D. Access
(1) Location Zones
223 Fwd Upper Deck Passenger Cabin
125 Area Below Forward Cargo Compartment
E. Procedure
S 864-101
(1) Make sure this circuit breaker is open:
(a) P7 Overhead Circuit Breaker Panel:
1) 7A5, TCAS
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747-400 MAINTENANCE MANUAL
S 214-102
(2) Visually examine the contact surfaces of the antenna and the airplane for corrosion and unwanted substances.
NOTE: If the surfaces are not clean, the ground will not be
____ sufficient, and incorrect system operation will occur.
S 114-104
(3)
Clean the contact surfaces with the solvent, BMS 11-7 (AMM 20-11-14/701).
S 624-080
(4)
Apply Alodine 1200 to the contact surfaces of the antenna and the airplane (AMM 51-24-13/701).
S 624-110
(5)
Apply a layer of BMS 3-24 on the O-ring and O-ring groove.
S 424-105
(6)
Install the TCAS antenna.
(a) Make sure that an O-ring is installed on the new antenna.
(b) Connect the coaxial cables to the antenna as follows:
~......................................................
| CABLE SLEEVE | MATE WITH | TCAS ANTENNA |
| COLOR | TAPE *[1] | CONNECTOR |
........................................................
| Yellow | J1 or 1 | J1 |
........................................................
| Black | J2 or 2 | J2 |
........................................................
| Blue | J3 or 3 | J3 |
........................................................
| Red | J4 or 4 | J4 |
2................…................…....................1
*[1] For airplanes without cable color sleeves, use the MATE WITH TAPE on each coaxial cable to identify the connection to the corresponding antenna connector.
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747-400 MAINTENANCE MANUAL
(c) Tighten the TCAS Antenna connectors 4 to 6 in-lbs (hand tight plus 1/8 turn).
NOTE: If the four antenna cables are routed in the same
____ direction, it will be easier to service the antenna from outside the airplane the next time.
(d)
Put the antenna into position.
(e)
Install all of the screws except one.
NOTE: Leave one screw out to do the electrical bond check.
____
(f)
Tighten the screws to 20-25 pound-inches of torque.
(g)
Make sure the resistance from the antenna base to the airplane skin is not greater than 0.001 ohms.
(h)
Install the last screw in the antenna.
(i)
Tighten the screw to 20-25 pound-inches of torque.
S 864-107
(7) Remove the DO-NOT-CLOSE tags and close this circuit breaker:
(a) P7 Overhead Circuit Breaker Panel:
1) 7A5, TCAS
F. TCAS Antenna Test
S 864-090
(1)
Supply electrical power (AMM 24-22-00/201).
S 734-108
(2)
Do a TCAS operational test (AMM 34-45-00/501).
S 424-106
(3)
Complete the TCAS antenna installation:
(a)
Apply the weather aerodynamic sealant, BMS 5-95, to the outer edge of the antenna (AMM 51-31-01/201).
(b)
Fill the screw holes with cotton and apply sealant to cover the holes (AMM 51-31-01/201).
NOTE: Do not apply more than 1/8 inch of sealant into the
____
screw hole.
(c)
Remove the unwanted sealant from around the antenna base (AMM 51-31-01/201).
