Welcome Guest. Sign in or Signup

3 Answers

Alternator fail

Asked by: 8913 views , , , ,
Student Pilot

im in a cessna 172, if the alternator failed, would the engine still run? is it fuel injected?

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

3 Answers

  1. Best Answer


    Wes Beard on Aug 22, 2013

    Yes. If the alternator and battery both failed the engine would still run. There are two magnetos installed as accessories to the engine. These magnetos are basically DC generators whose only job is to supply power to the spark plugs. They are typically connected to one spark plug for each cylinder so if one magneto fails the cylinder is lost. There are two spark plugs per cylinder.

    The way the engine starts is the starter turns the engine shaft, which is directly connected to the propeller. As the engine shaft rotates, the magnetos begin to create electricity and power is available to the spark plugs.

    Fuel gets to the engine through gravity and a carburetor.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes



  2. Mark Kolber on Aug 23, 2013

    I once had a student who just refused to believe it. So, during a lesson, I shut down all the electrical equipment, including the master switch.

    To answer the other part of the question, whether your 172 is carbureted or fuel injected depends on the model year. Look at the POH.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes



  3. Adam Broun on Sep 19, 2013

    ..and they do fail!

    As Wes said, your engine will be just fine. But now all your electrical systems (GPS, radios, lights, turn coordinator) will be running off the battery, so you should think about getting on the ground before the power runs out, as well as shedding/saving power..know your systems, know what you can shut off, and know your options!

    0 Votes Thumb up 0 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.