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747-400 MAINTENANCE MANUAL
(g)
Tighten the bolts to 32-39 pound-inches.
(h)
Make sure the face of the sensor aligns to 0.01 inch or less of the surface of the airplane.
S 764-026
(8) Measure the resistance between the body of the sensor and the surface of the airplane.
(a) The resistance must be 0.010 ohm or less.
S 864-246
(9) Remove the DO-NOT-CLOSE tags and close these circuit breakers:
(a) P7 Overhead Circuit Breaker Panel
1) 7A10 ADC L PWR
2) 7A12 AOA L
3) 7A13 AOA ALTN L
4) 7A14 ADC R PWR
5) 7A16 AOA R
6) 7A17 AOA ALTN R
7) 7J15 ADC C PWR
S 864-268
(10) Remove the DO-NOT-CLOSE tags and close these circuit breakers:
(a) P6 Main Power Distribution Panel
1) 6C33 AOA HEAT L
2) 6C34 AOA HEAT R
S 744-269
(11)
Do the BITE self-test for the left ADC as follows:
(a)
Push the self-test switch on the ADC.
(b)
Make sure the "external sensor fault" display shows a dash (-) which means that no external sensor faults were found.
(12)
Do the self-test again for the right ADC.
(13)
Do the self-test again for the center ADC.
S 714-030
(14)
Do the Ground Test for the heater circuit of the installed angle of attack sensor (AMM 30-31-00/501).
(15)
Remove electrical power if it is not necessary (Ref 24-22-00/201).
S 744-270
S 744-271
S 864-016
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S 394-031
WARNING: DO NOT TOUCH THE ANGLE OF ATTACK SENSOR WHEN THE SENSOR HEAT IS
_______ ON. YOU CAN BURN YOURSELF ON THE ANGLE OF ATTACK SENSOR.
(16) Install the sealant (Ref 51-31-01/201):
(a)
Apply a thin layer of the sealant on the nylon cord.
(b)
Wind the cord one time around the bottom of the sensor and one time around the outer surface of the hole.
NOTE: If the space is too small to install the nylon cord
____ around the full periphery, install the cord where possible.
(c)
Fill the empty space between the sensor and the fuselage with BMS 5-95 Class B-1/2 sealant.
(d)
Let the sealant dry until it cannot be dented.
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747-400 MAINTENANCE MANUAL
ADC SOURCE SELECT RELAY - REMOVAL/INSTALLATION
______________________________________________
1. General_______
A. This subject contains two tasks. The first task is to remove an ADC source select relay. The second task is to install an ADC source select relay.
B. You will find the captain's and the first officer's ADC source select relays in the main equipment center.
C. The relays are installed on the aft side of the floor beam, at STA 420, above the electronics equipment racks.
D. The removal and installation of the relay is the same for the captain's relay and first officer's relay.
TASK 34-12-04-004-275
2. ADC Source Select Relay Removal_______________________________
A. Access
(1) Location Zones 117/118 Electrical and Electronics Compartment
B. Procedure
S 864-687
(1)
Make sure the two F/D switches on the MCP are in the OFF position.
S 864-310
(2)
Open these circuit breakers and attach DO-NOT-CLOSE tags:
