500 hrs mag inspection - mandatory or reccmendation

bavreze

bavreze

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bavareze
Hello!

I have a 1974 150cp C172M with O-320 engine

the annual lapsed for 2 months so I was unable to fly it to the place I usually do the annual inspections, so I had to use an IA on the field where I am (KCPM) an I do not really know or trust him too much and I am writing here to see if his squawks are legitimate or just a way to increase his labor hrs at my expense:

- he found that my side windows need replacement. I see very well through them, day or night. They are a bit green, but I guess that is ok, most cars have some tint in the windows to block the sun, is this not ok with airplanes? how is it to be determined - eyeballing and personal opinion only?

- he also noticed that the last mag inspection was done 550hrs ago. however, there is no abnormal sign coming from them, the ignition seems totally fine and the mag check RPM drop is what it is supposed to be, about 100rpm. he says there is a 500 hrs service interval for this kind of mags. is this a compulsory service interval (AD) or something like a TBO on the engine (you should do it but it is ok if you don't, as long as it checks ok)

If he is right I will obviously do what it is needed, but since I am not knowledgeable and I do not know the guy I am a bit skeptical

thanks!
 
bavreze said:
Hello!

I have a 1974 150cp C172M with O-320 engine

the annual lapsed for 2 months so I was unable to fly it to the place I usually do the annual inspections, so I had to use an IA on the field where I am (KCPM) an I do not really know or trust him too much and I am writing here to see if his squawks are legitimate or just a way to increase his labor hrs at my expense:

- he found that my side windows need replacement. I see very well through them, day or night. They are a bit green, but I guess that is ok, most cars have some tint in the windows to block the sun, is this not ok with airplanes? how is it to be determined - eyeballing and personal opinion only?

- he also noticed that the last mag inspection was done 550hrs ago. however, there is no abnormal sign coming from them, the ignition seems totally fine and the mag check RPM drop is what it is supposed to be, about 100rpm. he says there is a 500 hrs service interval for this kind of mags. is this a compulsory service interval (AD) or something like a TBO on the engine (you should do it but it is ok if you don't, as long as it checks ok)

If he is right I will obviously do what it is needed, but since I am not knowledgeable and I do not know the guy I am a bit skeptical

thanks!
Click to expand...

Of course, you could have asked the FADO for a ferry permit and flown to your usual shop... You did not have to use the local guy.

The windows came green from Cessna.

The 500 hour is not mandatory, but a really good idea...

Paul
 
bavreze said:
Hello!

I have a 1974 150cp C172M with O-320 engine

the annual lapsed for 2 months so I was unable to fly it to the place I usually do the annual inspections, so I had to use an IA on the field where I am (KCPM) an I do not really know or trust him too much and I am writing here to see if his squawks are legitimate or just a way to increase his labor hrs at my expense:

- he found that my side windows need replacement. I see very well through them, day or night. They are a bit green, but I guess that is ok, most cars have some tint in the windows to block the sun, is this not ok with airplanes? how is it to be determined - eyeballing and personal opinion only?

- he also noticed that the last mag inspection was done 550hrs ago. however, there is no abnormal sign coming from them, the ignition seems totally fine and the mag check RPM drop is what it is supposed to be, about 100rpm. he says there is a 500 hrs service interval for this kind of mags. is this a compulsory service interval (AD) or something like a TBO on the engine (you should do it but it is ok if you don't, as long as it checks ok)

If he is right I will obviously do what it is needed, but since I am not knowledgeable and I do not know the guy I am a bit skeptical

thanks!
Click to expand...

Ask him to complete,the *inspection* and give you a *separate* list of discrepancies, not to be recorded in the logbook. Then fly to your usual shop and have him address... Can be as easy as a maintenance record that the windows are Ok.
 
PaulMillner said:
Ask him to complete,the *inspection* and give you a *separate* list of discrepancies, not to be recorded in the logbook. Then fly to your usual shop and have him address... Can be as easy as a maintenance record that the windows are Ok.
Click to expand...

so, assuming the only discrepancy left is the one that the mags are 550 hrs since the last inspection, this would be no valid reason to reject issuing the PASSED annual inspection...

i will ask him to write the annual inspection with discrepancy, then list the mags "kinda old" as the sole discrepancy, but i guess he would have to write either an non-compliant AD or a non-compliant mag check there, or else the discrepancy list would be invalid as "kinda old" is not a reason to fail ...
 
Did he say the mag check was mandatory or recommended ? With over 500 hrs on the mags it would be a good idea to have the check or rebuild done. Most mechanics have their own idea of what should be done on an annual. The windows are probably fine.
 
These type of issues "should I look at" are designed to prevent problems. Odds are that your mags are going to have some wear after 500 hours. This will result in engine start issues (or worse) if left unattended. I speak from experience.
 
It depends on the mag, if yours is subject to the 500hr impulse coupling AD, that is mandatory. It would not likely be the green tint the IA is addressing, without a good photo it's hard to say if his call is justified or not. Excuse me if an anonymous owner claim of "I see out of them just fine" doesn't particularly impress me as evidence that the window doesn't need to be replaced. I have rented far too many planes with IMC in the cockpit on a CAVU day, "What are you complaining about? They're fine.":rolleyes:
 
bavreze said:
Hello!

I have a 1974 150cp C172M with O-320 engine

the annual lapsed for 2 months so I was unable to fly it to the place I usually do the annual inspections, so I had to use an IA on the field where I am (KCPM) an I do not really know or trust him too much and I am writing here to see if his squawks are legitimate or just a way to increase his labor hrs at my expense:

- he found that my side windows need replacement. I see very well through them, day or night. They are a bit green, but I guess that is ok, most cars have some tint in the windows to block the sun, is this not ok with airplanes? how is it to be determined - eyeballing and personal opinion only?

- he also noticed that the last mag inspection was done 550hrs ago. however, there is no abnormal sign coming from them, the ignition seems totally fine and the mag check RPM drop is what it is supposed to be, about 100rpm. he says there is a 500 hrs service interval for this kind of mags. is this a compulsory service interval (AD) or something like a TBO on the engine (you should do it but it is ok if you don't, as long as it checks ok)

If he is right I will obviously do what it is needed, but since I am not knowledgeable and I do not know the guy I am a bit skeptical

thanks!
Click to expand...

Unless the windows are cracked or broken, they are airworthy. That is a cosmetic issue. But as a IA it is his opinion, and his call.

The 500 hour mag inspection is a Service bulletin, they are not mandatory in part 91.

But again, when he does not feel they are airworthy, it is his call.
 
You have Slick 4371 (left) and 4370 (right) magnetos. They have a 500 hour "inspection" recommendation. It is just shy of an overhaul. I had mine (4373 and 4370 for an O-320-D2A) inspected at 500 hours by QAA of Tulsa Oklahoma back in 2013. One magento arrived incorrectly internally timed and would not allow the engine to start. My A&P opened it up, adjusted the internal timing, and got it to work. THEN he told me about it. Had he told me up front I would have told him to ship it back to QAA for them to fix. Fast forward to 2.5 years/144 hours later...I'm stuck on the ground with a dead Magneto and cannot get the plane started...only now it is out of warranty.

I bought two NEW magnetos, and am back up and running now. I WILL NOT fly behind anything QAA has touched.

The bad magneto is going back to them for them to try to figure out what happened.

They may be great for other people, but QAA has not been great for me. They offer an overhauled magneto for about 75% of the cost of a new magneto. No thanks, I'll either run to failure or I'll buy new every 500. I will not do another 500 hour inspection.

The cheapest kit I can find is here:
http://www.chiefaircraft.com/aircraft/ignition-system-mags-plugs/slick-magneto-kits.html
It looks like yours is either the SLK K4516-38 or SLK K4516-40 depending on if you want small barrel or large barrel plugs. The kit includes a 4370 and a 4371 magneto, a completely new wiring harness, and eight massive electrode champion spark plugs.
 
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Smart money is swapping your slicks out for bendix mags.

A overhaul is a bendix term, slicks are remove and replace.
 
James331 said:
Smart money is swapping your slicks out for bendix mags.
True
A overhaul is a bendix term, slicks are remove and replace.
Click to expand...
Not any more, all slicks can now be rebuilt.
 
That said, I'd still only fly behind bendix.
 
James331 said:
Smart money is swapping your slicks out for bendix mags.
Click to expand...

Smart money didn't have time to run a Field Change through the FAA and probably won't put 500 hours on his plane before he sells it anyway.

A overhaul is a bendix term, slicks are remove and replace.
Click to expand...

As of last year there are now Slick approved overhaul shops. QAA is one of them. I'll buy new instead.
 
Kiddo's Driver said:
Smart money didn't have time to run a Field Change through the FAA and probably won't put 500 hours on his plane before he sells it anyway.



As of last year there are now Slick approved overhaul shops. QAA is one of them. I'll buy new instead.
Click to expand...

Field change? Most planes it's just a log book entry.

For me, with a mag failure possibly getting me stuck on a lake in the middle of no where with no reception, Bendix it is.

Quite a few pilots would rather fly behind high time bendix compared to new slicks.
 
Mags are pretty important. I'd pull 'em and look at them.

My Bendix mags one of them had a broken spring behind one of the brushes that was not apparent flying or on runup.

When you think about the millions of revolutions they make during 500 hours they need to be pulled.
 
I spent most of a Saturday in Mexia, TX after a mag coil failed at just over 500 hours...I was really lucky to have a mechanic come out who had the parts on his shelf and got me going again.

IRAN the mags sooner rather than later. Doesn't have to be done by the guy on your field.
 
Coils...

#1 If your airplane was running great and you were told one of your coils was near death during a mag IRAN you'd balk at the costs. Slick coils are >$300 each no labor last time I looked

#2 If your airplane suffers a coil failure away from base you'll balk at the costs too.

#3 Coils just fail. There are certainly things that can influence it but they are essentially impossible to predict IMHO. I doubt a 500 inspection is going to catch much more than 25% of them that will pop before the next 500 hr.

If you pull the timing plugs or the harness caps and find no black powdery crap at 500 hrs, I'd feel fine with leaving them in service till my preferred mechanic can work them.
 
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I looked after a whole fleet of Slicks for a long time, and had very few problems with them outside of the quality control issues at the factory. Never had a coil failure. Never had an impulse problem. Had one, and one only, distributor block replacement. Never had any points or condenser problems. Looked at them every 500 hours and reset the E-gap, and at 1000 hours (the next 500) they usually needed new points.

Compare the list of ADs against Slick with the list against Bendixes, but be sure to look up all the Bendix ADs; there are at least three outfits that made them (Bendix, Bendix Electrical Controls, and TCM). 12 ADs among those three. Slick has a total of THREE ADs. I really get tired of some folks complaining about Slicks; they're thinking of the ancient versions that were a pain.

Both Bendix and Slick will suffer internal corrosion over time. They will both suffer aging of plastic parts. They will both have bearings that dry out and corrode and fall apart. Magnetos, no matter who makes them, need care just like Grandpa's old Chevy did.
 
The #of ads on brand x vs brand y really is somewhat meaningless...

I've seen crap that anyone would assume would be an AD and yet never make it to one. (Cracking wing spar caps on malibu comes to mind http://www.flyingmag.com/aircraft/m...ar-fatigue-crack-prompts-piper-pa-46-bulletin). Then there are some ADs that just seem over reaching or silly. Cessna 210 landing gear saddle cracking and life limit.

The carbon brush issue, had it been a Bendix, would probably been an AD. The slug of weak springs in points is another.

Champion spark plug resistances is another one that seemed to warrant an AD, and not even a peep via service letter or bulletin.

I've got an open slick coil that came from a fairly new mag, that failed on me shortly after takeoff in a Grumman AA-1C with a 150hp conversion.
 
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Dan Thomas said:
I looked after a whole fleet of Slicks for a long time, and had very few problems with them outside of the quality control issues at the factory. Never had a coil failure. Never had an impulse problem. Had one, and one only, distributor block replacement. Never had any points or condenser problems. Looked at them every 500 hours and reset the E-gap, and at 1000 hours (the next 500) they usually needed new points.

Compare the list of ADs against Slick with the list against Bendixes, but be sure to look up all the Bendix ADs; there are at least three outfits that made them (Bendix, Bendix Electrical Controls, and TCM). 12 ADs among those three. Slick has a total of THREE ADs. I really get tired of some folks complaining about Slicks; they're thinking of the ancient versions that were a pain.

Both Bendix and Slick will suffer internal corrosion over time. They will both suffer aging of plastic parts. They will both have bearings that dry out and corrode and fall apart. Magnetos, no matter who makes them, need care just like Grandpa's old Chevy did.
Click to expand...

One must remember that Bendix was making mags 50 years prior to Slick making one.

I worked there once upon a time.
 
My Humble opinion on mags,,

New is good, TCM is better.
 
bnt83 said:
I've got an open slick coil that came from a fairly new mag, that failed on me shortly after takeoff in a Grumman AA-1C with a 150hp conversion.
Click to expand...

I've got 50-60 old orange bendix coils that have the covers rotted off and still work, when dry. :)
 
James331 said:
That said, I'd still only fly behind bendix.
Click to expand...

Totally false. When Slicks first came out they couldnt be rebuilt. Couldnt get parts and mechanics only knew Bendix. Now they are known reliable and can be rebuilt. But this myth still refuses to die. Slicks are fine. I know from experience. Sure they can have problems, but no more than Bendix, possibly less. Lots of planes come with them. Mine have been very reliable.

One thing about mags. If you are going to service them, just do one. If they are old and you think you should replace, just replace one. That way they are very unlikely to fail at the same time.
 
coloradobluesky said:
Totally false. When Slicks first came out they couldnt be rebuilt. Couldnt get parts and mechanics only knew Bendix. Now they are known reliable and can be rebuilt. But this myth still refuses to die. Slicks are fine. I know from experience. Sure they can have problems, but no more than Bendix, possibly less. Lots of planes come with them. Mine have been very reliable.

One thing about mags. If you are going to service them, just do one. If they are old and you think you should replace, just replace one. That way they are very unlikely to fail at the same time.
Click to expand...

this........this is my experience also. A&P/IA :yes:
 
PaulMillner said:
Ask him to complete,the *inspection* and give you a *separate* list of discrepancies, not to be recorded in the logbook. Then fly to your usual shop and have him address... Can be as easy as a maintenance record that the windows are Ok.
Click to expand...

He'll still need a ferry permit if the IA didn't sign it off as airworthy.
 
bavreze said:
Hello!

I have a 1974 150cp C172M with O-320 engine

the annual lapsed for 2 months so I was unable to fly it to the place I usually do the annual inspections, so I had to use an IA on the field where I am (KCPM) an I do not really know or trust him too much and I am writing here to see if his squawks are legitimate or just a way to increase his labor hrs at my expense:

- he found that my side windows need replacement. I see very well through them, day or night. They are a bit green, but I guess that is ok, most cars have some tint in the windows to block the sun, is this not ok with airplanes? how is it to be determined - eyeballing and personal opinion only?

- he also noticed that the last mag inspection was done 550hrs ago. however, there is no abnormal sign coming from them, the ignition seems totally fine and the mag check RPM drop is what it is supposed to be, about 100rpm. he says there is a 500 hrs service interval for this kind of mags. is this a compulsory service interval (AD) or something like a TBO on the engine (you should do it but it is ok if you don't, as long as it checks ok)

If he is right I will obviously do what it is needed, but since I am not knowledgeable and I do not know the guy I am a bit skeptical

thanks!
Click to expand...

Since you know and trust your IA (the one you prefer to use), have you asked him for his opinion?

-Skip
 
coloradobluesky said:
Totally false. When Slicks first came out they couldnt be rebuilt.

This is true

mechanics only knew Bendix.

This is not, Slick did not supply parts or manuals for any of their early products.

Now they are known reliable and can be rebuilt. But this myth still refuses to die. Slicks are fine. I know from experience. Sure they can have problems, but no more than Bendix, possibly less. Lots of planes come with them. Mine have been very reliable.

One thing about mags. If you are going to service them, just do one. If they are old and you think you should replace, just replace one. That way they are very unlikely to fail at the same time.
Click to expand...

Slick sales were giving a $150 core charge for any old bendix mag, and won much of the market. Now TCM is using that same tactic to win back the market with the new TCM mags.
 
Tom-D said:
Slick sales were giving a $150 core charge for any old bendix mag, and won much of the market. Now TCM is using that same tactic to win back the market with the new TCM mags.
Click to expand...

Yep. Got a field approval to ditch two slicks (one impulse) and installed two TCM remans (both impulsed). Still happy to ditch the slicks and their ungodly parts costs.

Replace a bearing on a slick? Just throw the whole mag away. Need a new coil or distributor? Just buy a new mag and ebay the old one. Slicks are great lol.
 
bnt83 said:
Yep. Got a field approval to ditch two slicks (one impulse) and installed two TCM remans (both impulsed). Still happy to ditch the slicks and their ungodly parts costs.

Replace a bearing on a slick? Just throw the whole mag away. Need a new coil or distributor? Just buy a new mag and ebay the old one. Slicks are great lol.
Click to expand...

I once priced out the new parts to re-build a slick 6 cylinder mag, it was nearly the price of a new mag.
 
Checkout_my_Six said:
you were replacing all the parts? ....and the price was the same as new? :yikes:
Click to expand...

You can technically overhaul slick but per the book and the mandatory replacement parts, it costs so much just in parts it isn't economic. That doesn't include labor.
 
Yes, but Slicks regularly make it to when the engine gets rebuilt, never even opened. Even at that point, just replace one.
 
coloradobluesky said:
Yes, but Slicks regularly make it to when the engine gets rebuilt, never even opened. Even at that point, just replace one.
Click to expand...

I've had quite a different experience with slicks.
 
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