Understanding the A320 Engine System
Before diving into the manual engine start procedure, it's critical to understand the A320's engine system, which includes the engines, fuel system, and electrical systems.
Engine Overview
The Airbus A320 typically features either CFM56 or IAE V2500 engines. Both engine types are high-bypass turbofan engines known for their efficiency and reliability. Key components include:
- Fan: Provides the majority of thrust.
- Compressor: Compresses the incoming air.
- Combustor: Mixes fuel with compressed air for combustion.
- Turbine: Extracts energy from combustion gases to drive the compressor.
Importance of Manual Engine Start
Although the A320 is equipped with automatic systems for engine start, manual engine start capabilities are crucial for several reasons:
1. Emergency Situations: In case of a malfunction in the automatic start system, manual procedures ensure the pilot can still start the engines safely.
2. Training: Pilots must be proficient in manual procedures for certification and to maintain flying skills.
3. Operational Flexibility: In certain situations, such as extreme weather or unusual ground conditions, a manual start may be more effective.
Pre-Start Checks
Prior to initiating a manual engine start, several pre-start checks must be performed to ensure the aircraft is ready for the procedure.
Cockpit Preparation
- Ensure the aircraft is powered: Verify that the electrical systems are operational, either through APU or ground power.
- Flight Control Check: Confirm that the flight control surfaces are functioning correctly.
- Fuel Quantity Check: Ensure there is adequate fuel in the tanks for the intended flight.
- Fuel System Configuration: Set the fuel system to the appropriate configuration, usually to “AUTO” for normal operations.
System Configuration
1. Bleed Air Settings:
- Ensure that the APU bleed air is set to "ON" if using the APU for start.
- If using ground air supply, confirm the connection and settings.
2. Engine Mode Selector:
- Confirm that the engine mode selector is set to "IGN/START."
3. Throttle Position:
- Ensure the thrust levers are in the idle position.
Manual Engine Start Procedure
The manual engine start procedure can be broken down into specific steps that pilots must follow to ensure a successful engine start.
Step-by-Step Instructions
1. Select the Engine to Start:
- Determine which engine to start first (typically, the left engine).
2. Check the Start Sequence:
- Confirm that the engine start sequence is correct and safe to initiate.
3. Engage the Start Switch:
- Push the engine start button for the selected engine (ENG 1 or ENG 2).
4. Monitor Engine Parameters:
- Watch for indications on the ECAM (Electronic Centralized Aircraft Monitor), particularly:
- N2 (high-pressure rotor speed)
- Fuel flow
- Ignition status
- EGT (Exhaust Gas Temperature)
5. Start Sequence Monitoring:
- As N2 rises, the pilot should ensure that the fuel flow begins at the appropriate N2 percentage (usually around 25% for the A320).
- Observe the EGT; it should rise steadily as fuel is introduced.
6. Verify Engine Stabilization:
- Once the engine starts, monitor:
- N1 (low-pressure rotor speed)
- Oil pressure
- Engine vibrations
- Ensure that the engine stabilizes at idle speed.
7. Start the Second Engine:
- Repeat the above steps for the second engine, ensuring all parameters are within normal operating ranges.
Post-Start Checks
After both engines have successfully started, pilots should carry out several checks:
- Engine Parameters: Confirm that both engines are operating within normal limits.
- Bleed Air Configuration: Adjust bleed air settings as necessary for cabin pressurization and environmental control.
- APU Shut Down (if used): If the APU was utilized for starting, it can be shut down once the engines are stable.
Common Issues During Manual Engine Start
During the manual engine start procedure, pilots may encounter various issues. Understanding these problems and how to address them is crucial for ensuring safety and efficiency.
Possible Malfunctions
1. No Start:
- If the engine does not start, it may be due to:
- Insufficient fuel
- Electrical failure
- Bleed air issues
2. Hung Start:
- An engine may reach a certain RPM but fail to start fully. In this case:
- Confirm fuel flow and ignition.
- If the engine does not stabilize, initiate a shutdown and follow the appropriate emergency procedures.
3. Hot Start:
- If EGT rises rapidly and exceeds limits:
- Shut down the engine using the start switch.
- Allow the engine to cool before attempting another start.
Best Practices for Manual Engine Start
To enhance the effectiveness and safety of the manual engine start procedure, pilots should adhere to several best practices:
Training and Simulation
- Regular Training: Engage in recurrent training that includes manual engine start scenarios.
- Simulator Sessions: Utilize flight simulators to practice engine starts under various conditions.
Checklists and Procedures
- Follow Checklists: Always utilize the checklist for manual engine starts to ensure no critical steps are missed.
- Communication: Maintain clear communication among crew members during the start procedure.
Stay Calm and Focused
- Stay Calm: In case of issues during the start, remain calm and methodically address the situation.
- Prioritize Safety: Always prioritize safety over speed; if unsure, follow emergency procedures.
Conclusion
The A320 manual engine start procedure is a vital skill for pilots, ensuring they can confidently handle engine starts under various circumstances. By understanding the aircraft’s systems, adhering to pre-start checks, following the step-by-step manual start procedure, and being prepared for potential issues, pilots can enhance both their operational effectiveness and safety in the cockpit. Mastery of these procedures not only contributes to a successful flight but also fosters greater confidence in handling the complexities of modern aviation.
Frequently Asked Questions
What are the initial steps for a manual engine start on an A320?
The initial steps include ensuring the aircraft is properly configured with the parking brake set, fuel valves open, and the thrust levers in the idle position. Then, the external power must be connected or the APU started.
How do you engage the engine start sequence manually on an A320?
To engage the engine start sequence manually, you must turn the engine start switch to 'IGN' and then to 'START'. Monitor the N2 RPM and ensure it increases to the required threshold for ignition.
What indications should you look for during the manual engine start procedure?
During the manual engine start procedure, you should monitor the N2 RPM, EGT (Exhaust Gas Temperature), and fuel flow. Look for a successful N2 rise and a stable EGT after the ignition occurs.
What do you do if the engine fails to start during a manual engine start?
If the engine fails to start, you should first confirm that all pre-start checks are complete. If the N2 does not rise after 30 seconds, discontinue the start attempt, turn the engine start switch to 'OFF', and wait for a cooldown period before attempting again.
Are there any specific considerations for starting the A320 engines in cold weather?
In cold weather, it's important to ensure the engine is properly preconditioned if necessary, as low temperatures can affect fuel flow and ignition. Also, follow the manufacturer’s guidelines for engine start procedures in cold conditions.
