Mr Swanson's appointment increases the size of the FPL Group board from 12 to 13 members.
At Raytheon, Mr Swanson heads a technology and innovation team specializing in defense, homeland security and other government markets throughout the world.
Lew Hay, chairman and CEO of FPL Group, said: "We are pleased to have Bill join our board and to be able to draw upon his proven business leadership as well as his deep understanding of innovation and technology."
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