To: (Separate email addresses with commas)
From: (Your email address)
Message: (Optional)
Send
Cancel

Thanks!

Close

Quiz: 6 Questions To See How Much You Know About Turbofan Engine Start Sequences

This story was made in partnership with Republic Airways. Check out the full series here. Ready to apply for a pilot slot? Submit your application here.
Live from the Flight Deck

It's not as simple as a quick crank of the engine to get a turbine started...


  1. 1) The first step in starting a jet engine is using a bleed source to turn an air turbine starter, which rotates the N2 shaft. Where can this bleed source come from?

    Bleed sources normally come from the APU, however, in the event the APU is inoperative, you can start the rotation of the N2 shaft using a "Huffer" or high-pressure cart and/or crossbleed from another engine.

    Bleed sources normally come from the APU, however, in the event the APU is inoperative, you can start the rotation of the N2 shaft using a "Huffer" or high-pressure cart and/or crossbleed from another engine.

  2. 2) Bleed air is ducted to the air turbine starter, which in turn rotates the N2 shaft. Where is the air turbine starter located?

    It's attached to the accessory gearbox.

    It's attached to the accessory gearbox.

  3. 3) When and where is fuel normally introduced during start?

    Fuel is introduced in the combustion section and is normally introduced when N2 reaches about 20%.

    Fuel is introduced in the combustion section and is normally introduced when N2 reaches about 20%.

  4. 4) When does the starter cut-out?

    Starter cut-out occurs when the engine has reached a point at which it is self-sustaining and no longer requires the assistance of the air turbine starter. This usually occurs at 50% N2.

    Starter cut-out occurs when the engine has reached a point at which it is self-sustaining and no longer requires the assistance of the air turbine starter. This usually occurs at 50% N2.

  5. 5) You are monitoring the engine during its start sequence and you notice that the engine isn't accelerating as it should. What is this called and what should be done?

    This is called a hung start and is indicated by a slow acceleration of the engine during startup. N1 and N2 values will lag and EGT will reach an abnormally low temperature. This is usually caused by a faulty starter which prevents the engine from reaching an appropriate rotational speed during the start sequence. Once discovered, the engine should be shut down.

    This is called a hung start and is indicated by a slow acceleration of the engine during startup. N1 and N2 values will lag and EGT will reach an abnormally low temperature. This is usually caused by a faulty starter which prevents the engine from reaching an appropriate rotational speed during the start sequence. Once discovered, the engine should be shut down.

  6. 6) How will you know when the engine is fully started and at ground idle (approximately)?

    On most engines, the simple answer is when all engine parameters have stabilized. On turbofan engines, this will usually occur when N2 has reached 20%, inlet turbine temperature (ITT) is roughly 400 degrees Celsius and N2 has reached 60%.

    On most engines, the simple answer is when all engine parameters have stabilized. On turbofan engines, this will usually occur when N2 has reached 20%, inlet turbine temperature (ITT) is roughly 400 degrees Celsius and N2 has reached 60%.

That was rough...

You scored %. Better luck next time.

Share on Facebook Share on Twitter
Pic

Better luck next time...

You scored %. Keep at it and you'll be starting turbine engines like a pro.

Share on Facebook Share on Twitter
Pic

Someone studies!

You scored %. Nice work.

Share on Facebook Share on Twitter
Pic

Ready to start your airline career? Want to fly an E-170/175? Get started and apply to Republic Airways today.


Corey Komarec

Corey is an Airbus 320 First Officer for a U.S. Major Carrier. He graduated as an aviation major from the University of North Dakota, and he's been flying since he was 16. You can reach him at corey@boldmethod.com.

Images Courtesy:

Recommended Stories

Latest Stories

    Load More
    Share on Facebook Share on Twitter Share via Email