0-360 LH Slick Mag Failure

[TPC]

Hi,

I recently (1/16/22)  had a Slick Mag (4347) failure. After post inspection we found that the primary contact spring metal arm was cracked; leaving the contact open. 

This contact (M3637) was replaced 2/2020 and had about 70hrs on it.

My questions to the community:

1. Is this a common failure area

2. Is surface rust common on the spring metal arms (see pic)

Thanks,

Travis

 

PS: Installing a Surefly

Edited January 20, 2022 by TPC

[RLCarter]

rust / corrosion isn’t the norm. The circled area looks corroded and what is that little wire by the screw the arrow is pointing to?

[TPC]

Robert,

Good eye, the circled are appears to a slight yellowish coating on the surface and the arrow looks like some FOD....

My focus is on the contact assembly failure....metal cracked and surface rust after 70hrs. Makes me want to inspect the RH mag which the contacts where replaced at the same interval. 

 

Travis

[RLCarter]

6 minutes ago, TPC said:

Robert,

Good eye, the circled are appears to a slight yellowish coating on the surface and the arrow looks like some FOD....

My focus is on the contact assembly failure....metal cracked and surface rust after 70hrs. Makes me want to inspect the RH mag which the contacts where replaced at the same interval. 

 

Travis

I would definitely take a look….. there was a guy on here and the inside of his mag looked like it had been soaked with salt water on a daily basis………everything inside was rusted and corroded….. had to believe it worked at all

[philiplane]

The 4347 mags are problematic, since they cram two tiny breaker points into the small space available. This is a Slick design defect, their claim to fame is "lightweight".

Your right mag (4370?) would have entirely different points. No reason to look at it unless it has more than 500 hours in service.

Corrosion in a short time span means you had water get inside, somehow. The points do have a coating on the metal to resist corrosion. It normally outlasts the points. Something odd here, if the points only have 70 hours on them. But, Slick mags are a train wreck on a good day. Point actuator cams wear out in a few hundred hours, distributor rotors come loose from their gear between 300 to 800 hours in service, carbon brushes wear into a nail head shape in less than 500 hours... the list goes on. 

Kelly just introduced a Slick replacement that has some product improvements. Let's hope they last longer than the Slick junk we have to tolerate.

[carusoam]

Another thing going on inside the mags…

The high voltage environment generates plenty of O3… aka Ozone…

O₂ is great at oxidizing warm things…. O₃ is even better!

 

So… you are seeing some rust. And surely it is best to not have rust….

Did you notice that golden brown Nylon gear in there as well?

Those gears start out bright snow white…. And the surface slowly oxidizes to a dark brown color….

The more oxidized the gear surface gets… the more probable it is to snap a tooth off…

Broken gear teeth can result in ignition timing drift…

If you are replacing parts inside the mag… that gear is worth about fifty cents of nylon and processing…. Consider getting it replaced…

Look it up by part number, have a look at its pic, it probably is a bright snow white in the pics…

 

When discussing Magnetos… it is common practice to mention how many hours are on the device…. And when it was serviced last….

Many people like to OH their mags on 500hr intervals, and not OH both mags at the same time…

You will also find some dislike for Slick mags around here…. Stronger than a preference for the other guys… (Bendix)

I think you may have discovered why people’s opinions are so strong about the Slicks….

Add them to the stack of less favored devices… like Gill Batteries, and champion spark plugs…. The dislike for the manufactures lasts for decades….

 

PP thoughts only, not a mechanic…

Best regards,

-a-

 

[jetdriven]

41 minutes ago, philiplane said:

The 4347 mags are problematic, since they cram two tiny breaker points into the small space available. This is a Slick design defect, their claim to fame is "lightweight".

Your right mag (4370?) would have entirely different points. No reason to look at it unless it has more than 500 hours in service.

Corrosion in a short time span means you had water get inside, somehow. The points do have a coating on the metal to resist corrosion. It normally outlasts the points. Something odd here, if the points only have 70 hours on them. But, Slick mags are a train wreck on a good day. Point actuator cams wear out in a few hundred hours, distributor rotors come loose from their gear between 300 to 800 hours in service, carbon brushes wear into a nail head shape in less than 500 hours... the list goes on. 

Kelly just introduced a Slick replacement that has some product improvements. Let's hope they last longer than the Slick junk we have to tolerate.

You don’t have to tolerate it, you can replace the Slicks with Bendix that don’t have any of these problems.

[TPC]

@philiplane Thanks for the information. Yes, the RH mag is a single contact (point) with 70hrs from last service. 

 

@carusoam I've forgotten about that corrosive oxygen....thanks for guidance and definitely share most of those opinions...  

[Prior owner]

Time for a Surefly?

[TPC]

My thoughts exactly....Surefly delivers tomorrow.