This paper describes the approach developed to model the current return networks installed aboard aircrafts having parts made in composite materials. The surface partial element equivalent circuit (PEEC) method is adopted for its high-fidelity modeling capabilities, and its accuracy in the low-frequency region, which is of interest for the characterization of the return networks. State of the art of PEEC modeling is implemented in order to allow real-life aircrafts to be modeled. A special complex mock-up has been realized and measured. The numerical results are compared with measurements to assess their adequacy.