Fuel Flashcards
Why will center tank fuel be used before main tank fuel with all fuel tank pumps operating?
The two electric center tank pumps have higher output pressure than the main tank pumps.
When will the center tank pumps operate with the switched ON?
Center tank pumps are inhibited until the respective engine is running. This reduces electrical load.
Possible causes for an illuminated “FUEL CONFIG” light?
Fuel imbalance of 1,800 lbs. or more. Center tank has more than 1,200 lbs but pumps are off.
What does a fuel pump “PRESS” light indicate?
The respective pump has low output pressure.
What is the purpose of the crossfeed valve?
To balance the L/R main fuel tanks.
What does an illuminated crossfeed “VALVE” light indicate?
Valve is not in the commanded position (could be in transit).
What is the approximate fuel capacity per tank and the total?
Main tanks: 14,500 lbs.
Center tank: 46,000 lbs.
Total: 75,000 lbs.
“FUEL CONFIG” light illuminates and “LOW FUEL” Caution message is displayed when either the left or right main tank quantity drops below approx._______lbs.
2,200 lbs.
Fuel temperature indicator is an indication of the temperature in which tank?
Right
“PRESS” lights for the center tank pump switches are inhibited when….
the center tank pump switches are off.
During normal operation EICAS advisory messages CTR L FUEL PUMP and CTR R FUEL PUMP display to indicate what condition.
Depletion of center tank fuel.
Describe the purpose/operation of the scavenge system in the center tank.
When the center pumps are turned off due to depletion of center tank fuel, a small amount of fuel may remain. When the left tank is approximately half empty, the scavenge system will transfer the remaining fuel to the left tank.
Describe Suction Feed.
When main tank output pressure is low each engine can draw fuel from it’s respective tank through a suction feed line that bypasses the fuel pumps.
Describe APU fuel feed.
Fuel is supplied to the APU from the left fuel manifold. With AC power on the ground the left forward fuel pump operates automatically, regardless of switch position, to supply fuel to the manifold and therefore APU. With no AC power the DC pump in the left main tank operates automatically when the APU selector is positioned to the “ON” position.
