Lockheed Martin (NYSE: LMT) has selected Raytheon (NYSE: RTN) to replace Northrop Grumman (NYSE: NOC) as supplier of a key sensor system on its F-35 fighter aircraft, a move the lead contractor said will save the program more than $3 billion.Raytheon was selected to develop and deliver the next-generation distributed aperture system (DAS) for the F-35, a series of six cameras mounted around the aircraft that allows pilots a full-range of vision -- including directly below the aircraft -- day and night through video that is fed into the helmet.A Lockheed Martin F-35A.