Rotary-wing aircraft with firewall construction

Abstract

The present invention relates to a rotary-wing aircraft having a fuselage that forms an interior region of the aircraft, the fuselage including an upper main skin that separates the interior region of the aircraft from an upper cabin of the aircraft disposed above the fuselage, wherein the upper cabin of the aircraft includes an engine accommodation region having a firewall structure (10), the engine accommodation region accommodating at least one aircraft engine (11) within the firewall structure (10), wherein the firewall structure (100) includes at least one gasket (10g) for sealing a passage of a torque tube (15) that connects at least one aircraft engine (11) to a main gearbox (17) of the rotary-wing aircraft, and wherein the at least one gasket (10g) includes at least two fireproof casings (12b) and an annular flexible fireproof bellows (13).

Description

Technical Field

[0001] The present invention relates to a rotary-wing aircraft having a fuselage that forms an interior area of the aircraft, the fuselage including an upper main skin that separates the interior area of the aircraft from an upper deck of the aircraft disposed above the fuselage, wherein the upper deck of the aircraft includes an engine accommodation area having a firewall structure. Background Art

[0002] In a rotary-wing aircraft such as a small or medium-sized helicopter, the associated fuselage typically includes an upper main skin that separates the interior area of the aircraft formed by the fuselage from an upper deck of the aircraft disposed above the fuselage. The interior area of the aircraft typically houses at least one cockpit and may also house a cabin for passengers and / or cargo.

[0003] The upper deck of the aircraft typically includes an engine accommodation area that houses one or more engines (usually air-breathing gas turbines) and is thus also referred to as an "engine nacelle". Typically, one or more engines are disposed on the engine nacelle outside the interior area of the aircraft, at the top of the fuselage and near other main components of the corresponding powerplant, the main gearbox, and the main rotor.

[0004] One or more engines are typically adapted to drive the rotary-wing aircraft by providing power to a suitable propulsion unit (e.g., a main rotor, a propeller, etc.). More specifically, the power of one or more engines is transmitted to an associated power distribution unit (e.g., the main gearbox of the rotary-wing aircraft), which then provides the power to a suitable propulsion unit. For example, the power is transmitted from a designated engine to the corresponding main gearbox via an associated torque tube.

[0005] According to airworthiness certification regulations, the engine nacelle of a designated rotary-wing aircraft must be fireproof in the event of a fire. Thus, the engine nacelle is generally equipped with a suitable firewall structure as a whole, which forms a fireproof zone. The fireproof zone houses the engine within the firewall structure such that the firewall structure defines a fireproof partition between the engine and the interior area of the aircraft formed by the fuselage of the designated rotary-wing aircraft towards the front and rear regions of the engine nacelle. The firewall structure is also provided to ensure the required flammable fluid seal and to protect the corresponding environmental control system, main gearbox, and flight control devices of the designated rotary-wing aircraft.

[0006] More specifically, the firewall construction in the engine compartment generally includes a front firewall and a rear firewall, and is typically defined by the upper main skin of the fuselage forming the lower firewall and the fairing that represents the upper layer of the designated rotary-wing aircraft and covers the engine compartment. Such a front firewall and a rear firewall are designed to enhance the stability of the corresponding upper-level secondary structure of the aircraft, and while providing rigidity to the firewall with the covering fairing, keep the fairing in place. Since the fairing covers all the devices and equipment located on the upper-level compartment of the aircraft in the closed state, the fairing also forms a protection for the engine compartment, and more generally protects the upper-level compartment of the aircraft from the external environment of the designated rotary-wing aircraft. In addition, the fairing improves the corresponding aerodynamic characteristics of the designated rotary-wing aircraft due to its basic shaping, thus reducing the aerodynamic drag, while carrying all the generated flight loads and transferring them to the main structure of the designated aircraft, i.e., the designated aircraft frame. In addition, the fairing also supports and bears other loads, such as the loads of the designated regulation and ventilation systems, intake protection grilles, engine plenums, and engine exhaust nozzles of the rotary-wing aircraft.

[0007] If the rotary-wing aircraft is a twin-engine aircraft, the two engines are typically separated from each other by the center or intermediate firewall of the firewall construction to protect the two engines from affecting each other, such that each engine is disposed in a separate and independently enclosed engine compartment. Generally, in such a firewall construction, the corresponding front firewall and rear firewall and the intermediate firewall (if any) are auxiliary components typically made of titanium plates. The typical thickness of such titanium plates is 1.2 mm, although it has been considered that a minimum thickness of 0.4 mm can achieve fire resistance.

[0008] In any case, the (one or more) engines of the designated rotary-wing aircraft are attached to the upper main skin and corresponding structural members (e.g., beams or frames) by a plurality of engine mounts, and certain parts of the firewall construction are typically removable, so as to enable access to the (one or more) engines or other mechanical components, for example, during the maintenance phase. The front firewall and the rear firewall represent the corresponding front and rear barriers for the upper-level compartment of the designated aircraft. The fairing is typically at least partially removable to provide access to the engine, for example, for maintenance purposes.

[0009] Exemplary firewall constructions are described in documents EP2046638B1, EP2443034B1, EP2917532B1, US9868545B2, and US2018 / 0156131A1. Documents EP3131817, EP1482228, and US2020400250 are cited.

[0010] More particularly, document EP3056423A1 describes a rotary-wing aircraft having at least a fuselage defining an internal area and an engine accommodation area provided inside the fuselage and including at least one fire zone defined by at least one associated firewall structure. At least one fire zone accommodates at least one engine within at least one associated firewall structure such that the associated firewall structure defines a fire separation between at least one engine and the internal area of the fuselage. At least one associated firewall structure includes a plurality of interconnected firewalls defining at least one fire zone, including a front firewall, a rear firewall, a lower firewall, and an intermediate firewall.

[0011] In summary, the specified firewall structure ensures an airtight, watertight, and fluid-tight separation of each associated engine compartment. The remaining gaps between the movable and fixed components on the engine nacelle are tightly sealed with suitable fire seals and / or gaskets. The corresponding gaskets are used, for example, to seal the passage of the associated torque tube that connects the specified engine to the corresponding main gearbox of the specified rotary-wing aircraft. More particularly, the gasket is arranged to form a barrier against flammable fluids as well as a fire separation and heat insulation between the associated torque tube and the specified engine.

[0012] Gaskets generally more or less arranged to surround the associated tube for forming a heat insulation and / or fire barrier are described, for example, in documents US10,435,136B2, EP0900346B1, and WO1997 / 004838A1.

[0013] Document EP3556661A1 further describes a rotary-wing aircraft having an engine compartment that houses an aircraft engine and is provided with a firewall structure including a front firewall and a gasket. A torque tube (i.e., a drive shaft assembly) couples the aircraft engine to an associated reduction gearbox assembly. The torque tube is at least partially disposed within a flexible sealing member that is integrated into the front firewall and forms the gasket. The flexible sealing member is configured to accommodate the movement of the aircraft engine relative to an inlet hole formed in the front firewall and may be made of neoprene and / or silica and / or other (multiple) flexible fireproof materials in which fiberglass cloth is embedded.

[0014] However, during maintenance of the specified rotary-wing aircraft and its (multiple) aircraft engines, the corresponding torque tube must be fully accessible to allow verification and inspection of all connections, fasteners, etc. Therefore, the associated gasket surrounding the corresponding torque tube must be removed. However, this removal is typically only achieved by disassembling the torque tube from the associated main gearbox, loosening and separating the (multiple) aircraft engines, and displacing the (multiple) aircraft engines relative to the associated gasket. However, this is a very time-consuming and demanding operation. Summary of the Invention

[0015] Accordingly, an object of the present invention is to provide a novel rotary-wing aircraft having a firewall construction with a gasket that allows full access to an associated torque tube during maintenance. This object is solved by a rotary-wing aircraft having the features of the present invention.

[0016] More specifically, according to the present invention, there is provided a rotary-wing aircraft having a fuselage forming an interior region of the aircraft, wherein the fuselage includes an upper main skin that separates the interior region of the aircraft from an upper compartment of the aircraft disposed above the fuselage. The upper compartment of the aircraft includes an engine accommodation region having a firewall construction. The engine accommodation region accommodates at least one aircraft engine within the firewall construction such that the firewall construction defines a fire separation and a flammable fluid seal at least between the at least one aircraft engine and the interior region of the aircraft. The firewall construction includes at least one gasket for sealing a passage of a torque tube that connects the at least one aircraft engine to a main gearbox of the rotary-wing aircraft. The at least one gasket includes at least two fireproof shells removably attached to each other to form a tubular structure and an annular flexible fireproof bellows mounted on the at least two fireproof shells and configured to compensate for movement of the torque tube relative to the firewall construction.

[0017] Preferably, the firewall construction defines a fire separation and a flammable fluid seal not only between the at least one aircraft engine and the interior region of the aircraft but also more generally between the at least one aircraft engine and all other adjacent aircraft regions. These other adjacent aircraft regions include the interior region of the aircraft and the front and rear regions of the engine accommodation region, such as a gearbox or an exhaust accommodation region. The firewall construction may include a front firewall, a rear firewall, and an intermediate firewall.

[0018] Advantageously, the firewall construction allows complete elimination of damage to the fuselage by confining the fuselage, which forms the main structure of the rotary-wing aircraft, within an auxiliary protection element, i.e., within the firewall construction of the corresponding engine accommodation compartment, in the event of a fire. Thus, any repair work on the main structure of the aircraft after a fire can be eliminated or at least reduced to a minimum.

[0019] In addition, by providing at least one gasket for sealing a passage of an associated torque tube to the firewall construction, a fire separation and heat insulation between the associated torque tube and the at least one engine and a flammable fluid barrier between the associated torque tube and the at least one engine can be advantageously provided. The at least one gasket can be removably attached to the firewall construction by associated quick-release fasteners, particularly quarter-turn quick-release fasteners.

[0020] Advantageously, at least one gasket is modifiable and can be easily and comfortably installed onto the associated torque tube or removed therefrom by detaching the annular flexible fireproof bellows from at least two fireproof housings and separating the at least two fireproof housings from each other. Thus, loosening, disassembly, and displacement of at least one aircraft engine as described above can be advantageously avoided, thereby protecting and accelerating, for example, the corresponding maintenance operations.

[0021] Preferably, at least one gasket consists of two semi-cylindrical housings and a flexible bellows. The flexible bellows can be attached to the associated mating part of at least one aircraft engine by means of mushroom-headed pins. For example, the two semi-cylindrical housings can be removably attached to each other by associated housing clamps. This allows the gasket to be disassembled without affecting at least one aircraft engine. Advantageously, such a gasket is fireproof and ensures complete fluid tightness. In addition, the heat transfer of such a gasket avoids any high temperatures at the surface of the associated torque tube.

[0022] For example, the semi-cylindrical housings are semi-cylindrical titanium housings, and the flexible bellows is stitched together from an outer layer of silicone-coated fiberglass fabric according to ECS7229 and an inner layer of silicate fiberglass fabric according to ECS7241. The ECS7229 fabric is coated with silicone only on one side, which is preferably oriented towards at least one engine and is thus arranged on the side of the flexible bellows that is exposed to fire in the event of an engine fire. The flexible bellows can be fitted with internal and external titanium or stainless-steel rings at both ends of its axial direction. In addition, the flexible bellows can be stitched with coated stainless-steel yarn 13 / 2-MEZ-HELIOS to form a hollow tubular shape. Preferably, the flexible bellows overlaps with the semi-cylindrical housings in the axial direction of the gasket, rather than merely butting against the semi-cylindrical housings. In fact, this overlapping joint has improved burn-through resistance compared to a butting joint.

[0023] According to one aspect, at least one gasket forms a barrier against flammable fluids and is configured to provide fire separation and thermal insulation between the torque tube and at least one engine.

[0024] According to one aspect, at least one of the at least two fireproof housings contains titanium.

[0025] According to one aspect, at least one of the at least two fireproof housings is a semi-cylindrical titanium housing.

[0026] According to one aspect, the annular flexible fireproof bellows comprises a fiber-reinforced fabric.

[0027] According to one aspect, the fiber-reinforced fabric comprises at least one layer of silicone-coated fiberglass fabric.

[0028] According to one aspect, a fiber-reinforced fabric includes at least one layer of a silicate glass fiber fabric.

[0029] According to one aspect, an annular flexible fireproof bellows includes at least two metal rings to form an annular bellows structure.

[0030] According to one aspect, at least one of the at least two metal rings is removably mounted to at least two fireproof shells by associated fasteners, particularly rivets.

[0031] According to one aspect, the at least two metal rings are stainless steel metal rings.

[0032] According to one aspect, the at least two fireproof shells are removably attached to each other by associated shell clamps.

[0033] According to one aspect, at least one washer is removably attached to a firewall structure by associated quick-release fasteners, particularly quarter-turn quick-release fasteners.

[0034] According to one aspect, the firewall structure further includes at least a front firewall and a rear firewall interconnected by an intermediate firewall, wherein at least one washer is removably attached to the front firewall.

[0035] According to one aspect, the at least two fireproof shells at least partially overlap with the annular flexible fireproof bellows.

[0036] According to one aspect, the annular flexible fireproof bellows is attached to an associated mating part of at least one aircraft engine by mushroom head pins.

[0037] Preferred embodiments of the present invention are outlined by way of example in the following description with reference to the accompanying drawings. In these drawings, the same or functionally identical components and elements are labeled with the same reference numerals and letters, and thus are only described once in the following description. Description of the Drawings

[0038] - Figure 1 A perspective view of a rotary-wing aircraft having an engine accommodation area covered by a fairing and provided with a firewall structure is shown;

[0039] - Figure 2 A perspective view of the Figure 1 firewall structure is shown;

[0040] - Figure 3 Another perspective view of the Figure 1 firewall structure having a washer is shown;

[0041] - Figure 4 A perspective view of the Figure 3 washer is shown;

[0042] - Figure 5 shows the magnified details of Figure 3 ;

[0043] - Figure 6 shows a cross-sectional view of the magnified details of Figure 5 ;

[0044] - Figure 7 shows the magnified details of Figure 3 and a side view of the torque tube and the aircraft engine;

[0045] - Figure 8 shows the magnified details of Figure 3 and Figure 7 a cross-sectional view of the torque tube;

[0046] - Figure 9 shows the magnified details of Figure 3 and Figure 7 a cross-sectional view of the torque tube and the aircraft engine; and

[0047] - Figure 10 shows the magnified details of Figure 3 ; DETAILED DESCRIPTION

[0048] Figure 1 Shows an exemplary rotary-wing aircraft 1 represented as a helicopter. Thus, for simplicity and clarity, the rotary-wing aircraft 1 will be referred to hereinafter as "helicopter 1".

[0049] Preferably, the helicopter 1 includes at least one multi-blade main rotor for providing lift and forward or backward thrust during operation. The at least one multi-blade main rotor preferably includes a plurality of rotor blades mounted to a rotor shaft at an associated rotor hub, and the rotor shaft rotates about an associated rotor axis during the operation of the helicopter. In addition, the helicopter 1 includes a landing gear, such as a skid-type or wheel-type landing gear. However, for simplicity and clarity of the drawings, the illustration of the at least one multi-blade main rotor and the landing gear, as well as the illustration of other components that would only unnecessarily complicate the drawings, are omitted.

[0050] The helicopter 1 illustratively includes a fuselage 2 that forms the internal areas 2a, 2b of the aircraft. The internal areas 2a, 2b of the aircraft preferably accommodate at least a cockpit 2a and may also accommodate a cabin 2b for passengers and / or cargo. For example, a tail boom 3 is connected to the fuselage 2 of the helicopter 1.

[0051] The helicopter 1 illustratively further includes at least one anti-torque device 4, preferably with a shroud, which is configured to provide anti-torque during operation, i.e., to counteract the torque generated by the rotation of at least one multi-bladed main rotor in order to balance the helicopter 1 in yaw. The at least one anti-torque device 4 is illustratively disposed at the rear of the tail boom 3 and preferably includes a tail rotor 4a. The rear of the tail boom 3 preferably further includes a vertical fin 5.

[0052] According to one aspect, the fuselage 2 includes an upper main skin 2c that separates the internal regions 2a, 2b of the aircraft from the upper deck 6 of the aircraft disposed above the fuselage 2. In other words, the upper main skin 2c forms the upper end of the fuselage 2.

[0053] Illustratively, the upper main skin 2c includes a front cabin skin 2h, an engine nacelle skin 2i, and a rear cabin skin 2j. The engine nacelle skin 2i is associated with the engine nacelle 6a, which is part of the upper deck 6 of the aircraft and illustratively forms an engine accommodation area 7 having a firewall structure 10, which will be further described below with respect to Figure 2 For example, the engine accommodation area 7 includes two separate engine accommodation compartments 7a, 7b.

[0054] Preferably, the engine accommodation area 7 houses at least one aircraft engine within the firewall structure 10 such that the firewall structure 10 defines a fire separation and a flammable fluid seal at least between the at least one aircraft engine and the internal regions 2a, 2b of the aircraft. For example, the illustrated implementation represents a twin-engine configuration with one aircraft engine housed in each of the two separate engine accommodation compartments 7a, 7b.

[0055] It should be noted that the firewall structure 10 preferably defines a fire separation and a flammable fluid seal not only between the at least one aircraft engine and Figure 1 the internal regions 2a, 2b of the aircraft but also between the at least one aircraft engine and other adjacent aircraft regions. These other adjacent aircraft regions include, for example, the front and rear regions of the engine accommodation area 7, such as the gearbox or the exhaust accommodation area.

[0056] Illustratively, the engine accommodation area 7 and more generally the upper deck 6 of the aircraft are covered by a fairing 8 mounted on top of the fuselage 2. Preferably, the fuselage 2 includes side shells 2f, 2g, which illustratively enclose the internal regions 2a, 2b of the aircraft and are mounted to interconnected frames and stringers to form the main structure of the helicopter 1 designed and adapted for overall load-bearing work. Thus, the upper main skin 2c of the fuselage also participates in these overall load-bearing works and thus contributes to the overall load-bearing of the fuselage 2.

[0057] Figure 2 Is shownFigure 1 The firewall structure 10 preferably includes at least a front firewall 10a and a rear firewall 10b. Illustratively, the firewall structure 10 further includes an intermediate firewall 10c.

[0058] It should be noted that the intermediate firewall 10c is provided, by way of example, for forming the Figure 1 two engine accommodation compartments 7a, 7b required in the twin-engine structure described above, such that each aircraft engine can be individually accommodated in an associated one of the two engine accommodation compartments 7a, 7b. Conversely, the setting of the intermediate firewall 10c can be omitted in a single-engine structure.

[0059] Preferably, each of the front firewall 10a, the rear firewall 10b, and the intermediate firewall 10c includes a fireproof material, including at least one of titanium, steel, ceramics, polymer composites, or hybrid organic-inorganic composites. In one implementation, at least one of the front firewall 10a, the rear firewall 10b, or the intermediate firewall 10c has a titanium plate with a minimum thickness of at least 0.4 mm, preferably a thickness in the range of 0.6 mm to 0.8 mm, and preferably a thickness of 1.2 mm.

[0060] Illustratively, the intermediate firewall 10c, together with the front firewall 10a and the rear firewall 10b, forms a passage 10d that is adapted to at least partially accommodate the tail rotor drive shaft passing through Figure 1 the engine compartment 6a. In addition, the front firewall 10a is illustratively provided with an upper extension 10e and the rear firewall 10b is provided with a rear cover 10f.

[0061] Illustratively, the front firewall 10a further includes two removable panels 10h, 10i. The removable panel 10i is associated with the engine accommodation compartment 7a, and the removable panel 10h is associated with the engine accommodation compartment 7b. The removable panels 10i, 10h can be removed from the front firewall 10a to allow access to the corresponding aircraft engines accommodated in the engine accommodation compartments 7a, 7b.

[0062] According to one aspect, at least one, illustratively two, gaskets 10g, 10j are removably mounted on the front firewall 10a. As will be described in detail in Figure 7 below, the gaskets 10g, 10j are each preferably provided for sealing the passage of the associated torque tube.

[0063] Again, it should be noted that two removable panels 10i, 10h and two gaskets 10g, 10j are only required in a twin-engine structure. In other words, in a single-engine structure, a single removable panel and a single gasket are sufficient.

[0064] Figure 3 shows Figure 1 and Figure 2 of the firewall structure 10. According to Figure 2 , the firewall structure 10 illustratively includes a front firewall 10a, a rear firewall 10b, an intermediate firewall 10c, a channel 10d, an upper extension 10e, a rear cover 10f, removable panels 10h, 10i, and a gasket 10g, while the gasket 10j is not visible in Figure 3 . The gasket 10g is preferably removably attached to the front firewall 10a and illustratively at least partially attached to the removable panel 10i, which will be further described hereinafter with respect to Figures 4 to 6 .

[0065] Figure 4 shows Figure 3 of the gasket 10g. For example, only the gasket 10g is used as a representative implementation of the two gaskets 10g, 10j in Figure 2 , which will be described in detail hereinafter.

[0066] According to one aspect, the gasket 10g includes at least two fireproof casings and an annular flexible fireproof bellows 13. For example, two fireproof casings 12a, 12b are shown.

[0067] Preferably, at least one of the two fireproof casings 12a, 12b includes titanium. Illustratively, at least one of the two fireproof casings 12a, 12b is a semi-cylindrical titanium casing.

[0068] Figure 5 shows Figure 4 of the gasket 10g and Figure 2 and Figure 3 of the channel 10d of the firewall structure 10 and the front firewall 10a having the removable panel 10i. Preferably, the gasket 10g is removably attached to the firewall structure 10 and more specifically removably attached to the front firewall 10a by an associated quick-release fastener 14a. Illustratively, the gasket 10g is at least partially removably attached to the removable panel 10i. The quick-release fastener 14a can be implemented, for example, by a quarter-turn quick-release fastener and more generally can be implemented by any suitable cam-lock fixing device.

[0069] According to Figure 4 , the gasket 10g includes two fireproof casings 12a, 12b and an annular flexible fireproof bellows 13. The two fireproof casings 12a, 12b are removably attached to each other to form a tubular structure. Preferably, the two fireproof casings 12a, 12b are removably attached to each other by associated casing clamps 14b, illustratively by two casing clamps 14b. The casing clamps 14b can be implemented by any suitable clamp-type fastener.

[0070] The annular flexible fireproof corrugated pipe 13 is illustratively mounted to two fireproof housings 12a, 12b. Preferably, the annular flexible fireproof corrugated pipe 13 includes at least two metal rings 14e to form an annular corrugated pipe structure. The at least two metal rings 14e may be stainless steel metal rings. However, metal rings other than stainless steel metal rings, such as titanium metal rings, may also be considered.

[0071] Illustratively, the annular flexible fireproof corrugated pipe 13 further includes a mushroom-shaped fixing device 14c. For example, the mushroom-shaped fixing device 14c is implemented by a plurality of mushroom head pins.

[0072] Preferably, the annular flexible fireproof corrugated pipe 13 includes a fiber-reinforced fabric 14d. The fiber-reinforced fabric may be, for example, a silicone-coated fiberglass fabric.

[0073] Figure 6 The front firewall 10i of the fireproof housing 12b and the annular flexible fireproof corrugated pipe 13 having Figure 5 is shown. The annular flexible fireproof corrugated pipe 13 includes a mushroom-shaped fixing device 14c and a fiber-reinforced fabric 14d. Preferably, the annular flexible fireproof corrugated pipe 13 forms an additional fireproof barrier 14f. In addition, an outer housing clamp 14b of a gasket 10g is shown.

[0074] Figure 7 The Figures 4 to 6 gasket 10g is shown, which preferably forms a flammable fluid barrier and is configured to provide Figure 1 a fireproof separation and heat insulation between the torque tube 15 of the helicopter 1 and at least one aircraft engine 11 of the helicopter 1. The torque tube 15 preferably connects at least one aircraft engine 11 to the main gearbox of the helicopter 1 and illustratively includes a drive shaft 15a that transmits torque from at least one aircraft engine 11 to the main gearbox.

[0075] Preferably, the aircraft engine 11 is implemented as a suction-type propulsion gas turbine that burns a fuel / air mixture to generate power. However, any other suitable engine type, such as an electric engine, may also be considered. The aircraft engine 11 may be mounted to an associated engine mount provided in an associated engine compartment (i.e., Figure 1 the engine accommodation compartment 7a).

[0076] However, the aircraft engine 11 and the associated engine mount are not described in detail, and only a small part of the aircraft engine 11 is schematically shown without further details. In fact, the aircraft engine 11 and the associated engine mount may be implemented by engines and engine mounts known to those skilled in the art, and thus their detailed description may be omitted for the sake of brevity.

[0077] The same applies to the torque tube 15 and the drive shaft 15a. In fact, suitable torque tubes and drive shafts that can be used to implement the torque tube 15 and the drive shaft 15a are also well known to those skilled in the art, and thus their detailed descriptions can also be omitted for the sake of brevity.

[0078] Illustratively, the torque tube 15 is at least partially received in the gasket 10g, i.e., surrounded by the gasket 10g. In other words, the gasket 10g including Figure 5 the two fireproof housings 12a, 12b and the annular flexible fireproof bellows 13 forms a tubular or sleeve-like structure that at least partially surrounds and receives the torque tube 15, i.e., a cuff-like structure.

[0079] For example, the gasket 10g is removably attached to the firewall structure 10 and more specifically to the front firewall 10a by Figure 5 the associated quick-release fastener 14a. Illustratively, the gasket 10g is at least partially removably attached to the removable panel 10i of the front firewall 10a. Thus, the gasket 10g seals the passage of the torque tube 15 through the front firewall 10a. In this configuration, the annular flexible fireproof bellows 13 of the gasket 10g is configured to compensate for the movement of the torque tube 15 relative to the firewall structure 10. In addition, the gasket 10g illustratively includes Figure 5 the two housing clamps 14b that clamp the two fireproof housings 12a, 12b together.

[0080] Figure 8 Shown is Figures 4 to 7 the gasket 10g that at least partially receives, i.e., surrounds, the torque tube 15 and Figure 7 the drive shaft 15a. The gasket 10g includes the two fireproof housings 12a, 12b and the annular flexible fireproof bellows 13 including the fiber-reinforced fabric 14d.

[0081] Illustratively, as will be described in detail below for Figure 10 the annular flexible fireproof bellows 13 is mounted to the two fireproof housings 12a, 12b in an overlapping manner by at least one of Figure 5 the at least two metal rings 14e. In other words, the at least two fireproof housings 12a, 12b preferably at least partially overlap with the annular flexible fireproof bellows 13.

[0082] Figure 9 Shown is the front firewall 10a having Figure 3 the removable panel 10i and the intermediate firewall 10c and having Figure 5 the two housing clamps 14b of Figures 4 to 9The firewall structure 10 of the gasket 10g. The gasket 10g at least partially houses, i.e., surrounds, the Figure 7 at least one aircraft engine 11 that connects to Figure 1 the torque tube 15 of the main gearbox 17 of the helicopter 1.

[0083] However, the main gearbox 17 is not described in detail and only a small part of it is shown schematically without further details. In fact, the main gearbox 17 can be implemented by a main gearbox known to those skilled in the art, so its detailed description can be omitted for the sake of brevity.

[0084] Figure 9 Further shown is Figures 5 to 8 the fireproof housing 12b and the annular flexible fireproof bellows 13. For example, the fireproof housing 12b is removably attached to the front firewall 10a and is at least partially attached to the removable panel 10i through Figure 5 the quick-release fasteners 14a. The annular flexible fireproof bellows 13 illustratively includes Figure 5 the mushroom-shaped fixing device 14c and the fiber-reinforced fabric 14d. The mushroom-shaped fixing device 14c illustratively attaches the annular flexible fireproof bellows 13 to the associated mating part 11a of at least one aircraft engine 11 in the connection area 16.

[0085] Figure 10 Shown is Figure 9 the connection area 16 to further illustrate the fireproof housing 12b with the housing clamp 14b, the annular flexible fireproof bellows 13, and the attachment of the annular flexible fireproof bellows 13 to the associated mating part 11a of at least one aircraft engine 11 through the mushroom-shaped fixing device 14c. More specifically, Figure 10 illustrates the overlap of the annular flexible fireproof bellows 13 with the fireproof housing 12b, and the annular flexible fireproof bellows 13 is illustratively mounted to the fireproof housing 12b through Figure 5 at least one of the at least two metal rings 14e. Illustratively, at least one of the at least two metal rings 14e is removably mounted to the fireproof housing 12b through the associated fasteners 14g, especially rivets. For example, at least one of the at least two metal rings 14e can be fastened to the housing clamp 14b.

[0086] Illustratively, the annular flexible fireproof bellows 13 includes Figure 9 the fiber-reinforced fabric 14d. Preferably, the fiber-reinforced fabric 14d includes at least one layer 14h of silicone-coated fiberglass fabric. At least one layer 14h of silicone-coated fiberglass fabric is preferably the outer layer of the gasket 10g facing at least one aircraft engine 11.

[0087] In addition, the fiber-reinforced fabric 14d preferably includes at least one layer of silicate glass fiber fabric 14i. At least one layer of silicate glass fiber fabric 14i preferably faces Figure 9 the torque tube 15.

[0088] It should be noted that modifications to the above-described embodiments are within the common knowledge of those skilled in the art and are therefore also considered to be part of the present invention. It should also be noted that the drawings are only used to schematically represent the embodiments of the present invention and are not used to show their detailed structures.

[0089] List of Reference Numerals

[0090] 1 Rotorcraft

[0091] 2 Fuselage

[0092] 2a Cockpit

[0093] 2b Cabin

[0094] 2c Upper Main Skin of the Fuselage

[0095] 2f, 2g Side Shells of the Fuselage

[0096] 2h Front Cabin Skin

[0097] 2i Engine Compartment Skin

[0098] 2j Rear Cabin Skin

[0099] 3 Tail Boom

[0100] 4 Anti-Torque Device

[0101] 4a Tail Rotor

[0102] 5 Vertical Tail

[0103] 6 Upper Cabin of the Aircraft

[0104] 6a Engine Compartment

[0105] 7 Engine Accommodation Area

[0106] 7a, 7b Engine Accommodation Compartments

[0107] 8 Fairing

[0108] 10 Firewall Structure

[0109] 10a Front Firewall

[0110] 10b Rear Firewall

[0111] 10c Intermediate Firewall

[0112] 10d Tail Rotor Drive Shaft Passage

[0113] Upper extension of the 10e front firewall

[0114] 10f Rear cover

[0115] 10g, 10j Washers

[0116] Detachable panels of the 10h, 10i front firewall

[0117] 11 Aircraft engine

[0118] 11a Engine mating part

[0119] 12a, 12b Washer half-shells

[0120] 13 Washer bellows

[0121] 14a Cam locking fixing device

[0122] 14b Housing clamp

[0123] 14c Mushroom-shaped fixing device

[0124] 14d Bellows fiber fabric

[0125] 14e Metal ring

[0126] 14f Additional fire barrier

[0127] 14g Rivet

[0128] 14h Outer layer of the bellows

[0129] 14i Inner layer of the bellows

[0130] 15 Torque tube

[0131] 15a Drive shaft

[0132] 16 Connection area

[0133] 17 Main gearbox

Claims

1. A rotary-wing aircraft (1) having a fuselage (2) forming an internal aircraft area (2a, 2b), the fuselage (2) including an upper main skin (2c) separating the internal aircraft area (2a, 2b) from an upper aircraft compartment (6) provided above the fuselage (2), wherein the upper aircraft compartment (6) includes an engine accommodation area (7) having a firewall structure (10), the engine accommodation area (7) accommodating at least one aircraft engine (11) within the firewall structure (10) such that the firewall structure (10) defines at least a fireproof partition and a flammable fluid seal between the at least one aircraft engine (11) and the internal aircraft area (2a, 2b), and wherein the firewall structure (10) includes at least one gasket (10g) for sealing a passage of a torque tube (15) connecting the at least one aircraft engine (11) to a main gearbox (17) of the rotary-wing aircraft (1). Characterized in that, the at least one gasket (10g) includes at least two fireproof shells (12a, 12b) removably attached to each other to form a tubular structure and an annular flexible fireproof bellows (13) mounted on the at least two fireproof shells (12a, 12b) and configured to compensate for movement of the torque tube (15) relative to the firewall structure (10).

2. The rotary-wing aircraft (1) according to claim 1, Characterized in that, the at least one gasket (10g) forms a flammable fluid barrier and is configured to provide fireproof isolation and heat insulation between the torque tube (15) and the at least one aircraft engine (11).

3. The rotary-wing aircraft (1) according to claim 1 or 2, Characterized in that, at least one of the at least two fireproof shells (12a, 12b) contains titanium.

4. The rotary-wing aircraft (1) according to claim 3, Characterized in that, at least one of the at least two fireproof shells (12a, 12b) is a semi-cylindrical titanium shell.

5. The rotary-wing aircraft (1) according to claim 1, Characterized in that, the annular flexible fireproof bellows (13) includes a fiber-reinforced fabric (14d).

6. The rotary-wing aircraft (1) according to claim 5, Characterized in that, the fiber-reinforced fabric (14d) includes at least one layer of silicone-coated fiberglass fabric (14h).

7. The rotary-wing aircraft (1) according to claim 5, Characterized in that, the fiber-reinforced fabric (14d) includes at least one layer of silicate fiberglass fabric (14i).

8. The rotary-wing aircraft (1) according to claim 6, Characterized in that, the fiber-reinforced fabric (14d) includes at least one layer of silicate fiberglass fabric (14i).

9. The rotary-wing aircraft (1) according to claim 1, Characterized in that, The annular flexible fireproof bellows (13) includes at least two metal rings (14e) for forming an annular bellows structure.

10. The rotary-wing aircraft (1) according to claim 9, wherein, at least one of the at least two metal rings (14e) is removably mounted to the at least two fireproof housings (12a, 12b) by an associated fastener (14g).

11. The rotary-wing aircraft (1) according to claim 9, wherein, the at least two metal rings (14e) are stainless steel metal rings.

12. The rotary-wing aircraft (1) according to claim 1, wherein, the at least two fireproof housings (12a, 12b) are removably attached to each other by an associated housing clamp (14b).

13. The rotary-wing aircraft (1) according to claim 1, wherein, the at least one washer (10g) is removably attached to the firewall structure (10) by an associated quick-release fastener (14a).

14. The rotary-wing aircraft (1) according to claim 13, wherein, the firewall structure (10) further includes at least a front firewall (10a) and a rear firewall (10b) interconnected by an intermediate firewall (10c), and wherein the at least one washer (10g) is removably attached to the front firewall (10a).

15. The rotary-wing aircraft (1) according to claim 1, wherein, the at least two fireproof housings (12a, 12b) at least partially overlap with the annular flexible fireproof bellows (13).

16. The rotary-wing aircraft (1) according to claim 1, wherein, the annular flexible fireproof bellows (13) is attached to an associated mating part (11a) of the at least one aircraft engine (11) by a mushroom head pin (14c).

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