trailing edge). These curled tips are usually smooth inthe bend area of the airfoil distortion. However, youshould inspect the area at the change in normal airfoilfor tears or cracks. When you report tip curl, estimatethe percent of the chord length, the number of bladeswith curl, and the condition of the adjacent airfoil area.Record any evidence of impact and inspect for the originof the impact. Always look at the adjacent blades forevidence of tip clang.Missing Metal.— Missing metal from compressorrotor blade airfoils is a result of the progression ofcracked or tom airfoils that release part of the airfoil intothe flow path. Crack propagation in the root fillet areacan result in the separation of the entire blade. SevereFOD or DOD may result in several random rotor andstator airfoils with missing metal. The inspection reportshould include the stage, the number of blades withmissing metal, the amount, and the location on theairfoil. Estimate the percent of chord, the span of theairfoil that is missing metal, and the condition of theremaining airfoil.Airfoil Surface Defects.— Surface defects are theresult of object damage or adjacent blade interference(tip clang). Impacts in the center section of the airfoilare not common. Tip clang damage is the result of ablade leading edge tip contacting the adjacent blade tipat approximately one-third of the chord length forwardof the trailing edge on the low-pressure (convex) side ofthe blade (fig. 2-13). This is the result of compressorstall and is observed in stages 3 through 6. You shouldreport any observed defect on the airfoil surfaces in theinspection record.Your report should containFigure 2-13.—Compressor rotor blade tip clang damage.2-12
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