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Always check the magnetic plug

Roger Lee

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You should always check your magnetic plug at oil change. This is a Rotax service bulletin that has been out for some time.


Take a look and see why. Very rare indeed. This would be your nightmare, although I suspect it could be worse with multiple chunks. sad.gif

It should come out looking very clean as I see them with Amsoil or with only a very very slight black fuzz. (And I do mean very slight)

post-3-064088300 1293904889_thumb.jpg

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There is a piece on in that photo that looks to be about a mm long, I have seen that exact situation 3 times before including my own engine. That is not from the gear set, judging by it's shape it's more likely it came from the prop shaft splines just aft of the vacuum pump drive gear. I still have the 3 prop shafts sitting on my desk, all missing the same piece. Most of the metal on your mag plug is going to be from the (3) disk spring washers inside of the gearbox, they wear continuously through out the life of the engine. Although some oils drastically lower this wear. I have only seen one instance when metal has chipped off the main dog gear and that was because of a sever prop strike. I would highly recommend checking the shaft, you don't necessarily have to worry about a failure but it's something you want to get taken care of, if a chip more than 1.5 mm is found the aircraft must be grounded until the cause is determined.

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  • 10 months later...

Starting the new year right. wink.gif



I have put this out before, but for those who have never read or seen it here it is again.


An Oil Comparison. It shows what different motorcycle additives do for our engine to protect it and how a few oils compare.


Hey Roger,


Good speaking with you today. I was wondering; My Rotax came with Mobile 1 in it from the factory where they swear by it. I read its good with nolead mogas. But its had some 100ll put through it. So, its time and I will put aeroshell sport 4 in it. Anyway my concern is---will I be causing a problem with just draining the oil sump and changing filters? Is there old oil still in the oil lines and cooler which shouldn't be blended with the new different oil?


Also, I saw were CPS sells a air purge kit....I don't need that do I? I haven't disconnected any oil lines or turned the prop while the oil is out waiting for me to take off that stubborn filter. I'm changing the plugs too. So, should I take them all out, finish the oil change then spin the engine with the starter until oil presssure is observed, then put the plugs back in??



Thank You!


Doug in IL

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  • 3 weeks later...

No warning prior to it just stopping.


No hiccups, no roughness, just stopped. Prop also stopped, no windmilling whatsoever.


Pushed it to the pump and filled her up with 128 liters of fuel, started and taxied to the hangar.



Oh, forgot to say that I landed first.....

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