(4)  
AMM 51-31-01/201, Seals and Sealing

 D. Access
 (1)  Location Zones
 243/244 Area Above Ceiling (Exterior)
 253/254 Area Above Ceiling (Exterior)

 E. Procedure
 S 114-089
 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)  Clean the airplane mating surface with solvent, Series 88 (SOPM 20-30-88):
 (a)  
Make a clean cheesecloth moist (not soaked) with solvent, Series 88 (AMM 20-30-88).

 (b)  
Rub the airplane mating surface, inside the fastener holes, and connector hole with cheesecloth to clean the BMS 3-27.

 S 374-084
 (2)  If the airplane surface has corrosion or other damage, do these steps to prepare the airplane surface:
 (a)  Do this task to apply a layer of alodine to the airplane mating surface: Apply Alodine 1000 Solution (AMM 51-21-04/701).
 NOTE: This task removes corrosion, cleans the surface, and
____
 applies the alodine.

 (b)  Apply two layers of BMS 10-79 Type III primer to the airplane mating surface. 1) Let each layer dry for the correct cure time.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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747-400 MAINTENANCE MANUAL
 S 394-039
 (3)  Do these steps to do the corrosion protection for the mating surface and to install the o-ring:
 (a)  
Apply a layer of BMS 3-27 in the nutplate.

 (b)  
Apply a layer of BMS 3-27 inside the screw holes and the connector hole.

 (c)  
Apply a layer of BMS 3-27 on the pressurized and unpressurized sides of the o-ring.

 NOTE: Make sure BMS 3-27 does not get on the o-ring or
____
 in the o-ring groove.

 (d)  
Apply a layer of BMS 3-24 on the o-ring and o-ring groove.

 (e)  
Install the o-ring on the ADF antenna.

 (f)  
Apply a very thin layer of BMS 3-27 to the antenna base.

 (g)  
Apply a layer of BMS 3-27 on the threads and shanks of the fasteners.

 S 424-088
 (4)  Install the ADF antenna:
 (a)  
Remove the cover from the cable connector.

 (b)  
Connect the cable to the antenna.

 (c)  
Put the new antenna into position on the airplane surface.

 (d)  
Lightly tighten the mounting screws in sequence as shown in Figure 401.

 CAUTION: TIGHTEN THE SCREWS MANUALLY TO THE CORRECT TORQUE VALUE.
_______ USE OF POWER OR AIR TOOLS TO TIGHTEN THE SCREWS CAN CAUSE DAMAGE TO THE ANTENNA SURFACE.
 (e)  
Manually tighten the mounting screws to 20-25 pound-inches of torque in sequence as shown in Figure 401.

 (f)  
Carefully remove excess BMS 3-27 from around the fastener heads and around the periphery of the antenna with the solvent, Series 95 (AMM 20-30-95).

 NOTE: Use care to completely remove excess BMS 3-27.
____ If BMS 3-27 is not completely removed, poor adhesion of the weatherproof sealant will occur.
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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747-400 MAINTENANCE MANUAL
 F. ADF Antenna Resistance Measurement
 S 764-037
 (1)  Do a check of the continuity between the antenna and the airplane skin (Fig. 401):
 (a)  Connect the bonding meter between the tab/washer on the right rear screw and the airplane skin (AMM 51-21-04/701). 1) Make sure the measurement of continuity is less than 25
 milliohms.
 G. ADF Antenna Weatherproofing
 S 394-024
 (1)  Apply a weatherproof sealant, BMS 5-95 or BMS 5-142, in a 1/4 inch fillet seal, at 45 degrees, around the outer edge of the antenna base and over the top of the fastener heads (AMM 51-31-01/201).
　
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