W DOC AIRBUS | AMM A320F

FUEL RECIRCULATION - COOLING - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL
1. General
The Intergrated Drive Generator (IDG) oil-cooling system (Ref. AMM D/O 24-21-00-00) and engine oil system (Ref. AMM D/O 79-00-00-00) use part of the fuel supply to each engine. During oil cooling the temperature of the fuel increases. The fuel recirculation for the cooling system (recirculation system) moves the warm fuel from the engine to the wing tank.

Each engine has a recirculation pipe which moves the warm fuel to the wing tank. The interface between each engine and each recirculation pipe is a Fuel Return Valve (FRV) (Ref. AMM D/O 73-10-00-00).

The operation of the FRV is controlled by the Full Authority Digital Engine Control (FADEC) system (Ref. AMM D/O 73-20-00-00).

** ON A/C NOT FOR ALL
2. Component Location
F Recirculation System - Component Location ** ON A/C NOT FOR ALL
F Recirculation System - Component Location ** ON A/C NOT FOR ALL
FIN FUNCTIONAL
DESIGNATION		 PANEL ZONE ACCESS
DOOR		 ATA REF
** ON A/C NOT FOR ALL
123QM CHECK VALVE-FUEL RECIRCULATION, R 481 28-16-42
** ON A/C NOT FOR ALL
122QM CHECK VALVE-FUEL RECIRCULATION, L 471BL 471 28-16-42
** ON A/C NOT FOR ALL
122QM CHECK VALVE-FUEL RECIRCULATION, L 471CL 471 28-16-42
123QM CHECK VALVE-FUEL RECIRCULATION, R 481CR 481 28-16-42
** ON A/C NOT FOR ALL
122QM CHECK VALVE-FUEL RECIRCULATION, L 471 28-16-42
218QM VALVE-PRESSURE HOLDING 540 28-16-43
219QM VALVE-PRESSURE HOLDING 640 28-16-43
** ON A/C NOT FOR ALL
218QM VALVE-PRESSURE HOLDING 540JB 540 28-16-43
219QM VALVE-PRESSURE HOLDING 640JB 640 28-16-43
** ON A/C NOT FOR ALL
222QM CHECK VALVE 540 28-16-42
223QM CHECK VALVE 640 28-16-42
224QM CHECK VALVE 540 28-16-42
225QM CHECK VALVE 640 28-16-42
** ON A/C NOT FOR ALL
222QM CHECK VALVE 540AB 540 28-16-42
223QM CHECK VALVE 640AB 640 28-16-42
224QM CHECK VALVE 540AB 540 28-16-42
225QM CHECK VALVE 640AB 640 28-16-42
** ON A/C NOT FOR ALL
124QM VALVE-PRESSURE HOLDING, L WING TANK 540 28-16-41
125QM VALVE-PRESSURE HOLDING, R WING TANK 640 28-16-41
** ON A/C NOT FOR ALL
3. System Description
The recirculation system has (for each engine):
  • a recirculation pipe
  • a cooling fuel pipe
  • a piccolo tube
  • three recirculation check-valves 222QM(223QM), 224QM(225QM), 122QM(123QM)
  • a recirculation pressure-holding valve 218QM(219QM).

The recirculation system has (for each engine):
  • a recirculation pipe
  • a recirculation check-valve 122QM(123QM)
  • a recirculation pressure-holding valve 124QM(125QM).

The recirculation pipe connects to the FRV (Ref. AMM D/O 73-10-00-00) and the inboard face of RIB16 in the wing tank. Two holes at the end of the recirculation pipe let the fuel go into the wing tank. The piccolo tube is attached to the end of the recirculation pipe. The piccolo tube has six holes that let the fuel go into the wing tank.

The recirculation pipe is between the FRV (Ref. AMM D/O 73-10-00-00) and the pressure holding valve at the outboard face of RIB17 in the wing tank. Two holes, one each side of RIB16, let the warm fuel go into the wing tank outer cell.

The cooling fuel pipe attaches to the recirculation pipe at the outboard face of RIB15. The main fuel pumps (Ref. AMM D/O 28-21-00-00) move the fuel (at an ambient temperature) through the cooling fuel pipe to the recirculation pipe.
F Check Valve 122QM(123QM) - Location and Detail
The recirculation check valve 122QM(123QM) is attached (through a mounting block and an insulating block) to the lower surface of the wing bottom skin in the engine pylon. It connects the recirculation pipe from the engine to the recirculation pipe in the wing. When the recirculation system is not in operation, it closes to prevent a fuel flow from the wing tank to the engine.

F Check Valve 222QM(223QM), 224QM(225QM) - Location ** ON A/C NOT FOR ALL
The recirculation check valves 222QM(223QM), 224QM(225QM) are in a manifold that is attached to the inboard face of RIB2. When the related fuel pump is not in operation, they close to prevent a fuel flow from the recirculation system to the main fuel pumps.

F Pressure Holding Valve 218QM(219QM) ** ON A/C NOT FOR ALL
The pressure holding valve 218QM(219QM) is in an adapter that attaches to the inboard face of RIB15. When the recirculation system is in operation, the pressure holding valve keeps a pressure of 1.07 bar (15.5 psi) in the recirculation pipe. This pressure makes sure that the warm fuel in the recirculation pipe does not boil.

F Pressure Holding Valve 124QM(125QM) ** ON A/C NOT FOR ALL
The pressure holding valve 124QM(125QM) is on an adapter that attaches to the outboard face of RIB17. When the recirculation system is in operation, the pressure holding valve keeps a pressure of 1.07 bar (15.5 psi) in the recirculation pipe. This pressure makes sure that the warm fuel in the recirculation pipe does not boil.

** ON A/C NOT FOR ALL
4. Power Supply
Not applicable
** ON A/C NOT FOR ALL
5. Interface
F Recirculation System - Interfaces ** ON A/C NOT FOR ALL
F Recirculation System - Interfaces ** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
6. Component Description
A. Recirculation Check Valve FIN: 122-QM FIN: 123-QM FIN: 222-QM FIN: 223-QM FIN: 224-QM FIN: 225-QM
F Check Valve 122QM(123QM) - Location and Detail

The recirculation check valve has:
  • A valve body with a mounting flange
  • An end connection
  • A valve-plate, arm and spring.

The end connection is bolted to the valve body. An O-ring seal, between the valve body and the end connection, seals the joint. The valve-plate, arm and spring are attached to the end connection with a dowel pin.

The mounting flange attaches the valve body (through an adapter, insulating block and mounting block) to the lower surface of the wing bottom skin. An O-ring seal is installed (in a groove in the mounting flange) to prevent a fuel leak through the mounting flange. A bonding lug is attached to the mounting flange.

The valve body contains the valve-plate, arm and spring. A dowel pin connects these items to the valve body and the spring holds the valve-plate in the closed position. Inlet fuel pressure lifts the valve-plate which lets the fuel flow through the check valve. When the fuel pressure comes from the outlet direction, the valve-plate closes and prevents a fuel flow back through the check valve.
B. Recirculation Check Valve 222QM(223QM), 224QM(225QM)

F Check Valve 222QM(223QM), 224QM(225QM) - Location and Detail ** ON A/C NOT FOR ALL
The recirculation check valve has:
  • two half bodies (inlet and outlet)
  • a spindle and a special washer
  • a spring
  • a spindle guide.
The two half bodies are joined by three countersunk bolts and three nuts. An O-ring seal, between the the two half bodies, stops fuel leaks. The special washer, the spindle, the spring and the spindle guide are installed in the two half bodies to make the valve. The shank of the spindle goes through the spindle guide. The spring is installed between the spindle and the spindle guide to keep the valve in the closed position.
A flow of fuel from the main fuel pumps (Ref. AMM D/O 28-21-00-00) opens the valve against spring pressure. When the flow of fuel stops, the spring closes the valve.
C. Recirculation Pressure-Holding Valve
218QM(219QM)
F Pressure Holding Valve 218QM(219QM) ** ON A/C NOT FOR ALL

The recirculation pressure-holding valve has:
  • a valve body
  • a poppet valve
  • a screwed end
  • a spring
  • a seal.

The screwed end attaches to the valve body and is locked with a pin. This assembly contains the poppet valve, the seal and the spring. If the fuel pressure is less than 1.07 bar (15.5 psi), the spring keeps the poppet valve in the closed position against the seal.

124QM(125QM)
F Pressure Holding Valve 124QM(125QM) ** ON A/C NOT FOR ALL

The recirculation pressure-holding valve has:
  • a valve body
  • a poppet valve
  • a screwed end
  • a spring
  • a seal.

The screwed end attaches to the valve body and is locked with a pin. This assembly contains the poppet valve, the seal and the spring. If the fuel pressure is less than 1.07 bar (15.5 psi), the spring keeps the poppet valve in the closed position against the seal.

If the fuel pressure becomes larger than 1.07 bar (15.5 psi) the poppet valve lifts from the seal. This causes the pressure in the recirculation pipe to decrease to the set pressure. When this occurs, the spring moves the poppet valve to the closed position.
** ON A/C NOT FOR ALL
7. Operation/Control and Indicating
Some of the fuel supply to the engine is used to decrease the temperature of the oil in the engine and IDG. The fuel goes through the heat exchangers to the FRV. The recirculation system then moves the heated fuel along the recirculation pipe where it is joined by cold fuel from the cooling fuel pipe. The cold fuel decreases the temperature of the fuel in the recirculation pipe. The recirculation system then moves the (lower temperature) fuel into the wing tank through holes at the end of the recirculation pipe and the piccolo tube.

Some of the fuel supply to the engine is used to decrease the temperature of the oil in the engine and IDG. The fuel goes through the heat exchangers to the FRV. The recirculation system then moves the heated fuel along the recirculation pipe and into the wing tank outer cell. The pressure holding valve keeps the fuel in the recirculation pipe to a specified pressure, thus the fuel does not boil.
The control of the recirculation system operation is fully automatic. Level and temperature sensors (Ref. AMM D/O 28-46-00-00) in each wing tank send the fuel data to the FLSS (Ref. AMM D/O 28-46-00-00). The FLSS includes two computers:
  • the Fuel Level-Sensing Control Unit 1 (FLSCU1)
  • the Fuel Level-Sensing Control Unit 2 (FLSCU2).

The control of the recirculation system operation is fully automatic. Level and temperature sensors (Ref. AMM D/O 28-46-00-00) in each wing tank send the fuel data to the FLSCUs (Ref. AMM D/O 28-46-00-00). The FLSS includes two computers:
  • the Fuel Level-Sensing Control Unit 1 (FLSCU1)
  • the Fuel Level-Sensing Control Unit 2 (FLSCU2).

The fuel data from the LH wing goes to the FLSCU1, while the fuel data from the RH wing goes to the FLSCU2. Thus the FLSCU1 (together with the No. 1 engine FADEC) (Ref. AMM D/O 73-20-00-00) controls the recirculation system in the LH wing. The FLSCU2 (together with the No. 2 engine FADEC) controls the recirculation system in the RH wing.

Each FRV controls the fuel flow from the engine fuel-distribution system (Ref. AMM D/O 73-10-00-00) to the recirculation system. It will only open when the related FADEC sends an open signal.

The FLSCU1 or FLSCU2 sends a signal to close the related FRV (through the FADEC) if one of these conditions occur:
  • the fuel temperature sensor in the wing tank sends a high fuel temperature signal ( 52.5 deg.C (126.5 deg.F) approximately)
  • low fuel pump pressure occurs on that side of the aircraft (Ref. AMM D/O 28-21-00-00) (that is gravity fuel supply is in operation with the crossfeed valve closed)
  • low fuel pump pressure occurs on two sides of the aircraft (that is gravity fuel supply is in operation with the crossfeed valve open)
  • the surge-tank overflow sensor becomes 'wet'
  • the IDG shut-off valve sensor becomes 'dry' (wing tank fuel-contents decreases to 280 kg (617 lb)).

The FLSCU1 or FLSCU2 sends a signal to close the related FRV (through the FADEC) if one of these conditions occur:
  • the fuel temperature sensor in the wing tank inner cell sends a high fuel temperature signal ( 52.5 deg.C (126.50 deg.F) approximately)
  • the fuel temperature sensor in the wing tank outer cell sends a high fuel temperature signal ( 55 deg.C (131.00 deg.F) approximately)
  • low fuel pump pressure occurs on that side of the aircraft (Ref. AMM D/O 28-21-00-00) (that is gravity fuel supply is in operation with the crossfeed valve closed)
  • low fuel pump pressure occurs on two sides of the aircraft (that is gravity fuel supply is in operation with the crossfeed valve open)
  • the surge-tank overflow sensor becomes 'wet'
  • the sensor 38QJ1 or 38QJ2 becomes 'dry' (wing tank fuel-contents decreases to 280 kg (617 lb)).

The FADEC closes its related FRV if the IDG oil temperature is not between certain limits (Ref. AMM D/O 73-20-00-00).
A. Cockpit Indications

The temperature of the fuel in the wing tanks is given on the ECAM System Display (SD) FUEL page.
Fuel temperature warnings are given on the Engine/Warning Display (EWD) (Ref. AMM D/O 31-66-00-00).

The temperature of the fuel in the wing tank inner and outer cell is given on the ECAM System Display (SD) FUEL page.
Fuel temperature warnings are given on the Engine/Warning Display (EWD) (Ref. AMM D/O 31-66-00-00).
** ON A/C NOT FOR ALL
8. BITE Test
Not applicable
[Rev.10 from 2021] 2026.04.02 07:01:11 UTC
"WTRUIB" 2025