Aircraft engine assembly, comprising an attachment device for the engine equipped with a structural cover attached on a central box

1. An aircraft engine assembly comprising:

a double-flow engine comprising an intermediate casing, the intermediate casing comprising:

a hub;

an outer shell; and

radial arms linking the hub to the outer shell;

an attachment device for attaching an engine to a structure of the aircraft, the attachment device comprising a primary structure equipped with a central box section;

an attachment for attaching the engine to the primary structure of the attachment device; and

a structural cover of the primary structure surrounding the engine and connected to the central box section;

wherein the structural cover has an overall annular form centered on a longitudinal axis of the engine, and the structural cover comprises:

an outer skin internally delimiting a secondary annular channel of the engine; and

two thrust load take-up cradles arranged symmetrically relative to a median vertical plane of the engine assembly,

wherein the attachment comprises:

a group of main mounts; and

a group of secondary mounts arranged at a rear of the group of main mounts,

wherein the group of main mounts comprises a plurality of bolts distributed around the longitudinal axis of the engine and configured to fasten a front end of the structural cover to the hub of the intermediate casing, and

wherein the group of secondary mounts comprises a plurality of secondary mounts distributed around the longitudinal axis of the engine and configured to fasten a rear part of the engine to a rear end of the structural cover.

2. The engine assembly of claim 1 , wherein

the structural cover comprises a substantially annular front frame, forming the front end of the structural cover and substantially centered on the longitudinal axis of the engine, and

the substantially annular front frame is fastened to a front end of the central box section of the primary structure.

3. The engine assembly of claim 2 , wherein

the structural cover comprises one or more other additional substantially annular frame, of which two facing ends are fastened respectively on either side of the central box section of the primary structure, and

the front frame and the one or more additional frame/frames being are arranged in parallel in hypothetical transverse planes of the engine.

4. The engine assembly of claim 3 , wherein each thrust load take-up cradle has a front end fastened to a rearmost additional frame, and a rear end fastened to the central box section of the primary structure.

5. The engine assembly of claim 4 , comprising a plurality of pins arranged between the front end of the structural cover and the hub of the intermediate casing, wherein the pins are configured to correctly position the engine with respect to the primary structure and to take up shear and torque loads.

6. The engine assembly of claim 4 ,

wherein the structural cover comprises a substantially annular rear frame, forming the rear end of the structural cover and substantially centered on the longitudinal axis of the engine, the substantially annular rear frame being fastened to the central box section of the primary structure, forward relative to a rear end of the central box section, and

wherein the substantially annular rear frame is situated rearward relative to the rear ends of the thrust load take-up cradles.

7. The engine assembly of claim 3 ,

wherein the structural cover comprises a substantially annular rear frame, forming the rear end of the structural cover and substantially centered on the longitudinal axis of the engine, the substantially annular rear frame being fastened to the central box section of the primary structure, forward relative to a rear end of the central box section, and

wherein the outer skin of the structural cover covers the substantially annular front frame, the one or more additional frame, and the substantially annular rear frame.

8. The engine assembly of claim 7 , wherein the outer skin has a substantially annular form and is fixed to each of the substantially annular front frame, the one or more additional frame, and the substantially annular rear frame.

9. The engine assembly of claim 7 , wherein the outer skin has two facing ends fastened respectively on either side of the central box section of the primary structure.

10. The engine assembly of claim 7 , wherein

the outer skin takes the form of two mobile hoods each articulated on the central box section of the primary structure, each mobile hood having a front end cooperating with the front frame so as to form therewith, in a closed position of the hood, a mechanical link comprising a protuberance of trapezoidal section and a groove of complementary form receiving the protuberance, and

each mobile hood also has a rear end cooperating with the rear frame so as to form therewith, in the closed position of the hood, a mechanical link comprising a protuberance of trapezoidal section and a groove of complementary form receiving the protuberance.

11. The engine assembly of claim 10 , wherein

the plurality of secondary mounts are each produced using a connecting rod articulated on a fitting of the structural cover and articulated on a fitting of the engine, and

the connecting rods are arranged substantially tangentially to the engine.

12. The engine assembly of claim 11 , wherein the connecting rods forming the plurality of secondary mounts are arranged in a same hypothetical transverse plane of the engine.

13. The engine assembly of claim 3 , wherein the front frame and the one or more additional frame are fixedly linked together by longitudinal reinforcements distributed around the longitudinal axis of the engine.

14. The engine assembly of claim 1 , wherein the structural cover comprises a substantially annular rear frame, forming the rear end of the structural cover and substantially centered on the longitudinal axis of the engine, the substantially annular rear frame being fastened to the central box section of the primary structure, forward relative to a rear end of the central box section.

15. The engine assembly of claim 14 , wherein the substantially annular rear frame is fastened to a bottom longeron of the central box section of the primary structure.

16. An aircraft comprising at least one engine assembly as claimed in claim 1 , fastened under a wing of the aircraft.