Fuel Flashcards
Each wing tank is divided into an _____ and _____ tank, which are separated by a _____ _____. _____ transfer valves are installed within each of these.
Inner, Outer, Sealed Rib. Two
What protects the outer wing tanks from thermal expansion?
Vent tanks
What protects each fuel tank from overpressure?
Overpressure relief ports are located on the underside of each wing, connected to each tank except the center tank. These overpressure relief ports are carbon discs that will rupture during an overpressure condition. An overpressure protector is also located between the center tank and the left inner tank.
What provides information about the fuel system?
The Fuel Quantity Indication system (FQI) is controlled by a two channel computer. It provides information about the fuel system and transmits the actual total fuel quantity as well as the quantity and temperature of fuel in each tank. The FQI also controls automatic refueling. Channel one is primary, but if failed, channel two automatically takes over. If either channel fails, the system will operate in a degraded mode. In this mode, double hash marks are shown over the last two digits in each fuel quantity display to indicate that fuel indications are less accurate.
An amber half box appears around the FOB indications when fuel is trapped due to:
- Both center tank transfer valves fail in the closed position
- The outer to inner tank transfer valves fail to open
Is it possible to determine the fuel load on the ground if the FQI system is inoperative?
If the FQI system is inoperative, it is possible to determine the fuel load on the ground with Magnetic Level Indicators (MLIs).
What is the FLSCU?
The Fuel Level Sensing Control Unit (FLSCU) generates fuel level and fuel temperature signals in order to operate the switching functions for refueling and defueling. The system also controls the IDG cooling recirculation system and the center tank to wing-tank fuel transfer system.
The FLSCU is comprised of:
- Fuel level sensors in the tanks to sense high, low, and overflow levels
- A fuel temperature sensor to control the IDG cooling recirculation
When fuel quantity in one wing tank drops below _____ lbs, the _____ triggers an ECAM caution. This caution is completely _____ from the displayed fuel quantity indication of the tank.
1650 lbs, FLSCU, Independent
The fuel system is equipped with a Fuel Tank Inerting System that reduces the flammability in the center tank. The system is composed of:
- A Conditioned Services Air System (CSAS)
- An Inert Gas Generation System (IGGS)
What is the Conditioned Services Air System (CSAS)?
The CSAS taps engine bleed air and conditions it to a specific pressure and temperature, which then passes through the IGGS
What is the Inert Gas Generation System (IGGS)?
The CSAS taps engine bleed air and conditions it to a specific pressure and temperature, which then passes through the IGGS where an Air Separation Module extracts the nitrogen molecules. This oxygen depleted air (containing less than 12% oxygen) then replaces the ambient air of the center tank. This system operates whenever the engines are running.
Two FMGCs use _____ input and _____ _____ data to provide _____ information to the MCDU FUEL PRED page.
FQI, Fuel Flow, FOB
Are we able to determine the fuel quantity if a fuel tank sensor is inoperative?
The amount of fuel flow is measured by fuel flow sensors, which provides redundant sources of fuel quantity information when a fuel tank sensor is inoperative.
How are the Low Pressure (LP) fuel valves controlled?
Electrically controlled by the ENG MASTER levers or the ENG FIRE pbs.
Can the engines continue to operate if the wing tank fuel pumps fail?
The engines can still continue operating via gravity feed by suction valves. Depending on the model, some aircraft center tank pumps are not fitted with suction valves. Therefore, gravity feeding is not always possible from the center tank.
The _____ valve is used to manage a fuel _____ and during _____-_____ conditions to ensure fuel is available where needed.
Crossfeed, Imbalance, Non-Normal
The fuel system attempts to maintain fuel in the _____ wing tanks for as long as possible for proper _____ _____, which extends wing life.
Outer, Wing Loading
What are the purpose of the fuel transfer valves?
The transfer valves automatically open when either inner tank quantity reaches a low level. Once the transfer valves are open, they will not close until the next refueling operation. During a steep descent or accelerations, the transfer may open with more than 1650 lbs of fuel in each inner tank, and the WING TK LO LVL caution may be triggered.
When is the APU dedicated fuel pump activated?
The APU dedicated fuel pump is activated automatically if the left side of the fuel manifold is not pressurized and the APU MASTER SW pb is selected ON. Selecting the APU MASTER SW pb OFF closes the APU LP valve to cut off fuel to the APU.
Typically refueling is an _____ process using the control panel to distribute the fuel, however, manual refueling may be accomplished by using the _____ _____ controls on the Refueling Control Panel.
Automatic, REFUEL VALVE
Refueling is possible when only _____ power is available. _____ refueling is also possible via refueling points located on the top of the wings.
Battery, Gravity
When does the F. USED indication reset?
The F. USED indication resets during engine start.
Both _____ valves open at the same time when one _____ wing tank reaches approximately _____ lbs.
Transfer, Inner, 1650 lbs
During automatic refueling, the _____ tanks are filled first. If the selected fuel load exceeds the wing tank capacity, the _____ tank is filled simultaneously. When the outer tanks are full, fuel then overflows into each inner tank through a _____ _____.
Outer, Center, Spill Pipe
Refueling time at nominal pressure is approximately:
- 17 minutes for the wing tanks and,
- 20 minutes for all tanks.
When does the REFUELG message appear in the memo section?
The REFUELG message appears in the memo section when the Refueling control panel door is open.
What is the refueling sequence?
- The outer tanks are filled first
- If the selected fuel load exceeds the wing tank capacity, the center tank is filled simultaneously
- When the outer tanks are full, fuel then overflows into each inner tank through a spill pipe
When the aircraft has been refueled to maximum capacity, the fuel can expand by _____ % (_____ °C temperature rise) without spilling.
2%, 20°C
How many fuel tanks does the A321 have?
5,
* 1 Center Tank
* 2 Wing Tanks
* 2 Vent Tanks
What are the purpose of the pressure reduction valves on the wing tank pumps?
All wing tank pumps remain on throughout the flight. They are fitted with pressure relief sequence valves which ensure that, when all pumps are running, the center tank pumps will deliver fuel preferentially and to subsequently burn center tank fuel first.
Fuel Feed Sequence
The tanks empty in the following sequence:
1. The center tank.
1. The inner tanks: Each inner tank empties down to 750 kg (1 650 lb).
1. The outer tanks: Fuel transfers into the inner tanks.
How do the Intertank Transfer Valves operate?
Two level sensors are installed in each inner tank. Each sensor controls two transfer valves, one in each wing, ensuring simultaneous transfer to both wings
What bus is the APU Feed pump powered from?
APU Feed pump normally runs off the AC ESS SHED, but runs off the AC STAT INV BUS if the AC ESS SHED fails.
Briefly explain the Fuel Recirculation System
Some of the fuel supplied to each engine goes from the high-pressure fuel line in that engine, through the integrated drive generator (IDG) heat exchanger (where it absorbs heat), to the fuel return valve and to the outer fuel tank. This operation ensures the IDG cooling when the oil temperature is high or when at low engine power.
The FADEC controls the fuel return valve. If the outer tank is already full, the fuel overflows to the inner tank through a spill pipe. If center tank is feeding, the wing tank will tend to overfill and the system automatically selects the CTR TK PUMP off when the inner tank is full. The wing tank pumps will feed until the engine have used approximately 500 kg (1 100 lb) of fuel when the fuel level reaches the underfull sensors. The logic circuits then restart the center tank pumps.
Which side must the aircraft be refueled from?
One (two) refueling point(s) is (are) installed under the wings, enabling the aircraft to be refueled from either the right or left (if installed) side.
L (R) TK PUMPS pb-sw FAULT LT
Amber light and ECAM caution come on, when the delivery pressure drops. It does not come on when OFF is selected
MODE SEL pb-sw FAULT LT
Amber light comes on and ECAM caution come on, when:
- The center tank has more than 550 lbs of fuel and the left or right wing tank has less than 11000 lbs
CTR TK PUMP 1 (2) pb-sw FAULT LT
Amber light and associated ECAM caution come on, when the pump is in operation and the delivery pressure drops
What is the AUTO mode of the MODE SEL pb-sw?
- Pumps run at engine start for 2 minutes
- Before or after engine start sequence, the pumps run if the slats are retracted
- Pumps stop automatically 5 minutes after center tank low level is reached
CTR TK L(R) XFR pb-sw FAULT LT
Amber light and associated ECAM caution comes on, if the associated wing tank overflows
Do we use the TAT or SAT when monitoring the fuel temperature?
TAT
If after takeoff and slat retraction, the CTR TK FEEDING ECAM message does not display. Is there a problem?
It could be because the inner wing tanks are full and are currently burning 1100 lbs of fuel before switching back to the center tanks.
Which aircraft are capable of running the engines directly from the center tanks?
Only the older, non jet-pump systems.
