D. Prepare the mating surfaces.
 S 118-027
 WARNING: DO NOT GET SOLVENTS IN YOUR MOUTH, OR YOUR EYES, OR ON YOUR
_______ SKIN. DO NOT BREATHE THE FUMES FROM 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.
 (1)  
Use a cloth that is moist with solvent, Series 98 (AMM 20-30-98) to clean the mating surface.

 S 118-017

 (2)  
Use a cloth that is moist with acetone to clean the mating surface of the teflon pad.

 S 958-018

 (3)  
Apply a mask to the opposite side of the teflon pad mating surface.

 E. Etch the teflon pad mating surface as follows:
 NOTE:____You can get teflon rub pads that are etched. This paragraph applies only to teflon pads that are not etched.
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747-400 MAINTENANCE MANUAL
 S 118-036
 WARNING: TEFLON ETCHING MATERIALS ARE CORROSIVE, TOXIC, FLAMMABLE,
_______ AND/OR EXPLOSIVE. OBSERVE SAFETY REQUIREMENTS PRESENTED IN PAR. 5.A. TEFLON ETCHING MATERIALS CAN CAUSE INJURY OR DAMAGE.
 (1)  Etching Method I (FluoroBond or Tetra-Etch)
 (a)  
Put the part in the etchant solution for a minimum of 30 seconds and a maximum of 60 seconds.

 (b)  
The part must have a dark brown color in 60 seconds. If the part is not dark brown in 60 seconds the etchant solution must be replaced with new etchant solution.

 (c)  
Immediately clean the part. Use a 3 to 5 percent solution (by volume) of water in n-butyl alcohol to remove all of the etchant from the part.

 (d)  
Wash the part in clean water. Remove the mask. Wash the masked surface with a clean cloth that is wet with acetone.

 S 118-037
 WARNING: TEFLON ETCHING MATERIALS ARE CORROSIVE, TOXIC, FLAMMABLE,
_______ AND/OR EXPLOSIVE. OBSERVE SAFETY REQUIREMENTS PRESENTED IN PAR. 5.A. TEFLON ETCHING MATERIALS CAN CAUSE INJURY OR DAMAGE.
 (2)  Etching Method II (Sodium-ammonia)
 (a)  
Mix the etchant solution in a clean, dry container. The container must be made of either polyethylene or stainless steel.

 (b)  
Put anhydrous ammonia into the container. Make sure the part will be fully covered by the ammonia. You can use rubber or Tygon tube to move the liquid ammonia into the container.

 (c)  
Add 10 grams of metallic sodium chips to the solution for each liter of ammonia.

 (d)  
Mix the solution with a rod made of glass or polyethylene. Make sure all of the sodium is mixed into the solution.

 NOTE: You can neutralize the solution by one of the following
____
 methods:

 -Either, add a 3 to 5 percent solution (by volume) of water in n-butyl alcohol to the etchant until the etchant has no color.
 -Or, let the ammonia become dry.  Rinse the container with a 3 to 5 percent solution (by volume) of water in n-butyl alcohol. Add the rinse solution until no color remains. As a last step, flush the container with water.
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747-400 MAINTENANCE MANUAL
 (e)  
Put the rub pad in the solution for 10 to 20 seconds. Make sure the part is completely covered by the solution. If it is necessary, wet one end of the pad and then wet the other end of the pad.

 (f)  
The pad must have a dark brown color after a maximum of 20 seconds in the solution. If the pad is not dark brown after 20 seconds in the solution, add 10 grams of sodium for each liter of ammonia of the solution.

 (g)  
Wash the pad as shown in steps (1)(c) and (1)(d).

 (h)  
Use a clean cloth that is moist with solvent, Series 98 (AMM 20-30-98) to clean the surface of the teflon pad.
　
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