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747-400 MAINTENANCE MANUAL
 E. Repair the Duct End
 S 348-116
 (1)  
Apply a thin, smooth layer of resin on the duct end and on the surface of the duct a minimum of 1/2 inch from the duct end.

 S 348-117

 (2)  
Wind the cloth around the duct end so that it overlaps a minimum of 1/2-inch on both sides of the end.

 S 348-118

 (3)  
Soak the Fiberglass cloth with the resin.

 S 348-119

 (4)  
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.
 S 348-120
 (5)  
Remove the plastic sheet from the cloth.

 S 348-121

 (6)  
Let the resin cure for 24 hours at room temperature.

 S 168-122
 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)  Clean the area with a wiping cloth and solvent to remove unwanted resin.
 F. Put the Airplane Back to Its Usual Condition
 S 428-123
 (1)  If insulation was removed from the duct joint, install new
 insulation.

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747-400 MAINTENANCE MANUAL
 S 418-124
 (2)  Install the panels or other airplane structure removed to gain access to the duct joint.
 TASK 21-23-02-308-125
 7.  Rigid Foam Duct - External Patch Repair (Fig. 802)_______________________________________
 A. General
 (1)  This procedure gives instructions for the repair of a rigid foam air conditioning duct if the damage is less than 1/4 inch deep and 1 inch long. If the damage is larger, use the procedure to make a structural repair to a 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

 (7)  
Wiping cloth, lint-free (commercially available)

 C. References
 (1)  AMM 36-00-00/201, Pneumatics - General
 D. Prepare for the Repair
 S 868-126
 (1)  
Remove the pneumatic power (AMM 36-00-00/201).

 S 868-127

 (2)  
On the bleed air control module on the pilots' overhead panel, put the pack control switches in the OFF position.

 S 018-128

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

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

 S 028-129
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 (5)  S 348-130Examine the inner surface of the duct for damage.
 NOTE:____ If the inner lining is damaged, then do the Duct Section Replacement task for rigid foam ducts.
 (6)  S 348-131Examine the damage to the duct.
　
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