Through dye penetrant testing of blades (shown as Fig. 5), it was found that cracks with a length of 2–8 mm propagate transversely on the inner arc face with a distance 95–205 mm from the blade tip, most in a distance of 130–170 mm. The cracks initialize from the edge of the suction side, which do not connect with erosion pits examined from the surface as generally expected. It shows that erosion pits are not the crack initiation point.