Diagnosing your magneto


Magneto Issues can be daunting. I will talk about how to narrow down the problems and then get to a fix with the help for your A&P. I am not a mechanic and these guidelines for your reference and understanding only.

So you have a mag problem? Or may be you just want to be careful and get them updatedoverhauled any ways.

When to overhaul mags?

Generally, every 500 hours. You want to have them overhauled and looked over. This is generally true for all types of magnetos.

What types of magnetos are there?

Mostly Bendix and Slick. I am sure there are more types. I just have not done the research. Bendix is the older, heavier kind.

You can find the advocates for both of them. Slick used to sell a kit to upgrade from Bendix at a very reasonable price. That is not true anymore. So Price wise, there is very less differential from going one route or the other. More then likely if you have slick, you would want to stick with it or the other way around.

Bendix has some hard core fans and is a very reliable system. People who use slick swear by them.

How to diagnose?

The process is generally very simple.
1. Make sure you do a mag check.
2. If 1 is okay you are likely good.
3. If 1 is not okay. Remove and inspect your spark plugs. You want to make sure that they are all okay. By okay; I mean clean and gapped properly. This is a simple thing to do that an owner is allowed to do.
4. Most people would also recomend that you do an inflight mag check (if possible). That also helps isolate if the mags are working as they should.
5. If we are still running into trouble; have an A&P check your mag timing per the engine specification. If the timing is okay then you have ruled out another potential problem.
6. While you are checking the timing; also check the p-leads and other wires. Turning the engine off and turning back on would also rule out any grounded wires etc.
7. If you are still troubleshooting then you are likely running into a mag issue. I would recomend overhauling both magnetos at the same time. There are many places to get the mag overhauled. Quality Aircraft service in OK is one of them I believe.

You can also get exchange units from aircraft spruce and chief aircraft (some time even at a good price). In my case; the exchange unit was cheaper then the cost of the overhaul.

Hope that this helps! Let me know if you have questions and any feedback.