Magneto servicing

[milotron]

Howdy,

Going in for annual this month and getting some preventative work done.

What is the recommendation on mags?  Rebuild; replace; service on condition? 

Engine is TSIO360MB in a M20K. No real ignition related issues noted with a lean mag check at altitude. They are at about 320 hours.

 

How about vac pump? At 250 hours on that one.

 

Thanks!

 

iain

[Shadrach]

I stagger my mag service every 500. I get 1000hrs between IRANs but always have one mag with <500 hrs since IRAN.  Depending on the kind of pump you have, most are warrantied to 500 or 1000hrs. 

[FoxMike]

If the mags were properly rebuilt 320 hours ago I would not touch them  I fly my vac pumps till they break.  I normally get 1200hrs out of them.  

[milotron]

Good advice, I like it! I have electric standby AI which is all the pump drives so I will only lose the autopilot if it fails.

I like the idea of staggering the mags; keeps one as a control sample at all times.

 

iain

[Guest]

Which brand of magneto do you have?  Slick or Bendix?  Slick seem to have more issues than Bendix.  500 hours would be normal service hours.

Be sure they are timed using MSB 94-8D.

Clarence

[milotron]

They are the Slick 6324 pressurized. One was completely replaced previously, the other had some parts replaced. I'll look at the hours closer and aim for 500 hours with a stagger in the interval.

thanks Clarence.

[Bryan]

I, too, am going into annual next week with about the same hours on my Slick pressurized mags and have the same questions.

TSIO-360-SB

Had planned to follow SWTA - Mooney Service Center’s recommendation on them.

[Guest]

8 minutes ago, milotron said:

They are the Slick 6324 pressurized. One was completely replaced previously, the other had some parts replaced. I'll look at the hours closer and aim for 500 hours with a stagger in the interval.

thanks Clarence.

I don’t know if staggering the work is really required.  Send them to a reliable shop for the 500 and sleep easy.  You can’t buy a new airplane with mismatched magneto hours and they are falling out of the sky.  You can’t order a new twin with a used engine on one side and a new one on the other.

We use Aircraft Magneto Service in Montana with great success.

Clarence

[milotron]

What does a typical rebuild cost? A rebuild unit is $750CDN from Spruce.

[Guest]

28 minutes ago, milotron said:

What does a typical rebuild cost? A rebuild unit is $750CDN from Spruce.

Opening line for a 500 hour inspection is typically $500.00, and it goes up from there depending on internal condition.  Slick pressurized mags tend to corrode badly inside.

Clarence

 

[Shadrach]

44 minutes ago, M20Doc said:

I don’t know if staggering the work is really required.  Send them to a reliable shop for the 500 and sleep easy.  You can’t buy a new airplane with mismatched magneto hours and they are falling out of the sky.  You can’t order a new twin with a used engine on one side and a new one on the other.

We use Aircraft Magneto Service in Montana with great success.

Clarence

Staggering the work is certainly not required. I've just found that it's a reasonable approach for me in maintaining the Bendix 200 series. Your comments on the Slicks are well taken. I did not know of their propensity to corrode.  A staggered approach in the case of a new airplane with with 0 time works like this - At 500hrs TT the Left is IRAN'd and the right remains in service. At 1000hrs TT the right has 1000hrs and is now IRAN'd while the left with 500hrs since IRAN remains in service. At 1500hrs TT right has 500hrs and left has 1000hrs. The left is IRAN'd and the right remains in service and so on. For me, it ensures that half of the ignition system always has =<500hrs in service without needlessly tearing apart a mag that's operating well.

[carusoam]

More specific to the vac pump...

1) If you only have one... the change at 500hrs(?) is the norm for not having it fail...

2) Some people have back-up vac systems in the tail...

3) The Back-up vac system type that is connected to the intake manifold is too limited for most MSers...wants and needs... you get the choice of full power OR full vacuum... not both...

4) a new electric TC is an OK back-up to a vac AI... a worn TC bounces around in turbulence and makes a crummy back-up...

5) vac pumps have a tendency to undergo infant mortality issues... so exchanging early doesn’t make enough sense...

PP thoughts regarding vac pumps only, not a mechanic...

Best regards,

-a-

[bradp]

Half the number of hours that @Shadrach uses for his Bendix if you have slicks ... something needs to be done every 250-500 hrs to a slick in my brief experience. 

Highly recommend Aaron Williams Select Magneto service in Lancaster Texas.  Excellent work and fair prices for an IRAN.  

Be suspicious of Champion / Slick part quality.  Go with IRAN vs overhaul if possible on these.

If given an opportunity consider what @jetdriven did and swap to bendix mags, it might not be much more than the cost of a harness plus service.

Brad 

[jaylw314]

2 hours ago, Shadrach said:

Staggering the work is certainly not required. I've just found that it's a reasonable approach for me in maintaining the Bendix 200 series. Your comments on the Slicks are well taken. I did not know of their propensity to corrode.  

I think he was referring to pressurized Slicks, not necessarily Slick mags in general.  Since they're pressurized with inlet air, they're also pressurized with any moisture you fly through.

[Shadrach]

5 hours ago, jaylw314 said:

I think he was referring to pressurized Slicks, not necessarily Slick mags in general.  Since they're pressurized with inlet air, they're also pressurized with any moisture you fly through.

Likely correct, though anecdotally I seem to see more complaints about Slicks and see accolades for Bendix in general.

[ArtVandelay]

Half the number of hours that [mention=8069]Shadrach[/mention] uses for his Bendix if you have slicks ... something needs to be done every 250-500 hrs to a slick in my brief experience.

Slicks eat points, but they don’t require a full overhaul.


Tom

[Oldguy]

@gsxrpilot Paul, don't you have some pics of the inside of your mags showing what can happen? I recall seeing them, but cannot find them.

[xcrmckenna]

I’m planning on sending my Bendix mags for 500 hr inspection at annual. Where do you guys recommend they go?


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[carusoam]

John,

Somebody posted pics of nylon gears that were really brown from the high level of ozone that is generated inside a magneto...

The normal white color of the nylon gears was very oxidized by the O3

There was probably a missing tooth as well. That is the final day befor OH...

Old fuzzy PP memories... probably enough detail, that a search might find it...

Best regards,

-a-

[xcrmckenna]

[mention=11970]gsxrpilot[/mention] Paul, don't you have some pics of the inside of your mags showing what can happen? I recall seeing them, but cannot find them.

https://mooneyspace.com/topic/24692-time-for-a-new-mag/?tab=comments#comment-396918


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[Guest]

6 hours ago, xcrmckenna said:

I’m planning on sending my Bendix mags for 500 hr inspection at annual. Where do you guys recommend they go?


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Aircraft Magneto Service in Montana, fairly close to you.

Clarence

[steingar]

I've never liked periodic servicing of magnetos.  An inspection is indistinguishable from a rebuild, and I think you're as likely to encounter maintenance induced failures in serviced ones as age related failures in unserviced.

[milotron]

8 hours ago, xcrmckenna said:

https://mooneyspace.com/topic/24692-time-for-a-new-mag/?tab=comments#comment-396918


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Good read.

 

What is the cause for the left mag on the TSIO360 being an ongoing issue; is it related to the vent hole being clogged?

I see in my logs that the left mag has been serviced almost twice as much as the right. 

 

iain

[kortopates]

Good read.
 
What is the cause for the left mag on the TSIO360 being an ongoing issue; is it related to the vent hole being clogged?
I see in my logs that the left mag has been serviced almost twice as much as the right. 
 
iain

Nah, they don’t clog easily. Check the routing of the UDP hoses and make sure the mag air filter is being changed regularly on the same 500hr/5yr or sooner interval. The left side has the shorter hose length to it so it could be exposed to more moisture if the filter isn’t getting it.


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[philiplane]

Slick mags are notorious for poor quality, mostly since 2006. They are still having problems with premature point cam wear, premature wear of the Oilite bushings in the distributor block, carbon brush wear, and loose internal drive gears. Also, the distributor gear tangs are coming loose on the shafts in 300-400 hours. 

I would do a 500 hour on them asap. You may get lucky, or they may be junk and ready to fail on the next flight. With Slicks, it's a crapshoot.

I repair dozens of magnetos every year and most Bendix mags need little maintenance, but Slicks are generally a train wreck.

If your mag timing has been adjusted more than 4 degrees total in the prior 320 hours, your point cams are worn and the internal timing has retarded.

Edited January 10, 2019 by philiplane