The length and width of this region were approximately 5.08 mm and 1.016 mm, respectively (Fig. 4a). Looking at the pressure-side of the leading-edge area revealed that the anomaly and surrounding fracture surface were approximately 2.54 mm above the blade dovetail (Fig. 4b). The above described anomaly was not detected at the stereoscopic views of blade #3.
The fracture surface of the midchord area for blade #1 was relatively flat and displayed well-defined crack growth marks, while the trailing-edge fracture surface presented a rough surface morphology typical of a final overload region. The overload region accounted for approximately 50% of the airfoil cross-section (Fig. 5).
On the other hand, the leading-edge and trailing-edge fracture surfaces of blade #3 revealed a rough surface morphology. Contrarily to blade #3 finding, the midchord fracture surface presented significant plastic deformation but no crack growth marks (Fig. 6).
In addition, the examination of the dovetail surface on the failed 1st stage compressor blade #1 presented only a uniform loading marks.