TASK 21-23-02-308-193
10. Rigid Foam Duct - Duct Section Replacement (Fig. 802)__________________________________________
A. General
(1) This procedure gives instructions to replace a section of rigid foam air conditioning duct.
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(2) If time or materials are not available to do this procedure, use the procedure to repair a taped duct joint to make a temporary repair. If a temporary repair is made, do this procedure as soon as possible to make a permanent repair.
B. Consumable Materials
(1)
Fiberglass cloth - minimum 0.007 inch thick (MIL C-9084 Type VIII) -commerically available
(2)
Plastic sheet - polyethylene or vinyl (commercially available)
(3)
Rigid foam duct
(4)
Resin - BMS 8-201 Type II (Epocast 50-A)
(5)
Solvent - Butyl carbitol (alternative to B01011, Series 91) -commercially available (AMM 20-30-91/201)
(6)
Solvent - B01011, Series 91) - commercially available
(AMM 20-30-91/201)
(7)
Squeegee - commercially available
(8)
Wiping cloth, lint-free (commercially available)
C. References
(1) AMM 36-00-00/201, Pneumatics - General
D. Prepare for the Repair
S 868-194
(1)
Remove the pneumatic power (AMM 36-00-00/201).
S 868-195
(2)
On the bleed air control module on the pilots' overhead panel, put the pack control switches in the OFF position.
S 018-196
(3)
Remove the applicable ceiling, sidewall, or floor panels to gain access to the damaged air conditioning duct.
S 028-197
(4)
If insulation is installed on the duct joint, remove the insulation.
S 348-198
(5)
Do these steps to prepare the damaged area of the duct:
(a) Cut and remove the damaged section of rigid foam air conditioning duct.
NOTE: Cut the duct so the edges are straight and perpendicular
____ to the circumference of the duct.
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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.
(b)
Use the solvent and a wiping cloth to clean the damaged area.
(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 348-199
(6) Prepare a piece of rigid foam duct that matches the damaged duct and is the correct length to replace the damaged section of the duct.
NOTE: Cut the replacement section with clearance for the material
____ that will be added by the duct end repair procedure.
S 348-200
(7)
Do the Duct End Repair task for rigid foam ducts for each end of the replacement duct section and for each end of the damaged duct.
S 348-201
(8)
Cut a piece of fiberglass cloth 3 inches wide and long enough to wind around the duct a minimum of four times.
S 348-202
(9)
Prepare the resin.
E. Repair the Taped Joint
S 348-203
(1) Apply resin to the duct ends.
NOTE:____Let the resin to partially dry until it is sticky. Press the duct ends together by aligning the installation checkmarks.
S 348-204
(2) Apply resin to the joint area a minimum of 3 inches on both sides of the joint.
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