Section XII - FUEL System Flashcards
What circumstances would cause a FUEL CONFIG light to illuminate?
- Low Fuel Quantity (total useable fuel in either tank drops below 2200lbs)
- Imbalance of 2000lbs between left and right main tanks
- If more than 1200lbs of fuel in the center tanks with center pumps off
Where is the temperature on the fuel quantity indicator measured?
LEFT MAIN Tank
How many fuel pumps are located within each tank?
a. Left Tank: 2 x AC fuel pumps + 1 DC fuel pump
b. Center Tank: 2 x AC fuel pumps
c. Right Tank: 2 x AC fuel pumps
When are the center tank fuel pumps inhibited?
To reduce electrical loads, the center tank pumps are inhibited when the associated N2 is less than 50%.
Both center electric pumps are inhibited when the engines are shutdown
What is the significance of a PRESS light on a fuel pump switch?
If any pump has low output pressure, the appropriate switch PRESS light illuminates and the pump pressure EICAS message is displayed. If the main tank pump switches are OFF, the low pressure lights are illuminated and the EICAS messages for the pumps are displayed. When the center pump switches are OFF, the low pressure lights and EICAS messages for the center pumps are inhibited.
T/F: The fuel manifolds are arranged so that any fuel tank pump can supply either engine.
True
What would cause a VALVE light to illuminate on a fuel cross feed switch?
DISAGREEMENT
Valve position does not agree with its switch position
In the event of a single fuel pump failure, would one pump be enough to provide fuel pressure to the associated tank?
A single pump CAN supply sufficient fuel to operate one engine under all conditions.
What is the minimum inflight fuel tank temperature? Maximum temperature?
- 3°C (5°F) above the freeze point of the fuel being used. (L.10.8)
- The maximum fuel temperature is 49°C (120°F)
What is the maximum allowable fuel imbalance between the left and right main tanks for all flight operations?
a. 2,500lbs - If main tank fuel load is 48,000lbs or less
b. 2,500lbs - 1,500lbs ( Linear Reduction )- If main tank fuel
48,000 – 79,800lbs
c. 1,500 lbs If main tank fuel load is +79,800 lbs
From which fuel tank does the APU draw its fuel supply from?
APU fuel is supplied from the left fuel manifold
Describe a scenario in which a DC fuel pump would supply fuel to the APU.
Fuel for the APU is supplied from the left manifold. A dedicated DC fuel pump is energized when the APU selector is placed in the ON position if no AC power is available.
From which tank(s) does the Fuel Jettison system dump fuel from? At what rate would the two pumps jettison fuel?
Center tank
Approximately 2600lbs per minute
Upon doing your initial preflight you observe the absence of a PRESS light on the left FWD ac fuel pump. Is it necessary to call maintenance?
No. This is a normal function of the aircraft. The left FWD AC fuel pump automatically operates regardless of fuel pump switch position with the APU running.
While in cruise you notice that a CDU scratchpad displays “INSUFFICIENT FUEL”. What scenario would cause this message to appear?
Predicted fuel at destination is less than the FMC reserves.
