Preliminary Requirements

Procedure

1. SUBTASK 72-50-22-350-072 General Instructions for the Blend Repair of the Stage 4 Turbine Vane

   1. Blend the nicks and pits of the stage 4 turbine vanes.

      1. Do the blend repair, with the stage 4 turbine vane installed to an action swivel vise.

         Use files, needle files and stones to blend the nicks and pits.

         Use the illuminated comparator magnifier to examine the areas during blend repair.

   2. Polish the blended areas.

      1. Use fine stones to polish the blend repaired areas.

         After the blend repair the surface must be as smooth as the initial surface.

         Edges and corners are not permitted.

2. SUBTASK 72-50-22-350-073 Blend Repair the Stage 4 Turbine Vane

   NOTE

   1. Refer to SUBTASK 72-50-22-350-072before you do the blend repairs.

   2. Do not blend repair dents, but blend repair dents on leading and trailing edge.

   3. The blend ratio, length to depth, must be a minimum of 5:1, refer to Figure.

   4. Keep the material removal to the minimum necessary to remove damage.

   5. The surface texture of all repaired surfaces must have the same or better quality to that of the adjacent not damaged area.

   6. Nicks within acceptable limits do not require blend repair. If there, remove raised material only.

   7. Repeated blending in one place is acceptable to the specified maximum depth, measure from the initial unblended surface.

   8. Area definition is identical with area definition at visual inspection.

   1. Refer to: Figure and Figure

   2. 
      CAUTION
      THE MINIMUM DISTANCE BETWEEN BLENDS AT LEADING AND TRAILING EDGE IS 0.500 IN. (12.7 MM).

      Blend the surface in area A1.

      1. Blend depth from initial surface 0.010 in. (0.254 mm).

         The blended area must not be more than 10 percent of area A1.

   3. Blend the surface in area A2.

      1. No blends permitted.

   4. Blend the surface in area A3.1.

      1. Blend depth from initial surface 0.020 in. (0.508 mm).

         The maximum permitted total depth of opposite blends on leading and trailing edge is 0.020 in. (0.508 mm).

         The total length of all blends on leading edge must not be more than 0.700 in. (17.78 mm).

   5. Blend the surface in area A3.2.

      1. Blend depth from initial surface 0.100 in. (2.54 mm).

         The maximum permitted total depth of opposite blends on leading and trailing edge is 0.100 in (2.54 mm).

         The total length of all blends on leading and trailing edge is 0.100 in. (2.54 mm).

         The total length of all blends on leading edge must not be more than 0.700 in. (17.78 mm).

   6. Blend the surface in area A4.1.

      1. Blend depth from initial surface 0.020 in. (0.508 mm).

         The maximum permitted total depth of opposite blends on leading and trailing edge is 0.020 in. (0.508 mm).

         The total length of all blends on trailing edge must not be more than 0.700 in. (17.78 mm).

   7. Blend the surface in area A4.2.

      1. Blend depth from initial surface 0.100 in. (2.54 mm).

         The maximum permitted total depth of opposite blends on leading and trailing edge is 0.100 in. (2.54 mm).

         The total length of all blends on trailing edge must not be more than 0.700 in. (17.78 mm).

   8. Blend the surface in area A5.

      1. Blend depth from initial surface 0.010 in. (0.254 mm).

         The blended area must not be more than 10 percent of area A5.

   9. Blend the surface in area A6.

      1. Blend depth from initial surface 0.010 in. (0.254 mm).

         The blended area must not be more than 10 percent of area A6.

   10. Blend the surface in area A7.

       1. No blends permitted.

   11. Blend the surface in area A8.

       1. Blend depth from initial surface 0.010 in. (0.254 mm).

          The blended area must not be more than 10 percent of area A8.

   12. Blend the surface in area A9.

       1. Blend depth from initial surface 0.010 in. (0.254 mm).

          Blend cracks only. Blending of nicks, dents and pits is not permitted.

          emove raised material only.

3. SUBTASK 72-50-22-230-111 Examine the Blend Repaired Areas for Cracks

   1. Do the test for cracks.

      1. Refer to the SPM TASK 70-23-05-230-501.

         Use ultra high sensitivity level.

         No cracks are permitted.

4. SUBTASK 72-50-22-220-233 Examine the Blend Repaired Area Visually and Dimensionally

   1. Examine the surface of the blended areas visually.

      1. Use illuminated comparator magnifier.

         The surface must be as smooth as the initial surface.

         Edges and corners are not permitted.

   2. Examine the blend repaired areas dimensionally.

      1. Measure the dimensions of the blended areas with dial caliperand external dial caliper.

         The limits are given in Step.

         Use radius gage set to examine the radius at each blend repaired area.

         Refer to Figure.

         Use dial caliper to identify the extension of leading and trailing edge areas.

         Refer to Figure.

5. SUBTASK 72-50-22-220-234 Replace the Coating of the Stage 4 Turbine Vane

   1. Replace the coating of the stage 4 turbine vane.

      1. Refer to Repair, VRS4264 TASK 72-50-22-300-050 (REPAIR-050) or Repair, VRS4266 TASK 72-50-22-300-052 (REPAIR-052).

Figure: Blend repair the stage 4 turbine vanes

Blend repair the stage 4 turbine vanes



Figure: Details for the blend repair of the stage 4 turbine vanes

Details for the blend repair of the stage 4 turbine vanes