Breaking in a Mag?

[201er]

Ok, so my mag has been repaired and 500 houred while we had it out anyway. Now my question is whether or not there is any need for a break in procedure? My plan is to take off, fly a tight outbound pattern, climb to altitude, and then run an LOP mag check at high power on it. Is there any reason to hold off and take it easy on the mag for any length of time?

[Fly By Night]

I've never heard of "breaking in" a Mag, but there is a lot I've never heard of.

[Andy95W]

It is prudent to keep an eye on it the first flight, but other than that just run it normally. Your plan sounds good to me- but there's a lot I don't know either.

[DonMuncy]

The repair folks should have bench tested it for proper operation before they gave it back to you, and there is no break-in required. However, shortly after I had one repaired, the points inside broke and again disabled the mag. Thank goodness we have two.

[carusoam]

Break in is a term used for devices that have tight tolerances and expect to wear quickly until the finished tolerances are obtained.

I have not heard of a magneto wearing in.

If there is a procedure of cleaning it after the first 10 or 100 hours, that would be an indication of a break in period...

My factory reman doesn't mention any special mag related items. (That I recall)

No special oil change related to it.

Sounds like a good idea to keep an eye on it after each flight to make sure it is still attached properly.

How does that sound?

I am not, and have never been, a mechanic...

Best regards,

-a-

[WardHolbrook]

How would you even "take it easy" with a mag? Only run it part time?  

 

I would not recommend doing a high power mag check LOP or otherwise. It would be way to easy to mess it up and accidentally shut the engine off and as they say in the barrio, that would be no bueno.

 

What I would personally do is just go fly the airplane - normally. But be alert for anything untowards that might manifest itself after the mechanics have been rooting around in the engine compartment.

[201er]

How would you even "take it easy" with a mag? Only run it part time?

Well, I would presume that lower RPM would equate to lower mag use per time and less heat on the mag. Not that it's necessary, but isn't this true?

[Marauder]

How was your trip this evening?

Sent from my iPad using Tapatalk

[WardHolbrook]

Well, I would presume that lower RPM would equate to lower mag use per time and less heat on the mag. Not that it's necessary, but isn't this true?

I don't know, it's like saying that lower RPMs impose less stress on the plugs and leads. Maybe so, but is it enough to make a difference? I don't see it, but your mileage may vary. Mags are 19th century technology and have been installed on aircraft pretty much since day one. They tend to either work or not and an inoperative mag is pretty self evident. Personally, if it starts and passes the mag check (appropriate drop) I would not worry about it and I would just go fly the airplane in a normal manor. If it makes you feel any better, then by all means fly those initial hours any way you want, but I don't see how you'd be doing anything worthwhile by doing anything more than what the mag manufacturer or overhauler recommends and I've never seen (or heard of) a break-in recommendation.  

[kellym]

How would you even "take it easy" with a mag? Only run it part time?

 

I would not recommend doing a high power mag check LOP or otherwise. It would be way to easy to mess it up and accidentally shut the engine off and as they say in the barrio, that would be no bueno.

 

What I would personally do is just go fly the airplane - normally. But be alert for anything untowards that might manifest itself after the mechanics have been rooting around in the engine compartment.

A high power LOP check is the only real check of a magneto. The only caution is if the engine doesn't operate well or quits on one mag, do NOT turn the key back to both without reducing throttle  and leaning mixture first. If you leave settings where they were you risk having unburned fuel in the muffler explode, with dire effects on the muffler. Having the engine cease producing power for a few seconds to allow clearing the exhaust of any fuel is no big deal. As soon as spark and fuel are resumed to normal settings the engine will produce power.

The only significant wear parts in a mag are the points and the rubbing block on the points. Neither one need break-in.

[WardHolbrook]

A high power LOP check is the only real check of a magneto. The only caution is if the engine doesn't operate well or quits on one mag, do NOT turn the key back to both without reducing throttle  and leaning mixture first. If you leave settings where they were you risk having unburned fuel in the muffler explode, with dire effects on the muffler. Having the engine cease producing power for a few seconds to allow clearing the exhaust of any fuel is no big deal. As soon as spark and fuel are resumed to normal settings the engine will produce power.

The only significant wear parts in a mag are the points and the rubbing block on the points. Neither one need break-in.

Like I said, the risk of doing damage is greater than the benefits of doing the test. If you've got an indication of a bad mag during the runup then it is warranted, but as a routine check? Not for me thank you. 

[ArtVandelay]

Like I said, the risk of doing damage is greater than the benefits of doing the test. If you've got an indication of a bad mag during the runup then it is warranted, but as a routine check? Not for me thank you. 

I agree if you do your runups LOP, the leaner the better. IF like most you do it full rich, then that is not really a good stress test.

I've only done the inflight mag test once, when I thought I might have a mag problem, I did it while I was almost directly above an airport.

[WardHolbrook]

I agree if you do your runups LOP, the leaner the better. IF like most you do it full rich, then that is not really a good stress test.

I've only done the inflight mag test once, when I thought I might have a mag problem, I did it while I was almost directly above an airport.

I love Mike Busche, seriously, I do. He brings a lot of experience to the table and gives you plenty to chew on. There is a lot that we can learn from him and others like him. But there are caveats too. 

 

Bottom line it that there's little additional to be gained and a whole lot of additional opportunity to muff something up. Beside, what's a person to do if he doesn't have GAMI injectors and a full-blown engine analyser?    Experience has taught me that the time to troubleshoot a problem (practically any problem) is on the ground, not in the air.

 

A few months back, we had a generator come apart (literally) during climb out. The resulting voltage surge took out the remaining two generators and left both electrical systems unpowered except for the batteries. The guy I was flying with is also an A&P and AI. We ran the checklists, isolated the bad generator and got the other two back online. After we told ATC we needed to return to SBA my copilot/mechanic decided it would be a good idea to run some diagnostic checks and do a little trouble shooting - "It will save Ron some time when we get back to the hangar." I had to remind the mechanic part of my copilot that we now had reestablished a safe and fully functioning electrical system save for a loss of a generator due to unknown reasons. Did he really want to poke a stick at the compromised system by playing around with it while we were in flight? He found it hard to believe that I wouldn't allow him to start flipping switches. Mechanics look at things differently, not necessarily better than pilots, just differently.

 

The question is what does the electrical system of a 3-engine business jet have to do with a mag check on a Mooney? Quite a lot actually. It's all about systems knowledge and what you're actually checking when you run your various checks. When you do your various systems checks what are you really checking and why? Granted the Falcon has a lot more (and more complex) systems, but a pilot needs to know and understand what's really happening (or should be happening) when he moves the ignition switch and cycles the prop during the engine runup. Now, if you've got an engine analyser that's nice, they are worth their weight in gold, but even then, if you discover that you've got a problem with your ignition system the proper course of action is to simply do what you have to do to insure a running engine until you can get the airplane back on the ground. Running additional checks to verify "Yes, we do have a problem" is pointless.

 

There are some pretty good primers on aircraft magnetos and their operation and maintenance on the internet. Not all of them are written by Mike Busche. Just do a google search.