S 012-068

 (3)  
Remove the applicable ceiling, sidewall, or floor panels to gain access to the damaged air conditioning duct joint.

 S 012-069

 (4)  
If insulation is installed on the duct joint, remove the insulation.

 S 342-070

 (5)  
Do these steps to prepare the damaged area of the duct.

 WARNING: DO NOT GET SOLVENTS IN YOUR MOUTH, OR YOUR EYES, OR ON
_______ YOUR SKIN. DO NOT BREATHE THE FUMES FROM THE SOLVENTS. SOLVENTS ARE HAZARDOUS MATERIALS. SOLVENTS MAY BE FLAMMABLE OR HARMFUL TO THE ENVIRONMENT. REFER TO PRODUCT MATERIAL SAFETY DATA SHEETS (MSDS) AND LOCAL REQUIREMENTS FOR PROPER HANDLING PROCEDURES.
 (a)  
Use the solvent and a wiping cloth to clean the damaged area.

 (b)  
Sand the damaged area to remove any remaining adhesive and contamination.

 (c)  
Use the solvent and a wiping cloth to clean the damaged area.

 S 342-071
 (6)  
Cut a piece of the fiberglass or Kevlar cloth that is 3 inches wide and long enough to wind around the duct a minimum of two times.

 E.
Repair the Taped Joint

 S 342-072
 (1)  Apply a thin, smooth layer of the primer to the duct joint area and let it dry at room temperature for a minimum of 1 hour.
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 S 342-073
 (2)
Apply the sealant to one side of the fiberglass or Kevlar cloth.

 S 342-074

 (3)  
Wind the fiberglass or Kevlar cloth around the duct joint a minimum of two times.

 NOTE: Make sure that the sealant on the fiberglass or Kevlar cloth
____
 is in contact with the duct.

 S 342-075
 (4)  
Put a piece of plastic sheet on the fiberglass or Kevlar cloth and press lightly with a squeegee or with your hand. Make the fiberglass or Kevlar cloth smooth from the center to the edges of the fiberglass or Kevlar cloth to remove any bubbles or any wrinkles and to remove unwanted resin.

 S 342-076

 (5)  
Remove the plastic sheet from the fiberglass or Kevlar cloth and remove unwanted resin with a wiping cloth.

 S 342-077

 (6)  
Wind the glass cloth tape around the two edges of the fiberglass or Kevlar cloth repair.

 NOTE: Make sure the tape is flat with no wrinkles or gaps.
____
 F. Put the Airplane Back to Its Usual Condition
 S 412-078
 (1)  
If insulation was removed from the duct joint, install new insulation.

 S 412-079

 (2)  
Replace the panels or other airplane structure removed to gain access to the duct joint.

 TASK 21-23-01-302-080
 3. External Patch Repair - Fiberglass or Kevlar Duct (Fig. 201)
_________________________________________________
 A. General
 (1)  
This procedure gives instructions for the repair of a crack or cut in a fiberglass or Kevlar air conditioning duct with an external patch.

 (2)  
An external patch is applicable when the cut or the crack is less than 1/4 inch wide and is less than 3 inches long.

 B.
Consumable Materials

 (1)  
Fiberglass cloth - minimum 0.007 inch thick (MIL-C-9084 type VIII) -commercially available

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 (2)  
Kevlar cloth - minimum 0.007 inch thick (alternative to the
 fiberglass cloth)

 (3)  
Plastic sheet - polyethylene or vinyl - commercially available

 (4)  
Resin for repair of fiberglass duct - R109A Hetron 92 Polyester

 (5)  
Resin for repair of Kevlar duct - BMS 8-201 Type II (Epocast 50-A)

 (6)  
Sandpaper - 320 grit - commercially available
　
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