The aim of this paper is to present an investigation on a fatigue stress corrosion phenomenon of a propeller shaft. The area where damages were found (propeller shaft close to the seal) is described together with working conditions of the whole propulsion plant. Then non-destructive and destructive tests methods used in order to evaluate, localize and characterize damages are explained. A complete description of the damages are summarized taking into account information drawn out from tests. Moreover the environmental conditions in way of the seal are studied with reference to the shaft’s material. Investigation findings provide different reasons of the event. Chemical, metallurgical and structural considerations lead to corrosion, stress and fatigue phenomena which are altogether analyzed. Also comparison with tests available from literature is reported.