The Airbus A320 engine start process involves a combination of automated and manual steps. Here’s a detailed breakdown:

1. Prepare for Engine Start

• Bleed Air Source:

  • The engines are started using compressed air supplied by either:

    • The APU (Auxiliary Power Unit).

    • An external pneumatic source (ground air cart) if the APU is unavailable.

• System Checks:

  • Ensure the APU is running (if used) and supplying bleed air to the pneumatic system.

  • Verify that the engine mode selector on the overhead panel is set to NORM.

• Beacon Light ON:

  • Turn on the beacon light to indicate that engines will be started.

• Parking Brake:

  • Ensure the parking brake is set.

2. Engine Start Sequence

• Select Engine Start Mode:

  • Turn the ENG MODE selector on the overhead panel to IGN/START.

  • This action opens the start valves and prepares the system for ignition.

• Initiate Start (Engine 1 or Engine 2):

  • Move the corresponding engine master switch (1 or 2) on the overhead panel to ON.

    • For a typical start, Engine 2 is started first.

• Start Valve Opens:

  • The pneumatic system sends compressed air to the engine’s air turbine starter, spinning the high-pressure compressor.

3. Monitor Engine Parameters (ECAM Display)

• N2 (Compressor RPM):

  • Ensure that N2 increases steadily. Typically, ignition occurs around 20-25% N2.

• Fuel Flow:

  • Fuel is introduced automatically when the engine master switch is turned on.

• EGT (Exhaust Gas Temperature):

  • Monitor EGT to ensure it stays within limits.

• N1 (Fan RPM):

  • N1 starts increasing as the engine spools up.

4. Engine Stabilization

• Once the engine reaches idle parameters:

  • N2 stabilizes around 60%.

  • N1 stabilizes around 20-25%.

  • EGT stabilizes within normal limits.

• The start valve closes automatically, and the pneumatic system switches off the starter.

5. Repeat for the Other Engine

• Start the second engine by following the same process.

6. Post-Start Procedures

• Return the ENG MODE selector to NORM.

• Verify that both engines are running and all parameters are stable.

• Perform system checks as per the checklist (e.g., hydraulic, electrical, and pneumatic systems).

• If the APU was used, it can be turned off after engine start.

The process is highly automated and monitored by the ECAM system, which alerts the crew in case of abnormal conditions.