(d)  
Make sure that the EICAS advisory message HEAT P/S R AUX does not show.

 (e)  
Make sure that the lower right pitot probe head temperature increases at a lower rate.

 (f)  
Hold the S2 switch on the YMLA007 ENG 4 N2 speed card to NORMAL.

 (g)  
Alternative steps to do a check of the probe heater operation: 1) Hold the S2 switch on the YMLA007 ENG 1 N2 speed card to

 TEST. 2) Measure the voltage at Pin B1 of Relay socket DR7436. 3) Make sure the voltage measurement is from 60 to 65 volts,
 with a digital multimeter on the AC scale.
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 4)  Hold the S2 switch on the YMLA007 ENG 1 N2 speed card to NORMAL.
 (h)  
Open 6D35, PROBE HEAT IND R and 6D33, PROBE HEAT AUX PITOT R circuit breakers on the P6, Main Power Distribution Panel.

 (i)  
Install relay, R7438, in the P415, Right Power Distribution Center.

 J.  Left TAT Probe Heat Test
 S 865-040
 (1)  
Close 6D34, PROBE HEAT IND L and 6D28, PROBE HEAT TAT L circuit breakers on the P6, Main Power Distribution Panel.

 S 715-041

 (2)  
Make sure that the left TAT probe heater operates:

 (a)  
Make sure that the EICAS advisory message HEAT L TAT does not show.

 (b)  
Make sure that the left TAT probe temperature does not increase.

 (c)  
Open 7F23, LANDING GEAR DSP & CONT ALTN circuit breaker on the P7, Overhead Circuit Breaker Panel.

 (d)  
Make sure that the EICAS advisory message HEAT L TAT shows.

 (e)  
Make sure that the left TAT probe temperature increases.

 (f)  
Close 7F23, LANDING GEAR DSP & CONT ALTN circuit breaker on the P7, Overhead Circuit Breaker panel.

 S 865-042
 (3)  Open 6D34, PROBE HEAT IND L and 6D28, PROBE HEAT TAT L circuit breakers on the P6, Main Power Distribution Panel.
 K.  Right TAT Probe Heat Test
 S 865-043
 (1)  
Close 6D35, PROBE HEAT IND R and 6D29, PROBE HEAT TAT R circuit breakers on the P6, Main Power Distribution Panel.

 S 715-044

 (2)  
Make sure that the right TAT probe heater operates:

 (a)  Make sure that the EICAS advisory message HEAT R TAT does not show.
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747-400 MAINTENANCE MANUAL
 (b)  
Make sure that the right TAT probe temperature does not increase.

 (c)  
Open 7H8, GND SAFETY RELAY circuit breaker on the P7, Overhead Circuit Breaker Panel.

 (d)  
Make sure that the EICAS advisory message HEAT R TAT shows.

 (e)  
Make sure that the right TAT probe temperature increases.

 (f)  
Close 7H8, GND SAFETY RELAY circuit breaker on the P7, Overhead Circuit Breaker Panel.

 S 865-045
 (3)  Open 6D35, PROBE HEAT IND R circuit breaker on the P6, Main Power Distribution Panel.
 L. Left AOA Probe Heat Test
 S 865-046
 (1)  
Close 6D34, PROBE HEAT IND L and 6C33, AOA HEAT L circuit breakers on the P6, Main Power Distribution panel.

 S 715-047

 (2)  
Make sure that the left AOA sensor vane heater operates:

 (a)  
Make sure that the EICAS advisory message HEAT L AOA shows.

 (b)  
Make sure that the left AOA vane temperature does not increase.

 (c)  
Open 7F23, LANDING GEAR DSP & CONT ALTN circuit breaker on the P7, Overhead Circuit Breaker Panel.

 (d)  
Make sure that the EICAS advisory message HEAT L AOA does not show.

 (e)  
Make sure that the left AOA vane temperature increases.

 (f)  
　
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