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 (10) Remove the DO NOT CLOSE tag and close the applicable cicuit breaker for the R/T to be used for tests:
 (a)  P7 Overhead Circuit Breaker Panel
 1) 7B3, RADIO ALTM L
 2) 7B4, RADIO ALTM C
 3) 7C21, RADIO ALTM R

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 (11) Prepare the Ramp Test Set for the simulation tests:
 (a)  
Set the power ON/OFF switch to the ON position. 1) Make sure the 5 VDC and the HOLDING lights come on.

 (b)  
Set the NO COMPUTED DATA switches to the NORMAL position.

 (c)  
Push and release the START ALT key.
 1) Make sure START ALT shows on the LEDs.

 (d)  
Use the keypad to put in a value of 4000 (ft).

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 (e)  Push and release the ENTER key.
 1)  Make sure the radio altitude value shown on the PFDs is blank.
 S 862-319
 (12) Prepare the captain's and the first officer's EFIS control panels for the simulation tests:
 (a)  
Push and release the RST (reset) button.

 (b)  
Turn the DH controls to show DH 550 at the captain's PFD and DH 440 at the first officer's PFD.

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 (13) Set these controls on the Ramp Test Set:
 (a)  
Push and release the STOP ALT key.
 1) Make sure the LEDs show STOP ALT.

 (b)  
On the keypad, put in a value of -20 (ft).

 (c)  
Push and release the ENTER key.
 1) Make sure the LEDs show STOP ALT -20.

 (d)  
Push and release the VERT SPD key.
 1) Make sure the LEDs show VERT SPD.

 (e)  
On the keypad, put in a value of -4000 (fpm).

 (f)  
Push and release the ENTER key.
 1) Make sure the LEDs show VERT SPD -4000fpm.

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 (14) Do the radio altitude rate simulation (ramp) test:
 (a)  
Push the RAMP/HOLD key on the Ramp Test Set.
 1) Make sure the RAMPING light comes on.

 (b)  
Push the PRESS ALT key on the Ramp Test Set.

 (c)  
Look for these displays on the captain's and the first officer's PFDs: 1) The radio altitude goes out of view (for approximately 22.5

 seconds) while the altitude shown on the Ramp Test Set decreases from 4000 to 2500 feet.
 2)  After the timeout of 22.5 seconds in the previous step, a radio altitude of 2499 feet comes into view on the PFDs and decreases to zero.
 (d)  
Look for these displays on the captain's PFD when the radio altitude decreases to 550 feet: 1) The DH value changes from a white color to a yellow color. 2) The DH flashes for approximately 3 seconds. 3) The radio altitude continues to decrease toward zero.

 (e)  
Look for these displays on the first officer's PFD when the radio altitude decreases to 440 feet: 1) The DH value changes from white color to a yellow color.

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747-400 MAINTENANCE MANUAL
 2) The DH value flashes for approximately 3 seconds. 3) The radio altitude continues to decrease toward zero.
 (f)  Look for these displays on the captain's and first officer's PFDs as the radio altitude decreases to zero feet: 1) The radio altitude value changes to a white color. 2) The DH changes to the numbers set at the captain's and
 first officer's EFIS control panels.
 F. Put the Airplane in its Usual Condition.
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 (1)  Open these circuit breakers and attach DO NOT CLOSE tags:
 (a)  P7 Overhead Circuit Breaker Panel
 1) 7B3, RADIO ALTM L
 2) 7B4, RADIO ALTM C
 3) 7C21, RADIO ALTM R

 S 862-287
 (2)  
　
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