Fuel Flashcards
How are the outboard tanks structured?
divided into 3 sections by baffles
What do the main tank surge boxes do? Where is it located?
prevents fuel boost pumps from becoming fuel starved during nose-down, wing-down, or negative-g attitudes by keeping the boost pumps submerged in fuel Inboard aft corner of each main tank
How many transfer pumps are in the aux tanks?
1
How many transfer pumps are in the external tanks?
2
What is the purpose of the fuel tank vent system?
vents all fuel tanks to the atmosphere to equalize pressure and prevent damage to the wing or tank
What kind of vent system do the inboard and aux tanks have?
wrap-around vent system
How are the outboard tanks vented?
vented by float-controlled vent valves
How are the external tanks vented?
vented through the space at the top of the baffles, separating the tank compartments, and through the fuel vent line
What do FLCVs do?
automatically stops fuel from flowing into the tank when its full
How many FLCVs are in each tank?
3 in 1 and 4 1 in all the others
If the FLCVs lose electrical power, what position do they fail in?
spring-loaded closed
What is the boost pump rated at?
15 to 24 psi
What is the transfer pump rated at?
28 to 40 psi
Do both transfer pumps in the external tank run at the same time?
No they alternate. They only run at the same time during fuel dumping
The compensators in the fuel tanks measure what to get a more accurate fuel level reading?
density of the fuel, not the quantity
What monitors and controls the basic aircraft fuel system?
the dual channel Fuel Management Controller (FMC)
What buttons in the cockpit control the FLCVs? The transfer pumps?
TO button FROM button
What turns on the boost pumps?
selecting the ENGINE START switch to RUN
In case of power failure, the fuel valves fail to what position?
hold the last energized position
The dump valve switches control which valves?
dump mast shutoff valves interconnect valves
If the AR pumps are being used for dumping, what do the interconnect valves do and why?
Remain close or close upon activation to prevent high pressure fuel from entering the cross-ship manifold
Where is fuel returned to from the SPR manifold?
Tank 3
Placing the SPR DRAIN switch to ON does what?
opens the drain valve, closes the SPR valve, and activates the drain pump to initiate the drain cycle.
How long does the fuel drain cycle run? How many cycles are required to completely drain the SPR manifold?
2.5 mins 2
What do the interconnect valves do?
Isolates the AR manifold and the cross-ship manifold during AR
Why do we not want to land with fuel in the externals?
to prevent pylon fatigue cracking
Fuel Weight Tanks 1 and 4
8310
Fuel Weight Tanks 2 and 3
7650
Fuel Weight Aux Tanks
5810
Fuel Weight External Tanks
8900
Fuel Weight Fuselage Tanks
24390
How much fuel can be dumped?
All usable except approx. 1520 lbs in each main tank
Dump rate with 4 transfer pumps
2000 lbs/min
Dump rate with 6 transfer pumps
2770 lbs/min
Dump rate with 8 transfer pumps
2950 lbs/min
Dump rate with 10 transfer pumps
3900 lbs/min
Dump rate with 2 AR pumps
5440 lbs/min
How is dumping prevented on the ground?
WOW system
How do you dump fuel if you’re using a fuselage tank?
Fuselage tank fuel is dumped by the AR pumps, fuel from the other tanks may not be dumped directly overboard but may be transferred simultaneously into the fuselage tank.
In case of power failure, what do the crossfeed valves do?
hold last energized position
The fuel pressure indicator is located where on the FUEL MANAGEMENT panel?
right side of the cross ship manifold
How do you display fuel pressure from the left side of the cross ship manifold?
the cross ship valve OR both interconnect valves must be open
What type of material is used in the fabrication of the cross-ship manifold and why?
Inconel low thermal expansion property
What do the FLCVs require to open? What are they controlled by?
electrical power FMC
If the primary FMC fails followed by a failure of the secondary FMC, what is displayed?
the fuel tank quantity indicators on the flight station overhead FUEL MANAGEMENT panel will display dashes while the quantity indicators at the ACS FUEL MANAGEMENT panel will display the last valid values.
What type of tanks are the aux tanks?
Bladder type
Why are the external tanks compartmented with baffles?
to prevent surges between compartments that would affect CG
What does the main tank water removal system do?
provides continuous water removal from the tank low points during boost pump operation maintains the fuel level around the boost pump when the aircraft is in a nose-down attitude with low fuel level in the tank
