S 412-097
(2)
Replace the panels or other airplane structure removed to gain access to the duct joint.
TASK 21-23-01-302-098
4. Structural Repair - Fiberglass or Kevlar Duct (Fig. 201)
_____________________________________________
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 more than 3 inches long but less than 5 percent of the total surface area of the duct. If the damage is more than 5 percent of the total surface area of the duct, replace the duct section.
B.
Consumable Materials
(1)
Fiberglass cloth - minimum 0.007 inch thick (MIL-C-9084 Type VIII) -commercially available
(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
(7)
Solvent - Butyl carbitol (alternative to B01011, Series 91) -commercially available (AMM 20-30-91/201)
(8)
Solvent - B01011, Series 91 - commercially available (AMM 20-30-91/201)
(9)
Wiping cloth, lint-free - commercially available
(10)
Squeegee - commercially available
C.
References
(1)
AMM 36-00-00/201, Pneumatic - General
D.
Prepare for the Repair
(1)
Release the pressure from the pneumatic system (AMM 36-00-00/201).
S 862-099
NOTE: This will make sure that there is no airflow in the ducts
____
when you do the repair.
S 862-100
(2) On the bleed air control module on the pilots' overhead panel, P5, put the pack control switches in the OFF position.
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21-23-01
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 757 MAINTENANCE MANUAL
(3) S 012-102Remove the applicable ceiling, sidewall, or floor panels to gain access to the damaged air conditioning duct.
(4) S 012-103If insulation is installed on the duct, remove the insulation.
(5) S 342-104Do 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) (b) (c) (d) (e) Use the solvent and a wiping cloth to clean the damaged area.Cut away the damaged area to make a rounded opening with a smooth shape. Cut the sides of the opening at an angle to make a taper of 1/2 inch between each ply of material.Sand the edge of the opening to make a smooth surface.Sand the surface of the duct around the opening a distance of 1/2 inch for each ply in the duct. For example, if there are 6 plies, sand 3 inches from the opening on all sides (1/2 x 6 = 3 inches).Use the solvent and a wiping cloth to clean the edge of the opening and the sanded surface of the duct.
(6) S 342-105Prepare the Fiberglass or Kevlar cloth. (a) Cut sufficient pieces of fiberglass or Kevlar cloth to equal the thickness of the duct. (b) Cut each piece of fiberglass or Kevlar cloth 1/2 inch larger to fit the taper of the opening. (c) Cut one piece of fiberglass or Kevlar cloth a minimum of 2 inches larger on all sides than the opening in the duct.
(7) S 342-106Cut a piece of plastic sheet 2 to 3 inches larger on all sides than the opening.
(8) S 342-107Cut a piece of cardboard or aluminum 2 to 3 inches larger than the opening on all sides.
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