Abstract: In a method and apparatus for repairing a metal or composite structure such as an aircraft component wherein the component is repaired utilizing a heat spreader or caul plate and heat is applied to the caul plate or through the heat spreader to a repair whereby the component placed in operative relationship to the heat spreader or caul plate is heated to a desired and non-uniform temperature, the improvement comprising applying differential heat to the caul plate or through the heat spreader utilizing a plurality of spaced-apart heaters, and controlling the temperature of each of the plurality of heaters independently from each other to achieve a substantially uniform heat temperature applied to in the component being prepared, and the caul plate is a sheet of material capable of exhibiting superplasticity and is removed after the repair has been effected.