Fire seal end cap and associated multi-member assembly and method

A multi-member assembly including a first structural member, a second structural member opposed from the first structural member, a crossover seal positioned between the first and second structural members, wherein the crossover seal defines a bore, and an end cap including a cap portion and a plug portion protruding from the cap portion, wherein the plug portion is at least partially received in the bore such that the cap portion bridges the first and second structural members.

FIELD

This application relates to fire barriers and, more particularly, to apparatus and methods for establishing a fire seal that eliminates (or at least reduces) gaps.

BACKGROUND

Aircraft engines are typically housed in a nacelle. A pylon extends from the nacelle to couple the engine to the aircraft. As one example, the pylon may couple the engine to a wing of the aircraft (e.g., the engine may be suspended below the wing). As another example, the pylon may couple the engine directly to the fuselage of the aircraft (e.g., the engine may be mounted to the side of the fuselage proximate the rear of the fuselage).

In modern aircraft, various steps are taken to inhibit the spread of flames to the wings and fuselage of the aircraft in the event of an engine fire. For example, all structural interfaces within the engine/pylon assembly are sealed with fireproof (or fire-resistant) material to eliminate gaps through which flames may propagate.

Structural interfaces vary with manufacturing tolerances and many are dynamic and, thus, are difficult to seal. For example, the interface between the forward side of the pylon and the aft side of the engine firewall can be quite dynamic—the engine firewall moves fore/aft, side-to-side and up/down relative to the pylon. A crossover seal is often positioned between the engine firewall and the pylon to provide the necessary seal, while accommodating the movement of the engine firewall. It is convenient when arranging the seal routings for the thrust reverser fire seal to lie over the crossover seal, but such a configuration may create gaps.

Accordingly, those skilled in the art continue with research and development efforts in the field of aircraft fire barriers.

SUMMARY

In one aspect, the disclosed fire seal end cap may include a cap portion and a plug portion, wherein the plug portion protrudes from the cap portion, and wherein the cap portion and the plug portion are formed from fire-resistant material.

In another aspect, the disclosed multi-member assembly may include a first structural member, a second structural member opposed from the first structural member, a crossover seal positioned between the first and second structural members, wherein the crossover seal defines a bore, and an end cap including a cap portion and a plug portion protruding from the cap portion, wherein the plug portion is at least partially received in the bore such that the cap portion bridges the first and second structural members. Optionally, a third structural member may lie over the cap portion of the end cap.

In another aspect, the disclosed multi-member assembly may include a pylon, an engine fire wall opposed from the pylon, a crossover seal positioned between the pylon and the engine fire wall, wherein the crossover seal defines a bore, and an end cap including a cap portion and a plug portion protruding from the cap portion, wherein the plug portion is at least partially received in the bore such that the cap portion bridges the pylon and the engine fire wall. Optionally, a thrust reverser and associated thrust reverser fire seal may lie over the cap portion of the end cap.

In yet another aspect, disclosed is a fire sealing method. The method may include the steps of (1) providing a first structural member opposed from a second structural member; (2) positioning a crossover seal between the first structural member and the second structural member, wherein the crossover seal defines a bore; (3) providing an end cap including a cap portion and a plug portion protruding from the cap portion; and (4) positioning the end cap such that the plug portion is at least partially received in the bore and the cap portion bridges the first structural member and the second structural member.

Other aspects of the disclosed fire seal end cap and associated multi-member assembly and method will become apparent from the following detailed description, the accompanying drawings and the appended claims.

DETAILED DESCRIPTION

Referring toFIG. 1, an aircraft, generally designated10, may include a fuselage12, wings14, engines16and pylons18. The pylons18may couple the engines16to the aircraft10(e.g., to the wings14).

As shown inFIGS. 2A and 2B, each pylon18may include a strut box20proximate (at or near) the forward end19of the pylon18. The strut box20may be connected to, or integral with, the pylon18. Optionally, thrust reverser hinges22,24may be connected to the pylon18proximate the strut box20.

Each engine16(FIG. 1) may be mounted to the aircraft10(FIG. 1) by way of an associated pylon18. Each engine16may include an engine fire wall26. The engine fire wall26may be attached to the fan case (not shown) of the engine16.

A crossover seal28may be positioned at the interface30between the pylon18(a first structural member) and the engine16(a second structural member). In one configuration, as shown inFIG. 3, the crossover seal28may be connected to the strut box20of the pylon18, such as with mechanical fasteners and/or adhesives (e.g., RTV106 silicone adhesive available from MG Chemicals, Ltd. of Canada). The crossover seal28may be in abutting engagement with, but not directly connected to, the engine fire wall26of the engine16. Therefore, the crossover seal28may seal the interface30(FIG. 2B) between the strut box20and the engine fire wall26without inhibiting fore/aft, side-to-side and up/down movement of the engine fire wall26relative to the strut box20. In another configuration, the crossover seal28may be connected to the engine fire wall26, but not to the strut box20.

Referring toFIG. 3, the crossover seal28may include an elongated body32that laterally extends along the strut box20. The elongated body32of the crossover seal28may be a single monolithic body and may have a first end34and a second, opposite end36. The elongated body32of the crossover seal28may define a bore38, which may extend (continuously or not) from the first end34of the elongated body32to the second end36such that openings to the bore38are presented at the first and second ends34,36of the crossover seal28.

The crossover seal28may be formed from a fire-resistant material that is deformable yet resilient. Selection of a suitable fire-resistant material may allow the crossover seal28to inhibit flame propagation. Selection of a suitable deformable yet resilient material may allow the crossover seal28to deform and relax (like a bumper or boat fender) such that the crossover seal28maintains a seal between the engine fire wall26and the strut box20even as the engine fire wall26moves relative to the strut box20. As one example, the crossover seal28may be formed from a silicone rubber material. As another example, the crossover seal28may be formed from a foamed material. As yet another example, the crossover seal28may be formed from a foamed silicon rubber material.

Thus, as shown inFIGS. 10A and 10B, the crossover seal28may deform (FIG. 10B) and relax (FIG. 10A) between the engine fire wall26and the strut box20as the engine fire wall26moves fore/aft (arrow A) relative to the strut box20, thereby maintaining a seal between the engine fire wall26and the strut box20. Configurations in which the crossover seal28is deformed in other directions (e.g., up/down or side-to-side) are also contemplated.

Referring toFIG. 4, the disclosed fire seal end cap40may be connected to the crossover seal28, such as by inserting a portion of the fire seal end cap40into the bore38of the crossover seal28. Therefore, the fire seal end cap40may overlap (e.g., loosely overlap) both the strut box20and the engine fire wall26, thereby bridging the interface30between the strut box20and the engine fire wall26without inhibiting fore/aft, side-to-side and up/down movement of the engine fire wall26relative to the strut box20.

Referring toFIGS. 5-7, the disclosed fire seal end cap40may include a plug portion42and a cap portion44. The plug portion42of the fire seal end cap40may be inserted into the bore38(FIG. 4) of the crossover seal (FIG. 4) to connect the fire seal end cap40to the crossover seal28and to position the cap portion44of the fire seal end cap40to bridge the interface30between the strut box20and the engine fire wall26.

The cap portion44of the end cap40may have a maximum lateral width W (FIG. 7) sufficient to bridge the interface30between the strut box20and the engine fire wall26. Additionally, the cap portion44may have a maximum vertical height H (FIG. 7) sufficient to provide the required seal function. As one specific, non-limiting example, the lateral width W of the cap portion44may range from about 3 to about 5 inches (e.g., 3.75 inches) and the vertical height H of the cap portion44may range from about 2 to about 4 inches (e.g., 3 inches). As another specific, non-limiting example, the lateral width W of the cap portion44may range from about 2 to about 10 inches and the vertical height H of the cap portion44may range from about 1 to about 8 inches. As yet another specific, non-limiting example, the lateral width W of the cap portion44may range from about 1 to about 20 inches and the vertical height H of the cap portion44may range from about 1 to about 15 inches. These ranges are provided for illustrative purposes only—actual dimensions may depend on the specific application.

The maximum cross-sectional thickness T (FIG. 6) of the cap portion44may be dictated by, among other things, the types of materials used to form the end cap40. Materials that are relatively less fire-resistant may warrant a cap portion44having a greater cross-sectional thickness T, while materials that are relatively more fire-resistant may facilitate using a thinner cross-sectional thickness T. As one specific, non-limiting example, the maximum cross-sectional thickness T of the cap portion44may range from about 0.0625 inches to about 0.25 inches, such as about 0.125 inches. As another specific, non-limiting example, the maximum cross-sectional thickness T of the cap portion44may range from about 0.03 inches to about 1 inch. As yet another specific, non-limiting example, the maximum cross-sectional thickness T of the cap portion44may range from about 0.001 inches to about 2 inches.

As shown inFIG. 5, the maximum cross-sectional thickness T of the cap portion44may occur proximate the center of the cap portion44. However, the cross-sectional thickness may taper down (thin) from the center outward (e.g., from the center to the left and right inFIG. 7).

Thus, the cap portion44may have a first major surface46(FIG. 7) and a second, opposed major surface48(FIG. 8).

The cap portion44may have a generally rectilinear shape (e.g., rectangular shape) in front view. Any corners may be rounded (radiused), as best shown inFIG. 7, to eliminate sharp corners that may cause snags and the like. Additionally, as best shown inFIG. 6, the cap portion44may be curved (e.g., from the top edge50to the bottom edge52) such that the cap portion44is slightly concave, thereby allowing the cap portion44to better conform to the contours of the surrounding structure. While a specific cap portion44is shown and described, those skilled in the art will appreciate that cap portions having various shapes and configurations may be used without departing from the scope of the present disclosure.

The plug portion42of the end cap40may be integral with the cap portion44(the plug portion42and the cap portion44may be formed as a single monolithic body). Alternatively, the plug portion42may be formed separately from the cap portion44and then later connected to the cap portion44, such as with adhesives, mechanical fasteners and/or any other appropriate joining technique.

The plug portion42may protrude outward a maximum distance D (FIG. 6) from the first major surface46of the cap portion44. As one specific, non-limiting example, the protruding distance D of the plug portion42may range from about 0.5 to about 2 inches, such as about 1 inch. However, the actual protruding distance D may depend on the specific application and other factors, such as the depth of the bore38(FIG. 4) in the crossover seal28(FIG. 4). As shown inFIG. 7, the plug portion42may protrude from proximate the center of the first major surface46of the cap portion44, though various off-sets from center may be used depending on application.

The plug portion42may be substantially normal to the first major surface46of the cap portion44. However, as shown inFIG. 6, the plug portion42may protrude at a non-zero angle θ relative to normal. As one specific, non-limiting example, the angle θ may range from about 1 to about 20 degrees.

Optionally, the plug portion42of the end cap40may be shaped to accommodate deformation/compression of the crossover seal28when the plug portion42is received in the bore38of the crossover seal, as shown inFIGS. 10A and 10B. The particular shape of the plug portion42, particularly the cross-sectional shape in front view, may be dictated by, among other things, the shape of the bore38defined by the crossover seal28.

In one particular implementation, the plug portion42of the end cap40may have a generally hemispherical (or D-shaped) cross-section in front view. Specifically, referring toFIGS. 5, 7, 10A and 10B, the plug portion42may include a substantially flat forward end54and a curved rear end56. The curved rear end56of the plug portion42may closely correspond to the contour of the bore38of the crossover seal28. The substantially flat forward end54of the plug portion42may define a gap58(FIG. 10A) between the crossover seal28and the plug portion42such that the plug portion42of the end cap40does not interfere with compression (FIG. 10B) of the crossover seal28by the engine fire wall26.

The fire seal end cap40may be formed from various fire-resistant materials or combination of materials. Suitable fire-resistant materials (or combinations) may render the end cap40substantially stiff yet pliable such that the end cap40generally maintains its shape but conforms to the surrounding structure. Therefore, the end cap40may be self-adjusting to accommodate variations from manufacturing tolerances, flight deflection and vibrations, thermal growth and the like.

In one particular construction, the end cap40may be formed from a first fire-resistant composite material. The first fire-resistant composite material may include a woven ceramic fabric infused with a silicone matrix material. For example, the end cap40may be formed from a fire-resistant composite material that includes NEXTEL® woven ceramic fabric (3M Company of St. Paul, Minn.) infused with high temperature silicone (e.g., BMS 1-74), which may include a red iron oxide component that may render the composition heat-resistant.

In another particular construction, the end cap40may be formed from a second (e.g., fire-resistant) composite material. One (e.g., the cap portion44) or both the cap portion44and the plug portion42may be formed from the second composite material. The second composite material may include a woven ceramic fabric and a low friction material infused with a silicone matrix material. The low friction material may have a static coefficient of friction of at most about 0.15. One specific, non-limiting example of a low friction material is polyester fiber (or fabric). The polyester fiber/fabric may be positioned proximate the first and second major surfaces46,48(FIG. 6) of the cap portion44of the end cap40to provide smooth, low-friction surfaces46,48(e.g., a static coefficient of friction of at most about 0.15). Non-limiting examples of suitable polyester fibers/fabrics include DACRON® polyester fiber (Invista North America of Wichita, Kans.), NOMEX® polyester fabric (E. I. du Pont de Nemours and Company of Wilmington, Del.) and sailcloth. As one specific example, the end cap40may be formed from a fire-resistant composite material that includes NEXTEL® woven ceramic fabric (3M Company of St. Paul, Minn.) and DACRON® polyester fiber (Invista North America of Wichita, Kans.) infused with high temperature silicone (e.g., BMS 1-74), which may include a red iron oxide component that may render the composition heat-resistant.

In yet another particular construction, the end cap40may be constructed from a molded, isotropic material, such as a flexible ceramic, that is fire-resistant and smooth, low friction.

At this point, those skilled in the art will appreciate that various fire-resistant materials, including various fire-resistant composite materials, may be used to form the disclosed fire seal end cap40. In addition to fire-resistance, material selection may additionally consider vibration wear, scrubbing of seals relative to open/close of thrust reverser, high velocity air impinging along seal, tearing, and environment, such as heat (heat embrittlement), fuel and oil.

Referring toFIGS. 8 and 9, the end cap40may be deployed by inserting the plug portion42of the end cap40into the bore38of the crossover seal28such that the cap portion44of the end cap40overlaps both the strut box20and the engine fire wall26(FIG. 4). An adhesive60may be used to connect the end cap40to the strut box20and/or the crossover seal28. For example, the adhesive60may connect a portion of the first major surface46of the cap portion44of the end cap40to a portion of the strut box20and to a portion of the first end34of the crossover seal28. Additionally, the adhesive60may connect the curved rear end56of the plug portion42of the end cap40to a corresponding portion of the bore38(the bore wall) of the crossover seal28.

The adhesive60may be a fire-resistant adhesive, such as RTV106 silicone adhesive available from MG Chemicals, Ltd. of Canada. Pressure clamps and heat (e.g., heat lamps) may be used to properly set the adhesive60and fix the end cap40in place. At this point, those skilled in the art will appreciate that mechanical fasteners, such as brackets, clips, rivets and the like, may be used in addition to, or as an alternative to, the adhesive60.

With the end cap40deployed, the cap portion44of the end cap40may bridge the interface30(FIG. 4) between the strut box20and the engine fire wall26without inhibiting fore/aft (FIGS. 10A and 10B), side-to-side and up/down movement of the engine fire wall26relative to the strut box20. Therefore, as shown inFIG. 11, a thrust reverser62(a third structural member) and associated thrust reverser fire seal64may lie over the cap portion44of the end cap40without creating gaps.

Accordingly, the disclosed fire seal end cap40may facilitate a multi-member assembly (e.g., pylon, engine and thrust reverser) that is fire sealed and substantially free of gaps despite significant movement of one member (the engine) relative to the other members (pylon and thrust reverser). While a particular multi-member assembly (engine/pylon/thrust reverser) is shown and described, the disclosed fire seal end cap40may find application in various T-shaped seal junctions.

Also disclosed is a fire sealing method, generally designated100. The method100may begin at block102with the step of providing a first structural member opposed from a second structural member. The first structural member may be a pylon and the second structural member may be an engine.

At block104, a crossover seal may be positioned between the first structural member and the second structural member. The crossover seal may define a bore and may be connected to the first structural member (but may not be connected to the second structural member) to facilitate movement of the second structural member relative to the first structural member.

At block106, an end cap may be provided. The end cap may include a cap portion and a plug portion. The plug portion may protrude from the cap portion.

At block108, the end cap may be deployed. Specifically, the end cap may be positioned such that the plug portion is at least partially received in the bore of the crossover seal. Therefore, the cap portion may bridge the first structural member and the second structural member.

At block110, a third structural member may be provided. For example, the third structural member may be a thrust reverser, which may include an associated thrust reverser fire seal. The third structural member may be positioned against the cap portion of the end cap (block112), thereby providing a fire sealed multi-member assembly that is substantially free of gaps.

Referring toFIG. 13, another aspect of the disclosed fire seal end cap, generally designated200, may include a cap portion202, but no plug portion. Therefore, the fire seal end cap200may bridge the interface between the engine16(FIG. 1) and the pylon18(FIG. 1) without extending into the bore38(FIG. 3) defined by the crossover seal28(FIG. 3).

In yet another aspect, the disclosed fire seal end cap may be integral with the crossover seal (i.e., the crossover seal and the end cap may be formed as a single, monolithic body).

Although various aspects of the disclosed fire seal end cap and associated multi-member assembly and method have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.