Root Cause Analysis of a Gas Turbine Compressor Stator Blade Failure

Three identical 85 MW combustion turbines experienced cracking and failure of several first stage compressor stator (S1) blades. The root cause analysis involved the following distinct stages: 1. Examination of failed blades including fractography and analyses of the mechanics of their fracture; 2. Blade vibration analysis to determine the modes of vibration and corresponding resonant frequencies; 3. Inlet plenum flow and acoustical analysis to identify possible sources of excitation. This paper summarizes the methodology and results of the root cause analysis investigation and outlines the convergence of results obtained from the independently conducted mechanical and acoustical analyses.