Time for a new Mag

[Greg_D]

2 hours ago, mooniac15u said:

Again, I think we have different definitions of marginally better.  There are things that an LOP mag check will find that a regular runup check won't.  There's a big gap between that and marginal value.  You seem to be convinced otherwise so I won't waste anymore time debating it with you.

Good enough since you aren’t debating the issue,  but dancing around it.  You haven’t shown the value difference between a simple continuity check and a full rich run up.  I believe they are approximately the same after seeing live data on a highly instrumented engine test stand.  And I’ll go as far as saying the full rich run up may even give a false sense of security that everything is OK.  The OP’s example is clear evidence of how that could happen.

[xcrmckenna]

Good enough since you aren’t debating the issue,  but dancing around it.  You haven’t shown the value difference between a simple continuity check and a full rich run up.  I believe they are approximately the same after seeing live data on a highly instrumented engine test stand.  And I’ll go as far as saying the full rich run up may even give a false sense of security that everything is OK.  The OP’s example is clear evidence of how that could happen.

I’m only asking, not debating. Since my Home Airport is above 3000’ I will lean on run up and take off. I actually lean just a little more during my run up since I only do it at 2000rpm’s would you say that useful situation or still view it as more harm than good? I’m not saying I will stop doing my run up tests but I did do my first inflight mag test yesterday and will put that into my check list.


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[MIm20c]

10 hours ago, gsxrpilot said:

Once I get back this weekend, we'll pull the right mag and take a look at it.

If you could update this thread with your findings I would appreciate it. I have one mag with 400 hrs on it and the other with 250. Trying to decide if both should be pulled at the next annual. 

[LANCECASPER]

5 hours ago, MIm20c said:

If you could update this thread with your findings I would appreciate it. I have one mag with 400 hrs on it and the other with 250. Trying to decide if both should be pulled at the next annual. 

If it was me i'd do them opposite years - the 400 hour one on next annual and then other one the year after that.

Seems like less potential for maintenance induced failure on critical parts.

[bradp]

Maybe just open look at the gears and for gross evidence of corrosion a-la the left mag and leave enough alone as lance suggests.

I had mag problems after last mag overhaul; fortunately it was the left and not both of them, but MIFs are a real concern. 

[MIm20c]

15 minutes ago, LANCECASPER said:

If it was me i'd do them opposite years - the 400 hour one on next annual and then other one the year after that.

Seems like less potential for maintenance induced failure on critical parts.

I was wondering about that. Keeping them staggered or having them both IRAN’d for extra safety. 

[kortopates]

It was something about the RPM gauge being connected to the left mag and blocking the vent hole. 

I am not buying it. The 2 mag's are identical part no's - both have impulse coupling. Both are pressurized by the same UDP air and mag air filter. Both are required to be fitted with vented plug that uses a calibrated orifice. The RPM sensor doesn't change this, it fits on as a washer below the vented cap. There is actually an additional washer to protect the rpm sensor - it's quite delicate and easily broken and not cheap. With the only difference being the equivalent of a couple washers under the vented cap, I can't see how he would say that.
However, there are some other installations such as the Cirrus SR22T where the Cirrus rpm sensor is being installed without a vented cap and it's lack of a vented cap is suspected of causing a lot early mag failures. But this isn't a problem with our Mooney's


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[jackn]

24 minutes ago, kortopates said:

I am not buying it. The 2 mag's are identical part no's - both have impulse coupling. Both are pressurized by the same UDP air and mag air filter. Both are required to be fitted with vented plug that uses a calibrated orifice. The RPM sensor doesn't change this, it fits on as a washer below the vented cap. There is actually an additional washer to protect the rpm sensor - it's quite delicate and easily broken and not cheap.

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I guess I’ll have to post a photo when I get a chance. The right mag does indeed have the gasket & washer, but that feeds the jpi. The rpm pickup on the left mag was a solid unit. Btw, here is the 100 hr inspection guide for the pressurized slick mags. Note 3.2.9

 

Edited December 15, 2017 by jackn

[kortopates]

I guess I’ll have to post a photo when I get a chance. The right mag does indeed have the gasket & washer, but that feeds the jpi. The rpm pickup on the left mag was a solid unit. Btw, here is the 100 hr inspection guide for the pressurized slick mags. Note 3.2.9
 

Good point, I wasn't thinking OEM pickup since Paul has a JPI EDM-900


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[LANCECASPER]

6 hours ago, jackn said:

I guess I’ll have to post a photo when I get a chance. The right mag does indeed have the gasket & washer, but that feeds the jpi. The rpm pickup on the left mag was a solid unit. Btw, here is the 100 hr inspection guide for the pressurized slick mags. Note 3.2.9

 

I hope that's every 500 hours and not every 100 hours.

[jackn]

9 hours ago, LANCECASPER said:

I hope that's every 500 hours and not every 100 hours.

Section 3.2 of L-1363F is for the 100 hr. Mostly it’s checking wires, p-leads and in- line filter. Although not required for part 91, it’s a really good idea. 

[LANCECASPER]

5 minutes ago, jackn said:

Section 3.2 of L-1363F is for the 100 hr. Mostly it’s checking wires, p-leads and in- line filter. Although not required for part 91, it’s a really good idea. 

Ok, sounds like a good idea every annual.

[kortopates]

I hope that's every 500 hours and not every 100 hours.

There are separate 100hr and 500hr inspections.


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[MB65E]

I wouldn't mind keeping a set staggered if I knew who did the last 500hr inspection. However, I haven't had good luck with new mags after about 400hrs. Very few high HP applications make the 500hrs. So that said if I have an issue with a mag after say 250-300h, I'll pull both to fix them, as the other mag probably is not too far away from the same condition as the one that has issues. 

-Matt

[jetdriven]

The Bendix mags whether S20s or 1200s go 500 hours regularly. In fact almost always. Slick mags maybe 50/50. They have a rash of issues. Cool failure. Burned Points. Melted breaker point cams. Melted  distributor rotors. Enough so that I pulled them off my plane and my boss, after having 3 mag failures on 2 years, pulled his off too. 

And they’re more expensive too. A Slick 4373 is 1150$ and a 4370 is 1009. You can buy Bendix cores from eBay and get overhauled Bendix mags for 700$ each. Then sell the slicks to RV builders. 

http://m.aircraftspruce.com/catalog/eppages/slickmag4300.php?gclid=CjwKCAiApdPRBRAdEiwA84bo3_m1qTRkiyhw4KNpB6jUgdy4D7Tl_WV4QtD8vht501o6QYvGIJBG4RoCRNoQAvD_BwE

yes you can get rebuilt Slick mags from Kelly now, but if you think New Slick mags are pieces of crap Then take a look at rebuilt mags with reused coils and condensers. And reused breaker point cams, they’re plastic.  They got approval for reusing parts in their whole overhaul process. Worse than the new, which is garbage to begin with.  Think I’m kidding? Google “slick mags” here and on other aviation websites. 

Edited December 17, 2017 by jetdriven