S 028-066
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 21-23-02
 ALL  ú ú 01A Page 806 ú Jun 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 S 348-047
 (5)  Do these steps to prepare the damaged area of the duct:
 WARNING: DO NOT GET SOLVENTS IN YOUR MOUTH, OR IN YOUR EYES, OR ON
_______ YOUR SKIN. DO NOT BREATHE THE FUMES FROM 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.
 (a)  
Use the solvent and a wiping cloth to clean the damaged area.

 (b)  
Drill a hole at each end of the cut or crack to prevent the cut or crack from getting larger.

 NOTE: The holes should be a maximum of 1/16-inch diameter.
____
 (c)  
Sand the damaged area to remove any remaining adhesive and contamination.

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

 S 348-048
 (6)  Prepare the Fiberglass or Kevlar cloth patch:
 (a)  
Cut sufficient pieces of cloth to equal the thickness of the duct.

 (b)  
Cut the Fiberglass or Kevlar cloth pieces 1/2 inch larger on all sides than the damage.

 (c)  
Round the corners of the pieces of the Fiberglass or Kevlar cloth.

 S 348-049
 (7)  Prepare the applicable resin.
 E. Repair the Air Conditioning Duct
 S 348-050
 (1)  Apply a thin, smooth layer of resin to the duct where the cloth patch will be applied.
 NOTE: Make sure the area of the resin is a minimum of the size and
____
 shape of the cloth patch.

 S 348-051
 (2)  Place a piece of cloth patch on the resin so that it extends beyond the cut or crack a minimum of 1/2 inch on all sides.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 21-23-02
 ALL  ú ú 01A Page 807 ú Jun 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 S 348-052
 (3)  
Soak the cloth patch with the applicable resin.

 S 348-053

 (4)  
Put a piece of plastic sheet on the cloth and press lightly with a squeegee or with your hand.

 NOTE: Make the Fiberglass or Kevlar cloth patch smooth from the
____ center to the edges of the cloth to remove bubbles or wrinkles and to remove unwanted resin.
 S 348-054
 (5)  
Remove the plastic sheet from the cloth patch and remove unwanted resin with a wiping cloth.

 S 348-055

 (6)  
Place another piece of cloth on the first piece, soak it with resin, and smooth it.

 NOTE: Continue using the same procedure until the thickness of the
____ patch equals the thickness of the duct.
 S 348-056
 (7)  Allow the resin to cure for 24 hours at room temperature.
 F. Put the Airplane Back to Its Usual Condition
 S 428-059
 (1)  
If insulation was removed from the duct joint, install new insulation.

 S 418-058

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

 TASK 21-23-02-308-060
 4. Fiberglass or Kevlar Duct - Structural Repair (Fig. 801)
_____________________________________________
 A. General
 (1)  
This procedure gives instructions for making a structural repair to a fiberglass or Kevlar air conditioning duct.

 (2)  
A structural repair is applicable when the damage to the air conditioning duct is a cut or a hole that is more than 1/4 inch wide and 3 inches long but less than 5 percent of the surface area of the duct. If the damage is substantial replace the duct section.

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：747-400 AMM 飛機維護手冊 空調 AIR CONDITIONING 1(33)