The A320 fuel system is designed to efficiently manage fuel storage and distribution. Fuel storage tanks include inner and outer wing tanks plus the center tank. The left-wing tank supplies fuel to the left engine, while the right-wing tank supplies fuel to the right engine.

When tanks are filled, the system monitors fuel volume to maintain proper center of gravity. Main fuel pumps provide fuel to engines and also fuel to the auxiliary power unit. Engineers regularly check the fuel quantity and related fuel parameters.

The system utilizes fuel lines on both sides of the fuel system to ensure reliability. Fuel vent systems regulate pressure as fuel in each tank is consumed. The design helps allow fuel transfer between tanks when needed.

The process begins with fuel being stored in multiple fuel tanks in the aircraft, primarily the wing tanks and center tank. When the aircraft is ready for operation, fuel pumps activate to supply fuel to the engines and the auxiliary power unit. Initially, fuel from the center tank is consumed first until the center tank is low, after which the system transitions to the main fuel stored in the wings.

The inner workings of the fuel system include tank pumps and jet pumps that ensure proper flow of fuel. The crossfeed valve allows for tank transfer when necessary, while fuel valves regulate the distribution. The fuel management is monitored through the overhead panel and control panel in the cockpit, where pilots can track fuel quantity and adjust settings as needed.

Safety features of the Airbus 320 include surge tanks to prevent fuel overflow during refuel operations and fuel tank inerting systems to reduce combustion risks. The entire design promotes efficient fuel usage while maintaining safety. Wing tank pumps serve as backup when needed, and the system is engineered to detect any potential fuel leak. The workings of the fuel system ensure that the proper amount of fuel reaches the engines throughout all phases of flight.

Learn how the Airbus A320 fuel system works—from engine start to landing. Clear breakdown of feeding sequence, tanks, valves, and logic.A320 Fuel Tanks Overview

  • Center Tank – located in the fuselage
  • Inner Wing Tanks – inboard section of each wing
  • Outer Wing Tanks – outboard sections designed for structural and balance considerations

Note: When auxiliary tanks are installed, they are used first, as defined in the FCOM.

Step-by-Step Fuel System Feeding Sequence Explained

1. Engine Start: Inner Tanks Only

When starting the engines, the aircraft draws fuel from the inner wing tanks.

2. After Engine Start: Switch to Center Tank Feeding

Shortly after both engines are running, the system begins feeding from the center tank, if fuel is available there.

3. Takeoff Configuration: Return to Inner Tanks

To prevent center tank feeding during takeoff, the system switches back to inner tanks when slats are extended during taxi-out.

4. Post Takeoff: Center Tank Resumes

Once slats are retracted after takeoff, center tank feeding resumes and continues until the tank is fully empty.

Fuel Recirculation & Return Flow

Not all the fuel sent toward the engines is burned. Some of it is used to cool:

  • Integrated Drive Generator (IDG)
  • Fuel-Cooled Oil Cooler (FCOC)

This fuel returns to the outer tanks. If they are full, excess flows via spill pipes into the inner tanks.

FLSCU (Fuel Level Sensing Control Unit) monitors tank levels and controls feeding logic accordingly.

Smart Feeding Cycle

  • Feeds from center tank
  • If inner tanks are full, center tank feeding stops
  • ~500 kg used from each inner tank to make space
  • Center tank feeding resumes

This cycle repeats until the center tank is empty.

Diagram of Airbus A320 fuel tank sequence showing flow from inner to center and outer tanks, including transfer logic, slat configuration triggers, and valve activation points.Feeding from Inner Tanks Until Low Level

Engines continue to feed from inner tanks until the fuel level drops to ~750 kg. At this point:

  • Transfer valves open
  • Outer tanks drain into inner tanks
  • Valves remain open until next engine start

Why Outer Tanks Are Used Last

Outer tanks have no pumps. This design:

  • Maintains fuel near the wingtips
  • Reduces wing bending moments
  • Prevents flutter

Summary Chart: A320 Fuel Feeding Order

Phase Fuel Source Trigger/Event
Engine Start Inner Tanks Manual/Automatic
After Engine Start Center Tank Auto-switch after start
Takeoff Config (Taxi) Inner Tanks Slat extension
After Takeoff Center Tank Slat retraction
Center Tank Empty Inner Tanks Fuel level monitoring
Inner Tanks Low (~750 kg) Outer Tanks drain to inner Transfer valves open
Final Feed Inner Tanks (combined) Until fuel exhaustion

What Pilots Should Remember

  • Center tank feeding is prohibited during takeoff
  • FLSCU logic prevents tank overfill
  • Outer tanks draining = approaching final reserve
  • Transfer valves stay open until next engine start
  • Always monitor the ECAM fuel page

Related Topics to Explore

Final Thoughts

The A320’s fuel system is a masterclass in automation and safety logic. Whether you’re preparing for a type rating, teaching others, or just geeking out over aircraft systems, understanding the fuel feeding process deepens your appreciation for how smart this aircraft really is.

Got a question? Leave a comment or connect with us at Pilot.Sinej.com.


Infographic available below – showing the complete visual sequence of the A320 fuel feeding process.

Infographic showing the Airbus A320 fuel feeding sequence, including fuel flow from inner tanks during engine start, center tank feeding after start, inner tank usage during takeoff, and automatic transfer from outer to inner tanks at low levels.
Infographic showing the Airbus A320 fuel feeding sequence, including fuel flow from inner tanks during engine start, center tank feeding after start, inner tank usage during takeoff, and automatic transfer from outer to inner tanks at low levels.

People Also Ask

What is the fuel feeding sequence on the Airbus A320?

The A320 follows a specific fuel feeding order: it starts with the inner wing tanks during engine start, switches to the center tank after start-up, reverts to inner tanks for takeoff (when slats are extended), resumes center tank feeding post takeoff, then moves back to inner tanks until low-level sensors trigger transfer from the outer wing tanks.

Why is center tank feeding prohibited during takeoff?

Center tank feeding is inhibited during takeoff to prevent excessive pitch imbalance and ensure safe fuel pressure stability. The system automatically switches to inner tank feeding when slats are extended during the takeoff configuration.

How does the A320 manage fuel return from the engines?

Some of the fuel routed toward the engines passes through the Integrated Drive Generator (IDG) and Fuel-Cooled Oil Cooler (FCOC) before returning to the wing tanks—primarily the outer tanks. If they’re full, the fuel is routed via a spill pipe to the inner tanks. The Fuel Level Sensing Control Unit (FLSCU) monitors tank levels to stop center tank feeding if overflow is likely.

What triggers fuel transfer from the outer tanks to the inner tanks?

When inner tank levels drop to approximately 750 kg, a low-level sensor opens transfer valves. These valves allow gravity-based drainage of fuel from the outer tanks to the inner tanks. The valves remain open until the next engine start.

Why are outer tanks used last in the fuel sequence?

Outer tanks do not contain pumps and are intentionally kept full longer to help reduce wing bending moments and prevent flutter. This improves the structural integrity of the wings during flight.

What happens if inner tanks are too full during center tank feeding?

If returned fuel from engine cooling loops would cause an overflow, the system stops center tank feeding. Approximately 500 kg of fuel is used from the inner tanks to make space, then the center tank feeding resumes. This alternating cycle continues until the center tank is empty.

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Airbus A320 Fuel System Feeding Sequence Explained The A320 fuel system is designed to efficiently manage fuel storage and distribution. Fuel storage tanks include inner and outer wing tanks plus the center tank. The left-wing tank supplies fuel to the left engine, while the right-wing tank supplies fuel to the right engine. When tanks are filled, the system monitors fuel volume to [...]
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