Casing structure interposed between the engine and the nacelle having a mounting plate with bolts

A casing structure fitted for providing the mechanical junction between the engine and the nacelle of an aircraft, the structure comprising:

• a shroud destined to surround the engine and made up of a plurality of sectors, each of said shroud sectors having a groove recessed from a shroud surface in a thickness direction of the shroud;
• a plurality of radial arms, each radial arm being mounted between two adjacent shroud sectors and each having a base;
• and
• a plurality of fasteners for fastening said plurality of shroud sectors to said bases of said plurality of radial arms;
• wherein said plurality of fasteners comprise a plurality of plates each mounted flush with the shroud surface in a respective one of the grooves and of a shape corresponding with the respective one of the grooves, and a set of headed bolts having shanks and threads extending through each respective plate in the thickness direction of the shroud, the bolts being held captive in said plates due to their shanks and their threads presenting different diameters;
• a set of captive nuts being fastened on said bases to provide respective secure connections between said plurality of shroud sectors and said plurality of radial arms, each of the nuts receiving the thread of a respective captive bolt of said set of headed bolts,
• wherein said captive nuts are made in two portions, a first portion forming the nut proper being made of a first material, and a second portion, forming a retaining cage and acting as a clip, being made of a second material that is more flexible than the first material and that provides the connection with the base via a projecting portion formed in a hole in the base that is to receive said captive bolt.