The Technical Development Feasibility project to develop a composite fuselage rear section (cone and Fenestron) for the EC155 was equally financed by the Civil Aeronautics Program Directorate (DPAC) and Eurocopter. The stated objective of the project was to generate significant cycle and cost-related savings through the fiber placement technology already in use at Airbus (A380 rear section), CASA Espacio (Ariane launcher), and MTAD (A400M aileron support fairings), applying the same technology to a helicopter sandwich structure subassembly for the first time.

Fiber placement technology involves placing unidirectional composite material on the lay-up mold automatically. Working with a fabric split into rovings measuring a quarter of an inch, the machine can handle up to 32 filaments autonomously, allowing highly flexible fiber placement.

The key advantage of this technology is that tapes with several rovings can be automatically removed and cut out to match complex geometrical shapes, reducing the number of off-cuts and manual operations (precutting and compacting of plies, trimming), thus shortening the manufacturing cycle. On the whole, versatile fiber placement associated with the re-engineering of the cone/Fenestron assembly has allowed certain components to be fully integrated, halving the number of parts (from 32 to 16) and eliminating some of the assembly phases.

Furthermore, fewer parts reduce the weight of the fuselage rear section by between 5 and 10%. The assembly is currently undergoing qualification tests for static loading (and fatigue during 20,000 hours). These tests will demonstrate the technical and technological maturity level, which will similarly be applicable to light helicopters equipped with a Fenestron tail rotor or a conventional tail unit. Other elements, including the intermediate structure, tail booms, and fairings, are already being studied.