Patent ID: 8137069

Claim:
A cast turbine blade comprising: a blade root and a blade tip; at least one internal cooling passage that passes from an inlet in the blade root to an outlet in the blade tip, the cooling passage having a zone that is at a distance which is remote from the inlet of the cooling passage when the distance from the inlet is measured along the cooling passage, but that is closer to the inlet when the distance from the inlet is measured in a straight line; a supplementary passage that extends between the zone and the inlet through an internal wall of the cooling passage, wherein the supplementary passage is elongate and passes in a straight line from an aperture in an external surface of a base of the blade root, through the blade root, the inlet and the internal wall, to the zone; and a plug which obturates the supplementary passage, wherein the plug is elongate and substantially co-extensive with the supplementary passage.