Hydraulic turbine runners are used in electricity generation. These consist of a cylinder around which are welded, at regular spacings, a number of blades whose weights differ slightly. It is desired to locate the blades around the cylinder in order to minimize the distance between the center of mass of the blades and the geometric center of the cylinder. The problem can be formulated as a quadratic assignment problem. it is solved by adapting an interchange algorithm devised by Or for the travelling salesman problem. Computational results are reported.