A320Q

Inside the A320 engine

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Fan + LP compressor
Fan + 4 stagesFan + 3 stages
HP compressor
9 stages10 stages
HP turbine
1 stage2 stages
LP turbine
4 stages7 stages
Thrust reverser
4 pivoting doorsTranslating sleeves
Auto-start ignition
On 16%, off 50% N2On ~20%, off 55% N2

A simplified model of the CFM56-5BLEAP-1A, drawn for revision. Stage counts and systems follow the A320 flight crew documentation; shapes and proportions are illustrative. Some A320 family operators use IAE V2500 or PW1100G engines instead.

Part by part

What each part of the A320 engine does

The fan divides the incoming air into two streams. Most air bypasses the core and provides most of the thrust. Core air passes through the LP and HP compressors, mixes with fuel in the combustion chamber, and expands through the HP and LP turbines. The LP spool (N1) and HP spool (N2) turn independently.

  1. Air inlet cowl

    Guides air smoothly into the fan. With engine anti-ice on, hot air bled from the HP compressor heats the inlet, and FADEC adjusts the thrust limit and idle to suit.

  2. Spinner

    The cone at the centre of the fan. It turns with the fan on the LP shaft.

  3. Fan

    The front of the LP compressor, driven by the LP turbine. Most of the air it moves flows around the core and provides most of the thrust. Fan speed is N1, which FADEC uses to set thrust.

  4. Fan case and cowls

    Surrounds the fan and forms the outside of the bypass duct. The FADEC computer is mounted on the fan case.

  5. Thrust reverser

    On the CFM56-5B, four pivoting blocker doors swing into the fan airstream and deflect it forward. A hydraulic jack moves each door: green system on engine 1, yellow on engine 2. FADEC controls and monitors the system.

    On the LEAP-1A, translating sleeves slide aft and blocker doors turn the fan airflow forward through cascades. Green hydraulics power engine 1 and yellow engine 2; deployment takes about 2 seconds under FADEC control.

  6. LP compressor (booster)

    FourThree compressor stages behind the fan, on the LP shaft. They further compress the core stream before it reaches the HP compressor.

  7. HP compressor

    NineTen stages compress the core air. Its speed is N2. Bleed air for the aircraft is normally taken from an intermediate stage, switching to a high-pressure stage at low engine speed.

  8. Combustion chamber

    An annular chamber, between the HP compressor and HP turbine, with fuel nozzles and two igniters. FADEC sets the fuel/air mixture from thrust lever position and flight conditions.

  9. Igniters

    Two igniters on two independent circuits, normally controlled by FADEC channels A and B. In an automatic ground start, ignition comes on at 16% N2 and cuts off at 50% N2about 20% N2 and cuts off at 55% N2.

  10. HP turbine

    The HP turbine has one stagetwo stages. It drives the HP compressor through the HP shaft.

    FADEC controls HP compressor bleed air to cool the HP turbine case and control blade-tip clearance, improving performance and lowering EGT.

    FADEC controls fan air to cool the HP turbine case and control blade-tip clearance. A separate modulated cooling system uses HP compressor air to cool the HP turbine blades.

  11. LP turbine

    FourSeven stages that drive the fan and LP compressor through the LP shaft.

  12. Exhaust nozzle and plug

    Core gas leaves through the nozzle, around the exhaust plug.

  13. LP and HP shafts

    Two shafts, one inside the other. The LP shaft joins the LP compressor and LP turbine; the HP shaft joins the HP compressor and HP turbine. N1 is fan speed and N2 is HP rotor speed, both shown in percent.

  14. Core casing

    Encloses the compressors, combustion chamber and turbines. The air that bypasses the core flows around it.

  15. Accessory gearbox

    Driven by the HP shaft. It drives the oil feed pump, the main fuel pump, the engine-driven hydraulic pump, the IDG and generator, and the FADEC alternator. The starter turns the engine through it.

  16. Pneumatic starter

    An air-driven starter on the accessory gearbox. During start it turns the HP rotor through the gearbox. FADEC opens and closes the start valve that supplies its air.

  17. IDG and generator

    The integrated drive turns the generator at constant speed. Each generator supplies up to 90 kVA of 115/200 V, 400 Hz AC: GEN 1 on engine 1, GEN 2 on engine 2. Fuel cools the IDG oil. Electrical practice

  18. FADEC computer

    Mounted on the fan case, with two channels: one active, one on standby. It receives power from its own alternator or the aircraft electrical network. It manages fuel, start and ignition, thrust and the thrust reversers.

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