(2)
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 865-036
(3)
Make sure the airplane is in the ground mode (the airplane is not jacked and the targets are not installed).
F.
Single-Point Sensor Control Card Initiated Test Procedure
S 865-014
(1)
Find the fuel quantity in the No. 2 and 3 main fuel tank.
(a)
Use one of the systems that follows:
1) The P42, refuel control panel indicators
2) The EICAS FUEL synoptic display
3) The fuel measuring sticks.
S 975-019
(2)
Write down the fuel quantity values.
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(3)
Find the card A2 (MGMT M2 M3 SPS) installed in the M7852 fuel system card file.
NOTE: Access to the card file is in the left crawlway adjacent
____
to the nose wheel well.
S 745-037
(4)
Look at the LED indicator light for CH1, on card A2.
(a)
The green light will show if the fuel level in the No. 2 main tank is below the single point sensor (the sensor is dry).
(b)
The green light will not show if the fuel level in the No. 2 main wing tank is above the single point sensor (the sensor is wet).
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747-400 MAINTENANCE MANUAL
S 745-038
(5)
Move the BIT switch on the card to the CH1 position and hold.
S 745-039
(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, Reserve Tank Transfer 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 745-043
(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.
(g)
Make sure the CH1 light changes to its initial condition.
(8)
Do these steps if the CH1 light is on.
S 745-042
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.
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747-400 MAINTENANCE MANUAL
S 745-041
(9)
Do the procedure again for the CH2 (for the single point sensor in the No. 3 main tank).
S 865-040 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747-400 AMM 飞机维护手册 燃油 FUEL 2(7)
