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TASK 72-21-02-200-801
1 . General.
A.This procedure gives instructions to do an inspection of the aft fan case.
•
Aft fan case (01-020 , 72-21-00) (SIN 84100)
•
Aft fan case (01-021 , 72-21-00) (SIN 84100) (SB 72-0156).
2 . Tools, Equipment, and Materials.
NOTE:
You can use equivalent alternatives for tools, equipment, and consumable materials.
A.Tools and Equipment.
(1)Special Tools. None.
(2)Standard Tools and Equipment. None.
(3)Locally Manufactured Tools. None.
B.Consumable Materials.
 
Code No.
Description
 
C03-006
Deleted
 
C03-077
Primer, Epoxy, Water-Reducible, (BMS-10-11V Type 1, Class A, Grade E)(primer)
 
C03-079
Primer, Epoxy, (MIL-P-53030 No class needed) (primer)
C.Referenced Procedures.
 
ATA No.
Description
 
70-32-02
Fluorescent Penetrant Inspection
 
70-42-00
Blending And Removal Of High Metal Procedures
 
70-43-07
Chemical Touch-Up Surface Refinishing Process for Aluminum
D.Expendable Parts. None.
3 . Visual Inspection.
Refer to Figure 801.
Subtask 72-21-02-220-001
A.Do an inspection of the aft fan case mounting flanges for:
(1)Cracks:
Maximum serviceable limit:
Not serviceable.
Repair method:
Replace the aft fan case.
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Figure 801   (Sheet 1 ) Aft Fan Case - Inspection Areas
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Figure 801   (Sheet 2 ) Aft Fan Case - Inspection Areas
Subtask 72-21-02-220-002
(2)Nicks and scratches:
Maximum serviceable limit:
Any amount, 0.010 inch (0.25 mm) in depth after removal of high metal. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) .
Maximum repairable limit:
Any amount, 0.030 inch (0.76 mm) in depth after removal of high metal. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) .
Repair method:
Blend to a minimum radius of 0.250 inch (6.35 mm). Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) .
Subtask 72-21-02-220-003
(3)Wear:
Maximum serviceable limit:
Any amount, 0.005 inch (0.13 mm) in depth after removal of high metal. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) .
Maximum repairable limit:
Any amount, 0.020 inch (0.51 mm) in depth, in an area not more than 2.0 sq in. (1290 sq mm).
Repair method:
Blend to a minimum radius of 0.250 inch (6.35 mm). Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) .
Subtask 72-21-02-220-004
B.Do an inspection of the aft fan case ribs for:
(1)Cracks:
Maximum serviceable limit:
Not serviceable.
Repair method:
Replace the aft fan case.
Subtask 72-21-02-220-005
(2)Nicks and scratches in the web area:
Maximum serviceable limit:
Any amount, 0.020 inch (0.51 mm) in depth with no less than 1.0 inch (25 mm) between defects.
Maximum repairable limit:
•
Any amount, 0.025 inch (0.64 mm) in depth with no less than 1.0 inch (25 mm) between defects unless in area D
•
Any amount can be repaired in area D
•
The repaired area must be contained in area D.
Repair method:
Blend to a minimum radius of 0.250 inch (6.35 mm). Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) .
Subtask 72-21-02-220-006
(3)Dents:
Maximum serviceable limit:
Smooth contour dents 0.125 inch (3.18 mm) in depth with no less than 36.0 inches (914 mm) between defects, if the bracket assembly is not damaged.
Repair method:
Replace the aft fan case.
  Subtask 72-21-02-220-029
  (4)Thread marks in rib bolt holes:
  Maximum serviceable limit:
Any amount, 0.015 inch (0.38 mm) in depth, after the removal of high metal. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) .
  Maximum repairable limit:
Maximum hole diameter up to 0.327 inch (8.3 mm).
  Repair method:
Ream until damage is cleared, not exceeding 0.327 inch (8.3 mm) in ID (inner diameter) of bolthole. Refer to TASK 70-42-01-350-003 (POLISHING BOLT HOLE SURFACES) . Apply C03-006  coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) . Apply C03-077  primer (44-GN-60   ) or C03-079  primer . Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) .
Subtask 72-21-02-220-007
C.Do an inspection of the aft fan case shell for:
(1)Cracks:
Maximum serviceable limit:
Not serviceable.
Repair method:
Replace the aft fan case.
Subtask 72-21-02-220-025
(2)Nicks, scratches, and scores in boltholes:
Maximum serviceable limit:
0.001 inch (0.03 mm) in depth.
Repair method:
Replace the aft fan case shell.
Subtask 72-21-02-220-008
(3)Nicks and scratches around the OGV boltholes:
Maximum serviceable limit:
Any amount, 0.005 inch (0.13 mm) in depth after removal of high metal with no less than 1.0 inch (25 mm) between defects. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Sharp grooves are not permitted.
Maximum repairable limit:
•
One per bolt hole 0.010 inch (0.25 mm) in depth after removal of high metal on 0.406 inch (10.31 mm) diameter bolt holes. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES).
•
One per bolt hole 0.010 inch (0.25 mm) in depth and 0.10 inch (2.5 mm) in length after removal of high metal on 0.502 inch (12.75 mm) diameter bolt holes. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES).
•
One per bolt hole 0.010 inch (0.25 mm) in depth after removal of high metal on 0.656 inch (16.66 mm) diameter bolt holes. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES).
Repair method:
Blend to a minimum radius of 0.250 inch (6.35 mm). Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) .
Subtask 72-21-02-220-010
(4)Nicks and scratches on all other areas:
Maximum serviceable limit:
Any amount, 0.005 inch (0.13 mm) in depth after removal of high metal, with no less than 1.0 inch (25 mm) between defects. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Sharp grooves are not permitted.
Maximum repairable limit:
Any amount, 0.040 inch (1.02 mm) in depth after removal of high metal, and no less than 1.0 inch (25 mm) between defects. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) .
Repair method:
Blend to a minimum radius of 0.250 inch (6.35 mm). Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) .
Subtask 72-21-02-220-011
(5)Wear (all areas):
Maximum serviceable limit:
Any amount, 0.005 inch (0.13 mm) in depth after removal of high metal. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) .
Maximum repairable limit:
Any amount, 0.010 inch (0.25 mm) in depth after removal of high metal. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) .
Repair method:
Blend to a minimum radius of 0.250 inch (6.35 mm). Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) .
Subtask 72-21-02-220-012
(6)Dents:
Maximum serviceable limit:
Smooth contour dents, 0.125 inch (3.18 mm) in depth with no less than 6.0 inches (152 mm) between defects.
Maximum repairable limit:
Any amount.
Repair method:
Cold work to original contour. Refer to TASK 70-47-05-350-023 (COLD-WORKING REPAIR).
Subtask 72-21-02-220-013
(7)Loose or missing rivets:
Maximum serviceable limit:
Not serviceable.
Maximum repairable limit:
Any amount.
Repair method:
Replace the rivet. Refer to TASK 70-13-00-390-001 (RIVETED JOINTS).
Subtask 72-21-02-220-014
(8)Loss of the locking feature of the anchor nuts:
Maximum serviceable limit:
Run-on torque must be more than 10 lb in. (1.1 N.m.).
Maximum repairable limit:
Any amount.
Repair method:
Replace the anchor nut as follows:
NOTE:
Remove the mid outer liner bolt for inspection. Refer to TASK 72-00-01-040-805 (72-00-01, DISASSEMBLY 001). Do an inspection of the mid outer liner bolt for corrosion/pitting. Refer to TASK 72-21-99-200-801 (72-21-99, INSPECTION 001).
(a)Remove the anchor nuts. Refer to TASK 70-13-00-390-001 (RIVETED JOINTS).
(b)Do an inspection of the aft fan case shell for corrosion and pitting. Refer to Subtask 72-21-02-220-024 (paragraph 3.C.(11)).
(c)Apply coating in free state before the anchor installation. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM).
(d)Apply C03-077  primer (for example, primer P/N 10P4-2NF/EC-117S   ) to the aft fan case mating surface with the anchor nut.
(e)Perform a wet installation of the replacement anchor nuts P/N MS21076L4N   and rivets P/N 9025M79P06   as follows:
1Use C03-001  primer for the installation of the rivets.
2Rivet head must be within 0.0095-0.0105 inch (0.242-0.266 mm) below the surface of the aft fan case.
3Do an inspection of the formed rivets. Refer to TASK 70-13-01-390-002 (ACCEPTABILITY LIMITS FOR FORMED RIVETS).
(f)Install the mid outer liner bolt. Refer to TASK 72-00-01-430-803 (72-00-01, ASSEMBLY 001).
Subtask 72-21-02-220-015
(9)Damaged anchor nut cage:
Maximum serviceable limit:
Not serviceable.
Maximum repairable limit:
Any amount.
Repair method:
Replace the anchor nut cage as follows:
NOTE:
Remove the mid outer liner bolt for inspection. Refer to TASK 72-00-01-040-805 (72-00-01, DISASSEMBLY 001). Do an inspection of the mid outer liner bolt for corrosion/pitting. Refer to TASK 72-21-99-200-801 (72-21-99, INSPECTION 001).
(a)Remove the anchor nuts. Refer to TASK 70-13-00-390-001 (RIVETED JOINTS).
(b)Do an inspection of the aft fan case shell for corrosion and pitting. Refer to Subtask 72-21-02-220-024 (paragraph 3.C.(11)).
(c)Apply coating in free state before the anchor installation. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM).
(d)Apply C03-077  primer (for example, primer P/N 10P4-2NF/EC-117S   ) to the aft fan case mating surface with the anchor nut.
(e)Perform a wet installation of the replacement anchor nuts P/N MS21076L4N   and rivets P/N 9025M79P06   as follows:
1Use C03-001  primer for the installation of the rivets.
2Rivet head must be within 0.0095-0.0105 inch (0.242-0.266 mm) below the surface of the aft fan case.
3Do an inspection of the formed rivets. Refer to TASK 70-13-01-390-002 (ACCEPTABILITY LIMITS FOR FORMED RIVETS).
(f)Install the mid outer liner bolt. Refer to TASK 72-00-01-430- 803 (72-00-01, ASSEMBLY 001).
Subtask 72-21-02-220-016
(10)Missing primer:
Maximum serviceable limit:
Not serviceable.
Maximum repairable limit:
Any amount.
Repair method:
Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) . Apply C03-077  primer or C03-079  primer or 44-GN-60  primer in accordance with manufacturer's instructions.
Subtask 72-21-02-220-024
(11)Corrosion and pitting:
Maximum serviceable limit:
Not serviceable.
Maximum repairable limit:
Any amount not more than 0.002 inch (0.05 mm) in depth in area A. None permitted in area B.
Repair method:
Blend to remove corrosion. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) . Maximum depth must not be more than 0.002 inch (0.05 mm). Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM) . Refer to Figure 802.
Subtask 72-21-02-220-027
(12)Corrosion and pitting of the anchor nut cages and rivets:
Maximum serviceable limit:
Not serviceable.
Maximum repairable limit:
Any amount.
Repair method:
Replace the rivets and anchor nuts as follows:
NOTE:
Remove the mid outer liner bolt for inspection. Refer to TASK 72-00-01-040-805 (72-00-01, DISASSEMBLY 001). Do an inspection of the mid outer liner bolt for corrosion/pitting. Refer to TASK 72-21-99-200-801 (72-21-99, INSPECTION 001).
(a)Remove the anchor nuts. Refer to TASK 70-13-00-390-001 (RIVETED JOINTS).
(b)Do an inspection of the aft fan case shell for corrosion and pitting. Refer to Subtask 72-21-02-220-024 (paragraph 3.C.(11)).
(c)Blend to remove corrosion with pitting. Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES) and as follows:
1Maximum depth must not be more than 0.040 inch (1.02 mm).
2Blend to a minimum radius of 0.250 inch (6.35 mm).
3Blend minimum material thickness to completely remove pitting.
4Do an inspection if there is any evidence of corrosion or pitting in boltholes.
5Blend to make a smooth adjacent surface ensuring proper contact surface between aft fan case and anchor nut.
(d)The gap between the anchor nut and the blended surface of the aft fan case, before the anchor installation in free state, must be not more than 0.015 inch (0.38 mm).
(e)Apply coating in free state before the anchor installation. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM).
(f)Apply C03-077  primer (for example, primer P/N 10P4-2NF/EC-117S   ) to the aft fan case mating surface with the anchor nut.
(g)Perform a wet installation of the replacement anchor nuts P/N MS21076L4N   and rivets P/N 9025M79P06   as follows:
1Use C03-001  primer for the installation of the rivets.
2Rivet head must be within 0.0095-0.0105 inch (0.242-0.266 mm) below the surface of the aft fan case.
3Do an inspection of the formed rivets. Refer to TASK 70-13-01-390-002 (ACCEPTABILITY LIMITS FOR FORMED RIVETS).
(h)Install the mid outer liner bolt. Refer to TASK 72-00-01-430- 803 (72-00-01, ASSEMBLY 001).
Subtask 72-21-02-220-026
D.Do an inspection of the aft fan case peek wear pads for:
(1)Wear or flaking:
Maximum serviceable limit:
Any amount, 0.005 inch (0.13 mm) in depth.
Repair method:
Replace the aft fan case.
Subtask 72-21-02-220-028
E.Do an inspection of the forward flange (interface with forward fan case) for:
(1)Corrosion and pitting at and around the mounting flanges (forward and aft fan case) and case surfaces:
Maximum serviceable limit:
Not serviceable.
Maximum repairable limit:
Any amount, up to 0.030 inch (0.76 mm) in depth.
Repair method:
Repair the mounting flanges and case surfaces as follows:
(a)Clean the aft fan case corrosion residue. Refer to TASK 72-21-02-100-801 (72-21-02, CLEANING 001). The use of C10-010  scotch brite is recommended to assist with the removal. Make sure not to use C10-010  scotch brite on the composite forward fan case.
(b)Clean the composite forward fan case corrosion residue. Refer to TASK 72-21-01-100-801 (72-21-01, CLEANING 001).
(c)Blend to remove corrosion to a radius of 0.250 inch (6.35 mm). Refer to TASK 70-42-00-350-002 (BLENDING AND REMOVAL OF HIGH METAL PROCEDURES).
(d)Apply coating. Refer to TASK 70-43-07-380-007 (CHEMICAL TOUCH-UP SURFACE REFINISHING PROCESS FOR ALUMINUM).
(e)Apply C03-077  primer or 44-GN-60  primer in accordance with manufacturer's instructions.
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Figure 802   Aft Fan Case Pitting Areas