Most of the heli-decks are constructed with aluminum extrusions. The heli-deck product company supplies structural analysis data to the shipbuilding companies: so, if the shipbuilding co. needs to make up for the weak points in the current system, they only need to analyze the substructure through the FEA. In this paper, we will concentrate on the following issues: analysis of aluminium extrusions regarding the structural analysis data, and check safety about the substructure through the FEA.