A hollow, air-cooled turbine blade of the type having a plurality of ridges and projections extended inwardly from an interior surface of said blade, an insert snugly fitted into a space defined and supported by the ridges and projections and cooling air passages for communicating the space inside the insert with an exterior blade surface, said air passage including a first passage for communicating the space through a space defined between the insert and a wall of the blade with the exterior blade surface and a second air passage for communicating the space within the insert through at least some of the projections directly with the exterior blade surface.