The thesis project aims to support the design and the integration of an HEC (Human External Cargo) System on the AS350 B3e helicopter. The work consists in demonstration of compliance with requirements to EASA, in order to make the aircraft with the new modification airworthy. The project was carried out in collaboration with the company TPS Aerospace Engineering, that has supported the work at every stage with specialists. First of all, the thesis provides a framework on the Safety Process and Reliability Analyses that must be executed to design the system architecture, to continue with the explanation of the analyses led for the case of study and presentation of the system design configuration.