Magneto 500 hr Inspection Requirement

Fearless Tower

Fearless Tower

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Fearless Tower
500 hr magneto inspections - is it an airworthiness requirement, or is it like an engine TBO?

If regulatory, what is the reference?
 
What magneto -- Slick or Bendix? Which model? And yes, the answer does vary on those bases.
 
Ron Levy said:
What magneto -- Slick or Bendix? Which model? And yes, the answer does vary on those bases.
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I believe they are Slicks....have to check on the model. It's a C170 with a Continental O-300A, so just judging by the price diff between Slick and Bendix, I doubt that anyone would have installed Bendix mags in this bird.

According to the logs (and overall external condition of the mags would confirm this), they did not overhaul the mags when they overhauled the engine.
 
Depending on the model, there are also multiple ADs (74-26-09, 78-09-07 R3, 94-01-03 R2 for Bendix, 94-01-03 R2 for coils, 96-12-07 for impulse coupling) to name just a few.

You can visit the FAA's website on ADs and pull all of them and see which apply.
 
Why wouldn't any one install Bendix mags? that is what it cam with, the 500 hours inspections are a service bulletin, maybe a good idea, but not mandatory.

your mags will give you a good indication of failure long before they become dangerous. you have two of them, they may fail, but very very seldom will both fail at the same time.

the only failure items that effect both are the engine gear train, and the mag switch.
 
An O-300-A could have either Bendix or Slick mags. Better check the dataplate on the magneto for make/model.
 
Ron Levy said:
What magneto -- Slick or Bendix? Which model? And yes, the answer does vary on those bases.
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Show me a mandatory 500 hour inspection on any mag in part 91 service.

When you are up to date on AD compliance, you are up to date on inspections required.
 
Ron Levy said:
An O-300-A could have either Bendix or Slick mags. Better check the dataplate on the magneto for make/model.
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They can also have EISEMANN
 
Tom-D said:
Why wouldn't any one install Bendix mags? .
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My opinion/assumption only loosely based on current Bendix vs Slick prices and the overall condition of the plane - it has been kept airworthy, but not much extra expenses put in over the years.

your mags will give you a good indication of failure long before they become dangerous. you have two of them, they may fail, but very very seldom will both fail at the same time.
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They;re good on the runup, but definitely looking like they need replacement - at least one has oil leaking out of it identified on the pre-buy.

Based on the logs, the mags currently have around 1300 hrs or so with no inspection. I suspect that an inspection will reveal that at least one if not both needs significant overhaul if not outright replacement.

I am thinking that in the long run, it may pay to negotiate the selling price as-is and then replacing both mags and harness myself.
 
Tom-D said:
When you are up to date on AD compliance, you are up to date on inspections required.
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Well, yeah, of course that's true. But AD's are regulatory and thus mandatory (even for Part 91 operators), and without knowing the make/model of magneto, there's no way to tell if those AD's are fully c/w as of today.
 
Fearless Tower said:
According to the logs (and overall external condition of the mags would confirm this), they did not overhaul the mags when they overhauled the engine.
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If you are worried about the condition of the Bendix mags, do this,

remove the 1/2" inspection/timing plug at the top of the mag, and inspect for a "RED" coil toward the front of the mag, using a flashlight and a small inspection mirror. If you have a red coil, do not worry about the mags until you get a high mag drop.

If you got slicks, worry all the time. Specially if the are newer ones.
 
Fearless Tower said:
Based on the logs, the mags currently have around 1300 hrs or so with no inspection.
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If you have the maintenance records, those should include identification of the mag make/model as well as a record of AD applicability and compliance. If they don't, you might want to think twice about what else isn't in the records, and from that, whether you want to even consider buying this plane at all.

I am thinking that in the long run, it may pay to negotiate the selling price as-is and then replacing both mags and harness myself.
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...except (at the risk of sounding like Bill Clinton) you don't really know what "as is" is if the aircraft records are incomplete, so check the records before going further.
 
Ron Levy said:
Well, yeah, of course that's true. But AD's are regulatory and thus mandatory (even for Part 91 operators), and without knowing the make/model of magneto, there's no way to tell if those AD's are fully c/w as of today.
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The newest mag AD we have is "AD2005-12-06" and it applies to the impulse coupling not the interior of the mag. the only AD we have that requires opening the mag housing is AD 94-01-03R2 that requires a coil change.

READ the AD and see if you'd like to bet a "C" note that it is flying good with out a RED coil, and the AD complied with.
 
Ron Levy said:
If you have the maintenance records, those should include identification of the mag make/model as well as a record of AD applicability and compliance. If they don't, you might want to think twice about what else isn't in the records, and from that, whether you want to even consider buying this plane at all.

...except (at the risk of sounding like Bill Clinton) you don't really know what "as is" is if the aircraft records are incomplete, so check the records before going further.
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I have a better IDEA, have some body that knows his elbow from his ____ inspect the aircraft. 170s are brick simple but they do have their soft spots.

and if you buy a 170 with any of the well known soft spots they can get damned expensive to repair. specially the main spar cabin carry thru corrosion, where the whole top cabin skin and carry thru must be replaced, and you can't see it with out a bore scope.

OR
a bent gear box, which most have.

OR
a cracked rear fuselage bulkhead.

the list goes on and on.

have some body that knows 170s do the prebuy.
 
Tom-D said:
I have a better IDEA, have some body that knows his elbow from his ____ inspect the aircraft. 170s are brick simple but they do have their soft spots.
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Ain't much point paying a mechanic to do the physical inspection if an ordinary pilot can see the records ain't right. I wouldn't invest in that pre-purchase inspection if the records and the aircraft didn't look right to me as the buyer -- I consider that another step or two down the line.
 
Ron Levy said:
Ain't much point paying a mechanic to do the physical inspection if an ordinary pilot can see the records ain't right. I wouldn't invest in that pre-purchase inspection if the records and the aircraft didn't look right to me as the buyer -- I consider that another step or two down the line.
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With out knowing what is right and what's not how will you know the difference?
 
Ron Levy said:
Do what the OP did, and ask for help here. ;)
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Here is the wrong place. he should have found his A&P-IA before he found his aircraft.

The 170 is a wonderful old aircraft but they are upwards of 60 years old, and a 15 minute walk around will tell you if the aircraft is even worth considering.

Specially the 48 rag wing, which is the only 170 that requires a fuel pump. Which if missing can't be retro fitted because there are no parts. the check valve that allows it to work is a one of a kind, and they are chicken lips, there just isn't any.

will the logs tell you that?

Nope do the walk around first, then the logs, because the log retro fit is just paper work, the material condition is a greater money matter than the ink.
 
Tom-D said:
specially the main spar cabin carry thru corrosion, where the whole top cabin skin and carry thru must be replaced, and you can't see it with out a bore scope.
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Tom, can you ellaborate on this one....this was one area that my pre-buy guy did not do (He unzipped the interior lining and took a good look inside - very clean interior actually, but he did not boroscope anything). There was no other corrosion identified anywhere else on the plane though. Should I still be concerned?
 
Tom-D said:
Specially the 48 rag wing, which is the only 170 that requires a fuel pump. Which if missing can't be retro fitted because there are no parts. the check valve that allows it to work is a one of a kind, and they are chicken lips, there just isn't any.
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Okay, this part is bothering me........I'll admit that I went a little backward - found airplane then went and found independent knowledgeable A&P, although I did not think to ask if he was knowledgeable with 48's vs A's and B's.

So, I was not looking for a fuel pump and I don't know if he was either. In other words, at the moment I have no idea if there was a fuel pump installed or not.

Is that fuel pump required only due to the design of the fuel lines in the '48s, or is it related to the orginal C-145 engines? This plane as a newer O-300A installed and it has a carb accel pump, but not sure about a separate fuel pump. I'll have to ask the owner on that one.

I have a bad feeling that the fuel pump is somewhere still attached to the original C-145 that was removed when the installed the overhauled O-300.

Where is the fuel pump supposed to be mounted?
 
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Fearless Tower said:
Tom, can you ellaborate on this one....this was one area that my pre-buy guy did not do (He unzipped the interior lining and took a good look inside - very clean interior actually, but he did not boroscope anything). There was no other corrosion identified anywhere else on the plane though. Should I still be concerned?
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Very much so,,,, the front spar carry thru is hidden from view from the interior, you must stick a bore scope into the wing root towards the cabin at the wing attachment point, past the bolt that holds the wing on the carry thru, to see the condition of interior of the carry thru.

also the glue that Cessna used to hold the interior in place was corrosive, the rear cabin formers at the rear seat upper supports is usually the first to show the problem. These are usually hidden under the head liner glued to the formers now.

When was the present interior installed?
 
As it now appears the OP already had a mechanic do a pre-purchase inspection, I will modify what I said above.

If, after conducting a pre-purchase inspection on this plane, the mechanic who did it can't tell the OP whether there are any AD-mandated inspections/etc on the installed mags, and if so, whether or not they were done, and whether that leaky mag needs work or replacement or can be flown as is, the OP picked the wrong person for the job. I'd want my money back, and would then find someone more competent to perform this piece of work.
 
The mags physically looking ugly does not mean that they are in need of overhaul. All four of my mags look ugly, that's just the case. Remember the internals can be replaced a number of times without problems.

As Tom pointed out, you have two of them. While I don't necessarily agree with just flying around until you lose a mag, you do have redundancy there.
 
Fearless Tower said:
Okay, this part is bothering me........I'll admit that I went a little backward - found airplane then went and found independent knowledgeable A&P, although I did not think to ask if he was knowledgeable with 48's vs A's and B's.

So, I was not looking for a fuel pump and I don't know if he was either. In other words, at the moment I have no idea if there was a fuel pump installed or not.

Is that fuel pump required only due to the design of the fuel lines in the '48s, or is it related to the original C-145 engines? This plane as a newer O-300A installed and it has a carb accelerator pump, but not sure about a separate fuel pump. I'll have to ask the owner on that one.

I have a bad feeling that the fuel pump is somewhere still attached to the original C-145 that was removed when the installed the overhauled O-300.

Where is the fuel pump supposed to be mounted?
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The required fuel pump on the C145 A is mounted just forward of the #5 cylinder, and can be seen by looking in the right nostril vent, if it is not installed there will be a triangle cover over the mount pad.

The pump was needed to pass certification due to engine shut down at high angle of attack, because fuel will not flow down to the carb with the 48's fuel line position. the "A"s and "B"s are routed different, and thus do not need the pump.

The 48 will fly great with out it, until you try flying slow. then the engine quits.

and of course the aircraft isn't in compliance with its type certificate with out it. but many A&P-IAs do not know it is required on the 48. so it gets passed at annuals.
 
Ted DuPuis said:
The mags physically looking ugly does not mean that they are in need of overhaul.
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True, but I'd say that pretty good oil leak from the mag seal is indicative of a need for repair.

Remember the internals can be replaced a number of times without problems.
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I guess what I am trying to figure out is considering the fact that the mags are around 1300 hrs and were not overhauled when the engine was overhauled and considering the current condition, if it is even worth it pay for a 500 hr inspection on both mags knowing that they will probably need to be worked on. Seems like the cost could go up pretty good to where I'd wish I bought new mags in the first place. I've seen at least one quote for 500 hr inspection that was $250 per mag just for the inspection and 100/hr for repair costs plus any parts. Brand new slick mags and harness kit is around $21-2200.

But then again, I will admit that I am a newbie as a potential first-time plane owner.
 
Tom-D said:
let us hope they cleaned and treated the corrosion, ( they all have some) you will not know until the glue holding the fabric rots off.
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Actually it looked like they cleaned it pretty well - the mechanic was suprised how clean it was inside the lining.
 
Tom-D said:
The required fuel pump on the C145 A is mounted just forward of the #5 cylinder, and can be seen by looking in the right nostril vent, if it is not installed there will be a triangle cover over the mount pad.
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Is it the same for the O-300A?

I just called the shop - A&P says it did have a fuel pump. I think I'll check myself to make sure before writing a check!
 
Ron Levy said:
As it now appears the OP already had a mechanic do a pre-purchase inspection, I will modify what I said above.

If, after conducting a pre-purchase inspection on this plane, the mechanic who did it can't tell the OP whether there are any AD-mandated inspections/etc on the installed mags, and if so, whether or not they were done, and whether that leaky mag needs work or replacement or can be flown as is, the OP picked the wrong person for the job. I'd want my money back, and would then find someone more competent to perform this piece of work.
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What leaky mag,,,,,, did I miss something?

You must realize the 170 has no MM as such. many A&P-IAs use the 100 service manual, but it does not cover the 170, there is a book called the 170 service notes that will give the details of the 170 but most A&Ps don't have it. so a lot of stuff gets missed at annual time.

like the rear fuselage bulkhead cracking, there is no AD, but every 170 type know that is where the elevator stops are and they get banged a lot and the stops get pushed thru the aluminum bulkhead. I have replaced 4, it requires a fuselage jig, and about 5 days labor. at today shop rates.

I restored 3, and know that you can buy better aircraft than you can build.

Know what the serial number of your 170 is, and which style elevator is installed, there are three different types, and all fit, but only one can be flown to stall. and you survive.

Once the ragwing is metalized, it can never be returned to fabric, the aluminum sheet is held to the rib by rivets, the ribs are destroyed by drilling the holes for them, and there are no replacement ribs for the 170, unless you buy a different wing.
 
Fearless Tower said:
True, but I'd say that pretty good oil leak from the mag seal is indicative of a need for repair.
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Not necessarily. It's indicative of a need for the seal to be repaired. That's pretty simple. I had some mags that were leaking badly from the back seal. New seal, problem solved.

I guess what I am trying to figure out is considering the fact that the mags are around 1300 hrs and were not overhauled when the engine was overhauled and considering the current condition, if it is even worth it pay for a 500 hr inspection on both mags knowing that they will probably need to be worked on. Seems like the cost could go up pretty good to where I'd wish I bought new mags in the first place. I've seen at least one quote for 500 hr inspection that was $250 per mag just for the inspection and 100/hr for repair costs plus any parts. Brand new slick mags and harness kit is around $21-2200.

But then again, I will admit that I am a newbie as a potential first-time plane owner.
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If you're going to tear them apart, just pay the extra couple of bucks and overhaul the mags.
 
Fearless Tower said:
Is it the same for the O-300A?

I just called the shop - A&P says it did have a fuel pump. I think I'll check myself to make sure before writing a check!
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C-125, C-145, O-300-A are all the same case, in this respect. Only the C-170 48 rag wing needs the pump, remember its a aircraft appliance.
 
Ron Levy said:
As that's not listed in the TCDS, I'm guessing that's some sort of STC or other aftermarket approval.
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nope it was taken off when the company went out of business.
 
Fearless Tower said:
They;re good on the runup, but definitely looking like they need replacement - at least one has oil leaking out of it identified on the pre-buy.
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OK found it,

I'd really be certain it is the mag, because that is where all leaks in the Continental ends up.

If it is a mag leak, remove it, disassemble clean and replace the front seal. about 2 hours total labor.
 
Fearless Tower said:
True, but I'd say that pretty good oil leak from the mag seal is indicative of a need for repair.

Yes, but its an easy do... don't throw away good mags just for that.

I guess what I am trying to figure out is considering the fact that the mags are around 1300 hrs and were not overhauled when the engine was overhauled and considering the current condition, if it is even worth it pay for a 500 hr inspection on both mags knowing that they will probably need to be worked on. Seems like the cost could go up pretty good to where I'd wish I bought new mags in the first place. I've seen at least one quote for 500 hr inspection that was $250 per mag just for the inspection and 100/hr for repair costs plus any parts. Brand new slick mags and harness kit is around $21-2200.

But then again, I will admit that I am a newbie as a potential first-time plane owner.
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Overhauling a mag is a bad idea, you do what is called a IRAN, Inspect and repair as necessary. the red coils never go bad, and the rotor never has any problems, yet they get replaced during the overhaul, new parts have a habit of being cheaply built, the older mag parts are of a better quality than the new stuff.
the only thing that have problems in a mag are the distributor finger gets eroded, and the points get worn/pitted, plus the distributor gear gets pitted also. You can price these parts at AS&S to see what they cost, it isn't nearly the price you think.
 
Just figure into your negotiations to send the mags off at overhaul cost.
 
Tom-D said:
Overhauling a mag is a bad idea, you do what is called a IRAN, Inspect and repair as necessary. the red coils never go bad, and the rotor never has any problems, yet they get replaced during the overhaul, new parts have a habit of being cheaply built, the older mag parts are of a better quality than the new stuff.
the only thing that have problems in a mag are the distributor finger gets eroded, and the points get worn/pitted, plus the distributor gear gets pitted also. You can price these parts at AS&S to see what they cost, it isn't nearly the price you think.
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Ain't that the truth. I was dreading the mag inspection on my first annual since it had something like 800 hours since last inspection/repair. Fortunately the A&P knew his business and just replaced a few parts for about 0.3 AMU or so total. Cheap compared to what I was expecting.
 
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