FUEL PANEL Flashcards
DESCRIBE THE L & R BOOST PUMP SWITCHES.
ON – When switchlight is pressed in, it is armed for automatic activation. When the switchlight is selected out the pump is deactivated. ON will illuminate when the switchlight is pressed in and pump is activated for the following reasons:
During engine start
When low fuel pressure is detected in any engine feed line
Both pumps are activated in the event of a failure of a main ejector pump
L BOOST PUMP is powered by the DC BATT BUS
R BOOST PUMP is powered by DC BUS 2
NOTE: Selecting just one boost pump will energize both pumps.
INOP – Illuminates when:
Low pump output pressure
Pump has failed
Pump has not been armed
DESCRIBE THE GRAVITY XFLOW SWITCH-LIGHT.
OPEN – Illuminates when the gravity SOV is open.
FAIL – Illuminates when the gravity crossflow SOV is not in the commanded position.
DESCRIBE THE L/R XFLOW SWITCH-LIGHT.
ON – Indicates the respective crossflow SOV is open and the crossflow/APU pump is on. This can happen automatically or manually. In order to turn the pump on manually, the XFLOW OVERRIDE switchlight must first be manually selected and illuminated MAN.
FAULT – Indicates the respective crossflow SOV is not in the commanded position or Crossflow/APU pump failed to energize with the crossflow SOV open.
DESCRIBE THE XFLOW AUTO OVERRIDE SWITCH-LIGHT.
MAN – illuminates when the switchlight is selected in and causes the APU/Crossflow pump to be armed for manual crossflow while also disabling the automatic crossflow and balancing.
When the switchlight is in and not illuminated the APU/Crossflow pump is armed for automatic fuel transfer and balancing.
The system will automatically rebalance the fuel tanks when there is an imbalance of more than 200 lbs of fuel. Cross flow is automatically stopped when the fuel quantity of the low tank exceeds the other tank by 50 lbs.
Another auto transfer exists between the center tanks and wing tanks. When a wing tank fuel level drops below 94% of its total capacity, the fuel system computer will use the transfer ejectors to fill the respective low wing tank.
WHAT ARE THE RESPECTIVE BOOST PUMPS POWERED BY?
L BOOST PUMP is powered by the DC BATT BUS
R BOOST PUMP is powered by DC BUS 2
WHAT IS THE MAXIMUM FUEL IMBALANCE BETWEEN TANKS?
800 LBS
WHAT IS THE IMBALANCE LEVEL AT WHICH THE TANKS WILL BEGIN TO TRANSFER?
The system will automatically rebalance the fuel tanks when there is an imbalance of more than 200 lbs of fuel. Cross flow is automatically stopped when the fuel quantity of the low tank exceeds the other tank by 50 lbs.
