Bendix S20/200 magneto 500hr maintenance

[FlyingDude]

Guys, 
I'm perplexed.  In prep for the annual, where we were going to do the 500hr maintenance on the magnetos, I started reading the maintenance and overhaul document.  But while it says that the contacts need to be checked the first 50hrs and then at 100 hrs and every 100 hrs; it says that the 500 hr overhaul is required for magnetos on Teledyne Continental engines.  What am I missing?  (i.e. why is it required only on Continental engines and not all engines?)

Thanks...

[FlyingDude]

[carusoam]

Call it highly recommended…

From MS experience…

People with the most experience, and a decent maintenance budget….

Like to service mags every 500 hrs…

And have their mags on separate schedules…

And have a specific mag shop to do the work…

 

PP stuff I read around here…

-a-

[philiplane]

It's not an overhaul, it's just inspect and replace parts as needed every 500 hours. A competent mechanic can do it in two hours per mag. At 500 since new or overhauled, they generally only need cleaning, lubrication, and point adjustment. At 1000-1500 hours, they might need points. 

Edited April 2, 2022 by philiplane

[Prior owner]

One thing to consider- not every mechanic has a tin of the correct grease for the Bendix bearings though…and they typically won’t be able to check the run-in speed at the correct spark gap, or have the setup to do all the required capacitor checks and then re- magnetize the magnets…I understand that many will think this is unnecessary, but it’s nice to have a magneto shop do all that and then bench test them after inspection/overhaul.

[philiplane]

12 hours ago, PilotCoyote said:

One thing to consider- not every mechanic has a tin of the correct grease for the Bendix bearings though…and they typically won’t be able to check the run-in speed at the correct spark gap, or have the setup to do all the required capacitor checks and then re- magnetize the magnets…I understand that many will think this is unnecessary, but it’s nice to have a magneto shop do all that and then bench test them after inspection/overhaul.

None of the tests you mentioned are in the 500 hour inspection. A magneto shop is not going to do them either, as they are only part of the overhaul process. They are two distinct and separate processes, each with its' own tasks, and billable hours. If you pay for a 500 hour inspection at a magneto shop, and the shop is a Part 145 repair station, they will do exactly what is in the Continental X42002-3 Service Support Manual, Chapter 6-2.3, and nothing more, unless they've added extra tasks into their Op Specs.

The 500 hour inspection is designed to be done in the field. You need a puller if it has an impulse coupling, some hand tools, a timing light, and the $40 tub of bearing grease. 

Edited April 2, 2022 by philiplane

[Prior owner]

11 minutes ago, philiplane said:

None of the tests you mentioned are in the 500 hour inspection. A magneto shop is not going to do them either, as they are only part of the overhaul process. They are two distinct and separate processes, each with its' own tasks, and billable hours.

The 500 hour inspection is designed to be done in the field. You need a puller if it has an impulse coupling, some hand tools, a timing light, and the $40 tub of bearing grease. 

I might agree to that provided the aircraft hasn’t seen any dormant periods during the previous 500 hours….but I rarely see planes that are flown regularly or that have not sat for years at some point between 500 hour inspections.

This is where I send my mags, and this is the list of items performed during their 500 hour inspection.

Aircraft Magneto Service

[philiplane]

Here is what Bendix (now Continental) says a 500 hour inspection is, it's not as complicated as some might think, so there's no reason not to do this every 500 hours. Some shops think you have to overhaul the mags at 500 hours, and that is just overkill.

[Fly Boomer]

2 hours ago, PilotCoyote said:

This is where I send my mags, and this is the list of items performed during their 500 hour inspection.

Pretty handy web site.  I like the "estimated turn time" for various mags.

[FlySafe]

3 hours ago, PilotCoyote said:

I might agree to that provided the aircraft hasn’t seen any dormant periods during the previous 500 hours….but I rarely see planes that are flown regularly or that have not sat for years at some point between 500 hour inspections.

This is where I send my mags, and this is the list of items performed during their 500 hour inspection.

Aircraft Magneto Service

FlyingDude, you might give some of the mag shops you’re considering a direct call as you are deciding your next steps. I recently spoke with the helpful folks at aircraft magneto as my 500hrs. IRAN is approaching. They currently are running about 18-21 days shop time for service on Bendix S20/S200 style mags. Kelly stated they are averaging ~5 days but it varies. Both have a reputation for doing good work.  Unrelated, any realtionship to the Big Lebowski? take care

k

[jaylw314]

23 hours ago, FlyingDude said:

Guys, 
I'm perplexed.  In prep for the annual, where we were going to do the 500hr maintenance on the magnetos, I started reading the maintenance and overhaul document.  But while it says that the contacts need to be checked the first 50hrs and then at 100 hrs and every 100 hrs; it says that the 500 hr overhaul is required for magnetos on Teledyne Continental engines.  What am I missing?  (i.e. why is it required only on Continental engines and not all engines?)

Thanks...

 

I wonder if they could only say that for TCM engines because Bendix is owned by TCM?

[FlyingDude]

9 hours ago, philiplane said:

Here is what Bendix (now Continental) says a 500 hour inspection is, it's not as complicated as some might think, so there's no reason not to do this every 500 hours. Some shops think you have to overhaul the mags at 500 hours, and that is just overkill.

Thanks for sharing these excerpts. Do you mind sharing the link? The document I have is dated 1989...

Thanks for all the help and suggestions, guys.

[Guest]

7 hours ago, FlyingDude said:

Thanks for sharing these excerpts. Do you mind sharing the link? The document I have is dated 1989...

Thanks for all the help and suggestions, guys.

Search for Continental manual X42002, S20 $ S200 manual.

Clarence

[philiplane]

I think most mechanics are scared to even open a magneto, because the magic might spill out, and they might not be able to get it back in. 

[carusoam]

The chemical environment inside the mag is as nasty as it gets…

Ozone, or O₃, is produced when electric sparks fly…

Nothing oxidizes better than ozone…

A good sign of oxidation inside the mag… the fancy white plastic gear turns a nice golden brown at the surface…

Surface cracks are initiated… leading to missing teeth as time and use goes on…

Soooo if you have a nice golden brown gear in there… check out what a new one is supposed to look like…

PP thoughts only, not a mag guy…

Best regards,

-a-

[cliffy]

One of my pet peeves!

EVERY A&P learned how to service mags in school. H*)) I learned on a VAG 9 mag and big mags on R-2800 Radial engines with compensated cams.

Used to do lots of double mags for Navajos on my shop bench and NEVER had one fail. 

Now they all turn out to be nothing but parts changers after schooling. 

Mags have been around since the late 1800s. Nothing MAGIC about them. Maybe I've just been around too long but any A&P that can't do a 500 hr

check on a mag is doing a disservice to his customers.  It ain't rocket science. 

BTW, reading maintenance manual requirements is a learned skill much like understanding MELs (Minimum Equipment Lists) on big iron.  One has to read very carefully to determine just what it is saying. 

NOTHING in the manual says it needs an "overhaul" at 500 hrs.

An OVERHAUL is an entirely different animal in scope than a 500 hr inspection. 

Like what was mentioned- some particular tools and a tub of the correct grease and any A&P worth his salt can do a 500 hr inspection. 

AND it should be done every 500 hrs. 

[Guest]

This week alone I’ve got two first time inspections going on in the shop, both have issues with the magneto installation.  The Continental powered plane has Lycoming gaskets installed, the nuts were so overtorqued that the hold down clamps are bent.  When we pulled the mags, there were remnants of old gasket material which was causing the leaks.  The Lycoming powered plane has Continental gaskets under the Bendix mags, these gaskets don’t fully support the magneto and can lead the the ears breaking off.

So while I agree that most maintainers should be able to do a 500 hour inspection, if they can’t install them correctly, should they be working inside the mag?

Clarence

[cliffy]

Game, set, match! Point taken.

They shouldn't be working on airplanes in the first place!

The lack of knowledge or skills is appalling in several A&Ps.

Just look to how many mags have fallen of due to reusing lock washers.

 I've seen many where one look at the lock washers and you know they haven't been changed in many years. 

This is just one small item of many issues that have come through the shops I have been affiliated with. 

Had a Mooney come through where it was 60 days out of annual (in for a loose stabilizer, 1/2" movement fore and aft, bad hinge bolts) but we found that the gear

wouldn't come with in 4 inches of being in the wells (wrong gear motor installed!). How does this even get signed off? 

First time inspections are always interesting. 

[FlyingDude]

16 hours ago, cliffy said:

EVERY A&P learned how to service mags in school.

Ok, I think I should say this: my mechanic wasn't weaseling out of or getting shy of servicing the mags... We'll do it this weekend (R now, L in about 50-75 hrs). I raised the question because I found it weird that the maintenance schedule only addresses Continental engines and not Lycomings... Anyway, the revised manual doesn't distinguish between engines, so my question has lapsed in time...

[FlyingDude]

Hi Guys, I'm back.

I read the manual and feel happier already.  But there is one thing: parts.  I feel like the standard and deluxe repair kits do not contain all of the necessary parts. 

The manual mentions some parts that need to be replaced every time you open it up.  I looked at the materials list of the standard kit that I got from Spruce, and it seems like some parts are missing.  (Discrepancies: lock washers, screws, retaining ring, oil deflector (unless this is the oil slinger), identification data plate (why should that be replaced?), pin.).  Looking at the parts list of the manual, Continental specific parts numbers are referenced, so how could I procure the missing parts?  

Thanks for all the help.

 

According to the manual, these parts must be replaced every time you open it up:

But this is what's in the kit: 

 

Discrepancies: lock washers, screws, retaining ring, oil deflector (unless this is the oil slinger), identification data plate (why should that be replaced?), pin.

This is how parts are listed.  They have Continental part numbers, so how could I obtain equivalent parts?  Or, should I have purchased them separately from Spruce along with the repair kit???

 

 

[Guest]

The devil is in the details, few field completed and some shop completed 500 checks don’t meet the requirements in the manual.  Our local engine guy(now retired) preferred Slick mags because of the parts requirements for Bendix mags.

Here is watch gets replaced by AMS.

Clarence

[FlyingDude]

8 minutes ago, M20Doc said:

The devil is in the details,

Agreed  But I can't be the first guy to notice that the repair kit from spruce doesn't contain everything. What do you guys do regarding these missing parts?

[philiplane]

The reason the kit doesn't come with screws and lock washers is because few people, and few shops, replace those, other than at overhaul time. That said, the screws and washers are standard MS/NAS parts.

The intent of a 500 hour inspection is to find problems such as burned points and carbon tracking inside the distributor. Those are the hardest working parts in the magneto, and if they're faulty, they will cause ignition problems. Most Bendix mags just need cleaning and adjustments for the first 1000 hours, then you might need new points, or a distributor block, at 1500 to 2000 hours. 

 

Edited April 5, 2022 by philiplane

[Guest]

5 hours ago, FlyingDude said:

Agreed  But I can't be the first guy to notice that the repair kit from spruce doesn't contain everything. What do you guys do regarding these missing parts?

When sending the mag to a shop, choose carefully and ask questions.  I’ll have to disagree with philiplane, the screws are special, the lock washer is part of the screw.  Locking devices like these are supposed to be one time use, hence the requirement to replace each time they’re removed from the mag.

Clarence

[FlyingDude]

21 minutes ago, M20Doc said:

Locking devices like these are supposed to be one time use, hence the requirement to replace each time they’re removed from the mag.

So, where do I get them?