DOC AIRBUS | AMM A320FWING CENTER TANK EXTERNAL VENTILATING SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
The center tank external venting system:
** ON A/C NOT FOR ALL The center tank external venting system:
- has a vapor seal membrane that seals the bottom of the center tank from the air conditioning compartment (ZONE 191/192)
- lets a flow of air to go through the space between the membrane and the bottom of the center tank to air through the drain mast
- lets fuel drain to air through the drain mast.
2. Component Location
** ON A/C NOT FOR ALL 
Center Tank - Vapor Seal Area Venting| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 500QM | MONITOR-LEAK | 195AB | 195 | 28-13-44 | |
| ** ON A/C NOT FOR ALL | |||||
| 500QM | MONITOR-LEAK | 195 | 28-13-44 | ||
3. System Description
The system has:
Pressurized air from the air conditioning system flows through the space between the vapor seal and the center tank. A continuous flow of air is caused by the difference of air pressure (of the air conditioning system) and the ambient air pressure.
A system of drains at the rear of the vapor seal move the drainage and ventilating (exhaust) air through a drain mast. A leak monitor in the drain line keeps a small quantity of drainage for fuel leak analysis.
** ON A/C NOT FOR ALL The system has:
- a vapor seal
- a ventilating air supply pipeline
- a drainage line.
Pressurized air from the air conditioning system flows through the space between the vapor seal and the center tank. A continuous flow of air is caused by the difference of air pressure (of the air conditioning system) and the ambient air pressure.
A system of drains at the rear of the vapor seal move the drainage and ventilating (exhaust) air through a drain mast. A leak monitor in the drain line keeps a small quantity of drainage for fuel leak analysis.
4. Component Description
Vapor Seal
The vapor seal membrane is a sheet of composite material (Nomex fabric with Viton rubber) attached to 'Z' members on the underside of the tank with aluminum clamp strips and bolts.
Formed aluminum edge strips, seal the membrane to the perimeter of the tank. Aluminum fittings are used where the ventilating air supply pipe and the manual magnetic indicator (Ref. AMM D/O 28-43-00-00) pass through the membrane.
Leak Monitor
The leak monitor has a spur pipe that connects to the drain line between the center box and drain mast. A manually operated check valve is installed on the end of the spur pipe. The check valve lets a sample of the drainage to be taken to show if there is any fuel leakage from the root-ribs of the wing tank. The valve is operated to release the fuel by depressing the valve piston. This lifts the check valve and lets the fluid flow through the outer valve assembly.
Drain Mast
The drain mast is an aluminum fairing bolted to the underside of the fuselage. The vapor seal drainpipe and the belly fairing drain to atmosphere through the drain mast.
** ON A/C NOT FOR ALL Vapor Seal
The vapor seal membrane is a sheet of composite material (Nomex fabric with Viton rubber) attached to 'Z' members on the underside of the tank with aluminum clamp strips and bolts.
Formed aluminum edge strips, seal the membrane to the perimeter of the tank. Aluminum fittings are used where the ventilating air supply pipe and the manual magnetic indicator (Ref. AMM D/O 28-43-00-00) pass through the membrane.
Leak Monitor
The leak monitor has a spur pipe that connects to the drain line between the center box and drain mast. A manually operated check valve is installed on the end of the spur pipe. The check valve lets a sample of the drainage to be taken to show if there is any fuel leakage from the root-ribs of the wing tank. The valve is operated to release the fuel by depressing the valve piston. This lifts the check valve and lets the fluid flow through the outer valve assembly.
Drain Mast
The drain mast is an aluminum fairing bolted to the underside of the fuselage. The vapor seal drainpipe and the belly fairing drain to atmosphere through the drain mast.
5. Operation/Control and Indicating
The operation of the wing center tank external ventilating system is fully automatic. There is no control of the system and the system gives no indications.
The operation of the wing center tank external ventilating system is fully automatic. There is no control of the system and the system gives no indications.