747-400 AMM 飞机维护手册 空调 AIR CONDITIONING 2(41)

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 RAM AIR DUCTS - APPROVED REPAIRS
________________________________
 1.  General_______
 A.  Repair of the fiberglass ducts that has ruptures, gouges, punctures and cracks, are made with the duct sections removed from the airplane. To repair these ducts, refer to paragraph 2.
 B.  If the duct is delaminated, remove and inspect the inside and outside of the duct. Other layers may be delaminated under the surface and cause the duct to fail. The entire delaminated surface should be removed prior to repairing the duct.
 C.  To repair honeycomb core ducts, refer to SRM 51-70-08, Glass Fabric Reinforced Epoxy Laminates and NonMetallic Honeycomb Sandwich Repairs.
 TASK 21-51-12-308-024
 2.  Fiberlass Ram Air Ducts Repair______________________________
 A.  Equipment and Materials
 (1)  
Abrasive cloth - 400 grit, or equivalent

 (2)  
Adhesive Tape - 1 inch large, No. 474 vinyl plastic tape (AMM 20-30-07/201 Miscellaneous Materials)

 (3)  
Adhesive - BMS 5-126 (AMM 20-30-01/201 Adhesives, Cements, Sealants)

 (4)  
Cheesecloth - Or other ther lint-free wiping material containing not more than 0.75% (dry weight) oil or grease content

 (5)  
Cleaning Solvent - Series 91 solvent (AMM 20-30-02/201, Cleaners and Polishes)

 (6)  
Cleaning Solvent - BMS 3-2 (AMM 20-30-02/201, Cleaners, Polishes)

 (7)  
Fiberglass Cloth - Style 181 (AMM 20-30-04/201, Miscellaneous Materials)

 (8)  
Polyvinyl alcohol (PVA) parting film (AMM 20-30-04/201, Miscellaneous Materials)

 (9)  
Resin - 50AW9816 (AMM 20-30-07/201, Miscelleaneous Materials)

 (10)
 Squeegee - Commercially available

 B.  Fiberglass Ram Air Duct Repair Procedure
 S 018-025
 (1)  
Put the ram air duct section on a bench in a well ventilated area.

 S 328-002

 (2)  
Drill the ends of the crack to prevent the crack from becoming larger.

 (3)  
Clean the damaged and the adjacent area.

 S 118-003
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
ADHESIVE TAPE

Ram Air Ducts - Approved Repair
Figure 801

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
E51956
A
747-400
MAINTENANCE MANUAL

 WARNING: DO NOT GET SOLVENTS INTO YOUR MOUTH, OR YOUR EYES, OR ON
_______ YOUR SKIN. DO NOT BREATHE THE FUMES FROM SOLVENTS. SOLVENTS ARE HAZARDOUS MATERIALS. REFER TO PRODUCT MATERIAL SAFETY DATA SHEETS (MSDS) AND LOCAL REQUIREMENTS FOR PROPER HANDLING PROCEDURES.
 (a)  Apply a cleaning solvent, series 91, with a clean absorbent material.
 NOTE: Make sure you use clean rubber or cotton gloves and the
____ cheesecloth (or similar material) when you clean the surface.
 (b)  
Wipe off the the solvent before it evaporates, with a clean, oil and lint-free, absorbent, disposable material.

 (c)  
Sand the surface lightly to prepare the surface. The sanding should extend 1.0 inch (2.5 cm) more than the repair area.

 (d)  
Apply a cleaning solvent, series 91, with a clean absorbent material again.

 (e)  
Wipe off the the solvent before it evaporates, with a clean, oil and lint-free, absorbent, disposable material.

 S 348-026
 (4)  
Fill the crack (or damaged area) with BMS 5-126, if you are able.

 S 348-027

 (5)  
Prepare the fiberglass cloth

 (a)  Cut three plys of fiberglass cloth, the smallest covering an area 1.0 inch (2.6 cm) from the defect. (See figure 801) Cut each suceeding ply so that it is at least 0.80 inch (2.0 cm) larger all around than the preceeding ply. The third ply should be wrapped completely around the duct, overlapping 0.80 inch (2.0 cm) on the sides.
　
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