Abstract: Hollow fluid cooled turbine blades of the multi-pass type used in gas turbine engines have suffered from separation of cooling fluid from longitudinally extending walls defining longitudinally extending passages as the cooling fluid is turned through a turning passage from one longitudinally extending passage to an adjacent one. The invention provides an aerodynamically shaped end portion arranged at an angle with respect to the remainder of the wall to increase the turning radius, and a turning vane is positioned in turning passage to form a convergent passage with the end portion of wall. The turning vane has a large turning radius and a large surface area for retention of a boundary layer of cooling fluid thereon. The turning vane directs the cooling fluid flowing through the convergent passage and over the turning vane substantially parallel to the wall to reduce separation in order to reduce pressure losses.