How long before I take a serious look at the mags?

DavidWhite

DavidWhite

Final Approach
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My engine was overhauled 9 years and 1200 hours ago. Jay Honecks recent string of mag issues has me wondering if I need to take a look at my mags soon?
 
The manufacturer will want you to have looked at them twice already.

My OEM slicks went 27 years and 1500 hrs with out a hitch before I yanked em for Bendix units.

Up to you Mr 91 operator.
 
If they're Slicks, you're about 700 hours late already for the recommended inspection. But even if they're Bendix, a good IA will be checking mag timing and function at annual. Beyond that, it's pretty much IRAN (inspect and repair as necessary).
 
DavidWhite said:
My engine was overhauled 9 years and 1200 hours ago. Jay Honecks recent string of mag issues has me wondering if I need to take a look at my mags soon?
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Your mags will talk to you, they will show high mag drops long before they fail.

were they new 1200 hours ago?
 
DavidWhite said:
My engine was overhauled 9 years and 1200 hours ago. Jay Honecks recent string of mag issues has me wondering if I need to take a look at my mags soon?
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Dunno which mags you have but my Bendix are supposed to be IRAN'd every 500. They can run much longer or they may quit early. It isn't fun when they quit, although there were some interesting aircraft in Mexia and the BBQ was good.
 
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Ron Levy said:
If they're Slicks, you're about 700 hours late already for the recommended inspection. But even if they're Bendix, a good IA will be checking mag timing and function at annual. Beyond that, it's pretty much IRAN (inspect and repair as necessary).
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You do know you can buy new Bendix now? they are called TCM now.
 
Tom-D said:
Your mags will talk to you, they will show high mag drops long before they fail.
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My mag drops were fine an hour before the mag failed. By fine I mean within POH specs. They were talking to me in the sense there was a slight vibration at some RPM settings. Darn difficult to tell it was a mag that was going.
 
Ron Levy said:
If they're Slicks, you're about 700 hours late already for the recommended inspection. But even if they're Bendix, a good IA will be checking mag timing and function at annual. Beyond that, it's pretty much IRAN (inspect and repair as necessary).
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I know he checked the timing at annual, and yes they are slicks. It passes the mag checks well but I was curious when I should yank them and slap some new ones in there.
 
Mine were talking, and that's why I pulled them, timming was starting to drift. Drops were always good though and if I wasn't the one doing the annuals it might have gone unnoticed.
 
Clark1961 said:
My mag drops were fine an hour before the mag failed. By fine I mean within POH specs. They were talking to me in the sense there was a slight vibration at some RPM settings. Darn difficult to tell it was a mag that was going.
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That's what you really buy engine monitors for, not leaning but diagnostic information.
 
DavidWhite said:
My engine was overhauled 9 years and 1200 hours ago. Jay Honecks recent string of mag issues has me wondering if I need to take a look at my mags soon?
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The beauty of that tach you've got is the two LED's will at least give you a heads up immediatley regarding a malfunction of the respective left or right magneto.

Check your logbook for the last mag overhaul...
 
DavidWhite said:
I know he checked the timing at annual, and yes they are slicks. It passes the mag checks well but I was curious when I should yank them and slap some new ones in there.
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Up to you, but with my Slicks, I just do the inspection every 500 hours, and then they'll be overhauled with the engine when that becomes necessary. If a problem develops before that, i'll deal with it when it does, but I'm not doing prophylactic mag replacement. Ditto the other engine accessories like alternator and vacuum pump.
 
Ron Levy said:
Up to you, but with my Slicks, I just do the inspection every 500 hours, and then they'll be overhauled with the engine when that becomes necessary. If a problem develops before that, i'll deal with it when it does, but I'm not doing prophylactic mag replacement. Ditto the other engine accessories like alternator and vacuum pump.
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.....+1
 
CFI-Guy said:
The beauty of that tach you've got is the two LED's will at least give you a heads up immediatley regarding a malfunction of the respective left or right magneto.

Check your logbook for the last mag overhaul...
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There isnt anything about the mags between now and when the engine was done
 
DavidWhite said:
Guess I will be calling my mechanic to put some new ones in there then.
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:confused::confused::confused: Why dat?You have Slicks or Bendix? You're probably too young to remember points ignitions in cars and such, but they are what need replacing and possibly adjusting on a regular basis. When I have a bad mag I look at the points. 98% of the time, you will find them slipped closed or pitted and worn or stuck. BTW, if you have a pile on one point face and a pit in the other, you need to use a different microfarad condenser.
 
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DavidWhite said:
When we're installing the JPI next week I'll have them look at it. If I wait until next annual it is going to drive me crazy between now and then.
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I cant remember if your JPI comes with a DVD or not but if so take a good look at it and discover everything the JPI can tell you that you wouldnt normally realize its capable of, including the discussion on the run-up and what indications you should see or might see with a problem.

As for it driving you crazy, ...... that discussion is for Dr. Bruce....:goofy:
 
CFI-Guy said:
The beauty of that tach you've got is the two LED's will at least give you a heads up immediatley regarding a malfunction of the respective left or right magneto.
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Ummm, nope. The Horizon never blinked when my mag failed.
 
Henning said:
That's what you really buy engine monitors for, not leaning but diagnostic information.
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That's somewhat clear after the fact. The CHT's and EGT's look a lot better (much more uniform) after the mag rebuild. They never looked so good for the year or so after the EI install and prior to the mag failure. The mag had evidently been a little weak on spark for quite some time. The RPM drops were fine, well below max allowed and within 20 RPM of each other.

Now that I know what the engine monitor should look like I have something to go on...
 
CFI-Guy said:
Depends on the failure mode.
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Then why would you make the statement you did? I'm confused why you would assure someone reading this thread that the electronic tach would indicate mag failure.
 
DavidWhite said:
When we're installing the JPI next week I'll have them look at it. If I wait until next annual it is going to drive me crazy between now and then.
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Nothing wrong with inspecting the mags at 1200 hours since it hasn't been done prior to that, nothing at all...
 
Clark1961 said:
Then why would you make the statement you did? I'm confused why you would assure someone reading this thread that the electronic tach would indicate mag failure.
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I didnt indicate it would give an indication on every single type of mag failure...and David does have the op manual for his own Tach after all....
 
CFI-Guy said:
I didnt indicate it would give an indication on every single type of mag failure...and David does have the op manual for his own Tach after all....
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One of us needs to look into some training in communications.

"The beauty of that tach you've got is the two LED's will at least give you a heads up immediatley regarding a malfunction of the respective left or right magneto."

Sure looks like you state that any mag failure will be indicated.
 
Clark1961 said:
One of us needs to look into some training in communications.

"The beauty of that tach you've got is the two LED's will at least give you a heads up immediatley regarding a malfunction of the respective left or right magneto."

Sure looks like you state that any mag failure will be indicated.
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Fine...whatever...
 
Mags will not always talk to you, it depends on what fails. If it's the actual spark-producing parts, yes, you'll notice higher mag drops, drifting timing, etc.

Now let's say you have what my mag failures have typically been:

1) Nylon gear failure (these last about 2000 hours, and then fail)
2) Bearing failure

Nope, no warning on any of them. Before I took off on the flight when distributor cap bearing went out the other day I even commented on just how nice and low the mag drop was.

You don't necessarily need new ones, but at 1200 hours they should at least be inspected. Slicks are not my preference - Bendix mags are better. Your A&P can do them if he's comfortable, but I've met many A&Ps who don't want to touch mags, and just want you to send them out to get overhauled.
 
For all those who recommend that slick mag be torn down each 500 hours what will you use as a reference to return to service?

This one?
http://home.hiwaay.net/~sbuc/legaleagleXL/SlickMagOverhaulManual.pdf

If so read:
The following parts must be replaced at overhaul. Additional parts may require replacement depending on conditions as determined during magneto inspection. Install only Unison Replacement Parts.
ALL MAGNETOS Condenser
Double Sealed Bearing Bearing Cap Assembly Coil
Impulse Coupling
Oil Seal
Contact Point Kit
Rotor Gear
Distributor Block and Gear

So, do your home work, and price these parts from Slick and you'll see these parts cost more than a new mag.

Now you know why A&P mechanics don't want to touch slick mag, plus the fact the tooling is more than it is worth to except the liability. (Remember 43.2?)
 
Let'sgoflying! said:
+1 no-talking failure (nylon gear fracture; had maybe 200hrs on it).
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Any mag with 1200 hours usage, tells us it is operating fine. Too bad there isn't a way to see the mags history just prior to failure.

and remember Engines and mags can't talk to you if you aren't listing.
 
Rotor&Wing said:
Why should I have? Show me where that's required of the PIC.
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It's not required, but it is the smart thing to do, because that is how we get better parts, ADs and such.

Any good federal employee would have done that.
 
Yeah, I always was taught that Slicks are throw away mags. Basically you just service the points and toss them out at overhaul or when they go bad. Anyway that's the way I've always seen them dealt with, I never had set.
 
Tom-D said:
It's not required, but it is the smart thing to do, because that is how we get better parts, ADs and such.
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Again, please show me where the PIC on a flight is required to fill out such a form?

Tom-D said:
Any good federal employee would have done that.
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Where did I imply this happened while I was employed by the government?
 
Tom-D said:
Any mag with 1200 hours usage, tells us it is operating fine. Too bad there isn't a way to see the mags history just prior to failure.
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So explain to me how my gear failures at ~2000 hours would be seen.

and remember Engines and mags can't talk to you if you aren't listing.
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Plastic doesn't talk very loudly. You won't always hear the mag talking before a failure.
 
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