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747-400 MAINTENANCE MANUAL
 S 348-161
 (5)  Leave the plastic sheet on the repair area and allow the potting compound to cure for 5 hours at 125°F.
 NOTE: Apply heat with a heat gun, heat lamp or heating blanket.
____
 S 348-162
 (6)  Remove the plastic sheet and smooth the surface of the foam with sandpaper.
 S 168-165
 WARNING: DO NOT GET SOLVENTS IN YOUR MOUTH, OR IN 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 ENVIROMENT. REFER TO PRODUCT MATERIAL SAFETY DATA SHEETS (MSDS) AND LOCAL REQUIREMENTS FOR PROPER HANDLING PROCEDURES.
 (7)  
Use the solvent and a wiping cloth to remove any dust from the duct.

 S 348-164

 (8)  
Prepare the resin.

 S 348-166

 (9)  
Put a piece of fiberglass cloth on the resin so that it extends beyond the damaged area a minimum of 2 inches on all sides.

 S 348-167

 (10)
 Soak the Fiberglass cloth with the resin.

 S 348-168

 (11)
 Put a piece of plastic sheet on the cloth and press lightly with a squeegee or with your hand.

 NOTE: Make the cloth smooth from the center to the edges of the
____ cloth to remove any bubbles or wrinkles and to remove unwanted resin.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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747-400 MAINTENANCE MANUAL
 S 348-169
 (12)
 Remove the plastic sheet from the patch and remove unwanted resin with a wiping cloth.

 S 348-170

 (13)
 Follow the same procedure to apply the second piece of cloth.

 S 348-171

 (14)
 Let the resin cure for 24 hours at room temperature.

 S 168-172
 WARNING: DO NOT GET SOLVENTS IN YOUR MOUTH, OR IN 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 ENVIROMENT. REFER TO PRODUCT MATERIAL SAFETY DATA SHEETS (MSDS) AND LOCAL REQUIREMENTS FOR PROPER HANDLING PROCEDURES.
 (15) Remove unwanted resin from the edges of the patch with a wiping cloth soaked with solvent.
 F. Put the Airplane Back to Its Usual Condition
 S 428-173
 (1)  
If insulation was removed from the duct joint, install new insulation.

 S 418-174

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

 TASK 21-23-02-308-175
 9.  Rigid Foam Duct - Inner Lining Repair (Fig. 802)_____________________________________
 A. General
 (1)  This procedure gives instructions for the repair of the inner lining on a rigid foam air conditioning duct. Use this procedure if the inner lining has peeled away from the duct but the rigid foam is not damaged.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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747-400
MAINTENANCE MANUAL

 (2)  If the rigid foam is damaged, do the procedure to replace a section of rigid foam air conditioning duct.
 B. Consumable Materials
 (1)  
Fiberglass cloth - minimum 0.007 inch thick ( MIL-C-9084 Type VIII)

 -commercially available

 (2)  
Plastic sheet - polyethylene or vinyl (commerically available)

 (3)  
Resin - BMS 8-201 Type II (Epocast 50-A)

 (4)  
Solvent - Butyl carbitol (alternative to B01011, Series 91) -commercially available (AMM 20-30-91/201)

 (5)  
Solvent - B01011, Series 91 - commercially available
 (AMM 20-30-91/201)

 (6)  
Squeegee - commercially available
　
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