Utilising a comprehensive design tool suite and in-house knowledge, the root cause analysis of High Cycle Fatigue (HCF) failures on the first stage compressor blade in a gas turbine (GT) engine is presented in this paper.

Based on the experience gained from the root cause analysis more reliable lifetime prediction for compressor blade design is possible. Tip timing measurements of blades in service have been evaluated to obtain valuable information about the real vibratory stress levels of the first stage compressor blades, to validate design methods, and to identify the failure mechanism. Metallurgical evaluation and testing of the failed parts were also used as part of the investigation. During the failure investigations the impacts of important damage mechanisms, not identified in the original design process, were determined. These damage mechanisms included, water droplet erosion of blades due to impingement on highly stressed regions of airfoil, mistuning within manufactured blade sets, and a very strong transient aerodynamic loading.

Considering the damage mechanisms, improved design methodologies have been used to design robust compressor blade sets. These have been validated in successful engine tests. Subsequent continued successful operation of new blade designs has been recorded in engines during an extended validation period.

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