(e)
Allow the adhesive to cure under contact pressure for a minimum of 24 hours at 65-100°F. A minimum of 20% relative humidity is required for adhesive cure.
D. Install seal, baffle and nozzle assembly.
E. Secure overhead duct nozzle to duct with screws.
F. Install ceiling panels.
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21-23-11 Page 404 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Feb 20/92
OVERHEAD DISTRIBUTION DUCT - APPROVED REPAIRS
1. General
A. This procedure provides instructions for a temporary and permanent repair. If conditions do not allow a permanent repair, accomplish the temporary repair until such time that the permanent repair can be done.
B. The temporary repair is an in-service repair to reduce air leakage and noise.
2. Equipment and Materials
A. Cleaning Solvent (Ref 20-30-31)
(1)
Solvent – Final Cleaning of Metal Prior to Non-structural Bonding (Series 88) (Ref AMM/SOPM 20-30-88)
(2)
Toluene TT-T-548 or JAN-T-171 Grade A
B. HT1-41 Nomex tape, 4 inches wide (Ref 20-30-51)
C. Adhesive - BAC5010 Type 77 (Ref 20-30-11)
D. Adhesive - BAC5010 Type 98 (Ref 20-30-11)
E. Adhesive - BAC5010 Type 58 (BMS 5-7, Type II) (Ref 20-30-11)
NOTE: 3M P/N EC-4419 is recommended, but P/N EC-2155 may be used until existing stock is depleted.
F. Sponge Rubber - BMS 1-60 or BMS 1-68
3. Repair Overhead Distribution Duct - Permanent (Fig. 801)
A. Remove ceiling panel(s) as required.
B. Remove the disbonded fiberglass tape from the joint if the joint is completely disbonded.
NOTE: For minor delaminations of the fiberglass tape in the joint, install an overlapping piece of tape with adhesive over the delaminated area.
C. Use cloth moistened with solvent and remove any contamination from the surfaces of the ducts where the repair will be made.
WARNING: DO NOT GET SOLVENT IN YOUR MOUTH OR 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.
D. Remove all traces of solvent from ducts using dry, clean cheesecloth.
E. Prepare the tape for repairing the joint.
(1) Make a decision which adhesive you must use.
CAUTION: MAKE SURE THAT YOU USE THE SAME TYPE OF ADHESIVE FOR THE REPAIR THAT WAS USED ON THE INITIAL INSTALLATION OF THE DUCT JOINT. THE ADHESIVE WILL NOT BOND TO THE DUCTS UNLESS THE SAME TYPE OF ADHESIVE IS USED.
(a) Use BAC5010, Type 98 adhesive if the color of the adhesive on the initial installation is black.
May 01/98 21-23-11 Page 801 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
A44226
Disbonded Duct Joint Repair (Typical) 5C9
21-23-11 Figure 801 Jun 20/92
Page 802
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
(b)
Use BAC5010, Type 77 adhesive if the color of the adhesive on the initial installation is clear.
(c)
Use BAC5010, Type 58 adhesive if the color of the adhesive on the initial installation is yellow and green. 1) Mix the adhesive fully with one part of toluene to two parts of adhesive by
volume.
(2)
Apply a layer of the adhesive to a thickness of 0.020 to 0.030 inch to one side of the tape and to the ends of the ducts.
(3)
Install the tape, adhesive side down, on the disbonded joint section.
(a)
Make sure that the tape attaches to a minimum of 1.5 inches of each duct.
(b)
Make sure that the ends of the tape overlap 1 to 2 inches on each other except where a nozzle opening occurs.
(c)
Pull out the wrinkles in the tape so it is smooth and there are no air pockets.
(4)
Apply a layer of the adhesive to the tape to thoroughly saturate the tape.
F. Let the repair done with BAC5010, Type 58 adhesive dry for a minimum of 4 hours at a temperature of 65-100°F (18.3-37.8°C).
G. Let the repair done with BAC5010, Type 98 adhesive dry for a minimum of 24 hours at a temperature of 65-100°F (18.3-37.8°C).
H. Let the repair done with BAC5010, Type 77 adhesive dry for a minimum of 12 hours at a temperature of 65-100°F (18.3-37.8°C).
I. Install the ceiling panel(s) that was removed.
4. Repair Overhead Distribution Duct - Temporary
A. Remove the applicable ceiling panel in the passenger compartment to get access to the duct.
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