Figure 2-21.—Combustion liner dome igniter tube.INNER AND OUTER LINER ASSEMBLIES.—circumferential stiffeners and are not visible whenYou can inspect all areas of the inner and outer linerassemblies aft of the fuel nozzles by rotating and tiltingthe probe, and by varying the immersion depth. Someof the damage that you may find is described in thefollowing paragraphs.Circumferential Cracks.— Figure 2-22 shows anexample of circumferential cracking on a high-timecombustion liner. This type of cracking occurs over thearea of the inner liner stiffening bands. The bands areviewed through the borescope inside the combustorassembly. Before actual cracking, the thermal workingof the liner shows stress lines. These lines will be visiblein all panels. Take care to inspect for the presence ofcracks, not merely lines. A crack will be open and theseparation will show an edge. The distortion occurs sothat the inner liner lifts up into the flow path and theouter liner bends down into the flow path. Theseirregularities are usually obvious when the liners areFigure 2-22.—Inner/outer liner circumferential cracks.2-17
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