(2)  
Open this circuit breaker on the P6 Main Power Distribution Panel

 for the applicable engine:
 6J10 NACELLE ANTI ICE 1
 6J11 NACELLE ANTI ICE 2
 6J12 NACELLE ANTI ICE 3
 6J13 NACELLE ANTI ICE 4

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A
747-400
MAINTENANCE MANUAL

SEE A
ANTI-ICE DUCT
ELECTRICAL  NOSE COWL PRESSURE SWITCH (TAI) VALVE ANTI-ICE THERMAL (REF) 
CONNECTOR 

A
Nose Cowl Pressure Switch Installation
Figure 401

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A
747-400 MAINTENANCE MANUAL
 S 014-054
 (3)  
AIRPLANES WITH ACCESS DOOR ON THE FORWARD FAIRING; Open the TAI access door on the left side of the No. 3 forward fairing.

 S 044-055

 (4)  
AIRPLANES WITHOUT ACCESS DOOR ON THE FORWARD FAIRING; Remove No. 2 and No. 3 forward fairings (AMM 54-62-04/401).

 S 034-004

 (5)  
Remove the applicable electrical connector from the switch: ~................................ | Engine 1 | Connector DS789 | .................................. | Engine 2 | Connector DS790 | .................................. | Engine 3 | Connector DS791 | .................................. | Engine 4 | Connector DS792 | 2.............…..................1

 S 024-005

 (6)  
Unscrew the switch from the anti-ice duct and remove it with the packing.

 TASK 30-21-04-404-006
 3.  Install the Nose Cowl Pressure Switch (Fig. 401)_____________________________________
 A. References
 (1)  
AIPC 30-21-04, Fig. 1

 (2)  
SSM 30-21-01, SSM 30-21-02, SSM 30-21-03, SSM 30-21-04

 (3)  
WDM 30-21-11, WDM 30-21-21, WDM 30-21-31, WDM 30-21-41

 B. Access
 (1)  Location Zone 451 Engine 1 - Strut Forward Fairing, No. 3 Fairing 461 Engine 2 - Strut Forward Fairing, No. 3 Fairing 471 Engine 3 - Strut Forward Fairing, No. 3 Fairing 481 Engine 4 - Strut Forward Fairing, No. 3 Fairing
 C. Installation Procedure
 S 424-007
 (1)  Install the nose cowl pressure switch with a new packing in the anti-ice duct.
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747-400 MAINTENANCE MANUAL
 S 434-008
 (2)  
Torque the switch to 270 |13 pound-inches.

 S 434-009

 (3)  
Install lockwire on the switch.

 S 434-010

 (4)  
Install the electrical connector.

 D. Switch Operation Test
 S 984-042
 (1)
Manually look the engine inlet anti-ice valve in the open position.

 S 864-043

 (2)  
Supply electrical power (AMM 24-22-00/201).

 S 044-044

 (3)  
Deactivate the thrust reversers (AMM 78-31-00/201).

 S 864-053
 CAUTION: IF THE PNEUMATIC AIR IS HOT (APPROXIMATELY 350 DEGREE F), DO
_______ NOT OPEN THE PRESSURE REGULATING AND SHUTOFF VALVE FOR MORE THAN 30 SECONDS. AFTER YOU CLOSE THE VALVE, LET THE INLET COWL BECOME COOL. TOO MUCH HEAT CAN CAUSE DAMAGE TO THE INLET COWL.
 (4)  
Supply pneumatic power (AMM 36-00-00/201).

 (5)  
Manually open the pressure regulating and shutoff valve.

 S 714-047

 (6)  
Make sure that the EICAS advisory message N AI VALVE ENGINE 1, 2, 3, or 4 shows.

 S 984-046
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