Recently some commercial aircraft have been fabricated with more than 60% of the rivets replaced with FSW joins. The replacement locations have included the cabin, aft fuselage, wings and engine mounts. Benefits include a reduction in painting preparation time, a lighter airframe and smoother structure. In addition, fatigue resistance and durability are comparable with single-row riveted joints. Nevertheless, the degradation in FSW joins is known to be asymmetrical in nature, with the advancing and retreating side of the same weld behaving differently from the electrochemical and corrosion standpoint. During this work, the behavior of aluminum alloys with and without FSW joins has been investigated in an aggressive chloride containing aqueous environment. Joins were assessed for degradation properties using traditional electrochemical methods, EIS, SVET, microscopy and a novel in-situ corrosion fatigue monitoring technique which incorporates both mechanical and electrochemical monitoring.