500 hrs mag inspection - mandatory or reccmendation

bavreze said:
I can see 3 ADs for slick magnettos on FAA website:

74-18-05 8/28/1974 Magnetos
80-06-05 3/28/1980 Magnetos
81-16-05 8/6/1981 Magnetos

mine are model 4370 and 4371.

I can see that none of these ADs apply to mine. So, unless there is some other fault, the annual should be passed without needing to inspect and overhaul the mags, even if it is passed 500hrs.

Correct?
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Depends on the IA. I've seen more than enough Slick failures to know that ignoring the not-so-mandatory-for-private-owners service bulletins is a good way to find yourself flying a glider. Champion goes further than most to deny any problems with their ignition products, so when they do issue a SB, you know it's really bad. One other thing to consider is how many AD's started life as SB's that people ignored.

There are SB's on your mags for bad gears, bad contacts, bad cams, bad brushes and a bad impulse. Most can be checked by serial number, but I find Champion a bit conservative with their lists of affected units. Such as SB1-15 only affecting mags made in a eight month period. Strange that well over 25% of slicks I see have the same problem.

You might find an IA that will ignore common sense and safety and base the annual strictly on the regs, but if you need to look for someone like that, owning a plane might not be for you.
 
bavreze said:
I can see 3 ADs for slick magnettos on FAA website:

74-18-05 8/28/1974 Magnetos
80-06-05 3/28/1980 Magnetos
81-16-05 8/6/1981 Magnetos

mine are model 4370 and 4371.

I can see that none of these ADs apply to mine. So, unless there is some other fault, the annual should be passed without needing to inspect and overhaul the mags, even if it is passed 500hrs.

Correct?
Click to expand...

http://www.faa.gov/documentLibrary/media/Order/8620_2A.pdf
 
bavreze said:
I can see 3 ADs for slick magnettos on FAA website:

74-18-05 8/28/1974 Magnetos
80-06-05 3/28/1980 Magnetos
81-16-05 8/6/1981 Magnetos

mine are model 4370 and 4371.

I can see that none of these ADs apply to mine. So, unless there is some other fault, the annual should be passed without needing to inspect and overhaul the mags, even if it is passed 500hrs.

Correct?
Click to expand...


Correct.
 
Most people don't realize how bad a mag must be to not function as it should. This mag was installed new, ran to TBO and was operating properly at removal. yes it is a new error slick
 

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low idle check woulda caught that earlier.:yes:


....put that back on and try it, you'll see. :nono:
 
Tom-D said:
Caught what? or didn't you understand "operating properly"
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I'd argue that although it was operating.....it was not optimally.....and careful examination of the plugs would bear that out also.
 
Checkout_my_Six said:
I'd argue that although it was operating.....it was not optimally.....and careful examination of the plugs would bear that out also.
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you always can say any mag that has 2 revolutions on it, is no longer new and not operating optimally. that mag was operating normally and delivering normal mag drops and firing all plugs. what more can you ask?
 
Tom-D said:
you always can say any mag that has 2 revolutions on it, is no longer new and not operating optimally. that mag was operating normally and delivering normal mag drops and firing all plugs. what more can you ask?
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The plug on the other end of that lead will look different....and like I said a low idle mag check would reveal that. :yes:
 
In all rotor based distributor systems, including automobiles, the rotor does not make contact with the terminals. This is necessary by design so the spark jumps the air gap and pitting of both rotor tip and terminals is completely normal.

Back to Slick vs Bendix (or now Champion vs TCM) one thing not mentioned is that Bendix mags have an internal safety feature in that when the p-lead is disconnected the mag is shorted to ground and disabled. This would not function if the p-lead wire were cut, only if the actual plug were removed.
 
Silvaire said:
In all rotor based distributor systems, including automobiles, the rotor does not make contact with the terminals. This is necessary by design so the spark jumps the air gap and pitting of both rotor tip and terminals is completely normal.

Back to Slick vs Bendix (or now Champion vs TCM) one thing not mentioned is that Bendix mags have an internal safety feature in that when the p-lead is disconnected the mag is shorted to ground and disabled. This would not function if the p-lead wire were cut, only if the actual plug were removed.
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Don't count on that working every time. I've seen instances where it hasn't.
 
Checkout_my_Six said:
The plug on the other end of that lead will look different....and like I said a low idle mag check would reveal that. :yes:
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I doubt that very much, all any one sees are normal mag drops. no one ever does a idle mag check. Even if they did they would see nothing but a wider mag drop.
 
Checkout_my_Six said:
The plug on the other end of that lead will look different.
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no it will not, too many other influences. 99% of the plug color and appearances are from mixture. the appearances of plug will not change from a mag influences until the mag stops firing that plug.
 
This is why having a engine analyzer is great and always should be used during run ups, and looked at for not only BOTH, but compared at L and R too.
 
Tom-D said:
no it will not, too many other influences. 99% of the plug color and appearances are from mixture. the appearances of plug will not change from a mag influences until the mag stops firing that plug.
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but you didn't try it.....so, how would you know? :yikes:
 
If the carbon dust doesn't form the path of least resistance, it's irrelevant. It's like pregnant, there is no middle ground.
 
Henning said:
If the carbon dust doesn't form the path of least resistance, it's irrelevant. It's like pregnant, there is no middle ground.
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the resistance is higher.....by definition from the extra heating and arcing.
 
Checkout_my_Six said:
but you didn't try it.....so, how would you know? :yikes:
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Because I've been doing mags for a long long time. I did the prior to tear down run and know I got good numbers. the owner wanted new mags, and he got them. I tore the one you saw down just to see how bad they were.

When you start getting bad mag drops a mag is much worse than what you see in these pictures.

I have torn down mags that were giving bad mag drops, and most will not have any brass protrusions sticking out of the distributor block.

Like I've said most pilot/owners do not realize how bad a mag must be to give a bad mag check.

I guess by your willingness to argue about it, leaves you in that category.
 
Checkout_my_Six said:
the resistance is higher.....by definition from the extra heating and arcing.
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What extra?:dunno: Electrodes are massive enough that there is no significant gain in resistance there. The cabin away from the electrodes is meaningless until it forms a circuit that is less resistant than the plug. Electrodes in a distributor will always gain deposits from the arcing process, that's why modern ignition systems gave up distributors. But to say that it makes a significant performance difference before it provides a point of failure isn't accurate. Spark quality can vary through a wide range and still provide an identical combustion process.
 
Silvaire said:
Slicks carry the "throw away" stigma because they did, at one time, produce a magneto that was not repairable and actually was thrown out at the end of its service life. They no longer make that model.

The more disturbing thing about Slicks was their practice of offering specific discounts on their magnetos if you turned in a pair of Bendix mags for exchange - which they would then destroy.

They no longer do that and of course they have gone through a number of ownership changes since those days but I still carry a grudge even though it is probably no longer justified. Old feelings, beliefs, habits and ways are hard to break sometimes.
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Just because Slick did some things you don't approve of doesnt give you and mechanics like you a license to "stick it to" airplane owners that have Slicks.
 
Henning said:
Electrodes in a distributor will always gain deposits from the arcing process, that's why modern ignition systems gave up distributors. But to say that it makes a significant performance difference before it provides a point of failure isn't accurate. Spark quality can vary through a wide range and still provide an identical combustion process.
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More importantly, modern ignition systems gave up distributors because they couldn't handle the higher voltages being employed. The last distributors got so large so that the electrodes were much farther apart to prevent crossfiring. A sparkplug under compression resists sparking and if the voltage is high enough it will find an easier time flashing across to a nearby electrode for a cylinder that is on early compression or has already fired.

And spark strength does indeed make a performance difference. A weak spark will tend to fire a bit later and be very short; a late spark reduces peak pressures and a short spark might not even fire the mixture. I have very often noted a better-running engine right after I've changed the points and reset the E-gap, even though the engine had been running "OK".
 
coloradobluesky said:
Just because Slick did some things you don't approve of doesnt give you and mechanics like you a license to "stick it to" airplane owners that have Slicks.
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Yes it does. Here we are considered ****oles anyway, so we might as well have the game.
When we IAs have the authority to declare airworthiness, and take the liability for it, we can demand any thing we want. But we also know when we make it too unreasonable the cheap owners go away.
 
Tom-D said:
Yes it does. Here we are considered ****oles anyway, so we might as well have the game.
When we IAs have the authority to declare airworthiness, and take the liability for it, we think we can demand any thing we want. But some of us have learned that when we make unreasonable demands the owners go away.
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FTFY.
 
Send for a inspect and repair as necessary (IRAN). Better than an overhaul, will fix what is broken or worn as opposed to throwing out parts that are fine, and a thorough inspection. Very affordable.
 
to conclude this thread: I called a different IA and he did the annual again and passed without needing to remove and redo mags


thanks!
 
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