Preliminary Requirements

Procedure

1. SUBTASK 72-60-21-320-151 Remove the Support Bushes of the Main Gearbox Casing

   NOTE

   This repair must only be performed if TASK 72-60-21-300-030 (REPAIR-030) is not possible.

   1. Refer to Figure, Figure and Figure.

   2. Remove the support bushes, if necessary.

   3. Use appropriate tools.

2. SUBTASK 72-60-21-220-191 Inspect the Bores of the Support Bushes

   1. Refer to Figure.

   2. Inspect the diameter G of the bores of the casing.

      1. Scratches, scores and other damage are not allowed.

         1. If necessary, machine the bore to remove any damage.

         2. Remove the minimum amount of material to remove the damage.

      2. The maximum bore diameter allowed is 0.8480 in. (21.54 mm).

      3. Measure and record the diameter G.

         1. Use a bore gage.

            NOTE

            The position of the bore should be located in the same position as the inner diameter of the removed bushing or concentric with the original bore in the Gearbox Casing. If the position of the original bushing is unknown or the bore is damaged too much, it is acceptable to position the hole per the locations identified in Figure.

3. SUBTASK 72-60-21-220-192 Crack Test the Bores

   1. Do a local fluorescent penetrant inspection.

      1. Refer to SPM TASK 70-23-05-230-501 use CoMat 06-063 FLUORESCENT PENETRANT (POST-EMULSIFIED MEDIUM SENSITIVITY).

   2. Cracks are not allowed.

4. SUBTASK 72-60-21-220-193 Apply Chromate Conversion Coating

   1. Apply the chromate conversion coating to the machined surfaces.

      1. Refer to TASK 70-38-02-300-503.

5. SUBTASK 72-60-21-220-194 Produce the Bushings

   1. Refer to Figure.

   2. Machine the Bushing.

      1. Use the specified types of material. Do not use other types of material.

      2. The interference fit with the bore Diameter G must be 0.0016 in. to 0.0031 in. (0.04 mm to 0.08 mm).

   3. Check the hardness of the bushing.

      1. The hardness must be 331 HB to 401 HB (Brinell scale).

         NOTE

         The inner diameter of the bushing will be final machined after the bushing is installed to the Gearbox Casing.

6. SUBTASK 72-60-21-220-195 Crack Test the Bushings

   1. Do a fluorescent penetrant inspection.

      1. Refer to SPM TASK 70-23-05-230-501, use CoMat 06-063 FLUORESCENT PENETRANT (POST-EMULSIFIED MEDIUM SENSITIVITY).

   2. Cracks are not allowed.

7. SUBTASK 72-60-21-350-171 Install the Bushing

   NOTE

   The difference in temperature between the parts must be less than 250 deg F (120 deg C).
   1. 

      WARNING

      DO NOT TOUCH THE HOT PARTS WITHOUT PROTECTIVE GLOVES.

      

      WARNING

      HOT PARTS CAN CAUSE REDDENING AND BLASTING OF THE SKIN IF THE HANDS ARE NOT PROTECTED.

      

      WARNING

      IMMERSE THE CONTACTED AREA IN COLD WATER FOR 10 MINUTES IF THE SKIN IS BURNED. IMMEDIATELY GET MEDICAL ATTENTION IF THE PAIN OR BLISTERING PERSIST.

      Refer to Figure, and Figure.

   2. Use the hot air gun and/or the freezer to increase the temperature of the housing and/or decrease the temperature of the bushing.

      1. Make sure the temperature of the aluminum housing is not more than 250 deg F (120 deg C).

      2. Make sure that the temperature of the bushing is not less than minus 58 deg F (minus 50 deg C).

   3. Install the bushing into the machined bore.

      1. Use protective gloves.

      2. Use an arbor press, a drift and a guide pin.

      3. Give sufficient back - up support at the bushing bore area to prevent housing distortion when you install the bushing.

   4. 

      CAUTION

      INSTALL THE BUSHING IN THE MACHINED BORE IMMEDIATELY AFTER REMOVAL FROM THE FREEZER, OTHERWISE THE BUSHING CANNOT BE CORRECTLY INSTALLED.

      Let the part get to room temperature.

   5. Remove the drift and the guide pin.

8. SUBTASK 72-60-32-320-152 Machine the Inner Diameter of the Bushings

   1. Refer to Figure and Figure.

   2. Machine the inner diameters of the bushings.

   3. The final dimension must be done by line reaming the inner holes of the bushings.

      1. The final dimension must be 0.62559 in. to 0.62630 in. (15.8899 mm to 15.9080 mm).

         NOTE

         The position of the hole should be located in the same position as the inner diameter of the removed bushing. If the position of the original bushing is unknown or damaged too much, it is acceptable to position the hole per the locations identified in Figure.

9. SUBTASK 72-60-21-350-172 Identify the Repair

   1. Make a mark "VRS5709" adjacent to the part number. Use vibration peen method.

      1. Refer to SPM TASK 70-09-00-400-501, SUBTASK 70-09-00-400-001.

   2. Touch up the marking area.

      1. Refer to SPM TASK 70-38-02-300-503.

Figure: Repair Details

Repair Details



Figure: Repair Dimensions

Repair Dimensions



Figure: Casing Machining Dimensions

Casing Machining Dimensions



Figure: Bushing Dimensions

Bushing Dimensions