Airbus A330/A340 Inert Gas System (ATA 47)

Airbus A330/A340 (all Series) Inert Gas System (ATA 47)

• The document outlines the Inert Gas System for the Airbus A330 and A340 series aircraft, as per EASA Part-66 B1/B2 standards.
• Revision ID: 1, last updated June 03, 2013.

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General Overview of the Inert Gas System

• Decreases the quantity of oxygen in the air contained in the fuel tanks.
• Consists of the Inert Gas Generation System (IGGS), the Conditioned Service Air System (CSAS), and maintenance/test facilities.

FTIS Interfaces

• Fuel Systems
• Engine bleed air supply system
• Environmental Control Systems (ECS)
• Central Maintenance Computer (CMC) / ECAM

Fuel Tank Flammability Prevention

• Fuel tank flammability requires fuel vapor, an ignition source, and oxygen.
• The system decreases the rate of oxygen in the center tank to prevent flammability.

Function of the Fuel Tank Interting System

• Decrease flammability by decreasing oxygen

System Layout

• The Fuel Tank Inerting System (FTIS) has two sub-systems: the Conditioned Service Air System (CSAS) and the Inert Gas Generation System (IGGS).
• The CSAS cools hot air from the bleed air system to a level suitable for the IGGS.
• The IGGS filters conditioned air to produce Nitrogen Enriched Air (NEA) and Oxygen Enriched Air (OEA).
• The OEA is vented overboard.
• A Dual Flow Shut Off Valve (DFSOV) controls the NEA flow to the center tank and can isolate the IGGS.
• The Inert gas generation system Controller Unit (ICU) controls the system and has health-monitoring BITE functions.
• The Gate valve is a solenoid valve that is spring-loaded closed which allows air to flow between the CSAS and the IGGS and closes shut in the event of low pressure
• The CSAS Controller Unit (CCU) controls the system, has health-monitoring BITE functions, and interfaces with the FWS and the CMC

Control and BITE

• ICU sends/receives data to/from the CCU.
• The two controllers monitor the operational conditions independently.
• The CSAS receives temperature information and adjusts the temperature, if necessary.
• The Central Maintenance Computer (CMC) provides ICU test functions through the MCDU in the cockpit.
• The ICU also possesses BITE functions for the CCU.

Generation/Storage System Operation

• FTIS serves as a Flammability Reduction Means to lower the risk of fire and explosion in the fuel center tank by creating inert conditions using 78% nitrogen
• Oxygen concentration is maintained below 12% from sea level to 3048 m, between 12% and 14.5% from 3048 m to 12192 m, and decreases linearly above 12192 m.

FTIS Operations under these Conditions:

• Bleed air availability from ENG 1, ENG 2 (or A340 ENG 1&2, ENG 3&4), or all engines
• Weight On Wheels (WOW) is not sensed: NLG is not compressed
• Environmental Control System (ECS) in operation
• IGGS Latch status is not latched
• Air stream temperature into the IGGS is below 47°C (116.60°F)
• Absence of ENG 1 (or A340 ENG 1&2) FIRE condition

NEA Modes

• Low Flow, during climb and cruise, featuring the lowest oxygen and highest nitrogen levels in the fuel tank
• Mid Flow, during approach, maintains bleed air during slow descent
• High Flow, during normal descent, balances higher ambient air oxygen levels entering the fuel tank via the vent system

Sub-systems of FTIS

• Conditioned Service Air System (CSAS)
• Inert Gas Generation System (IGGS)

CSAS Function

• Supplies IGGS air at proper temperature, pressure and flow

IGGS Functions

• Removes OEA from airflow.
• The CSAS Controller Unit (CCU) and the IGGS Controller Unit (ICU) control FTIS automatically; the aircraft crew does not operate it.

Conditioned Service Air System (CSAS)

• The Conditioned service air system Controller Unit (CCU) does the system control and health monitoring BITE and has interfaces with the aircraft computers (FWS, CMS, SDAC) and system (ENG1 Fire Push−button).(A340 ENG1&2 Fire Push−button)
• The CSAS isolation valve gives protection to the system if the pressure is too low or too high or if the temperature is too high.

CSAS Components overview

• Isolation Valve: A solenoid that controls airflow to the TCM that closes when there is no bleed air pressure or electrical power
• Ozone Converter: Is installed between the CSAS Isolation Valve and the Heat Exchanger that protects the Air Separation Module (ASM) fibers.
• Temperature and Pressure Control

CSAS Heat Exchanger

• Temperature and air temperature is controlled by the Temperature Control Module (TCM), which has:a CSAS heat exchanger,
• The CSAS heat exchanger is installed in the ram air channel, upstream of the Pack 1 heat exchanger.

Hot air Bypass valve

• Adds hot air to the cold air after the heat exchanger to adjust tmperature

Temperture Sensor:

• A dual sensor monitors the temperature of the conditioned air before it flows to the Inert Gas Generation System
• This is transmitted to the CSAS Controller

Pressure Sensor

• A pressure sensor monitors conditioned air pressure in the duct before it flows to the Inert Gas Generation System.
• This is between the temperature sensor and inlet of the intert gas gen system

Maintenance Practices

• The CSAS isolation valve closes if pressure or temperature becomes too high.
• Interactive BITE test modes include system test without bleed air (checks electrical integrity) and system test with bleed air (checks electrical integrity and valve behavior).

Inert Gas Generation System (IGGS)

• The IGGS Controller Unit (ICU) supplies system health monitoring and BITE, and uses an ARINC 429 bus for its communications.
• The Double−Ultra Low Particle Air (D−ULPA) Filter cleans the air.
• The IGDS Components: an Isolation Gate Valve (IGV), a Dual Flow and Shut−Off Valve (DFSOV), a Dual−Flapper Check Valve, and an In−Tank Housing.
• Two Air Seperation Modules

D-ULPA Filter

• This is used to send airflow paramters to the ICU
• Is downstream of the D−ULPA filter, a temperature sensor T2 and pressure sensor P2

Air Separation Module (ASM)

• Used for preventing pressure build up in inter tank
• The IGGS Pallet has 2 ASMs (3 ASMs on A340−500/600)
• ASM intake temperature is 60 degrees celcius at 20-60 psi, and if ever overheat, the threshold is 85 degrees celcius

Function of the Oxygen Sensor

• The Oxygen sensor provides this to the ICU, who then asses the FTIS general preformance

DFSOV Purpose:

• Uses two poppets to control the appropiate NEA flow to the fuel tank

IGGS Contoller Unit

• The ICU uses a ARINC signal for communication
• Monitors the health of the IGGS Equipment
• Can set Nitrogen Enrich Air
• CAN send IGGS condition report to CSAS
• Can give all BITE test

FTIS Normal Functionality

• Requires bleed air from the correct enginer
• WOW not sensed, and Environmental Control Systems (ECS) in operation: Flow Control Valve 1 (FCV) is not Fully Closed, or FCV 2 is not Fully Closed and Cross Bleed Valve is open. The IGGS Latch status is not latched Air flow that goes into the IGGS must be less than 47°C (116.60 °F)
• No fuel fire or overheat

FTIS Abnomral Functionality

• When ICU senses a fault, that signal will transmit to (FWC1 and FWC2) then sent towards (FWC1 and FWC2 by the CCU
• If the O2 sensore is higher than 12%, this will shut down or deactivate the FTIS, and deenergize.

Maintaining Functionality

• do a system test without bleed air,
• do a system test with bleed air,
• get troubleshooting data,
• get fault reports.