Failure analysis of axial compressor rotor stage III of an aeroengine

A failed compressor rotor disc III stage of an aeroengine was sent to the laboratory for investigation. Examination revealed that one of the disc blades failed by fatigue leading to secondary damages to other blades. Fractographic examination confirmed that the failure was by fatigue. There were two fatigue crack origins on the concave surface of the blade close to the leading edge and the hub. Corrosion pits were observed at both the fatigue crack origins. Evidences suggest that the stress concentration arising from the corrosion pits was responsible for the premature fatigue crack initiation in the blade. Analysis shows that the most probable reason for the corrosion on the blade surface could be either improper surface preparation or non-detection of corrosion pits before the surface treatment process. A detailed analysis of the failure is presented in this report