A Maintenance Oriented Podcast For Airplane Owners, Pilots, and Mechanics

014 – Do You Have a Bad Mag? How to Know For Sure.

 

February 19, 2016

For an airplane owner, magneto checks are one of the most important items to be done during the preflight runup.

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But what is the best way to interpret a rough mag?  Are you maximizing the information that is being presented to you on your instrument panel?

In today’s episode, I will share with you an experience I had last week on a Piper Cherokee Six, and what we did to resolve it.  I’ll also share another story from this week, from a Piper Cherokee 140, and what we’re doing with that one.  (Both of these stories involve ignition system troubleshooting.

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Here is the green corrosion in the tower of the magneto;  this is what prevented the #6 bottom spark plug from firing.  (This was on the Cherokee Six.)

 

 

First, here are some tips for troubleshooting a rough magneto, starting with the simple things first.

Perform a thorough ground run and gather as much information as possible.

Remove the engine cowling and do a quick visual inspection of the ignition system.

Remove and check the affected spark plug or plugs.Test the affected ignition leads.

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If the lead is working properly, you will see a strong spark in the small window above the button that says “Push to Test.”

 

Check mag to engine timing and P-lead condition for further information.

Repair or change the magneto.

Keep in mind that the first 3 items on this list, you can perform as an airplane owner or operator, as preventive maintenance, and sign off yourself in your maintenance records.

AND, the more familiar you are with this whole process, the better prepared you will be to communicate with your mechanic when you need assistance.

Listen to the audio and get much more information than you see here.

And please… leave me a comment below if you found this helpful, and also give me your requests for any future episodes.

Thanks!

4 Comments

  1. Ashley Blythe

    Dean,

    Thank you for the mention on your show. Listening to it now.

    I think there’s a very good chance I’ll be a Piper owner soon and one thing you mentioned early in the podcast was soft brakes on a Piper. I have heard that this is a common problem. Would you talk more about that I’m a future episode?

    • Dean Showalter

      Thanks Ashley! Great to hear from you again. That is an excellent idea to discuss Piper brakes… I will definitely put that topic on my list for a future episode. After all these years, I learned a new technique last week for checking these airplane brake systems, so I will plan on sharing that when I do that episode.

  2. Allen

    Hi Dean, Great Podcast, very informative, but I have a challenge for you. My parents had to make an emergency landing last night. My father explained they lost power on 1 and 6 like switch. Both of us have piloting experience, he has been an IFR pilot for decades and owned the plane since the early 80s. No oil or other indication of a mechanical problem. We are perplexed at this time. Feel free to reach out via email if you’d like more info or make a guess at what they are going to find.

    • Dean Showalter

      Thanks Allen… I’ll send you an email and check in. You’ve got me curious about that engine now.

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