GB2201737A - Lightning strike protection gasket - Google Patents
Lightning strike protection gasket Download PDFInfo
- Publication number
- GB2201737A GB2201737A GB08804170A GB8804170A GB2201737A GB 2201737 A GB2201737 A GB 2201737A GB 08804170 A GB08804170 A GB 08804170A GB 8804170 A GB8804170 A GB 8804170A GB 2201737 A GB2201737 A GB 2201737A
- Authority
- GB
- United Kingdom
- Prior art keywords
- aperture
- closure member
- carbon fibre
- gasket
- lightning strike
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 18
- 239000002131 composite material Substances 0.000 claims abstract description 18
- 239000000835 fiber Substances 0.000 claims abstract description 17
- 239000000446 fuel Substances 0.000 claims abstract description 8
- 230000005540 biological transmission Effects 0.000 claims abstract description 3
- 239000011347 resin Substances 0.000 claims description 5
- 229920005989 resin Polymers 0.000 claims description 5
- 229910000838 Al alloy Inorganic materials 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 2
- 238000010276 construction Methods 0.000 abstract description 5
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 239000002828 fuel tank Substances 0.000 description 4
- 230000001419 dependent effect Effects 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 239000000806 elastomer Substances 0.000 description 2
- 229910001234 light alloy Inorganic materials 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D45/00—Aircraft indicators or protectors not otherwise provided for
- B64D45/02—Lightning protectors; Static dischargers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/02—Sealings between relatively-stationary surfaces
- F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
- F16J15/10—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing
- F16J15/12—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Aviation & Aerospace Engineering (AREA)
- Gasket Seals (AREA)
Abstract
A lightning strike protection arrangement for aircraft structures of carbon fibre composite construction, particularly structures comprising fuel storage tanks, as for example, aircraft wing tanks. The present invention provides a structural arrangement for the transmission and control of lightning strike current flow across an interface between an aperture 10 in the carbon fibre structure and a closure member 11 located in the aperture. An access opening in an aircraft wing is a specific example. <IMAGE>
Description
LIGHTENING STRIKE PROTECTION FOR AIRCRAFT STRUCTURE$ This invention relates to lightning strike protection for aircraft structures. More particularly it is concerned with those structures which are of carbon fibre composite construction.
When lightning strikes an aircraft a large electrical current may pass spanwise across the wing. In its path will be access openings in the wing structure and closure members such as access doors associated with the access openings and the current will pass fran structure to closure member to structure with the resultant possibility of arcing at the interface. If the closure members provide means of access to integral fuel tanks and the arcing takes place at the inside face of the closure members there is an explosion hazard.
With metal structure and metal closures the problem is overcane by achieving good metal to metal contact outside the fuel seal but this is reliant on the fact that metal is of good conductivity and is electrically hooogenous. Components manufactured from carbon fibre composites do not have these properties and it is therefore necessary to provide specific pathways for lightning currents to follow. A further problem resulting from the lower conductivity of carbon fibres is that the lightning current will tend to penetrate into the carbon structure whereas with metal structures there will be a tendency for it to remain on the surface. It is the object of the present invention to provide a solution to the problems associated with lightning strike and carbon fibre composite structures.
According to one aspect of the present invention, there is provided a structural arrangement for the transmission and control of lightning strike current flows across an interface between an aperture in a carbon fibre composite structure and a closure member located in said aperture, said arrangement including:
a composite skin structure comprising a rmltiplicity of resin bonded carbon fibre plies, and at least one outer metalic laminate layer::
an aperture in said composite skin structure,
a closure member substantially conforming to said aperture,
a carbon fibre composite landing member campr ising a multiplicity of resin bonded plies located to the underside of said skin structure and protruding into said aperture to provide a landing for said closure member;;
a metallic gasket comprising an outer flange ring and a stepped inner flange ring, said step substantially corresponding in depth to the overall thickness of said composite skin structure,
said gasket located to said structure such that the undersurface of said outer flange ring is in close contact with said outer metallic laminate layer and the undersurface of said inner flange ring seats on said landing and is clamped by and supports said closure member and said arrangement further including fuel sealing means.
the arrangement being such that current flows arising fran a lightning strike passing along the outer metallic laminate layer in the region of said aperture is constrained to flow through the gasket bridging the interface between said aperture and said closure member.
Preferably said outer metallic laminate layer is of a suitable metallic mesh.
Preferably, said gasket is located to said skin structure outer surface by countersunk headed fastener means and said closure member is clapped to said landing means by countersunk headed bolts engaging fastening means located to the undersurface of said landing means.
Preferably said closure member is of aluminium alloy.
One embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Figure 1 is a cross-section through one edge of a typical prior art arrangement of a light alloy access door and structure assembly, for example in an aircraft fuel tank.
Figure 2 is a typical plan view on an access door installation in an aircraft wing skin in accordance with the present invention.
Figure 3 is a plan view through a typical access door gasket arrangement in accordance with the invention.
Figure 4 is a longitudinal section, to a larger scale, through the access door arrangement along a line IV-Iv in Figure 2.
Figure 5 is a typical cross-section through the gasket of the present invention along V-V in Figure 3.
Referring to the drawings, Figure 1 depicts one edge of a conventional access door attachment in a wing skin 1 having an outer skin surface 2 and cut into the wing skin an access opening 3, the periphery of the opening including a tapered rebated panel seating 4 and a metallic mesh gasket 5 on to which seats the access door 6 whose outer surface 7 conforms to the wing outer skin surface 2. The door 6 includes an elastomer fuel seal 8 and the assembly is clapped together by a panel fastener 9. In this prior art example the skin 2, and the access door 6 are of light alloy.This arrangement serves to illustrate that with good metal to metal contact outside the fuel seal 8 good conductivity is achievable so that in the event of a lightning strike the electrical current passing spanwise across the wing will do so across the structure to access door interface without inducing hazardous arcing which is particularly unacceptable in an aircraft fuel tank situation.
In the case of a carbon fibre composite wing structure, or indeed any other aircraft structural component utilising carbon fibre composite and which may be subject to lightning strike, the conductive properties of the material are naturally lower. Carbon fibre wing structures are particularly singled out because of the well known use of aircraft wings for fuel storage.
Figures 2 and 4 show a typical access opening 10 and its associated access door 11 in an aircraft wing skin 12 of carbon fibre composite construction. This construction comprises a number of layers of carbon fibre laminates 13 resin bonded, the number of plies dependent on structural requirements. To protect the structure fran the effects of a direct lightning strike attachment the outer surface of the composite includes a layer of metallic mesh 14. The effective access opening 15 in this arrangement is determined by a carbon fibre door landing 16 of similar laminate construction but does not incorporate aluminium mesh. This door landing 16 is attached to the underside of the wing skin 12 by means of a number of proprietary fasteners 17 and 17a.The access door 11 is of aluminium alloy and is attached to the door landing 16 by a number of countersunk headed bolts 19 engaging fuel tight captive nuts 18 located to the underside of the landing. In both instances countersunk headed bolts are used in accordance with common aircraft practice although raised head bolts could be equally well employed if desired. An elastaner seal 21 is inserted between the door landing 16 and the door panel 11.
If the components so far described were bolted together considerable arcing within the tank could occur as the lightning current passed fran the structure 12 via the outer ring of bolts 17 to the door landing 16 and thence to the access door via the inner ring of bolts 19 with the reverse process occurring as the current leaves the access doors.
To overcame this, thus ensuring that the current transfers directly from structure to door and vice versa without entering the tank a metallic gasket 20 is introduced whose cross-section is as indicated in Figures 4 and 5. Obviously dimensional variations and configuration will be dependent on requirements such as panel and skin thicknesses and access opening arrangements. Figure 3 shows a plan view arrangement of a typical gasket.
The e gasket 20 comprises an outer flange ring 22 on a stepped inner flange ring 23, the step 23a corresponding to the structural thicknesses employed. The e outer flange ring 22 incorporates dimpled holes to accept the countersunk headed bolts 17. The e inner flange 23 ring terminates at 24, ie, just clearing the shank of the bolts 19.
The inner flange 23 further incorporates a raised bead 7 ring 25 for the purpose of ensuring continued electrical contact with the door after repeated door removals.
In operation the gasket is placed in position at the access position and the outer flange ring 22 is clapped down onto the outer metallic laminate layer 14 by means of the countersunk head bolts 17.
The e inner flange ring is clamped by the access door 11 when bolted in position. Electrical contact is therefore made via the gasket between the wing structural skin 12 via the layer of metallic mesh 14 at it outer surface and the underside of the door panel but outside the boundary of the elastomer seal 21, effectively therefore outside the fuel tank.
Claims (4)
1 A structural arrangement for the transmission and control of lightning strike current flows across an interface between an aperture in a carbon fibre composite structure and a closure member located in said aperture, said arrangement including:
a composite skin structure comprising a multiplicity of resin bonded carbon fibre plies and at least one outer metallic laminate layer.
an aperture in said composite skin structure;
a closure member substantially conforming to said aperture;
a carbon fibre composite landing member comprising a multiplicity of resin bonded plies located to the underside of said skin structure and protruding into said aperture to provide a landing for said closure member;
a metallic gasket comprising an outer flange ring and a stepped inner flange ring, said step substantially corresponding in depth to the overall thickness of said composite skin structure;;
said gasket located to said structure such that the undersurface of said outer flange ring is in close contact with said outer metallic laminate layer and the undersurface of said inner flange ring seats on said landing and is clamped by and supports said closure member and said arrangement further including fuel sealing means,
the arrangement being such that current flows arising fran a lightning strike passing along the outer metallic laminate layer in the region of said aperture is constrained to flow through the gasket bridging the interface between said aperture and said closure member.
2 A structural arrangement according to Claim 1 in which said outer metallic laminate layer is of metallic mesh.
3 A structural arrangement according to Claim 1 in which said
closure member is of aluminium alloy.
4 A structural arrangement substantially as hereinbefore described
and with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB878704585A GB8704585D0 (en) | 1987-02-26 | 1987-02-26 | Lighting strike protection |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8804170D0 GB8804170D0 (en) | 1988-03-23 |
| GB2201737A true GB2201737A (en) | 1988-09-07 |
| GB2201737B GB2201737B (en) | 1990-05-16 |
Family
ID=10613019
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB878704585A Pending GB8704585D0 (en) | 1987-02-26 | 1987-02-26 | Lighting strike protection |
| GB8804170A Expired - Lifetime GB2201737B (en) | 1987-02-26 | 1988-02-23 | Lightning strike protection for aircraft structures |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB878704585A Pending GB8704585D0 (en) | 1987-02-26 | 1987-02-26 | Lighting strike protection |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8704585D0 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0318839A2 (en) * | 1987-12-04 | 1989-06-07 | The Boeing Company | Apparatus for providing a lightning protective vehicle surface |
| EP0685389A1 (en) * | 1994-06-02 | 1995-12-06 | British Aerospace Public Limited Company | Method of fastening composite aircraft skins |
| JP2011524306A (en) * | 2008-06-17 | 2011-09-01 | エアバス オペラシオン（エス．ア．エス） | System for discharging lightning current generated by lightning discharge to aircraft |
| US20150014308A1 (en) * | 2006-10-13 | 2015-01-15 | The Boeing Company | Edge seals for composite structure fuel tanks |
| EP2500272A3 (en) * | 2011-03-14 | 2015-05-06 | Mitsubishi Aircraft Corporation | Coupling structure for airframe components |
-
1987
- 1987-02-26 GB GB878704585A patent/GB8704585D0/en active Pending
-
1988
- 1988-02-23 GB GB8804170A patent/GB2201737B/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0318839A2 (en) * | 1987-12-04 | 1989-06-07 | The Boeing Company | Apparatus for providing a lightning protective vehicle surface |
| EP0318839A3 (en) * | 1987-12-04 | 1990-11-14 | The Boeing Company | Apparatus for providing a lightning protective vehicle surface |
| EP0685389A1 (en) * | 1994-06-02 | 1995-12-06 | British Aerospace Public Limited Company | Method of fastening composite aircraft skins |
| US20150014308A1 (en) * | 2006-10-13 | 2015-01-15 | The Boeing Company | Edge seals for composite structure fuel tanks |
| US10384794B2 (en) * | 2006-10-13 | 2019-08-20 | The Boeing Company | Edge seals for composite structure fuel tanks |
| JP2011524306A (en) * | 2008-06-17 | 2011-09-01 | エアバス オペラシオン（エス．ア．エス） | System for discharging lightning current generated by lightning discharge to aircraft |
| EP2500272A3 (en) * | 2011-03-14 | 2015-05-06 | Mitsubishi Aircraft Corporation | Coupling structure for airframe components |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8704585D0 (en) | 1987-04-01 |
| GB8804170D0 (en) | 1988-03-23 |
| GB2201737B (en) | 1990-05-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0685389B1 (en) | Method of fastening composite aircraft skins | |
| US7554785B2 (en) | Lightning damage protection for composite aircraft | |
| US4479163A (en) | Integral lightning protection system for composite aircraft skins | |
| US5175665A (en) | Lighting resistant composite structures | |
| EP0580417A1 (en) | A lightning shield | |
| DE3686053T2 (en) | LIGHTNING PROTECTION DEVICE FOR CONDUCTING COMPOSITE STRUCTURES. | |
| US7936550B2 (en) | Fastening assembly including washer for sealing the assembly for lightning strike protection in composite structures | |
| RU2448875C2 (en) | Aircraft assembly | |
| US20110255205A1 (en) | Protection device against electrical discharges in aircraft | |
| EP2962933B1 (en) | Closing member for opening | |
| US4760493A (en) | Lightning protection system for composite material aircraft structures | |
| EP2830948B1 (en) | Fastener systems that provide eme protection | |
| US20120091269A1 (en) | Lightning strike protection in aircraft | |
| EP1826120B1 (en) | Method and system for electrical bonding of fuel tank penetrations | |
| US4884929A (en) | Flush head fastener | |
| EP0579675A1 (en) | A structural component | |
| EP2871132B1 (en) | Fastener systems that provide EME protection | |
| US4979281A (en) | Method of installing a flush head fastener | |
| GB2201737A (en) | Lightning strike protection gasket | |
| EP2465776B1 (en) | Lightning and corrosion protection arrangement in an aircraft structural component | |
| US2576734A (en) | Access door and method of making and mounting the same | |
| CN214986115U (en) | Novel lightning stroke protection structure of composite material integral oil tank non-bearing opening cover | |
| US20240009961A1 (en) | Structure with lightning-strike protection layer | |
| US20240140616A1 (en) | Device for creating a stiffened region on an outer structure of an aircraft for subsequently providing a service access if required, and method for producing and using such a service access |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19940223 |