Abstract: A helicopter main rotor pylon support structure including a framing structure for supporting the loads applied to the main rotor pylon, and a fire shield for preventing fire from transmitting from an engine or exhaust compartment into an adjacent compartment. The framing structure includes first and second composite main beams, each beam extending adjacent to a engine compartment and an exhaust duct compartment. A plurality of bridge members preferably extend between and connect with the first and second main beams and are formed integral therewith. A plurality of vertical posts are attached to and spaced along the main beams. The vertical posts are engaged with discrete attachment points on the helicopter. There is at least one fire panel mounted to each main beam. The fire panel has side edges which are slidingly engaged with the vertical posts, and a lower edge which is slidingly engaged with a flange formed on the helicopter.