Mags Overhaul / Replacement TBO

AdamZ said:
Who from POA had a mag failure several years ago and made the glide to an airport was that Lance?
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Lance F, I believe, in his Mooney, not the other Lance whose Baron has four mags (but only two on his Porterfield). IIRC, the Mooney may have had one of those double-mag installations, not the more familiar two separate mags.
 
Ron Levy said:
Well, it still provides electrical redundancy, and limited mechanical redundancy, but at the end of the day, you can only have so much redundancy with a single engine. The fact that these accidents are rare suggests that the system works to the extent the FAA requires for light Part 91 GA safety, but don't nobody think that there's no added risk in ignoring recommended mag maintenance on the grounds that "the second mag will get me home if the first one fails" because, sometimes, it doesn't. For those reasons, the 500-hour inspection seems to me to be cheap and cost-effective insurance.
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Two different discussions -- I was only commenting on the limited redundancy provided by dual ignition magneto systems.
 
Ron Levy said:
Well, it still provides electrical redundancy, and limited mechanical redundancy, but at the end of the day, you can only have so much redundancy with a single engine. The fact that these accidents are rare suggests that the system works to the extent the FAA requires for light Part 91 GA safety, but don't nobody think that there's no added risk in ignoring recommended mag maintenance on the grounds that "the second mag will get me home if the first one fails" because, sometimes, it doesn't. For those reasons, the 500-hour inspection seems to me to be cheap and cost-effective insurance.
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And it you've got a dual-mag situation (and I do on my plane) the maintenance and inspections are even more important.... depending on the failure, you can lose all power as Lance did.
 
Dan Thomas said:
If the points have a significant mound on one contact, the condenser might be going. If they're nice and gray on both, the condenser is OK and not likely to make trouble anytime soon. It should have a capacitance of around .34 mf. The distributor rotor bearings sometimes wear, much of the time they don't, but they do get sludged up. The plastic gears wear out and can cause serious misfiring (spark to the wrong cylinder) if they wear enough to skip a few teeth. That's one reason why we have the OFF-R-L-BOTH switch in the cockpit: to shut off a wayward mag so it can't drag the engine down. In the Slick the bearings are usually the last thing to cause trouble; in the older Bendixes they weren't sealed too well and would get rusty. I once had one fall apart in my hands when I opened it. Too many years of neglect.
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.34 milliFarads? That's a big capacitor. Or did you mean .34 uF (.34 microFarads)? I know, for a long time mF has been used, and mmF (micro micro Farads, or picoFarads). I'm a little anal about this one. What I really love are the marketing folks who brag about 900 mHz processors (Scott - that's aimed at your folks and their data sheet on my Droid). There is a difference between "m" and "M". "m" is "milli", as in .001. "M" is "mega", as in 1,000,000. Only 9 orders of magnitude difference. :D
 
Ghery said:
.34 milliFarads? That's a big capacitor. Or did you mean .34 uF (.34 microFarads)? I know, for a long time mF has been used, and mmF (micro micro Farads, or picoFarads). I'm a little anal about this one. What I really love are the marketing folks who brag about 900 mHz processors (Scott - that's aimed at your folks and their data sheet on my Droid). There is a difference between "m" and "M". "m" is "milli", as in .001. "M" is "mega", as in 1,000,000. Only 9 orders of magnitude difference. :D
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OK. It's Microfarads. 0.34µf, right?

Dan
 
Rotor&Wing said:
There are many shops around that do routine maintenance and overhaul of magnetos. It's a simple job for a rated A&P to remove the mags and take them to the shop to have an IRAN procedure done.

You are talking like an FSDO inspector again, thinking big shops FBOs that have the ability to comply with the return to service requirements, I' speaking of the freelanced A&P who can't or won't repair mags, they just pull them and send them in costing the customer way more than it should.

You seem to always contradict yourself. In a previous post you state the following:

Contradicting ? no, It isn't magic, but in the field it is becoming more and more difficult to find A&P mechanics that will do the proper trouble shooting and repairs that save the customer money.


It amazes me that a mechanic that holds an A&P along with an IA certificate advocates doing minimal maintenance and to run an critical engine component "to failure" in order to save money.

Who says That I advise any one to run to failure? Those are your words not mine.



Let's hope your "guessing" doesn't ever cost one of your customers his life.

Hasn't in 50 years or more.


You have zero statistics to back that up.

Nope, some times you just know. Every body loves to tell a horror story, but few will talk about mundane routine things. like running their mags to Engine TBO, and changing them out for new at overhaul. and never having a problem. I wish the FAA had a method to tell success as well as failure. we maybe would have real data then to off set the horror stories that make the manufactures do the CYA AD.

Just because someone didn't make a required log entry doesn't mean it wasn't done.

I've known this aircraft for most of that time and you can tell when some thing has not been off in a very long time.
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WoW, is every one really that scared of running their mags until they see any indication of impending failure? High Mag drops are not normal, do something about it. But you don't need to overhaul your mags every time the engine hiccups.

It's time somebody started to preach common sense in these web pages.
 
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Rotor&Wing said:
Advocating some of the practices you advise cannot be considered common sense but rather derogatory towards safety.
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I have never observed Tom to counsel practices which are unsafe; rather, I see common sense and experience at work.

Of course, Tom *does* have an irrational antipathy to Bonanzas, but I can forgive that... :D
 
SCCutler said:
I have never observed Tom to counsel practices which are unsafe; rather, I see common sense and experience at work.
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I don't see any "common sense" in recommending that someone ignore a service bulletin on a critical component of an aircraft without positive evidence that the recommended action has no measurable benefit, and given the results folks have seen on the Slick mag 500-hour inspections, this one certainly seems to have measureable benefit. Remember, we're not talking about throwing the mag away, just taking a look inside to see how it's doing.
 
COFlyBoy said:
I've heard the same recommendation. And, I've been on the receiving end of a dead Slick mag. I did not enjoy it. I had to spend 2 nights in Amarillo because of it.

I'm for rebuilding Slicks every 500 hours. Forget the inspection. The 2 Slick failures we've had would not have been caught at inspection anyway. One was a bad condensor and the other was a bad coil. You just can't catch those before they go bad.
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The thing is, coils and (modern) condensers (vs bearings, points and rotors) are not wear items and should last almost indefinitely unless they are subject to serious overheating (or in the case of the coil, operation without a load) Most likely the component failures you experienced were actually the result of manufacturing defects and would normally be classified as infant mortality issues. Replacing such components early on the bathtub curve sans failure can actually increase the chances for an early failure.
 
Rotor&Wing said:
Advocating some of the practices you advise cannot be considered common sense but rather derogatory towards safety.
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Just because I advocate owners do smart maintenance doesn't make me dangerous. If you believe that I am, you must really dislike Mike Bush and Sacramento sky ranch.
 
Ron Levy said:
just taking a look inside to see how it's doing.
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That statement tells a great deal on how much you know about the requirements for return to service of a mag.

Once you open the case and split the gear train in any mag it requires special tools and test equipment, (and the pubs), to return it to service.

IOWs how would you know the Lead, or lag angle with out the pub, plus the fact it requires a special protractor to set the lead/lag angles.

Those requirements are the reason most A&Ps operating in the field can't/won't repair mags.

To Add insult to the topic, Slick will not provide the overhaul manual to any one but their authorized repair centers.

So in my humble opinion if your mechanic has been opening your mags, and inspecting them, in his shop with out the proper authorization from Slick he is in violation of the FAR 43.13-(a) and you probably have a greater danger than one with age that came out of the box.

OBTW, I do have the manuals and tools for the SL version of the Bendix, and the DFM/A 7's but not the Slicks, thus I do not open Slicks, for reasons stated above.

If you ever read my Web page on the Fairchild you will notice that I even sent my own mags out for overhaul, simply because I wanted some one elses sign off in my logs to avoid the liability.
 
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Tom-D said:
That statement tells a great deal on how much you know about the requirements for return to service of a mag.

Once you open the case and split the gear train in any mag it requires special tools and test equipment, (and the pubs), to return it to service.

IOWs how would you know the Lead, or lag angle with out the pub, plus the fact it requires a special protractor to set the lead/lag angles.

Those requirements are the reason most A&Ps operating in the field can't/won't repair mags.

To Add insult to the topic, Slick will not provide the overhaul manual to any one but their authorized repair centers.

So in humble opinion if your mechanic has been opening your mags, and inspecting them, in his shop with out the proper authorization from Slick he is in violation of the FAR 43.13-(a) and you probably have a greater danger that one with age that came out of the box.

OBTW, I do have the manuals and tools for the SL version of the Bendix, and the DFM/A 7's but not the Slicks, thus I do not open Slicks, for reasons stated above.
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Does this fall into the "If it ain't broke, don't fix it" theory of maintenance?

Someone here I sure can elaborate on the increased risks associated with time-based inspections over condition-based maintenance.
 
gismo said:
The thing is, coils and (modern) condensers (vs bearings, points and rotors) are not wear items and should last almost indefinitely unless they are subject to serious overheating (or in the case of the coil, operation without a load) Most likely the component failures you experienced were actually the result of manufacturing defects and would normally be classified as infant mortality issues. Replacing such components early on the bathtub curve sans failure can actually increase the chances for an early failure.
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I agree with a note that the old coils in Bendix mags were ADed out because of cracking of the covering/coating. allowing moisture to short the windings.

If you are looking at any Bendix that has an Orange colored coil it is to be replaced. ( it should have been many years ago)
 
dmccormack said:
Does this fall into the "If it ain't broke, don't fix it" theory of maintenance?
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It's more along the lines of "don't stir smooth Scat, that doesn't stink"
 
Tom-D said:
OBTW, I do have the manuals and tools for the SL version of the Bendix, and the DFM/A 7's but not the Slicks, thus I do not open Slicks, for reasons stated above.
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So if I own a plane with Slick mags and decide to follow Slick's 500 hour inspection advisory, then the only thing you can really do is to take them out and ship them to an authorized service center?

How long is the turnaround?
 
Trapper John said:
So if I own a plane with Slick mags and decide to follow Slick's 500 hour inspection advisory, then the only thing you can really do is to take them out and ship them to an authorized service center?
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No. My one-man-shop local mechanic can do (and has done) the inspection just fine. I don't know what Tom's problem is.
 
I could never send an aircraft out of my shop without internally inspecting the mags. I can't set back and wait for one to break. Most mags like the 4300/6300 series Slicks and 20,200, 1200 and 2000/3000 series Bendix are very easy to at least open up and inspect on the engine without any special tools or books. The Malibu and Mirage mags must be removed to inspect. Finding the cam screw laying in the breaker box, the condensor wire rubbed nearly in two by the cam, and melted parts are just some of the many things I have found on low-time perfect running mags.

I get a bit upset when shops reference using the PA46-310P Piper inspection guide (example) for the annual inspection. It directs you to inspect the points and the dist. contacts. How can you do this in good faith without opening the mag? I feel that the shops are not doing the owner a good service setting them up for failure.

Kevin
 
Ron Levy said:
No. My one-man-shop local mechanic can do (and has done) the inspection just fine. I don't know what Tom's problem is.
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I suggest you call your local FSDO and ask how you get around the requirements of 43,13(a) with out a pub, tools.

or ask to see your mechanic's manual. because in this case the only excepted sign off to return to service on a slick is the overhaul manual's directions for assembly. (the service bulletin does not give you that)
 
Trapper John said:
So if I own a plane with Slick mags and decide to follow Slick's 500 hour inspection advisory, then the only thing you can really do is to take them out and ship them to an authorized service center?

Legally Yes,,,,,,,,

How long is the turnaround?
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not a clue, because Slick has no overhaul service, they issue new.

Their authorized service centers will overhaul, and that is dependent upon how busy they are.
 
Tom-D said:
I suggest you call your local FSDO and ask how you get around the requirements of 43,13(a) with out a pub, tools.
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Did some checking. The necessary manual is available free on line, and the all the tools you need cost less than $500 (shouldn't take too many customers to recoup that investment). And yes, my mechanic has both.
 
Tom-D said:
Just because I advocate owners do smart maintenance doesn't make me dangerous.
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You advise owners to do "cheap maintenance" and cut corners, thus ignoring safety.

Tom-D said:
. If you believe that I am, you must really dislike Mike Bush and Sacramento sky ranch.
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Nope, unlike you Mike Bush has a grasp on what it takes to be a certified mechanic.
 
Trapper John said:
So if I own a plane with Slick mags and decide to follow Slick's 500 hour inspection advisory, then the only thing you can really do is to take them out and ship them to an authorized service center?

How long is the turnaround?
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We had a shop in Flagler Beach I use to take mine too. He would turn them around in 24 hours.
 
dmccormack said:
Does this fall into the "If it ain't broke, don't fix it" theory of maintenance?

Someone here I sure can elaborate on the increased risks associated with time-based inspections over condition-based maintenance.
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Look at it this way. Would you want to be hard IFR with weather all around you down to minimums and have a magneto begin acting up? In a single engine plane?
 
Rotor&Wing said:
Look at it this way. Would you want to be hard IFR with weather all around you down to minimums and have a magneto begin acting up? In a single engine plane?
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Of course not. I'm not arguing for set it and forget it.

But over-inspection/ handling can have adverse effects as well.
 
Rotor&Wing said:
You advise owners to do "cheap maintenance" and cut corners, thus ignoring safety.

Where did I say that? I believe you read what you like into my posts.

Nope, unlike you Mike Bush has a grasp on what it takes to be a certified mechanic.
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He also believes in run to condition maintenance.
 
Ron Levy said:
Did some checking. The necessary manual is available free on line, and the all the tools you need cost less than $500 (shouldn't take too many customers to recoup that investment). And yes, my mechanic has both.
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Mind linking us in?
 
Rotor&Wing said:
"On Condition" maintenance requires periodic inspections as well as periodic servicing.

It does not mean "run till failure".
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Run to condition is when you operate a product until it shows you a reason to repair, it does not mean to run until it fails.

And run to failure was your words not mine. I have never advocated running a mag until it fails. But I will run a mag until trouble shooting shows it requires repair.

That option is given to us by the FAA by not requiring these SBs in part 91. and this prevents the manufacturer from selling parts thru the SB program.

You may believe every SB should be complied with but many maintainers and your boss doesn't, that is why we have the AD program / part 39.
 
Tom-D said:
This is the list of required pubs/

http://www.unisonindustries.com/docs/L-1085BC.pdf
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I have that entire F-1100 manual and the renewal subscription isn't all that expensive. Slick never hassled me when I ordered it and the parts are readily available almost anywhere. Expensive parts, like the coil and distributor assembly (around $300 each) can make overhaul uneconomical if enough bits have to be replaced on one mag. Slick must make a killing on some of that stuff.

Slick doesn't bother rebuilding mags because they can produce brand-new mags for less; that option isn't available to overhaulers other than the manufacturer. Lycoming overhauls and rebuilds engines but they never reuse cylinders or pistons or lifters, or the camshaft either, most likely; they can replace them with new for less than it would cost them to fix up the old ones. Sometimes we get a Lyc factory O/H engine and the only original parts are the crankcase, sump and accessory case: the bits with the data plate. Our economy has been moving in that direction for years, and we've seen the disappearance of places like TV and small appliance repair shops because automation, or offshore outsourcing, makes the new product far cheaper than any repair by a domestic technician. I used to make my living running a heavy-duty air and hydraulic brake component shop, and when I left it in 1992 we were seeing clones of the more popular components coming from South Africa, Brazil and Asia. That shop is no longer in existence, most likely because the labor rates here make rebuilding that stuff too expensive. Shoot, we now drive cars that almost never quit and run many more miles than their ancestors, and when they get old enough a simple thing like a fuel pump failure is often enough reason to junk it because the pump and the labor for its replacement outweighs the value of the car.

We do 500-hour inspections on Slicks and they don't give us any problems arising from having them apart. Conversely, we have sometimes had to take one apart well before the 500-hour because of a persistently high mag drop even after changing out the plugs. Once it was a worn distributor rotor bearing, which is made of oilite bronze, and the metal dust was fouling the points and caused some flashover in the distributor. SB2-08A dealt with the bent coil tab thing that caused rapid wear of the rotor brush, and the carbon from the brush caused flashover as well. Another time the rotor drive gear had plastic flashing left on it during manufacture, and that flashing got rubbed off by the edge of the distributor gear and the plastic dust fouled the points before it ever reached the first 500 hours.

Slick isn't the only company that screws up. Kelly Aerospace now does the Electrosystems alternator overhauls, and in two of them last year I found the slip rings fouled by the excessive grease that the rebuilder had stuck into the rear bearing. The grease messes with the brushes and stops the field current and the alternator dies. Never saw any SB on that.

Dan
 
Ron Levy said:
I don't see any "common sense" in recommending that someone ignore a service bulletin on a critical component of an aircraft without positive evidence that the recommended action has no measurable benefit, and given the results folks have seen on the Slick mag 500-hour inspections, this one certainly seems to have measureable benefit. Remember, we're not talking about throwing the mag away, just taking a look inside to see how it's doing.
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Isn't that the "IRAN" that Tom advocates? Inspect and Repair As Necessary.
 
Ron Levy said:
Tom recommended not doing the SB 500-hour inspection, just running until it breaks.
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I did not say run it until it breaks, But I do believe the 500 hour SB/inspection is an over kill
 
TangoWhiskey said:
Isn't that the "IRAN" that Tom advocates? Inspect and Repair As Necessary.
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Very much so.. when it shows you a reason to trouble shoot, find a cause and fix it.

Both Mag manufacturers say their mags are designed to run to the TBO of the engine. I believe most do.

That is why almost every engine rebuilder wants you to put new mags on at Overhaul.
 
I also have the pub and tooling to accomplish the 500hr on Slick/Bendix mags. I do not understand why a certified mechanic would not want to comply with this simple inspection. Its nice to go to bed at night knowing you have done your best to promote saftey.
 
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