S 745-053

 (6)  
Make sure the CH1 green light changes its condition.

 NOTE: If the light was on, the light will go off when the
____ BIT switch is moved to the CH1 position. If the light was off, the light will come on when the BIT switch is moved to the CH1 position. The time for the light to change its condition can be four seconds.
 (a)  If you find these two conditions, there is a problem with the SPS system:
 NOTE: Do the, Fuel Jettison System Single-Point Sensor
____ Card Ground Test, to find any ATA 28 fuel system related problems.
 1) The CH1 light is not on (for all fuel quantity levels) and, 2) The CH1 light does not change states (come on) when the BIT switch is moved to the CH1 position.
 S 745-054
 (7)  Do these steps if the CH1 light is off.
 NOTE: The fuel level in the No. 2 main tank is above the single
____
 point sensor (the SPS is wet).

 (a)  
Move the BIT switch to the CH1 position and hold (the CH1 green light will come on).

 (b)  
While the BIT switch is held to the CH1 position, move the FAIL SAFE TEST switch to the CH1 position and hold.

 (c)  
Make sure the CH1 light goes off.

 (d)  
Release the FAIL SAFE TEST switch.

 (e)  
Make sure the CH1 light comes on.

 (f)  
Release the BIT switch.

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747-400 MAINTENANCE MANUAL
 (g)  Make sure the CH1 light changes to its initial condition.
 S 745-055
 (8)  Do these steps if the CH1 light is on.
 NOTE: The fuel level in the No. 2 main tank is below the single
____
 point sensor (the sensor is dry).

 (a)  
Move the FAIL SAFE TEST SWITCH to the CH1 position and hold.

 (b)  
Make sure the CH1 light goes off.

 (c)  
Release the FAIL SAFE TEST switch.

 (d)  
Make sure the CH1 LED indicator light comes on.

 S 745-056
 (9)  
Do the procedure again for CH2 (for the single point sensor in the No. 3 main tank).

 S 865-057

 (10)
 Remove electrical power, if it is not necessary
 (AMM 24-22-00/201).

 G.
Fuel Jettison Single Point Sensor Card Ground Test

 S 865-058
 (1)  
Supply electrical power (AMM 24-22-00/201).

 S 865-059

 (2)  
Make sure the airplane is in the ground mode (the airplane is not held up by jacks and the targets are not installed).

 S 865-060

 (3)  
Make sure these circuit breakers are closed:

 (a)  
P6, Main Power Distribution Panel
 1) 6F6, FUEL SYS MGMT CH1
 2) 6F8, FUEL SYS MGMT CH2

 S 865-061
 (4)  Set the GND TESTS switch on the overhead maintenance panel, P461, to the ENABLE position.
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747-400
MAINTENANCE MANUAL

 S 865-062
 (5)  
Prepare the CDU for the test:

 (a)  
Push the MENU key on the CDU to show the MENU.

 (b)  
Push the line select key (LSK) that is adjacent to <CMC to show the CMC MENU.

 (c)  
If <RETURN shows after you push the LSK, push the LSK that is adjacent to <RETURN until you see the CMC MENU.

 (d)  
Push the LSK that is adjacent to <GROUND TESTS to show the GROUND TESTS menu.

 (e)  
Push the NEXT PAGE key until you find <28 FUEL.

 (f)  
Push the LSK that is adjacent to <28 FUEL to show the GROUND TESTS menu for the fuel system.

 (g)  
　
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