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Slick 500 SB

vic syracuse

Well Known Member
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We see many airplanes come in way past the recomended Slick magneto 500 hr SB. Most of them have some worn parts in them, and some are potentialy pretty serious. I opened one up today that had right at 502 hours on it, and thought I would share with you why these should be done.

This one was ready to fail. I'm actually surprised it was working with any reliabilty, considering all of the metal shavings inside it. It appears that the carbon brush had worn completely down, and now the shaft of the distributor gear was cutting directly into the coil contact.

I've not ever seen one this bad at 500 hours. We all know that the RV's have been commanding some premium prices for some time now, and as with any "opportunistic" times, there are builders that go on the cheap and make a pretty good profit for the unawares buyer. In this case, it was an RV-10, in which a field re-built engine was installed. My guess would be that a "new" magneto was not really used.

Do pay attention to SB's. They are there for a reason. For those of you who are non-builder owners, make sure you ask your A&P to cehck them for you.

Vic
 

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Vic

Thanks for your timely reminders and the effort you’ve been making with the YouTube videos to improve awareness of maintenance issues.
My mags were removed yesterday after 500 hours so waiting to see what there actually like inside.

Regards

Peter
 
Vic,

I’m sure you’ve developed some thoughts on the issue of not rebuilding but just replacement of Slick (or even Bendix) magnetos with electronic magnetos at the 500 hour overhaul time. Would you mind sharing those thoughts? Ie, performance, cost and safety considerations!

If you have a preferred replacement what would that be?
 
With regards to rebuild vs. adding an electronic ignition, it comes down to choices and budget for many pilots.

The 4-cylinder and 6 cylinder mags direct-drive are pretty cheap to overhaul at 500 hours, and there's not usually much wear at the 1000 hr mark.
The impulse ones at 1000 hours need some TLC usually.

I personally like one mag and one electronic ignition. IF there's smoke or an engine fire I want to be able to kill the master switch and not worry about the engine while I sort it all out.

I won't venture an opinion on this forum regarding EI ratings, as there are some really strong opinions on which one is the best. Suffice it to say, we have installed the Lightspeeds, PMAGS (4 cylinder only---I don't think there is enough data yet to warrant them on the 6 cylinders), and SureFly mags. Good experiences with all of them. I've got over 4500 hours behind lightspeeds, across multiple airplanes, and find them to be reliable, especially on the 6 cylinder with no moving parts.

The 4 cylinder Lightspeed with the Hall effect pickup and the PMAG both need to be checked at every CI. There is a SB for the PMAG that you should pay attention to. The seal on the Hall effect pickup for the Light speed can leak, but we've only seen a couple of those.

Vic
 
Another question

Excuse my ignorance, but is there a calendar time period for mags as well or just engine time? Do those plastic parts get dry and crack if they sit not running or on a shelf for a while?
 
Maybe to build in some added safety a prudent owner might have a look inside the mag/mags every 300 hrs??? The quality of the parts doesn’t seem to be what it used to be.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 
Slick SB3-08

There is a Slick mandatory SB that covers premature carbon brush wear. If this mag falls within that date range it should have been opened up long before the 500 hr Mark. Depending on its date of manufacture it should of been inspected as early as 50 hrs. Slick had a bad bunch of carbon brushes that were soft that caused this problem. I’ve seen carbon brushes that were manufactured correctly go to TBO.
I would be curious if the SB applies to this mag.
 
Failure?

We see many airplanes come in way past the recomended Slick magneto 500 hr SB. Most of them have some worn parts in them, and some are potentialy pretty serious. I opened one up today that had right at 502 hours on it, and thought I would share with you why these should be done.

This one was ready to fail. I'm actually surprised it was working with any reliabilty, considering all of the metal shavings inside it. It appears that the carbon brush had worn completely down, and now the shaft of the distributor gear was cutting directly into the coil contact.

I've not ever seen one this bad at 500 hours. We all know that the RV's have been commanding some premium prices for some time now, and as with any "opportunistic" times, there are builders that go on the cheap and make a pretty good profit for the unawares buyer. In this case, it was an RV-10, in which a field re-built engine was installed. My guess would be that a "new" magneto was not really used.

Do pay attention to SB's. They are there for a reason. For those of you who are non-builder owners, make sure you ask your A&P to cehck them for you.

Vic

It looks like there was a lot more going on with that mag than just a carbon brush failure. It's hard to tell from the pictures but it looks like one of the bushings in the distributor block for the distributor gear loosened and failed. Judging by the appearance of the particulates, it might also have been the distributor gear itself that failed causing contact with the distributor posts. Was the gear SB complied with?

Also, since this is on a 6 cylinder engine, were the drive couplings for these mags in good shape? Are there any accessories installed on the engine that could be causing accessory case/mag harmonic issues such as a vacuum pad alternator?

As a note, I run mags on my RV-8 and I pull, inspect/IRAN, and reset the points timing at every annual.

Skylor
 
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It looks like there was a lot more going on with that mag than just a carbon brush failure. It's hard to tell from the pictures but it looks like one of the bushings in the distributor block for the distributor gear loosened and failed. Judging by the appearance of the particulates, it might also have been the distributor gear itself that failed causing contact with the distributor posts. Was the gear SB complied with?

Also, since this is on a 6 cylinder engine, were the drive couplings for these mags in good shape? Are there any accessories installed on the engine that could be causing accessory case/mag harmonic issues such as a vacuum pad alternator?

As a note, I run mags on my RV-8 and I pull, inspect/IRAN, and reset the points timing at every annual.

Skylor

No, it was just the brush failure. Guys, it's really hard to tell if SB's were complied with on amateur-built aircraft just based on SN's without documentation, especially when it's a field rebuild.

Yes, drive couplings were in good shape, but I always replace the drive cushions at 500 hours as well. :)

Attached is a picture of another mag that was affected by SB3-08. You can clearly see the wear at the top of the carbon brush. BTW, these were both found the same week.

Vic
 

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