FR3115765A1 - Nacelle for an aircraft propulsion system, comprising a multifunctional structure forming a structural reinforcement or means of access - Google Patents

Abstract

The invention relates to a propulsion system nacelle (1) comprising a reinforcement structure (50) which can be placed in a maintenance position so as to form a ladder or an access ramp. Figure for abstract: Fig. 9

Description

Nacelle for an aircraft propulsion system, comprising a multifunctional structure forming a structural reinforcement or means of access

The invention relates to the field of propulsion systems for aircraft.

State of the prior art

An aircraft propulsion system needs to be regularly inspected, maintained and/or repaired.

Some inspection and/or maintenance operations can be carried out by an operator standing on the ground when the propulsion assembly has a relatively low ground clearance.

When the propulsion system is out of reach, the operator generally resorts to a means of access such as a lifting platform or a stepladder.

In general, the structure and dimensions of conventional means of access are not specifically adapted to the particular geometry of the propulsion system and the corresponding aircraft. Thus, it is not always possible to arrange the means of access available in an adequate and optimal position.

This results in particular in access difficulties or incomplete access to certain parts of the propulsion system, as well as an increase in the risk of an accident.

In addition, some airports, such as those intended for military or business aircraft, are generally poorly equipped. Such means of access are therefore sometimes unavailable.

An object of the invention is to provide a nacelle for an aircraft propulsion system making it possible to facilitate access for an operator to carry out an inspection and/or maintenance operation therein.

To this end, the subject of the invention is a nacelle for an aircraft propulsion system, comprising a movable multifunctional structure configured to fill:
– a first structural reinforcement function when it is placed in a flight position, the multifunctional structure in the flight position being configured to transmit forces between a first component of the nacelle and a second component of the nacelle or formed by another part of the aircraft, and
– a second access function when it is placed in a maintenance position, the multifunctional structure in the maintenance position forming a ladder or a ramp to allow an operator to access the propulsion assembly.

Said multifunctional structure thus constitutes an on-board means of access which makes it possible to dispense with additional means of access.

Depending on the architecture of the propulsion assembly, this structure may possibly replace, in the flight position, a conventional connecting or reinforcing beam.

Although this structure is likely to increase the mass of the nacelle, such an increase in mass is put to the benefit of an improvement in the structural strength of the nacelle and a better distribution of the loads within the propulsion assembly. .

Furthermore, the multifunctional structure of the invention has a geometry adapted to the geometry of the nacelle, which makes it possible to improve access to the propulsion assembly and to increase safety during inspection and maintenance.

In one embodiment, the multifunctional structure is connected to the first component when it is in the flight position and detached from the first component when it is in the maintenance position.

In one embodiment, the multifunctional structure is connected to the second component when it is in the flight position and detached from the second component when it is in the maintenance position.

In the present description, it is considered that the first component is distinct from the second component.

As indicated above, the second component can be a component of the nacelle or, alternatively, a component formed by another part of the aircraft, i.e. a component not belonging to the nacelle.

The nacelle may include an air inlet, a rear gas ejection section and a cradle, the cradle extending longitudinally between the air inlet and the rear section and supporting the air inlet and/or the rear section, the cradle extending on one side of a median longitudinal plane passing through a central longitudinal axis of the nacelle, the multifunctional structure extending in flight position on the other side of this median longitudinal plane.

Such an architecture makes it possible to reduce the loads applied to the turbomachine insofar as the air inlet and/or the rear section of the nacelle are supported by the cradle, and not the turbomachine.

Within the framework of such an architecture, the multifunctional structure makes it possible to improve the distribution of the loads within the propulsion assembly.

In one embodiment, the air inlet forms the first component.

In one embodiment, the rear section forms the second component.

Advantageously, the multifunctional structure can form, in flight position, an outer surface of the nacelle.

In one embodiment, the multifunctional structure comprises locking means able to lock the covers of the nacelle.

Preferably, the multifunctional structure comprises steps and/or one or more platforms capable of supporting an operator.

In one embodiment, the steps and/or the platform are retractable.

The invention also relates to a propulsion assembly for an aircraft comprising a nacelle as defined above as well as an aircraft comprising such a propulsion assembly or such a nacelle.

In one embodiment, the aircraft comprises a tail forming said second component.

According to another aspect, the invention also relates to a method for inspecting and/or maintaining a propulsion assembly comprising a nacelle as defined above.

This method preferably comprises a step of moving said multifunctional structure from the flight position to the maintenance position, a step of accessing the propulsion assembly via said ladder or ramp and a step comprising at least one maintenance operation.

Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows.

The following detailed description refers to the attached drawings in which:

is a schematic view of an aircraft propulsion system;

is a schematic view of a propulsion assembly mounted under an aircraft wing;

is a schematic view of two propulsion units mounted laterally in the rear part of an aircraft fuselage;

is a schematic view of a propulsion assembly mounted in the rear part of an aircraft fuselage, under an empennage of this aircraft;

is a schematic view of a propulsion assembly comprising a reinforcement structure arranged according to a first embodiment of the invention, the reinforcement structure being in a flight position;

is a schematic view of a nacelle support cradle for a propulsion assembly having an architecture in accordance with FIG. 5;

is a schematic view of the cradle of Figure 6 covered with outer skins;

is a schematic view of an aircraft wing frame under which are suspended the cradle of FIG. 6 and a turbomachine in accordance with the architecture of FIG. 5;

is a schematic view of the propulsion assembly of FIG. 5, the reinforcement structure being in a maintenance position;

is a schematic view of a propulsion assembly comprising a reinforcement structure arranged according to a second embodiment of the invention, the reinforcement structure being in the flight position;

is a schematic view of a propulsion assembly comprising a reinforcement structure arranged according to a third embodiment of the invention, the reinforcement structure being in the flight position;

is a schematic view of a propulsion assembly comprising a reinforcement structure arranged according to a fourth embodiment of the invention, the reinforcement structure being in the flight position;

is a schematic view of a propulsion assembly comprising a reinforcement structure arranged according to a fifth embodiment of the invention, the reinforcement structure being in the flight position.

Detailed description of embodiments

FIGS. 1 to 12 comprise an X, Y and Z reference frame respectively defining axial (or longitudinal), vertical and lateral directions orthogonal to one another.

There is shown in Figure 1 a propulsion assembly 1 for an aircraft, having a central longitudinal axis A1 parallel to the axial direction X.

The propulsion unit 1 comprises a nacelle 2 and a turbomachine 3.

In this example, the turbomachine 3 is a turbofan engine comprising, in a manner known per se, a fan 4, a gas generator 5 and an external casing 6 connected to the gas generator 5 by structural arms 7.

The longitudinal central axis A1 forms an axis of rotation of a rotor of the turbomachine 3.

The outer casing 6 of the turbomachine 3 extends axially forward of the propulsion assembly 1 so as to surround the fan 4.

Throughout the description, the terms "front" and "rear" are defined relative to a direction S1 of gas flow through the propulsion assembly 1 in the axial direction X.

In a manner known per se, the nacelle 2 comprises, from front to rear, a front section 10 forming an air inlet, an intermediate section 11 comprising fan cowls (not shown), and a rear section 12 gas ejection.

In this example, the rear section 12 is a fixed ferrule. In another embodiment, the aft section 12 includes a thrust reverser (not shown).

Figures 2 to 4 illustrate different conventional mounting configurations of such a propulsion assembly 1.

Figure 2 shows a propulsion unit 1 mounted vertically under a wing 20 of an aircraft.

Figure 3 shows two propulsion units 1 mounted on a fuselage 21 of an aircraft, laterally and in the rear part of the fuselage 21.

Figure 4 shows a propulsion unit 1 mounted on a fuselage 21 of an aircraft, in the extension of the fuselage 21 in the longitudinal direction X and extending vertically under a tailplane 22 of the aircraft.

The propulsion units 1 illustrated in Figures 2 to 4 are in these examples similar to that of Figure 1.

In the configuration of FIG. 4, the air inlet 10 comprises an air intake section 10A and an "S"-shaped section 10B connecting the section 10A and the intermediate section 11 to each other. from the nacelle 2.

In each of the configurations of Figures 2 and 4, the propulsion assembly 1 further comprises an inlet cone 15 making it possible to slow down the flow of air entering the air inlet 10.

The nacelle 2 and the turbomachine 3 of the propulsion unit 1 are supported by a support structure described in more detail below.

In the configuration of Figure 2, the support structure forms part of a frame of the wing 20.

In the configuration of Figure 3, the support structure forms part of the fuselage 21.

In the configuration of Figure 4, the support structure forms part of the empennage 22.

The invention is applicable to each of the configurations of FIGS. 2 to 4 and to variants of these configurations. For example, the invention can also be implemented in a propulsion assembly 1 without an inlet cone and mounted according to the configuration of FIG. 2 or 4, or even in a propulsion assembly 1 comprising an inlet cone and mounted according to the configuration of figure 3.

In addition, the invention also applies to a propulsion assembly, the turbomachine of which is different from that illustrated in FIG. -combustion.

By convention, it is considered in this description that the support structure belongs to the propulsion unit 1.

The invention is of particular interest for a propulsion assembly 1 having an architecture as illustrated in FIG. 5. However, the invention can be implemented within a propulsion assembly having a conventional architecture or one different from that of Figure 5 (see further below).

The propulsion unit 1 of Figure 5 comprises a support structure 30 which in this example forms a part of the wing frame 20, according to the configuration of Figure 2.

The following description applies by analogy to each of the configurations of Figures 3 and 4 and more generally to any configuration identical or similar to any of the configurations of Figures 2 to 4.

Referring to Figure 5, the turbine engine 3 is connected to the support structure 30 by first connecting means 31.

In this example, the first connecting means 31 comprise suspension arms configured to support the turbine engine 3.

The propulsion unit 1 of FIG. 5 also comprises an intermediate support structure 33 fixed to the support structure 30 by fixing members 34.

The intermediate support structure 33 forms in this example part of the intermediate section 11 of the nacelle 2 in the sense that it extends axially between the air inlet 10 and the rear section 12 of the nacelle 2.

In this example, the air inlet 10 and the rear section 12 are each connected to the intermediate support structure 33 by connection means 35 and 36, respectively.

The intermediate support structure 33 and the connecting means 35 and 36 form second connecting means, distinct from the first connecting means 31.

This architecture allows the support structure 30 to support on the one hand the turbine engine 3 via the first connecting means 31 and on the other hand the air inlet 10 and the rear section 12 of the nacelle 2 via the second means link.

In other words, the turbomachine 3 on the one hand and the air inlet 10 and the rear section 12 of the nacelle 2 on the other hand are supported by the support structure 30 independently.

By comparison with a conventional propulsion assembly in which the air inlet and the rear section of the nacelle are supported by the turbomachine, the architecture of the propulsion assembly of FIG. 5 makes it possible to reduce the mass of the turbomachine 3, the latter can therefore be devoid of flanges for fixing the air inlet 10 and the rear section 12, and makes it possible to avoid generating significant loads on the turbomachine 3 and thus affecting its dynamic behavior .

Of course, the second connecting means can be devoid of such an intermediate support structure 33 and the air inlet 10 and/or the rear section 12 of the nacelle 2 can be fixed directly to the support structure 30.

The following different categories of embodiments can thus be distinguished in particular. According to a first category of embodiments, the air inlet 10 and the rear section 12 are connected to the intermediate support structure 33. According to a second category of embodiments, the air inlet 10 is connected to the intermediate support structure 33 while the rear section 12 is directly connected to the support structure 30. According to a third category of embodiments, the rear section 12 is connected to the intermediate support structure 33 while the input of 10 is directly connected to the support structure 30. According to a fourth category of embodiments, the air inlet 10 and the rear section 12 are directly connected to the support structure 30.

The intermediate support structure 33 of FIG. 5 can have any geometry suitable for supporting the air inlet 10 and/or the rear section 12. For example, the intermediate support structure 33 can form a beam, a box , a cradle, a lattice structure or any other structure capable of connecting the air inlet 10 and/or the rear section 12 to the support structure 30.

In one embodiment, the intermediate support structure 33 forms a cradle as shown in Figure 6.

The cradle 33 comprises spars 40 and ring sections 41, 42 and 43 connected to each other so as to form a lattice structure.

Such a structure is both robust and not very massive.

In this example, the cradle 33 comprises six spars 40 extending parallel to the axial direction X and being circumferentially spaced from each other, as well as six ring sections 41, 42 and 43 spaced from each other along the X axial direction.

The cradle in FIG. 6 has a plane of symmetry Z-X passing through the central longitudinal axis A1, three of said longitudinal members 40 extending on one side of this plane of symmetry and the three other longitudinal members 40 extending on the other side of this plane of symmetry.

The cradle 33 also comprises a hooking structure 44 configured to cooperate with said fixing members 34 so as to fix the cradle 33 on the support structure 30 (see FIGS. 5 and 6).

The ring section 41 is located at one of the axial ends of the cradle 33 and forms a front frame. The ring section 43 is located at the other axial end of the cradle 33 and forms a rear frame. The ring sections 42 extend axially between the front frame 41 and the rear frame 43.

When the cradle is fixed to the support structure 30 of the propulsion unit 1, the ring sections 41, 42 and 43 and consequently the cradle 33 as a whole extend circumferentially around the central longitudinal axis A1.

In this example, the cradle 33 has a circumferential dimension of less than 180°, this dimension being in this case defined by the circumferential dimension of each of the ring sections 41, 42 and 43.

Figure 7 shows the cradle 33 partially covered with outer skins 49 forming a fairing.

Referring to Figures 5 and 6, the air inlet 10 of the nacelle 2 is in this example mounted cantilevered on the cradle 33, being connected to the front frame 41 of the cradle 33 by the connecting means 35.

Similarly, the rear section 12 of the nacelle 2 is in this example mounted cantilevered on the cradle 33, being connected to the rear frame 43 of the cradle 33 by the connecting means 36.

In this embodiment, the air inlet 10 and the rear section 12 of the nacelle 2 are in axial support, or capable of coming into axial support, respectively on the front frame 41 and the rear frame 43 of the cradle 33, that is to say over a circumferential sector of less than 180°.

In other embodiments not shown, the front frame 41 and/or the rear frame 43 of the cradle 33 are annular so that the air inlet 10 and/or the rear section 12 are mounted over their entire circumference in axial support on the cradle 33.

In this example, the suspension arms 31 of the turbine engine 3 pass through openings formed by the cradle 33 (see FIGS. 5, 6 and 8), that is to say openings delimited axially by two respective ring sections and by two respective beams of the cradle 33.

The concept of having the intermediate support structure 33, and more generally the second connecting means, pass through the first connecting means 31 is also applicable to an intermediate support structure having a geometry different from that of the cradle of FIG. For example, in an embodiment in which the intermediate support structure is a beam, openings can be provided in the beam so that the first connecting means can extend through these openings (not shown).

Figure 8 shows an aircraft part comprising a propulsion assembly 1 having the architecture of Figure 5 and comprising as an intermediate support structure 33 the cradle of Figure 6.

More precisely, FIG. 8 shows a frame 30 of an aircraft wing 20, the cradle 33 and the turbomachine 3 fixed to the frame 30 by the suspension arms 31 (only one arm being visible in this figure). The members 34 for fixing the cradle 33 to the frame 30 are not visible in Figure 8.

The invention relates more specifically to a multifunctional structure 50 of the nacelle 2.

In Figure 5, the multifunctional structure 50 is in a flight position in which it is configured to perform a structural reinforcement function.

In what follows, the multifunctional structure 50 is also called “reinforcing structure”.

In this example, the reinforcement structure 50 in flight position comprises a first end connected to the air inlet 10 by connecting means 51 and a second end connected to the rear section 12 by connecting means 52.

The reinforcement structure 50 in the flight position extends along the longitudinal direction X by defining a part of the intermediate section 11 of the nacelle 2. In other words, the reinforcement structure 50 extends between the inlet of air 10 and rear section 12.

The connecting means 51 and 52 are configured so that, in flight position, the reinforcing structure 50 can transmit forces between the air inlet 10 and the rear section 12.

A median longitudinal plane parallel to the plane formed by the X and Z directions and passing through the central longitudinal axis A1 is defined, i.e. in this example a horizontal plane.

Referring to Figure 5, the support structure 30 and the intermediate support structure 33 of the propulsion unit 1 extend on one side, vertically above, said median longitudinal plane while the reinforcement structure 50 extends on the other side, vertically below, of this median longitudinal plane.

In other words, the support structure 30 as well as the intermediate support structure 33 extend "at twelve o'clock" while the reinforcement structure 50 extends "at six o'clock".

Such a configuration makes it possible to avoid too abrupt an introduction of force into the intermediate support structure 33, in particular when the latter has a geometry such as illustrated in FIG. 6.

More generally, such a reinforcing structure 50 makes it possible to improve the distribution of forces within the propulsion assembly 1 and the aircraft that it equips.

The reinforcement structure 50 is movable between the flight position of Figure 5 and a maintenance position illustrated in Figure 9.

In this example, the connection means 51 connecting the reinforcing structure 50 and the air inlet 10 to each other forms a pivot connection and the connection means 52 is a detachable connection making it possible to separate the structure from reinforcement 50 and the rear section 12 from each other.

In this embodiment, the connecting means 51 comprises a clevis (not shown) fixed to the air inlet 10 and a pin (not shown) fixed to the reinforcing structure 50, the clevis and the pin cooperating together to form the pivot connection.

The connecting means 52 comprises in this example a ball pin mechanism known by the English name "quick-release pin" and making it possible to quickly connect/disconnect the reinforcing structure 50 and the rear section 12 with respect to each other. to the other.

Of course, the connecting means 52 can comprise any other locking-unlocking mechanism, including for example a mechanism of the screw-nut type if the duration of the maintenance interventions is not very restrictive in the applications envisaged.

To pass from the flight position to the maintenance position, the reinforcement structure 50 is manually separated from the rear section 12 and is then moved relative to the air inlet 10 along the pivot link 51.

In the maintenance position, the second end of the reinforcement structure 50 rests on a ground 60 receiving the aircraft so that the reinforcement structure 50 forms with the ground 60 a positive angle of inclination B1.

The reinforcement structure 50 in the maintenance position is configured to fulfill an access function, allowing an operator to access the nacelle 2 from the ground 60, for example with a view to inspecting or carrying out a maintenance operation on the turbomachine 3.

Thus, the reinforcement structure 50 in the maintenance position forms a ladder or an access ramp.

The angle of inclination B1 is for example between 30° and 80°, so as to allow secure access to the turbomachine 3.

In the example of Figure 9, the reinforcing structure 50 is equipped with foot steps 55 serving as a staircase.

In this example, the steps 55 are retractable so as to reduce the size of the reinforcing structure 50 when the latter is in the flight position.

According to an alternative not shown, the reinforcing structure 50 forms a ladder comprising two parallel bars joined by crosspieces.

In an embodiment not shown, the reinforcement structure 50 comprises a work platform designed to support a maintenance operator. This platform can be retractable in order to reduce the size of the reinforcing structure 50 in the flight position.

The reinforcing structure 50 can of course comprise both a staircase, formed for example by steps 55 and/or by a part of the structure 50 forming a ladder, as well as one or more platforms of the type described above. .

Depending on the dimensions of the nacelle 2 and its altitude when the aircraft is on the ground 60, the reinforcement structure 50 may comprise an extension capable of being retracted in the flight position and deployed in the maintenance position, or vice versa.

The reinforcing structure 50 can have a straight or curved shape and a constant or variable section depending on its position and its environment.

In one embodiment, the reinforcing structure 50 in the flight position extends inside the propulsion assembly 1 and is covered by other elements of the nacelle 2, for example by the fan cowls.

In this case, it is not necessary for the reinforcing structure 50 to be solid and the latter can for example form a trellis or a ladder defining openings.

In another embodiment, the reinforcing structure 50 forms a solid wall, formed for example of a self-stiffened panel, so as to define in flight position an outer surface of the nacelle 2.

Particularly in the context of this embodiment, the reinforcing structure 50 can carry locking means (not shown) capable of locking the fan cowls.

Many variants, some of which are described below, can be made to these different embodiments.

The foregoing description applies by analogy to each of the embodiments described below.

According to a variant embodiment, the connection means 51 does not form a pivot connection but a detachable connection.

For example, the connecting means 51 may comprise a first member (not shown) configured to cooperate with the first end of the reinforcing structure 50 in the flight position and a second member (not shown) configured to cooperate with the first end of the reinforcing structure 50 in the maintenance position. To pass from the flight position to the maintenance position, the reinforcing structure 50 and the first member of the connecting means 51 are for example separated from each other in order to be able to place the reinforcing structure 50 in the position of maintenance or in a position close to the maintenance position. The reinforcing structure 50 is then connected to the second member of the connecting means 51 to hold the reinforcing structure 50 in the maintenance position.

In this example, the first and the second member of the connecting means 51 are both fixed to the air inlet 10. According to a non-limiting alternative, the second member can be fixed to another part of the propulsion assembly 1 or the aircraft (not shown).

Of course, the connection means 51 and 52 of Figure 5 can be reversed so that the reinforcement structure 50 in the maintenance position cooperates with the rear section 12 and is detached from the air inlet 10.

Figures 10 and following illustrate other embodiments in which the reinforcing structure 50 is connected to other components of the nacelle 2 and/or of the aircraft.

In the embodiment of FIG. 10, the reinforcing structure 50 is connected on the one hand to a fixed part 70 of the aircraft by the connecting means 51 and on the other hand to the rear section 12 of the nacelle 2 by the connecting means 52.

In the embodiment of FIG. 11, the intermediate support structure 33 comprises an annular front frame 41B to which the reinforcing structure 50 is connected by the connecting means 51, the reinforcing structure 50 being moreover connected to the rear section 12 of the nacelle 2 by the connecting means 52.

In the embodiment of FIG. 12, the intermediate support structure 33 comprises an annular rear frame 43B, the reinforcing structure 50 being connected on the one hand to a fixed part 70 of the aircraft by the connecting means 51 and on the other hand to the rear frame 43B of the intermediate support structure 33.

In each of the examples of Figures 10 and 12, the fixed part 70 belongs for example to the fuselage 21 or to the tailplane 22 of an aircraft in which the propulsion assembly 1 is arranged according to the configuration of Figure 4.

Figure 13 illustrates another embodiment in which the propulsion assembly 1 has a substantially different architecture from that of Figures 5 to 12.

The turbomachine 3 of the propulsion assembly 1 of FIG. 13 is connected to the support structure 30 by first connecting means 31 forming in this example a cradle (not shown) and the air inlet 10 as well as the section rear 12 of the nacelle 2 are each carried by the turbomachine 3, via connecting means 75, in a conventional manner.

In this example, the reinforcement structure 50 in the flight position is connected to the air inlet 10 by the connecting means 51 and to the rear section 12 by the connecting means 52 in the same way as in the mode of embodiment of Figure 5 described above.

Of course, the above description relating to the embodiments of Figures 5 to 12 and their variants applies by analogy to the propulsion unit 1 of Figure 13.

Claims (10)

Nacelle (2) for an aircraft propulsion system (1), characterized in that it comprises a movable multifunctional structure (50) configured to fill:
– a first structural reinforcement function when it is placed in a flight position, the multifunctional structure (50) in the flight position being configured to transmit forces between a first component (10) of the nacelle (2) and a second component (12) of the nacelle (2) or formed by another part of the aircraft, and
– a second access function when it is placed in a maintenance position, the multifunctional structure (50) in the maintenance position forming a ladder or a ramp to allow an operator to access the propulsion assembly (1) . Platform (2) according to Claim 1, in which the multifunctional structure (50) is connected to the first component (10) when it is in the flight position and detached from the first component (10) when it is in the maintenance position and / or in which the multifunctional structure (50) is connected to the second component (12) when it is in the flight position and separated from the second component (12) when it is in the maintenance position. Pod (2) according to claim 1 or 2, comprising an air inlet (10), a rear gas ejection section (12) and a cradle (33), the cradle (33) extending longitudinally between the air inlet (10) and the rear section (12) and supporting the air inlet (10) and/or the rear section (12), the cradle (33) extending from one side of a median longitudinal plane passing through a central longitudinal axis (A1) of the nacelle (2), the multifunctional structure (50) extending in flight position on the other side of this median longitudinal plane. Pod (2) according to claim 3, wherein the air inlet (10) forms the first component and/or wherein the rear section (12) forms the second component. Nacelle (2) according to any one of Claims 1 to 4, in which the multifunctional structure (50) forms, in the flight position, an external surface of the nacelle (2). Nacelle (2) according to any one of claims 1 to 5, in which the multifunctional structure (50) comprises locking means capable of locking covers of the nacelle (2). Platform (2) according to any one of Claims 1 to 6, in which the multifunctional structure (50) comprises foot steps (55) and/or one or more platforms capable of supporting an operator, the steps (55) and / or the platform being preferably retractable. Propulsion unit (1) comprising a nacelle (2) according to any one of claims 1 to 7. Aircraft comprising a propulsion assembly (1) according to claim 8 and an empennage (22) forming said second component. Method for inspecting and/or maintaining a propulsion unit (1) comprising a nacelle (2) according to any one of claims 1 to 7, this method comprising a step of moving said multifunctional structure (50) from the flight position to the maintenance position, a step of access to the propulsion assembly via said ladder or ramp (50) and a step comprising at least one maintenance operation.