Mag issues

It appears that my left mag is getting tired. My 0-320 engine was getting hard to start so had the plugs changed last annual which helped some. However the rpm drop increased for the left mag with the new plugs, a little over 100 rpms. It is still hard starting sometimes.
My question is should I have the mag rebuilt or go with a certified e-mag? Anyone have experience with the SurFly ?


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When is the last time these mags had a 500 hr inspection?

Web

One Super Cub around here was getting those "lemme see a photo" annuals. I had to ferry it from a local airport one day, and noticed it was climbing poorly.

Mags had worn in the cam and point area, causing the timing to be seriously retarded. Cams were worn to the point where it was difficult to get them set correctly.

Overhauled both. Fixed.

What mags do you have? Slicks are natorious for having intermittent starting problems. I dumped mine for a set of Bendix and have been very happy. If you have Bendix mags send them to https://www.aircraftmagnetoservice....ls3y2I7GPsX0sDVa5e46HWg33aizwmvhoC5gMQAvD_BwE for rebuild/overhaul, they are great people to work with.
DENNY

Mags have ignition points like old cars. Over time the points and the follower wear a little. This changes the internal timing of the mag. If the points are in otherwise good condition just retime them to E-gap (the point of the highest magnetic flux prior to TDC) of the rotating magnet. You feel E-gap with your hands. All it takes is a 1/2" wrench, a screw driver, a piece of paper and a few minutes of time.

DENNY said:

What mags do you have? Slicks are natorious for having intermittent starting problems. I dumped mine for a set of Bendix and have been very happy. If you have Bendix mags send them to https://www.aircraftmagnetoservice....ls3y2I7GPsX0sDVa5e46HWg33aizwmvhoC5gMQAvD_BwE for rebuild/overhaul, they are great people to work with.
DENNY

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The older ones were horrible, the newest ones are better... I just have my customers send them to Aircraft Magneto Service, they are tested after overhaul and have a warranty. I am not a fan of the Kelly Aerospace products either. Tim

Just had my mags redone for the second time in the last 100hrs. Had a shop in Anchorage do mine...was a complete rebuild in theory...points were shot and coil was not new along with other internal parts....cost a bit over 1500$. This place did not stand behind their product/work...they did offer to rebuild them again for $500 each... I went with a different business...

Minimum 500 hour inspection by an informed A&P. Otherwise overhaul or replace. Not to be ignored.

SOOOOOOOO, winter has arrived because now we are posting about is flying a sport stuff. Just for giggles what is involve in a 500 hour inspection. I know what I want but what is involved in an AD for the Bendix mags? If you do have a mag issue go to post #5!!
DENNY

J5Ron said:

Just had my mags redone for the second time in the last 100hrs. Had a shop in Anchorage do mine...was a complete rebuild in theory...points were shot and coil was not new along with other internal parts....cost a bit over 1500$. This place did not stand behind their product/work...they did offer to rebuild them again for $500 each... I went with a different business...

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Kodiakmack said:

Minimum 500 hour inspection by an informed A&P. Otherwise overhaul or replace. Not to be ignored.

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I'm not picking on you two. Every time the topic of defective mags comes up, it appears that the universal solution is to "send them out". Mags are one of the simplest accessories to work on and to keep operating properly. Seldom does one need enough work which takes a long period of time to fix. The most complex tool needed is a gear puller. Short of needing a major part (like a coil), a mag can be returned to peak operating condition in not much more time than removing and reinstalling the cowling.

All Powerplant mechanics are trained in magnetos. Why do what appears to be a large number of them insist on sending them to someone else to "tune up"? Are none of them old enough to remember how to "tune up" a car?

Sorry for the rant. Mags are Soooo simple to tune up.

I agree Pete:smile:

astjp2 said:

The older ones were horrible, the newest ones are better... I just have my customers send them to Aircraft Magneto Service, they are tested after overhaul and have a warranty. I am not a fan of the Kelly Aerospace products either. Tim

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Define older.

skywagon8a said:

I'm not picking on you two. Every time the topic of defective mags comes up, it appears that the universal solution is to "send them out". Mags are one of the simplest accessories to work on and to keep operating properly. Seldom does one need enough work which takes a long period of time to fix. The most complex tool needed is a gear puller. Short of needing a major part (like a coil), a mag can be returned to peak operating condition in not much more time than removing and reinstalling the cowling.

All Powerplant mechanics are trained in magnetos. Why do what appears to be a large number of them insist on sending them to someone else to "tune up"? Are none of them old enough to remember how to "tune up" a car?

Sorry for the rant. Mags are Soooo simple to tune up.

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I don’t disagree at all, however when some thing does need rebuilt and you pay for work, IE, new everything inside, you expect that...once my IA and I pulled mine apart, after having mag issues it was obvious that there were old parts still in this rebuilt mag...that is why I returned it...was just disappointed in the workmanship of this business, and their unwillingness to stand behind their work. My “rebuilt” mag needed new points, bearing and coil ....

J5Ron said:

I don’t disagree at all, however when some thing does need rebuilt and you pay for work, IE, new everything inside, you expect that...once my IA and I pulled mine apart, after having mag issues it was obvious that there were old parts still in this rebuilt mag...that is why I returned it...was just disappointed in the workmanship of this business, and their unwillingness to stand behind their work. My “rebuilt” mag needed new points, bearing and coil ....

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Understood, With the mags coming back with old parts and a dissatisfaction in the call to the shop, the next call would be to Mr.FAA. That type of "workmanship" is uncalled for. I would have just ordered the replacement parts and done the job myself. Perhaps one hour's labor.

DENNY said:

SOOOOOOOO, winter has arrived because now we are posting about is flying a sport stuff. Just for giggles what is involve in a 500 hour inspection. I know what I want but what is involved in an AD for the Bendix mags? If you do have a mag issue go to post #5!!
DENNY

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The 500 hr AD on Bendix is only applicable on the 540s now. Here is a copy of the 500 hr inspection instructions for the Slicks. Might not be the latest revision. https://drive.google.com/file/d/1pCAudhhsldDSpYEHbRon78UFfZnvYvQK/view?usp=sharing

Didn’t say just send it out. 500 hr inspection can be done easily by your a&p. If he sees garbage that needs a full overhaul you’re gonna send em out. Yeah, they’re simple to tinker on (a&p not owner), but a full blown overhaul why not use a shop who specializes?

I just did both mags on a IO-540 in a Maule. The aircraft had around 500 hours TT and is nearly 20 years old. This plane is on floats and has been most of its life. Slick’s on it. So as in most cases there is more to consider. I talked it over with the owner and here is what we came up with. The airplane sits most of the winter, the mags are old , they spent most of there lives around water, they will spend the rest of its life around water, it gets flown to remote area’s when braking down is very bad.
So we decided to replace both with new, under $3000.00 , good to go for many years.
Just a quick note on the FlyRite mag’s we talked that over and the owner didn’t want to go electric because of the environment we operate in. Also keep in mine they recommend replacing the wiring harness with the mag.
Hard to go wrong with new.

Kodiakmack said:

Minimum 500 hour inspection by an informed A&P. Otherwise overhaul or replace. Not to be ignored.

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I have all of the best manuals in the world, I don’t have a machine to run and test them so therefore they get mailed to a certified shop who tests after repair, without the test, imho, the 500 hour is not complete. Tim

I don't see anywhere in the 500 hr inspection where is calls for a bench check. Adjusting e-gap, inspecting and wiping out carbon is pretty straight forward.

Steve Pierce said:

I don't see anywhere in the 500 hr inspection where is calls for a bench check. Adjusting e-gap, inspecting and wiping out carbon is pretty straight forward.

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That's the difference between a mechanic and a remove & replace technician.

skywagon8a said:

That's the difference between a mechanic and a remove & replace technician.

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One paragraph in the beginning of the Slick manual that says if you open the mag you need to test it, my pmi called me out on it so to eliminate any issues I farm it out. On my own airplane is one thing, paying customer it is just easier to let someone else have the liability. Same thing with carbs. It’s not that I can’t, it’s that I won’t. I got away with a lot more **** in Alaska, not the same rules in some FSDO districts so not much rogue in the lower 48 without the possibility of a whiner customer who runs to the feds over their bill because they get a real annual and not a walk by. You can take on anything you want, I just don’t want my pmi asking me, how did you test it, per the manual?” Besides looking at revision numbers and dates for my data. Tim

Legit question.

Do they specify how the testing is to be accomplished or any special equipment required for testing?

Web

wireweinie said:

Legit question.

Do they specify how the testing is to be accomplished or any special equipment required for testing?

Web

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First page last paragraph.
After any inspection or maintenance is done on Slick Magnetos, the testing procedures in Section Eight should be performed completely.

part of that should, shall, will, may argument. Not one to argue with my pmi over

Okay, so what are the testing requirements in section eight? Can you put up a pic of the page or a link to the manual?

Web

8.0 POST-ASSEMBLY TESTING 8.5
LONG TERM TEST (OPTIONAL)
Complete Magneto Reassembly, Section 7.0. Ensure that the T-118 Timing Pin has been removed.
A.
B.
4300 Series Magnetos
1. Test run the magneto for a minimum of three hours. Operate the magneto at 1725 RPM for the first two hours and 3400 RPM for the remaining hour.
2. Regular and consistent firing of the spark gaps is required during the entire test.
6300 Series magnetos
1. Test run the magneto for a minimum of three hours. Operate the magneto at 3000 RPM for the first two hours and 4500 RPM for the remaining hour.
2. Regular and consistent tiring of the spark gaps is required during the entire test.
TEMPERATURE TEST
8.1
A.
B.
8.2
A.
B.
8.3
A.
B.
8.4
A.
PRE-TEST PREPARATION
Mount the magneto on a suitable test stand in the same position as installed on the engine.
Install a Slick High-Temperature Ignition Harness on the magneto and connect each output led to a 5mm spark gap.
IMPULSE COUPLING
Rotate the test stand drive pulley in the same direction of rotation as stated on the magneto data plate.
The impulse coupling should engage the stop pin in the magneto frame below approximately 200 RPM. If the impulse coupling pawls slip past the stop pin or engage intermittently, the impulse coupling is not operating properly,
COMING-IN SPEED
Determine the lowest speed at which the magneto can be turned and still spark all 5mm gaps without missing.
The test gap must fire consistently at 200 RPM maximum on non-impulse magnetos and 350 RPM maximum on impulse coupled magnetos.
HIGH-SPEED TEST
4300 Series Magnetos
1. Operate the magneto at 1000, 2000 and 3000 RPM for five minute at each speed setting.
2. Observe sparking regularity at the spark gaps. Magneto must produce a consistent spark at all speed settings.
8.6
CAUTION: DO NOT OPERATE THE MAGNETO UNLESS THE IGNITION HARNESS IS INSTALLED AND THE OUTPUT LEADS ARE CONNECTED TO THE 5mm GAP.
Measure the temperature on the outside surface of the magneto frame during the long-term test at the highest RPM setting. The magneto will generate heat during normal operation. Maximum temperature on the outside surface of the magneto frame is 175°F when tested at room temperature.
8.7 PRESSURE TESTING - PRESSURIZED MAGNETOS ONLY
After magneto assembly, install a pressurize

Notice the word (optional) in line two. Obviously not even a moron would send a repaired/reassembled mag go without a test run and test flight. But the whole page you posted is marked optional by the magneto manufacturer.

Web

Non regulatory logbook entry. A decision each mechanic makes on his own.

wireweinie said:

Notice the word (optional) in line two. Obviously not even a moron would send a repaired/reassembled mag go without a test run and test flight. But the whole page you posted is marked optional by the magneto manufacturer.

Web

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The optional was for a long test, it really did not post well in the forum. Section 8.5

Do you have a manual number or title where I could pull this up?

Web

I don’t mess with them either or carbs as I have many options of shops that specialize in just that within a 20 minute drive. Mags and carbs. Those thing will bring you out of the sky(and I’m the guy that doesn’t care if your wing is ripped off, I’ll make it fly home safely) not worth it for me to learn and tool up for it to do one every few years... gave away all my test equipment I had. drop it off get a yellow tagged one back. As far as the anchorage shop, not sure if same shop. But Orville said the best thing for his business was pilots doing a bunch of inflight mag checks.... he had the accessory shop on Merril field decades ago.


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