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3 Answers

Alternator fail

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Student Pilot

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

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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.

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  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.

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  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!

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