Preliminary Requirements

Procedure

1. SUBTASK 72-60-21-220-172 Measure To Determine Repairability

   1. NOTE

      If the IDG housing bore bushing repair was previously performed by Repair-050 (VRS5422), TASK 72-60-21-300-050, this repair cannot be used to install repair bushings at the (eight) screw thread insert locations at the IDG bore location of the Main Gearbox Casing.

      NOTE

      This repair can only be used at a maximum of four locations. A maximum of three adjacent repaired locations is permitted.

      Refer to Figure.

   2. For each repair location, measure the minimum distance from the Lock Ring Counterbore to the IDG pad bore (Datum D).

      1. Not less than 0.157 in. (4.0 mm).

         1. This repair can be performed.

      2. Less than 0.157 in. (4.0 mm).

         1. This repair cannot be performed.

2. SUBTASK 72-60-21-350-282 Mask the Gearbox Casing

   1. Mask all bores, holes, passage ways in the proximity of the repair area.

      1. Use CoMat 02-002 ADHESIVE TAPE GENERALPURPOSE PAPER (masking tape or similar).

3. SUBTASK 72-60-21-300-157 Remove the Screw Thread Insert

   1. Remove the damaged or loose screw thread inserts and lock rings.

      1. Remove the screw thread inserts and lock rings by repair, VRS5256, TASK 72-60-21-300-005 (REPAIR-005) SUBTASK 72-60-21-350-053 and SUBTASK 72-60-21-350-054.

4. SUBTASK 72-60-21-300-158 Machine the Damaged Holes of the Gearbox Casing

   1. Refer to Figure.

   2. Inspect the damaged holes.

      1. Inspect the holes to find if this repair was done before.

      2. If the repair was not previously repair, go to operation Step.

      3. 

         CAUTION

         USE APPROPRIATE DRILLING EQUIPMENT TO REMOVE THE PIN FIRST, THEN REMOVE THE BUSHING. MAKE SURE THAT YOU DO NOT DAMAGE THE GEARBOX CASING.

         If this repair was previously performed, the bushing must be removed by machining.

      4. Go to Step.

   3. Drill the damaged holes.

      1. Refer to Figure and Figure.

      2. Use a drilling tool with flat head. The diameter of the hole must be 0.6892 - 0.6977 in. (17.505 - 17.721 mm). Drill to a depth of 0.886 - 0.905 in. (22.5 - 23.0 mm).

   4. Inspect the holes for cracks.

      1. Use a 10X Magnifying glass. As an alternative, do a local fluorescent penetrant inspection.

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

      3. Cracks are not allowed.

   5. Tap the holes.

      1. Tap the hole. The thread must be .750 - 16 UNJF - 3B. The depth of the full thread must be a minimum of 0.826 in. (21.0 mm) from the surface of the gearbox casing.

5. SUBTASK 72-60-21-220-173 Examine the Gearbox Casing

   1. Locally degrease the repaired area.

      1. Use CoMat 01-031 ACETONE (CH3)2CO or similar.

   2. Inspect the gearbox casing for cracks in the area of the bore.

      1. Use a 10X Magnifying glass.

   3. Locally restore the surface protection.

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

      2. Use CoMat 07-028 CHROMATE CONVERSION COATING FOR ALUMINUM.

6. SUBTASK 72-60-21-300-159 Produce a Bushing

   1. Refer to Figure.

   2. Machine the bushing.

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

      2. Make sure you comply with dimensions and tolerances.

         NOTE

         A convenient fixture to torque the bushing into its position in the main gearbox casing can be machined on the external flat surface.

   3. Inspect the bushings for cracks.

      1. Use a 10X Magnifying glass. As an alternative, do a local fluorescent penetrant inspection.

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

      3. Cracks are not allowed.

   4. Apply the chromate conversion coating to the bushing.

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

7. SUBTASK 72-60-21-300-160 Install the Bushing into the Machined Hole of the Gearbox Casing

   1. Screw the bushing in.

      1. Install the bushing in the threaded hole of the casing. Make sure that the bushing reaches the bottom. Do not exceed 220 lbf-in. (25 Nm).

   2. Machine the bushing.

      1. Machine the bushing end flush with the casing surface.

8. SUBTASK 72-60-21-300-161 Install an Antirotation Pin

   1. Refer to Figure.

   2. Drill the pin hole.

      1. Drill a hole axially across the counterbore between the gearbox casing and the bushing.

         1. Hole diameter for the pin must be between 0.077 - 0.079 in. (1.95 - 2.00 mm).

         2. The tolerance for the perpendicularity of the hole axis is the same as for the previous drilling.

         3. Hole depth is to be 0.193 - 0.200 in. (4.90- 5.10 mm).

         4. The angular location of the pin hole is to be at the location of maximum parent material thickness.

      2. Measure and record the pin hole diameter.

   3. Make a pin.

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

      2. Machine a pin to fit into the pin hole with an interference between 0.0004 in. - 0.0007 in. (0.010 mm - 0.020 mm). Pin length is 0.256 in. (6.500 mm) minimum.

   4. Visually inspect the pin for cracks.

      1. Use a 10X Magnifying glass.

      2. Cracks are not allowed.

   5. Apply surface protection coating to the pin.

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

   6. Install the antirotation pin.

      1. Install the antirotation pin within the dedicated hole. Freeze the pin up to minus 60 deg C. Use of nitrogen liquid is also allowed. Machine the pin end flush with the bushing surface.

9. SUBTASK 72-60-21-320-150 Drill and Tap the Holes for the Screw Thread Inserts in the Bushings

   1. Refer to Figure and Figure.

   2. Drill the hole.

      1. Use a drilling tool with flat head. The diameter of the hole must be 0.4814 - 0.4914 in. (12.228 - 12.480 mm). Drill to a maximum depth of 0.905 in. (23.0 mm).

   3. Drill the counterbore.

      1. Use a drilling tool with flat head. The diameter must be 0.593 - 0.596 in. (15.06 - 15.14 mm). Drill to depth of 0.172 - 0.202 in. (4.37 - 5.13 mm).

   4. Inspect the holes for cracks.

      1. Use a 10X Magnifying glass. As an alternative, do a local fluorescent penetrant inspection. Follow SPM TASK 70-23-05-230-501, use CoMat 06-063 FLUORESCENT PENETRANT (POST-EMULSIFIED MEDIUM SENSITIVITY).

      2. Cracks are not allowed.

   5. Tap the holes.

      1. Tap the hole. The thread must be .5625 - 12 UNJC - 3B. The depth of the thread must be 0.655 in. (16.60 mm) minimum from the surface of the gearbox casing.

10. SUBTASK 72-60-21-300-162 Install New Screw Thread Inserts

    1. Install the screw thread inserts and lock rings.

       1. Install the screw thread inserts and lock rings by VRS5256, TASK 72-60-21-300-005, SUBTASK 72-60-21-350-055 and 72-60-21-350-056.

    2. Apply surface protection coating.

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

11. SUBTASK 72-60-21-350-282 Identify the Repair

    1. Make a mark VRS5707 adjacent to the part number.

       1. Use Vibro-engraving equipment. Refer to SPM TASK 70-09-00-400-501, SUBTASK 70-09-00-400-001.

    2. Protect the marked area.

       1. Do the touch up process. Refer to SPM TASK 70-38-02-300-503.

Figure: Repair location

Repair location



Figure: Repair details

Repair details



Figure: Machine the Casing

Machine the Casing



Figure: Bushing Dimensions

Bushing Dimensions



Figure: Antirotation Pin Hole

Antirotation Pin Hole



Figure: Machine the Bushing

Machine the Bushing



Figure: Measure Minimum Distance

Measure Minimum Distance