ATA 29 - FUEL

• The A318, A319, and A320 share a common fuel system design. The fuel system also feeds the APU directly from the left side. It is possible to refuel on BAT (for max 10 mins).

• A refuel controlled from the belly fairing is cancelled when a refuel is set in the cockpit.

• The LH (RH) wing tank (inner cell) is between RIB1 and RIB15. The LH (RH) wing tank (outer cell) is between RIB15 and RIB22, CENTER tank-the RIB1(LH) and the RIB1 (RH).

• If the pressure in the center tank increases to a specified value, the overpressure protector breaks to release the pressure (into the LH wing tank).

• There’re 3 thermal switches are in the electrical circuit of the fuel pump element. If the temperature of the pump element increases to more than 175 deg°C (347°F) the switches operate. This causes the pump element to stop. It cannot operate again and must be replaced.

• A single coupling is attached to the forward face of each wing front spar, between RIB14 and RIB15.

• The pressure relief valve 97QM is installed in the RH RIB 1. If a center tank overflow occurs the pressure relief valve releases the fuel into the RH wing tank.

• CENTER TANK summary:

- Overpressure: releases pressure into LH wing tank

- Overflow: releases fuel into RH wing tank

- Ventilation: is provided by LH wing surge tank

• During normal operations XFEED VALVE is closed.

• No direct fuel feed from outer cells (A318, A319, A320).

• A321 doesn’t have inner and outer tanks, just wing tanks.

• APU has its own DC fuel pump, it takes fuel from LH inner cell engine feed line (A318, A319, A320) or from LH wing tank engine feed line (A321).

• The FQIC has two processing channels that are the same. The channels are identified as Channel 1 and Channel 2. One master and one slave.

• FQIC (Fuel Quantity Indication Computer) regulates fuel during refueling and de-fueling and provides TOTAL FUEL QTY indication to ECAM.

• FLSCU (Fuel Level Sensing Control Unit) controls:

- Fuel Temperature (LH and RH wing tanks only)

- Fuel Level

- Intercell valves (A318, A319, A320) with FQIC collaboration

- CENTER TANK FUEL PUMPS: activates o de-activates them automatically

• LP VALVES have 2 elec motors, one powered by A/C BUS and the other one powered by D/C BUS.

• Sequence check valves are responsible to get center tank empty first (normal operation)

• Each center-tank pump will operate until the sensor continues to be dry for five more minutes.

• The IDG shut-off sensors stop the IDG cooling when the fuel quantity is less than 280kg (616lb). The FLSCUs (Fuel Level Sensor Control Unit) signal the FADEC to close the FRV, which stops the fuel flow from the IDG cooling system to the recirculation system.

• MMI five in each wing tank and 1 in CTR tank (321 MLI 7 in each wing,1 in CTR tank).

• A321 Fuel is supplied to the engines from the wing tanks only.

• The VAPOR SEAL is a fabric membrane that isolate the center tank from the air conditioning compartment below.

• Wing RIB 15 separates inner cell to outer cell.

• Center tank has no temperature sensor.

• If APU PRESS SWITCH senses that fuel press is less than 22 PSI, ECB activates APU DC FUEL PUMP.

• A321 Center Tanks doesn’t have Fuel Booster Pumps. Fuel is transferred to wing tanks via JET PUMPS and Transfer Valves. Jet pumps operation is based on Venturi’s principle so they are not provided with electrical motors. CENTER TANK → Jet Pumps → WING TANKS → Wing Tanks Booster Pumps → ENGINES.

• Tanks ventilation is provided by a “NACA” port located on wing surge tanks.