February 19, 2016

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


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.




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.








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.