A heat transfer system for use within an avionics bay of an aircraft is provided by the present disclosure that includes, in one form, an aircraft panel comprising an upper skin, a lower skin, and a foam core disposed between the upper skin and the lower skin. At least one heat conducting array extends through the foam core and between the upper skin and the lower skin, the heat conducting array defining at least one upper cap, at least one lower cap, and a wall portion extending between the upper cap and the lower cap, the upper cap being disposed proximate avionics within the avionics bay. A heat conducting spreader is disposed between the lower cap of the heat conducting array and the lower skin of the aircraft panel.