,

[0039] FIG. 7 shows a flow diagram illustrating a method of attaching a landing gear door fairing to an aircraft according to a further embodiment of the invention.

DETAILED DESCRIPTION

[0040] FIG. 1a shows an aircraft 101 comprising a fuselage 105 and a pair of wings 106. The aircraft 101 also includes sets of landing gear door components 110, which provide a contiguous covering at the underside of the fuselage 105 and the pair of wings 106 for main landing gear assemblies (not shown) when in a retracted configuration.

[0041] Referring now also to FIG. 1b, a portion of the aircraft 101 is depicted with the left (port) side of the landing gear door components 110 of FIG. 1a shown in greater detail, now in an extended (deployed) position. These comprise a landing gear door 140, a landing gear door fairing 150, and hinged leg fairing 160. A main landing gear assembly 120 of the aircraft 101 is pivotally coupled to the wing 106 via pintles 125, such that when retracted the main landing gear assembly 120 is housed within a landing gear bay 130.

[0042] As mentioned above the landing gear door 140, landing gear door fairing 150, and hinged leg fairing 160 fit together when the main landing gear assembly 120 is retracted to form a contiguous covering of the landing gear bay 130. The landing gear door 140 is pivotally coupled via hinged mounts 135 to the fuselage 105, such that when the main landing gear assembly 120 is retracted, the landing gear door 140 partially closes the landing gear bay 130.

[0043] The landing gear door fairing 150 is attached to a main leg of the main landing gear assembly 120, such that when the main landing gear assembly 120 is retracted, the landing gear door fairing 150 also partially closes the landing gear bay 130. Furthermore, when the main landing gear assembly 120 is retracted, a lower edge 155 of the landing gear door fairing 150 is arranged to abut an edge 145 of the landing gear door 140.

[0044] Similarly a hinged leg fairing 160 is attached to the wing 106 via a hinged joint 125 such that when the main landing gear assembly 120 is retracted, the hinged leg fairing 160 rotates about the hinged joint 125 to close the hinged leg fairing 160. When closed, the hinged leg fairing 160 abuts an edge of the landing gear door fairing 150 (opposite the lower edge 155). In this way the arrangement of the landing gear door 140, landing gear door fairing 150, and hinged leg fairing 160 together close the landing gear bay 130 to the exterior when the main landing gear assembly 120 is retracted.

[0045] Since the landing gear door fairing 150 is not mounted to the aircraft 101 directly, but to the main leg of the main landing gear assembly 120 (which itself is subject to design, manufacturing and installation tolerances and must be fitted and suitably adjusted on the aircraft 101), it will be appreciated that significant adjustment of the position of the landing gear door fairing 150 may be required in order to achieve the abovementioned mutual alignment.

[0046] Referring now also to FIG. 3, a landing gear door fairing 300 is shown, which is suitable for being mounted on the main landing gear assembly 120 of the aircraft 101 according to a first embodiment of the invention. The landing gear door fairing 300 has an outer member 330 and an inner member 310. The inner member 310 is provided with first and second mounting arms 315 and 320 respectively for mounting the landing gear door fairing 300 to the aircraft 101 in a manner to be fully described below. It will be appreciated that the number of mounting arms may differ from that described above, and that in particular the provision of three mounting arms provides an advantageous arrangement in terms of the security of attachment and orientation of the landing gear door fairing 300 when mounted on the aircraft 101.

[0047] The outer member 330 is coupled to the inner member 310 by five configurable couplings 350, 360, 370, 380 and 390 respectively.

[0048] Each one of the five configurable couplings 350, 360, 370, 380 and 390 respectively is adjustable so as to be able to adjust the overall relative position of the inner member 310 with respect to the outer member 330. This may be achieved by, for example, the use of double-ball joints with telescopic arms or a selection of differently sized spacers. This allows adjustment in x-, y-, and z-axes, plus the three degrees of freedom of rotation. In other words all six degrees of freedom of movement.

[0049] It will be appreciated that the five configurable couplings 350, 360, 370, 380 and 390 respectively will be accessible from the sides of the landing gear door fairing 300, or via access holes or panels provided in the inner member 310. In this way configuration and adjustment of each one of the five configurable couplings 350, 360, 370, 380 and 390 respectively is facilitated, in a manner to be further described below.

[0050] It will also be appreciated that the precise arrangement of configurable couplings may vary from the five described above. Furthermore outer member 330 is illustrative of one landing gear door fairing example, other landing gear door fairing designs may have differently shaped outer member components to those described above, but with the common feature that the outer member is designed to fit within a specific space, and be oriented correctly to the loft lines (i.e. contours) of the underside of the wing 106 and/or fuselage 105 into which the main landing gear assembly 120 is designed to recess when retracted.

[0051] A datum reference point 325 defines a fixed point with respect to the second mounting arm 320, and therefore by extension a fixed point with respect to the whole inner member 310.

[0052] In operation, and referring now to the lower portion of FIG. 3, dimensional constraint parameters of the aircraft to which the landing gear door fairing 300 is to be fitted are provided. These dimensional constraint parameters may be measurements taken at the aircraft 101, or may be based on statistical or other data related to a fleet of aircraft, or a portion thereof. For example it may be that at a Final Assembly Line (FAL), the most recently assembled aircraft have been found to have an internal spatial relationship (represented by the dashed line 395) between the datum reference point 325 and one corner of a landing gear bay (represented by a reference point 345). In this example the reference point 345 may a corner where a rear sidewall of the landing gear bay 130 meets an edge of the hinged leg fairing 160 of aircraft 101, so an edge of outer member 330 should be dimensionally adjusted to that point in order that the landing gear door fairing 300 will make a flush fit with this corner.

[0053] It will be appreciated that the spatial relationship referred to above may be defined and provided as a parameter in a number of different ways, such as using relative orthogonal coordinates (x, y, z mm) from the datum point 325, within a predefined coordinate system having well defined x-, y-, and z-axes.

[0054] Thus by way of example only, a pre-adjusted landing gear door fairing 300a is shown, which is a representation of landing gear door fairing 300 but with each one of the five configurable couplings 350, 360, 370, 380 and 390 having been adjusted to new positions as shown by the five configurable couplings 350a, 360a, 370a, 380a and 390a in dependence upon a number of dimensional constraint parameters. As will be appreciated, this difference in spacing alters the position of the outer member 330 relative to the inner member 310. In the example shown, while the inner member 315 remains in the same position with respect to the datum point 325, the position of the outer member 330 relative to both the inner member 310 and the datum point 325 is adjusted. In particular, a corner of the outer member 330 has been adjusted to now coincide with the reference point 345, such that the outer member 330 is now pre-configured to correspond to the spatial characteristic of the aircraft 101 referred to above.

[0055] For the sake of clarity, only one reference point 345 is shown in FIG. 3. However it will be appreciated that a number of reference points may be required in order to provide all of the required spatial characteristics such that the outer member 330 of the landing gear door fairing 300a is preconfigured to fit the required area and contours of the aircraft 101. In particular it may be that four reference points defined by four dimensional constraint parameters are sufficient to align the outer member 330 with the required spatial characteristics of the aircraft 101.

[0056] Referring now also to FIG. 4, a landing gear leg 410 of the aircraft 101 of FIG. 1a is shown having first and second mounting points 415 and 420. The landing gear door fairing 300a which has been pre-configured as described above, is mounted to the landing gear leg 410 via the first and second mounting arms 315 and 320 which are fixed to the first and second mounting points 415 and 420 respectively via conventional and resilient means such as a bolt and captive-nut arrangement.

[0057] It will be appreciated that the resilient nature of this fixing of the mounting arms 315 and 320 respectively to the first and second mounting points 415 and 420 results in the inner member 310 having a fixed orientation with respect to the landing gear leg 410. Sidewalls 430 and 440 of FIG. 4 define the front and rear edges respectively of an orifice which is part of a landing gear bay into which the landing gear leg 410 is housed when retracted. For example sidewalls 430 and 440 may correspond to the front and rear edges of the landing gear bay 130 of the aircraft 101 of FIG. 1b.

[0058] Datum point 425 of FIG. 4 corresponds to datum point 325 of FIG. 3. As described above, a corner of outer member 330 has been preconfigured such that when mounted on the aircraft 101, the corner of outer member 330 aligns with the edge of the sidewall 440 at reference point 445. In this way the position of the landing gear door fairing 300a matches the required spatial characteristic (reference point 445) namely the edge of the sidewall 440. Similarly the spatial characteristics of other elements such as the sidewall 430 or other elements not shown in FIG. 4, are also matched through the preconfiguring described above.

[0059] Referring now also to FIG. 5, a landing gear leg 510 (which corresponds to landing gear leg 410 of FIG. 4 but viewed from the side) is shown in a retracted position within a landing gear bay 530 of aircraft 101. A landing gear door fairing 550 is coupled to the landing gear leg 510 via first, second and third mounting points 515, 520 and 525 respectively. The landing gear door fairing 550 has already been preconfigured according to the procedure referred to above and below, in order to satisfy the dimensional requirements of the landing gear bay 530 (the five configurable couplings being omitted for clarity).

[0060] A landing gear door 540 (which corresponds to the landing gear door 140 of FIG. 1b) is coupled to the aircraft 101 via a hinged joint 535 (corresponding to the joint 135 of FIG. 1b), and is actuated by a hydraulic actuator 570, one end of which is coupled to structure of the aircraft 101. In this way the landing gear door 540 is opened prior to extension of the landing gear leg 510, and closed after retraction of the landing gear door leg 510.

[0061] A hinged leg fairing 560 (which corresponds to the hinged leg fairing 160 of FIG. 1b) is coupled to the aircraft 101 via a hinged joint 580 (corresponding to the joint 125 of FIG. 1b), and is actuated by a hydraulic actuator 590, one end of which is coupled to the landing gear leg 510. In this way the hinged leg fairing 160 is opened with, or just prior to the extension of the landing gear leg 510, and closed with or just after retraction of the landing gear door leg 510.

[0062] When the landing gear leg 510 is retracted landing gear door 540, the landing gear door fairing 550 and the hinged leg fairing 560 form a contiguous covering of the landing gear bay 530. Since the landing gear door fairing 550 has been preconfigured according to the procedure referred to above and below, the landing gear door fairing 550 is aligned with the edge of the landing gear door 540 (arrow 545) and the edge of the hinged leg fairing 560 (arrow 555).

[0063] Referring now also to FIG. 6, a landing gear door fairing outer member 600 (corresponding to the outer member 330 of FIG. 3) is shown in plan view, with five locations 650, 660, 670, 680 and 690 respectively where the five configurable couplings 350, 360, 370, 380 and 390 respectively of FIG. 3 may, by way of example only, be located.

[0064] A frame 620 (corresponding to the inner member 310 of FIG. 3) is coupled to the outer member 620 via configurable couplings at the five locations 650, 660, 670, 680 and 690 respectively. Mounting points of the frame 620 (for attachment to the aircraft 101) are omitted for clarity.

[0065] In operation and referring now also to FIG. 7, a method of fitting a landing gear door fairing is described. At box 700, parameters of the aircraft 101 to which the landing gear door fairing 300 is to be fitted are received at a maintenance facility or assembly line. The parameters may represent spatial characteristics such as distances, internal dimensions, angles and other geometric values indicative of the required orientation and position of the landing gear door fairing 300 when attached to the aircraft 101. The parameters may, for example, relate to one or more points indicating the location (with respect to a known datum) of one or more of the following: [0066] a) front and rear edges of a landing gear bay such the sidewalls 430 and 440 of the landing gear bay 130 of FIG. 4, [0067] b) an edge of a landing gear door (such as the landing gear door 540 of FIG. 5), [0068] c) an edge of a hinged leg fairing (such as hinged leg fairing 560 of FIG. 5), and [0069] d) points where any two of the edges of a, b or c above meet.

[0070] These parameters may be measurements taken at the specific aircraft to which the landing gear door fairing 300 is intended to be fitted. Alternatively they may be based on statistical analysis of, for example, several aircraft of the same type as aircraft 101. Alternatively such statistical analysis may be derived from historical information stored relating to pre-adjustments made to other landing gear door fairings which have recently been adjusted for the same aircraft type.

[0071] It will be appreciated that the parameters may be provided in the form of a list, or by data to be read and interpreted by a computer (not shown).

[0072] At box 710, a jig is adjusted according to the received parameters from box 700. The jig may be provided with adjustable guide elements corresponding to elements of the aircraft 101, or there may be a number of reference points spatially distributed within the jig. The received parameters are used to adjust the position of the guide elements, or to specify required distances relative to the reference points in a manner to be further described below.

[0073] Alternatively the jig may be provided with one or more optical devices such as laser or camera guidance systems, which may be arranged detect the position of various elements of the door fairing 300 and to provide guidance, in dependence upon the received parameters, to a user of the system for adjusting the five configurable couplings 350, 360, 370, 380 and 390 respectively.

[0074] At box 720 the landing gear door fairing 300 is attached to the jig. This is preferably achieved via one or both of the first and second mounting arms 315 and 320 respectively.

[0075] At box 730 the five configurable couplings 350, 360, 370, 380 and 390 respectively of the landing gear door fairing 300 are each adjusted in order that the position of the outer member 330 conforms to the requirements specified by the parameters received above at box 700. This may be achieved by aligning the outer member 330 with the guide elements described above. Alternatively the position of the outer member 330 may be adjusted to satisfy required distances from the reference points as determined by an optical device such as laser or camera guidance system. For example edges of the outer member 330 may be temporarily fitted with visual target elements to be identified by the guidance system, such that the guidance system can recognise the positions of the edges of the outer member 330 and therefore specify the required adjustments to be made to the five configurable couplings 350, 360, 370, 380 and 390 respectively.

[0076] The five configurable couplings 350, 360, 370, 380 and 390 respectively are then tightened/locked in their adjusted positions. This may include the provision of locking wire, especially if the dimensional parameters described above are well defined and therefore there is a high degree of confidence that no further adjustment will be necessary when the landing gear fairing 300 is fitted to the aircraft.

[0077] It will be appreciated that adjusting the position of the outer member with respect to the inner member 310 on the jig is significantly faster and more straightforward than if the adjustments were made when the landing gear fairing 300 were attached to the landing gear leg 410 of the aircraft 101.

[0078] At box 740, the landing gear fairing 300a (after adjustment) is removed from the jig, and transferred to the location of the aircraft 101. It will be appreciated that the jig may be at the same facility as the aircraft 101, or it may be at a different location.

[0079] At box 750, the landing gear fairing 300a is attached to the landing gear leg 410 of aircraft 101.

[0080] Finally, at box 760, the landing gear leg 410 is retracted in order to verify that the correct position and clearances have been achieved.

[0081] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

[0082] For example, the jig could be provided with a computer controlled optical system with lasers, cameras or other detection devices attached to a computer. The system is arranged to process the received parameters and provide instructions on a screen for the required manual adjustment of the five configurable couplings 350, 360, 370, 380 and 390 respectively.

[0083] It will be appreciated that the number of configurable couplings could be fewer or greater than the five configurable couplings 350, 360, 370, 380 and 390 described above. Furthermore the number of mounting points may be fewer or greater than the three mounting points 515, 520 and 525 described above.

[0084] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.