NOTE: Do not hold or use a clamp on the rub strip.
____
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747-400 MAINTENANCE MANUAL
3) If the clearance between the mating surfaces of the rub strip and the assembly is greater than 0.125 inch, install a new rub strip with a clean roller to get a smaller clearance.
4) Apply a thin constant layer of adhesive (approximately 50 grams for each square foot) on each mating surface.
(c)
Assemble the parts in less than 25 minutes after you mix the adhesive.
(d)
Keep the minimum cure time is 6 hours. The minimum cure temperature is 64°F.
(e)
To apply the cure pressure, do these steps:
1) Apply a smooth constant pressure to the rub strip each 15 minutes during the first 3 hours after the parts are assembled.
2) Keep a continuous bead of the adhesive at the bond line to get a satisfactory bond between the mating surfaces. 3) Apply more pressure to remove air bubbles in the bond line during the first 3 hours after the parts are assembled.
TASK 51-51-00-308-013
4. Bonded Phenolic or Stainless Steel Rub Pad (field repair with a heat source)__________________________________________
A. Standard Tools and Equipment
(1)
Semco Sealing Gun
(2)
Heat Lamps - 250 Watts
(3)
Thermocouples
B. Consumable Materials
(1)
G00000 Wedge, Hardwood
(2)
G00000 Wedge, Plastic
(3)
A00250 Sealant - BMS 5-26, Class B-1/2
(4)
A00251 Sealant - BMS 526, Class B-2
(5)
B00184 Solvent - BMS 11-7
(6)
B00316 Solvent - Aliphatic Naphtha, TT-N-95
(7)
B00153 Solvent - Toluene (Toluol), TT-T-548
(8)
A00322 Paper - Abrasive, Aluminum Oxide, 100
Grit (minimum)
(9)
G00000 Cloth - Abrasive, Aluminum Oxide, 100
Grit (minimum)
(10)
G00034 Cheesecloth - Clean
(11)
G00000 Pads - Scotch-brite, Aluminum Oxide Impregnated, Type A
(12)
G00000 Spatula
(13)
G00000 Gloves - Rubber or Cotton
C. Repair the Bonded Rub Pads
S 118-032
(1)
Refer to the steps in the first procedure to apply the adhesive on the mating surface.
S 348-033
(2)
Do these steps to apply a new pad:
(a) Mix 22 (|2) parts (by volume) of BMS 5-26, Pro Seal 890 B-2 with activator, to 100 parts (by volume) of the base component.
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51-51-00
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A
747-400 MAINTENANCE MANUAL
(b) To install the new rub strip on the assembly, do these steps: 1) Make sure the mating surfaces are clean. 2) Put the rub strip flat against the assembly surface.
NOTE: Do not hold or use a clamp on the rub strip.
____
3) If the clearance between the mating surfaces of the rub strip and the assembly is greater than 0.125 inch, install a new rub strip with a clean roller to get a smaller clearance.
4) Apply a thin constant layer of the adhesive (approximately 50 grams on each square foot) on each mating surface.
(c)
Assemble the parts in less than 25 minutes after you mix the adhesive.
(d)
To cure the assembly, do these steps:
1) Use two heat lamps, 250 watts each, as a heat source. Put the lamps 9 inches apart and 6 inches from the rub strip. Make sure the heat lamps point down on the rub strip.
2) Apply heat on the assembly at a temperature of 90 (|5)°F. Allow a minimum of 1 1/2 hours from the time you mix the adhesive to the time you cure the adhesive.
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