Nowadays composite joints are becoming increasingly present in aeronautical and aerospace structures, These elements require in-depth studies to accurately predict behavior and catastrophic failure during operational hours on aircraft. Commercial software is effective at delivering accurate results but requires equally high computational resources and time. In this collaborative study with Leonardo Helicopters Division, we propose a more efficient approach to examine joints in bonded composite materials. Specifically, the focus is on bonding a panel to a spar located on the tailplane of a helicopter. Leveraging the capabilities of the MUL2 software, based on the CUF (Carrera Unified Formulation) theory, the results obtained from MUL2 will be compared with those from NASTRAN, conducted at the host company, for certification purposes.