The overall status of the compressor rotor assembly revealed a relatively clean condition. The first and third blades of the stage 1 have been fractured at the airfoil roots, remaining blades present a severe impact damage. The forward tab on the retainer clip for blade 1 was undamaged while the retainer clips for all the other 1st stage blades displayed severely distorted forward tabs (Fig. 3).
Detailed view of the failed first stage compressor blade #1 revealed fracture features indicating a primary fracture surface from the airfoil leading edge to the midchord. Investigating the blade #3 of the same stage shows a rough surface morphol- ogy over the entire fracture from the airfoil leading edge to the trailing edge. All the other rotor’s blades were still tied up to the rotor dovetail but severe impact damage to the airfoils was noticed. This damage is caused by the crash with the loosen blades #1 and #3 at high rotating speed.
Stereo-microscopic views of the fracture surfaces for both blade #1 and #3 were performed and compared. According to the leading-edge fracture surface on the failed 1st stage compressor blade #1, an internal anomaly displaying a golden coloration was detected. It is a rough surface morphology with a well-defined boundary surrounding the fracture surface.