Producing aircraft metallic spare parts by additive manufacturing to enhance Logistic Support

Leonardo is a global industrial group that builds technological capabilities in Aerospace, Defence & Security. In particular, the Customer Support of Leonardo's Aircraft Division is always attentive to the development of innovative solutions leveraging disruptive technologies to meet customer needs. Logistic Support and in particular the readiness of spare sparts is one of the critical factors to maximize aircraft availability. For this reason, there has been increasing interest in recent years on the utilization of Additive Manufacturing (AM) for the production of spare parts taking advantage on the flexibility of these technologies for manufacturing a wide variety of components on-demand. This master's thesis work studied the production by Laser Powder Bed Fusion (LPBF) of metallic components from several Leonardo's aircraft platforms and a deep characterization of the materials properties was carried out. Possible candidates for AM production are defined by several parameters to assess feasibility from a manufacturing standpoint and suitability from a logistics standpoint. An aluminum bracket, characterized by significant challenges in the supply chain, from the Main Landing Gear of the multi-mission transport C-27J aircraft was first selected. While the conventional material is not adapted to LPBF, the substitution with the attractive AlSi10Mg alloy was found encouraging. Two other components in LPBF-favorite Ti-6Al-4V were also selected from the Advanced Jet Trainers' family of Leonardo: a complex clevis from the Environmental Control System of the M-346 and a connector to the hydraulic accumulator of the Leading Edge Flap Actuation System of the M-345. The complete characterization showed that the materials produced by LPBF had better mechanical properties than their conventionally wrought counterpart. In all the cases a series of prototypes together with control specimens were produced on an EOS M270 at the Integrated Additive Manufacturing infrastructure of Politecnico di Torino. Stress relieving treatments as well as aging were carried out. Specimens were prepared by standard metallographic procedures and porosity and microstructure were verified. Roughness was measured and accurate control of the dimensions was compared to the conventional parts. Standard specimens for tensile tests were also prepared and the mechanical properties were compared to design requirements. All results were conscientiously reported and discussed, and suggested that Additive Manufacturing could be integrated in the supply chain of spare parts bringing about great benefits. The analysis presented in this thesis will support the already existing certification path for AM-produced components in Leonardo Aircraft.