Propulsion system for aircraft comprising turbojet engine, pylon and engine attachment

Abstract

The invention relates to an aircraft propulsion system (100) comprising: a turbojet engine (102) having a fan housing (103) with an aft face portion (103a); a pylon (104) with a front portion (106a) and a lower spar (106b) with a rear fitting (108) secured thereto; a front engine attachment (150) fixed between the upper portion and the front portion (106a) of the fan housing (103); a front arch (152) having two arms (152b-152c), each arm having a first end secured to the lower spar (106b) and a second end hingedly secured to the rear face (103a); and two lateral levers (154), each having a first end hingedly secured to the rear fitting (108) and a second end hingedly secured to the rear face portion (103a). In this arrangement, a force is transmitted to the rear of the pylon.

Description

Technical Field

[0001] The invention relates to the general field of attaching a turbojet engine under the wing of an aircraft. In particular, it relates to a propulsion system comprising a turbojet engine, in particular a twin-flow engine, a pylon and a front engine attachment, and an arch for fixing the turbojet engine under the pylon. It is also suitable for an aircraft equipped with such a propulsion system. Background Art

[0002] The most advanced propulsion system is attached under the wing of the aircraft. It has a turbojet engine and a pylon, by which the turbojet engine is attached under the wing. The pylon has a rigid structure, also called a primary structure, with attachment elements for attaching the turbojet engine.

[0003] These attachment elements consist of a front engine attachment, a rear engine attachment and a device for recovering the thrust generated by the turbojet engine.

[0004] The pylon also has other attachment elements allowing the pylon to be attached to the wing.

[0005] Although such a structure is satisfactory, it is desirable to find an alternative arrangement which would allow, inter alia, a better transfer of loads to the rear of the pylon. Summary of the invention

[0006] One object of the present invention is to propose a propulsion system comprising a turbojet, a pylon and elements for attaching the turbojet below the pylon with improved load transmission.

[0007] To this end, a propulsion system for an aircraft is proposed, the propulsion system comprising:

[0008] a turbojet engine extending about a longitudinal axis and having a vertical mid-plane passing through the longitudinal axis, and having a fan casing having a rear face perpendicular to the longitudinal axis;

[0009] - a pylon having a rigid structure with a front part and a lower spar with a rear fitting fixed thereto;

[0010] - a front engine attachment part, which is fixed between the upper part of the fan casing and the front part of the rigid structure;

[0011] a front arch having a body fixed to the lower spar and two arms arranged on either side of a vertical median plane, each arm having a first end integral with the body and a second end fastened in an articulated manner to the rear face; and

[0012] - Two lateral rods arranged on either side of the vertical median plane, each rod having a first end fastened in an articulated manner to the rear fitting, and a second end fastened in an articulated manner to the rear face.

[0013] With this arrangement, the forces are transferred to the rear of the pylon.

[0014] Advantageously, the pylon has a first rib fixed inside the rigid structure at a fixing portion between the body and the lower spar, and a second rib attached inside the pylon at a fixing portion between the rear fitting and the lower spar.

[0015] According to one embodiment, the second end of each arm is fastened directly to the rear face and the second end of each lateral rod is fastened to the arm on the same side of the vertical median plane.

[0016] Advantageously, each arm slopes from bottom to top and from the second end to the first end, and the propulsion system comprises, for each arm, a front bar having a first end fastened in an articulated manner to the rigid structure, and a second end fixed in an articulated manner to said arm.

[0017] Advantageously, on each side of the vertical median plane, the propulsion system comprises a rear rod having a first end fastened in an articulated manner to the rear fitting, and a second end fixed in an articulated manner to the rigid structure.

[0018] Advantageously, the articulation of the arm with the rear face is a rotation about an axis perpendicular to the vertical median plane.

[0019] According to one embodiment, the second end of each rod is fastened directly to the rear face and the second end of each arm is fastened to the rod on the same side of the vertical median plane.

[0020] Advantageously, the articulation of the lever with the rear face is a rotation about an axis perpendicular to the vertical median plane.

[0021] According to one arrangement, the front engine attachment comprises a front locking beam, which is fastened to the fan casing in an articulated manner via a first connection point arranged at a vertical middle plane, and to the front part via two second connection points arranged on each side of the vertical middle plane, the front locking beam being inclined from bottom to top and from front to rear, and the three hinged parts of the front locking beam being rotating parts around an axis perpendicular to the front locking beam.

[0022] According to one arrangement, the front engine attachment comprises a front collar beam which is fastened in an articulated manner to the front part via a first connection point and to the fan casing via two second connection points.

[0023] Advantageously, the first connection point and the second connection point are arranged at a vertical median plane, and each articulation of the front locking beam is a rotation about an axis perpendicular to the vertical median plane.

[0024] Advantageously, the front engine attachment comprises, at a vertical mid-plane, a cylindrical pin integral with the rigid structure and a housing integral with the fan casing, the axis of the cylindrical pin being vertical, the housing comprising a groove into which the cylindrical pin is introduced, the groove having a transverse dimension perpendicular to the vertical mid-plane and a longitudinal dimension parallel to the longitudinal axis, the transverse dimension being equal to the diameter of the cylindrical pin and the longitudinal dimension being greater than the diameter of the cylindrical pin.

[0025] Advantageously, the first connection point is arranged at a vertical median plane, the second connection point is arranged on either side of the vertical median plane, and each articulation of the front locking beam is a rotation about an axis parallel to the longitudinal axis.

[0026] The invention also proposes an aircraft comprising a wing and a propulsion system according to one of the aforementioned embodiments, the rigid structure of the propulsion system being fixed under the wing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The features of the present invention will become more apparent upon reading the following description of at least one embodiment, which is produced with reference to the accompanying drawings, in which:

[0028] Figure 1 Shows a side view of an aircraft according to the invention;

[0029] Figure 2 is a perspective view of a propulsion system according to a first embodiment of the present invention;

[0030] Figure 3 is a perspective view of a propulsion system according to a second embodiment of the present invention;

[0031] Figure 4 is a perspective view of a propulsion system according to a third embodiment of the present invention;

[0032] Figure 5 is a perspective view of a propulsion system according to a fourth embodiment of the present invention;

[0033] Figure 6 is a top view of a particular hinge used in some embodiments of the present invention; and

[0034] Figure 7 is an example of a dual axis used in the present invention. DETAILED DESCRIPTION

[0035] Figure 1 An aircraft 50 is shown, which has a wing 52, below which is mounted a propulsion system 100 according to the invention, comprising a pylon 104 and a turbojet engine 102, which is housed in a nacelle 200. Figure 1 In the illustrated embodiment of the invention, an aircraft 50 has a fuselage 53 with wings 52 fixed to each side of the fuselage 53 .

[0036] By convention, X is the longitudinal axis of the turbojet 102, this direction X being parallel to the longitudinal axis of the turbojet 102. On the other hand, Y is the transverse axis of the turbojet 102, which is horizontal when the aircraft is on the ground, and Z is the vertical axis or vertical height when the aircraft is on the ground, these three directions X, Y and Z being orthogonal to each other.

[0037] On the other hand, the terms “front” and “rear” are considered with respect to the direction of advance of the aircraft 50 during operation of the turbojet engine 102 , this direction being schematically indicated by the arrow F.

[0038] The pylon 104 is generally symmetrical relative to a vertical median plane XZ of the turbojet engine 102 , passing through the longitudinal axis X of the turbojet engine 102 and subsequently referred to as median plane P, to which the transverse axis Y is perpendicular.

[0039] The vertical axis Z is inscribed in the median plane P and is perpendicular to the longitudinal axis X.

[0040] Figures 2 to 5 Various embodiments of the propulsion system 100 of the present invention are shown.

[0041] The propulsion system 100 includes a turbojet engine 102 and a pylon 104, by which the turbojet engine 102 is attached to the wing 52 ( Figure 2 ). The pylon 104 is represented here by its rigid structure 106 , also called primary structure, carrying an engine attachment which ensures the attachment of the turbojet engine 102 underneath the rigid structure 106 .

[0042] The rigid structure 106 takes the form of a box having a front portion 106a at the front of the rigid structure 106, a lower spar 106b extending below the rigid structure 106, and an upper spar 106e extending to the top of the rigid structure 106. The rigid structure 106 also has two side walls 106c-106d on either side of the median plane P. These various spars and walls are fixed to each other to form the rigid structure 106.

[0043] In order to strengthen it structurally, the rigid structure 106 here has first ribs 172 and second ribs 174, which are fixed to various spars and walls inside the rigid structure 106. The second ribs 174 are located at the back of the first ribs 172. Of course, a greater number of ribs can be imagined.

[0044] The rigid structure 106 is fixed under the wing 52 by a fastening system which is not shown because it is outside the scope of the invention and which may take any form known to a person skilled in the art.

[0045] The turbojet engine 102 includes, from front to rear, a fan casing 103 in which the fan of the turbojet engine 102 is installed, and an engine casing 105 attached to the rear of the fan casing 103, and other elements of the turbojet engine 102 such as a compression stage, a combustion chamber, a turbine stage and an injection nozzle are accommodated in the engine casing 105.

[0046] The fan housing 103 has a rear portion 103 a perpendicular to the longitudinal axis X and therefore extending in a plane parallel to the plane YZ.

[0047] The propulsion system 100 includes a front engine attachment 150, which takes different forms in different embodiments. The front engine attachment 150 is fixed between the upper portion of the fan housing 103 and the front portion 106a of the rigid structure 106. In other words, the front engine attachment 150 is attached to the fan housing 103 at the 12 o'clock position.

[0048] The propulsion system 100 includes a front arch 152 having a body 152a fixed to and below the lower spar 106b, and two arms 152b-152c arranged on either side of a vertical midplane P. The body 152a is fixed above the engine case 105, while the arms 152b-152c are disposed on each side of the engine case 105 behind the rear face 103a of the fan case 103.

[0049] Each arm 152b-152c has a first end integral with the body 152a and also has a second end fastened to the rear face 103a in a hinged manner, particularly at the 3 o'clock and 9 o'clock directions. As described below, the fixation between the second ends of the arms 152b-152c and the rear face 103a can be direct fixation or indirect fixation.

[0050] The propulsion system 100 further comprises two lateral rods 154 arranged on each side of the vertical median plane P. Each rod 154 has a first end, the first end being fastened in an articulated manner to the rear fitting 108 via a rear connection point 10c, and a second end being fastened in an articulated manner to the rear face 103a. As explained below, the fixation between the second end of the rod 154 and the rear face 103a can be direct or indirect. Each hinge at the rear connection point 10c is a rotation part around an axis generally perpendicular to the vertical median plane P, i.e. parallel to the transverse axis Y.

[0051] With this arrangement, loads are introduced further to the rear of the rigid structure 106 , which reduces its inertia requirements and allows for a reduction in size at the front of the rigid structure 106 .

[0052] In order to ensure better rigidity at the lower spar 106b, the first rib 172 is fixed at a fixing portion between the main body 152a and the lower spar 106b, and is fixed to the main body 152a and the lower spar 106b at the same time. A fastening device that realizes the fixing of the main body 152a and the lower spar 106b is also attached to the first rib 172, for example, by sandwiching the lower spar between the first rib 172 and the main body 152a.

[0053] In order to ensure better rigidity at the lower spar 106b, the second rib 174 is fixed at the fixing portion between the rear fitting 108 and the lower spar 106b, and is fixed to the rear fitting 108 and the lower spar 106b at the same time. A fastening device that realizes the fixing of the rear fitting 108 and the lower spar 106b is also attached to the second rib 174, for example, by sandwiching the lower spar between the first rib 174 and the rear fitting 108.

[0054] exist Figure 2 , Figure 3 and Figure 4 In the embodiment, the second end of each arm 152b-152c is directly fastened to the rear surface portion 103a in an articulated manner via the front connection point 10a, and the second end portion of each lateral rod 154 is fastened to the arm 152b-152c in an articulated manner via the rear connection point 10b, particularly at the lower portion of the arm 152b-152c, on the same side of the vertical middle plane P, i.e., indirectly fixed to the rear surface portion 103a.

[0055] Here, the fixing to the rear face 103a is achieved by a collet connection, wherein a part of the collet, here the male part, is attached to the rear face 103a, and wherein a part of the collet, here the female part, is attached to the arms 152b-152c. A collet pin fixes the parts of the collet connection.

[0056] In each of these embodiments, the articulation of the arms 152b-152c with the rear face 103a (at the front connection point 10a) is here a rotation about an axis perpendicular to the vertical median plane P to manage loads along the longitudinal axis X and the vertical axis Z.

[0057] Each hinge at the rear connection point 10 b is a rotation about an axis generally perpendicular to the vertical median plane P, ie parallel to the transverse axis Y.

[0058] exist Figure 2 and Figure 3In an embodiment, each arm 152b-152c is inclined from bottom to top and from the second end to the first end, that is, the arms 152b-152c climb from front to back. For each arm 152b-152c, the propulsion system 100 also includes a front rod 156, which has a first end and a second end, the first end being fastened to the rigid structure 106, in particular to the lower spar 106b, in an articulated manner via a first sub-connection point 20a, and the second end being fastened to the arm 152b-152c in an articulated manner via a second sub-connection point 20b. The front rod 156 is generally vertical. Here, each fixation of the front rod 156 is achieved by a clamping piece connection, the axis of which is generally perpendicular to the vertical middle plane P, that is, parallel to the transverse axis Y.

[0059] In these embodiments, the interface is compact.

[0060] exist Figure 4 In the embodiment of the present invention, each arm 152b-152c is in the same plane that is generally perpendicular to the longitudinal axis X, and the load is transmitted along the longitudinal axis X and the longitudinal axis Z.

[0061] The propulsion system 100 comprises, on each side of the vertical median plane P, a rear rod 404 having a first end fastened in an articulated manner to the rear fitting 108 via a first rear sub-connector 30a and a second end fastened in an articulated manner to the rigid structure 106, in particular to the lower spar 106b, via a second rear sub-connector 30b, to transmit loads to the rear of the pylon 104 along the longitudinal axis X. Here, each fixing of the rear rod 404 is achieved by a clamping piece connection, the axis of which is generally perpendicular to the vertical median plane P. The clamping piece pins fix the parts of the clamping piece connection.

[0062] exist Figure 5 In the embodiment, the second end of each rod 154 is directly fastened to the rear surface portion 103a in an articulated manner via the front connection point 40a, and the second end of each arm 152b-152c is fastened to the rod 154 in an articulated manner via the rear connection point 40b on the same side of the vertical middle plane P, that is, each arm 152b-152c is indirectly fastened to the rear surface portion 103a.

[0063] Here, the fixing to the rear face 103a is achieved by a collet connection, wherein a part of the collet, here the male part, is attached to the rod 154, and wherein a part of the collet, here the female part, is attached to the rear face 103a. A collet pin fixes the parts of the collet connection.

[0064] In this embodiment, the hinge of the rod 154 with the rear face 103a (at the front connection point 40a) is here a rotation about an axis perpendicular to the vertical median plane P, in order to manage the loads along the longitudinal axis X and the vertical axis Z. Each hinge at the rear connection point 40b is a rotation about an axis generally perpendicular to the vertical median plane P, i.e. parallel to the transverse axis Y.

[0065] In this embodiment, each rod 154 is doubled by two identical elements attached together.

[0066] The front arch 152 and the rear fitting 108 are also doubled parallel to the longitudinal axis X.

[0067] In this embodiment, the propulsion system 100 includes a rear rod 606 on each side of the vertical mid-plane P, the rear rod having a first end rigidly fixed to the rear fitting 108, and a second end rigidly fixed to the arms 152b-152c.

[0068] exist Figure 2 and Figure 3 In the embodiment of the present invention, the front arch member 152 is made of two stacked sub-arch members, and when one of the sub-arch members is broken, the load is completely transmitted through the other sub-arch members.

[0069] The different front engine attachments 150 described below may be used with all of the embodiments described above.

[0070] In such Figure 2 In the first variant of the front engine attachment 150 shown, the front engine attachment comprises a front collar 202 which is fastened in an articulated manner to the fan casing 103 via a first connection point 50a and to the front portion 106a via two second connection points 50b.

[0071] The first connection point 50a is arranged at the vertical middle plane P, and the two second connection points 50b are arranged on each side of the vertical middle plane P.

[0072] Here, each connection point 50a-50b is realized by a clip piece connection, wherein a part of the clip piece, here the male part, is attached to the front lock beam 202, and wherein a part of the clip piece, here the female part, is attached to the fan housing 103 or the front part 106a. A clip piece pin secures the parts of each clip piece connection.

[0073] The front locking beam 202 is inclined from bottom to top and from front to back, and the three hinges (at the three connection points 50a-50b) of the front locking beam 202 are rotating parts around an axis perpendicular to the front locking beam 202. This means that the clamp pin of each clamp connection is inclined relative to the front locking beam 202.

[0074] For safety reasons, the front portion 106a is realized by two boxes 206a-206b, which are attached to the rigid structure 106 and are arranged on each side of the vertical median plane P. Each box 206a-206b is fixed to the front collar beam 202 by one of the second connection points 50b. In the event of a rupture of one of the boxes 206a-206b, the load is transmitted entirely through the other box 206b-206a.

[0075] In the same manner, the front locking beam 202 is made of two similar sub-locking beams fixed together to compensate for the breakage of one of the sub-locking beams.

[0076] Here, a vertical rib 208 parallel to the vertical middle plane P is arranged in the center of the boxes 206a-206b.

[0077] The orientation of the front locking beam 202 enables the second connection point 50b to transfer loads in the Y direction. Because the clamp pin of the first connection point 50a is oriented in a direction close to the longitudinal axis X, the front locking beam 202 allows a combined transfer along the projections of the X axis and the Y axis to transfer the load to the front portion 106a of the rigid structure 106.

[0078] The front engine attachment 150 is respectively as follows Figure 3 and Figure 4 In the second and third variants shown, the front engine attachment 150 comprises a front collar 302, 402, which is fastened in an articulated manner to the front portion 106a via a first connection point 60a, 70a and to the fan housing 103 via two second connection points 60b-60c, 70b. The second variant also Figure 5 Shown in.

[0079] In a second variant, the first connection point 60 a and the second connection points 60 b - 60 c are arranged at the vertical median plane P, and each hinge of the front locking beam 302 at the connection points 60 a - 60 c is a rotation part around an axis perpendicular to the vertical median plane, i.e. an axis parallel to the transverse axis Y. The second connection points 60 b - 60 c are fixed to the plate 303 , integral with the fan housing 103 .

[0080] In this variant, the front locking beam 302 is made of two similar sub-locking beams spaced apart from each other to compensate for the breakage of one of the sub-locking beams, and each connection point 60a-60c is realized by a clamping piece connection, wherein a part of the clamping piece, here the female part, is attached to the front locking beam 302a, and wherein a part of the clamping piece, here the male part, is attached to the plate 303 or the front part 106a of the fan housing 103. A clamping piece pin parallel to the transverse axis Y secures the parts of each clamping piece connection.

[0081] The upper second connection point 60 b and the first connection point 60 a form a line 301 inclined from bottom to top and from front to back, and the three hinge parts of the front lock beam 302 are rotation parts around an axis perpendicular to the front lock beam 302 .

[0082] For safety reasons, the front portion 106a is realized by two boxes 206a-206b, which are attached to the rigid structure 106 and are arranged on each side of the vertical median plane P. The two boxes 206a-206b are simultaneously fixed to the front collar beam 302 by means of a first connection point 60a. In the event of a rupture of one of the boxes 206a-206b, the load is transmitted entirely through the other box 206b-206a.

[0083] Here, a vertical rib 208 parallel to the vertical middle plane P is arranged in the center of the boxes 206a-206b.

[0084] Front locking beam 302 is oriented so as to transfer loads in the direction of line 301 .

[0085] exist Figure 3 In a variation of , each box 206a-206b has an L shape with a vertical panel and a horizontal panel. The two vertical panels have the same shape and are superimposed on each other so that the horizontal panels provide an overall uniform horizontal surface. In this embodiment, the flat horizontal surface is geometrically made of a combination of rectangles and diamonds. The boxes 206a-206b are symmetrical with respect to the vertical middle plane P to achieve the isolation necessary to provide fail-safe.

[0086] The two vertical panels are simultaneously secured to the front locking beam 302 via a first connection point 60a.

[0087] The lower second connection point 60c of the front lock beam 302 is a waiting fail-safe connection point that is inactive and becomes active if the upper second connection point 60b is interrupted. For example, the diameter of the clamp pin is smaller than the hole of the plate 303 in which the clamp pin is arranged, and in the event of a failure of the upper second connection point 60b, the contact between the clamp pin and the plate 303 becomes active.

[0088] like Figure 6 As shown, in a second variant, the front engine attachment 150 comprises, at the vertical midplane P, a cylindrical pin (socket) 602 , whose axis is vertical, ie parallel to the vertical axis Z. The cylindrical pin 602 is integral with the rigid structure 106 and extends downwardly towards the fan casing 103 .

[0089] The front engine attachment 150 also comprises a housing 604 integral with the upper part of the fan casing 103. The housing 604 comprises a slot 606 into which a cylindrical pin 602 is introduced, the slot 606 having a transverse dimension d1 perpendicular to the vertical median plane P, equal to the diameter of the cylindrical pin 602, and a longitudinal dimension d2 parallel to the longitudinal axis X, greater than the diameter of the cylindrical pin 602. With this configuration, only loads parallel to the transverse axis Y (not in the longitudinal direction X) are transmitted, and the loads are transmitted in the plane XZ.

[0090] One advantage of this embodiment consists in the simple engine installation on the pylon 104, which requires only a translation along the vertical axis Z of the turbojet 102 towards the pylon 104 and then the introduction of the collet pins. The slotted support of the cylindrical pins 602 makes the system statically determined and therefore makes tolerance management simpler.

[0091] In a third variant, the first connection point 70a is arranged at the vertical median plane P and the two second connection points 70b are arranged on either side of the vertical median plane P. Each articulation of the front locking beam 402 at the connection points 70a-70b is a rotation about an axis parallel to the longitudinal axis X. The loads are transmitted along the transverse axis Y and the vertical axis Z.

[0092] In this variant, each connection point 70a-70b is realized by a clip connection, wherein a part of the clip, here the female part, is attached to the front locking beam 402, and wherein a part of the clip, here the male part (not shown), is attached to the fan housing 103 or the front part 106a. A clip pin parallel to the longitudinal axis X secures the parts of each clip connection.

[0093] like Figure 7 As shown, each collet pin 700 can be doubled. The collet pin 700 includes an inner barrel 702 arranged in an outer barrel 704 in a concentric manner. Therefore, when one barrel breaks, the other barrel still remains.

Claims

1. A propulsion system (100) for an aircraft (50), the propulsion system (100) comprising: - a turbojet engine (102) extending about a longitudinal axis (X) and having a vertical mid-plane (P) passing through said longitudinal axis (X), and having a fan casing (103) with a rear face (103a) perpendicular to said longitudinal axis (X); - a pylon (104) having a rigid structure (106) with a front portion (106a) and a lower spar (106b) with a rear fitting (108) fixed thereto; - a front engine attachment (150) fixed between the upper part of the fan casing (103) and the front part (106a) of the rigid structure (106); - a front arch (152) with a body (152a) fixed to the lower spar (106b) and two arms (152b) arranged on either side of the vertical median plane (P) -152c), each arm (152b-152c) having a first end integral with the body (152a), and a second end hingedly fastened to the rear face portion (103a); and - Two lateral rods (154) arranged on either side of said vertical median plane (P), each rod (154) having a first end fastened in an articulated manner to said rear fitting (108) and a second end fixed in an articulated manner to said rear face (103a).

2. The propulsion system (100) according to claim 1, characterized in that The pylon (104) has a first rib (172) and a second rib (174), wherein the first rib is fixed inside the rigid structure (106) at a fixing portion between the main body (152a) and the lower spar (106b), and the second rib (174) is attached inside the pylon (104) at a fixing portion between the rear fitting (108) and the lower spar (106b).

3. The propulsion system (100) according to claim 1 or 2, characterized in that: The second end of each arm (152b-152c) is fastened directly to the rear face (103a), and wherein the second end of each lateral rod (154) is fastened to the arms (152b-152c) on the same side of the vertical median plane (P).

4. The propulsion system (100) according to any one of claims 1 to 3, characterized in that: Each arm (152b-152c) is inclined from bottom to top and from the second end to the first end, and wherein the propulsion system (100) includes, for each arm (152b-152c), a front rod (156) having a first end hingedly fastened to the rigid structure (106) and a second end hingedly fastened to the arm (152b-152c).

5. The propulsion system (100) according to any one of claims 1 to 3, characterized in that: The propulsion system (100) comprises, on each side of the vertical median plane (P), a rear rod (404) having a first end fastened in an articulated manner to the rear fitting (108) and a second end fixed in an articulated manner to the rigid structure (106).

6. The propulsion system (100) according to any one of claims 3 to 4, characterized in that: The hinged portion of the arms (152b-152c) and the rear portion (103a) is a rotating portion around an axis perpendicular to the vertical middle plane (P).

7. The propulsion system (100) according to claim 1 or 2, characterized in that: The second end of each rod (154) is fastened directly to the rear face (103a), and wherein the second end of each arm (152b-152c) is fastened to the rod (154) on the same side of the vertical median plane (P).

8. The propulsion system (100) according to claim 7, characterized in that The hinge portion between the rod (154) and the rear portion (103a) is a rotation portion around an axis perpendicular to the vertical middle plane (P).

9. The propulsion system (100) according to any one of claims 1 to 8, characterized in that: The front engine attachment (150) includes a front locking beam (202), which is fastened to the fan housing (103) in an articulated manner via a first connection point (50a) arranged at the vertical middle plane (P), and is fastened to the front part (106a) via two second connection points (50b) arranged on each side of the vertical middle plane (P), wherein the front locking beam (202) is inclined from bottom to top and from front to back, and wherein the three hinged parts of the front locking beam (202) are rotating parts around an axis perpendicular to the front locking beam (202).

10. The propulsion system (100) according to any one of claims 1 to 8, characterized in that: The front engine attachment (150) comprises a front locking beam (302, 402) which is hingedly fastened to the front part (106a) via a first connection point (60a, 70a) and to the fan housing (103) via two second connection points (60b-60c, 70b).

11. The propulsion system (100) according to claim 10, characterized in that The first connection point (60a) and the second connection point (60b-c) are arranged at the vertical middle plane (P), and wherein each hinged portion of the front lock beam (302) is a rotation portion around an axis perpendicular to the vertical center plane (P).

12. The propulsion system (100) according to claim 11, characterized in that The front engine attachment (150) comprises, at the vertical middle plane (P), a cylindrical pin (602) integral with the rigid structure (106) and a housing (604) integral with the fan casing (103), the axis of the cylindrical pin being vertical, the housing comprising a groove (606), the cylindrical pin (602) being introduced into the groove, the groove (606) having a transverse dimension (d1) perpendicular to the vertical middle plane (P) and a longitudinal dimension (d2) parallel to the longitudinal axis (X), the transverse dimension being equal to the diameter of the cylindrical pin (602), and the longitudinal dimension being greater than the diameter of the cylindrical pin (602).

13. The propulsion system (100) according to claim 10, characterized in that The first connection point (70a) is arranged at the vertical middle plane (P), the second connection point (70b) is arranged on each side of the vertical middle plane (P), and wherein each hinged portion of the front lock beam (402) is a rotating portion around an axis parallel to the longitudinal axis (X).

14. Aircraft (50) comprising a wing (52) and a propulsion system (100) according to any one of the preceding claims, a rigid structure (106) of the propulsion system being fastened underneath the wing (52).

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