Engine or mag problem - Need suggestions

[NotarPilot]

I recently had an issue that has left my A&P stumped and my plane AOG. Earlier this month I did a normal run-up and when I switched to the left mag I experienced increased roughness, about a 200-300 RPM drop, an increase in MP and a normal rise in EGT. I checked the right mag and no issue, normal RPM drop, normal EGT rise and no excessive roughness, everything appeared normal. I thought maybe I had a fouled plug so I tried running it up and leaning it out to no avail. 

I had my mechanic check it. He checked the spark plugs but they were not fouled. Next he swapped P-leads. When he did that the problem switched to the right mag which told him either the ignition switch was bad or we had a bad P-lead. The ignition switch was original and had a reoccurring AD so I didn't mind replacing that anyways. I bought a brand new ignition switch and P-leads were both replaced yet the problem persists. The Bendix dual mag was IRAN'd last Dec and only has about 55 hours on it. My mechanic called the place that did the mag work (Aero Accessories in Van Nuys) and they suggested sending back the dual mag so they can inspect it and see if there's a problem. I can't imagine it's the mag being that swapping the P-leads caused the problem to switch sides. I was convinced it was the ignition switch or a bad P-lead. 

Has anyone else had an issue like this? Any suggestions? Here's a screenshot of the EGTs and CHTs from the run-up the day I first experienced the problem. I probably checked it about three times which is why you see the ups and downs several times.

Edited September 24, 2016 by NotarPilot
Added additional information

[Hank]

I had a similar problem a year ago August. Retimed my mags, all better for two flights, then worse than before. Burning off made it worse. So I sent the left mag for R&R, been smooth since then. No idea what's inside a dual mag . . .

[Marauder]

I recently had an issue that has left my A&P stumped and my plane AOG. Earlier this month I did a normal run-up and when I switched to the left mag I experienced increased roughness, about a 200-300 RPM drop, an increase in MP and a normal rise in EGT. I checked the right mag and no issue, normal RPM drop, normal EGT rise and no excessive roughness, everything appeared normal. I thought maybe I had a fouled plug so I tried running it up and leaning it out to no avail. 
I had my mechanic check it. He checked the spark plugs but they were not fouled. Next he swapped P-leads. When he did that the problem switched to the right mag which told him either the ignition switch was bad or we had a bad P-lead. The ignition switch was original and had a reoccurring AD so I didn't mind replacing that anyways. I bought a brand new ignition switch and P-leads were both replaced yet the problem persists. The Bendix dual mag was IRAN'd last Dec and only has about 55 hours on it. My mechanic called the place that did the mag work (Aero Accessories in Van Nuys) and they suggested sending back the dual mag so they can inspect it and see if there's a problem. I can't imagine it's the mag being that swapping the P-leads caused the problem to switch sides. I was convinced it was the ignition switch or a bad P-lead. 
Has anyone else had an issue like this? Any suggestions? Here's a screenshot of the EGTs and CHTs from the run-up the day I first experienced the problem. I probably checked it about three times which is why you see the ups and downs several times.

Steve -- you could be dealing with an early mortality issue with the reworked mags. I know it is a PITA to pull them but if the usual suspects have been looked at, not sure what other factors could be involved that gave you those symptoms. Might be worthwhile to see if any the IAs on this site respond before I did anything.

Are you a SavvyAviator customer? I will be uploading copies of my data later tonight for them to take a look at it.


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[carusoam]

Steve,

Can you state what you did during the time of the graph?

first what MP/rpm are you using for the mag tests?  (Set the rpm using MP, right? Prop control all the way in)

then state what occurred.

Start, left, both, right, both...

I think I see four EGT peaks, and one quirky CHT change of slope.

One of the EGT peaks looks a bit different than the other three. Just a bump.

the last two look better than the first two...

 

What I am seeing...

Start-up occurs.  Then after 3:45 all temps begin to rise... when MP is set for mag test..

this rise continues the whole time sort of muddying the test...(?)

first mag test occurs just prior to 4:15... EGT4 goes ballistic. As raw fuel is being dumped to the exhaust. Not enough time elapses to show EGTs returning to normal.

second mag test occurs just after 4:30.... all four EGTs show a slight bump. All EGTs show a decline... too low of an MP to get a good drop(?) or maybe the mag didn't get fully cut out(?)

Third mag test occurs around 4:45...  all four EGTs show a rise. But 1&4 show a larger rise than 2&3....

Fourth mag test at 5:15 seems normal...  all four rise in a similar fashion. This is the one where the CHT2 starts heating at a slower rate.

 

keep in mind the standard data collection rate for a jpi is six seconds.  If you are quickly running through the mag tests, the data won't keep up with what you are sensing.  The data collection rate is adjustable. See what you have it set on...

It might be helpful to collect specific clean data to send to the guys at savvy.  Planning timed intervals before hand would make data collection much cleaner.

Throw an extra minute in with the MP set prior to the first mag test.

Use the recommended rpms for the mag test, too low of an MP setting doesn't work as well as 1800 rpm.

allow the EGTs to rise for a few seconds on each mag test, before allowing them to drop on both mags. Watch the graph on the panel while doing this.  One eye on the graph, one eye outside.

same thing on the next mag... allow the EGTs to rise, watch them come back in line.

bad plugs usually stand out individually.

Bottom plugs with lead balls are more of a challenge to identify.

Mags that aren't grounding properly don't have EGT peaks, because they don't send raw fuel to the exhaust.

mags that are grounded continuously don't fire.  Broken p leads don't ground out the mag...

 

only PP ideas.  Not a mechanic.

See if I got any of this right.

When everything is working right, abbreviated, quick mag tests at lower rpm are the norm.  But when a mag test doesn't seem right, take a little extra time and MP to make sure the EGTs rise evenly and return to normal on both...

Best regards,

-a-

 

 

[NotarPilot]

Chris, I am not a Savvy customer. I might consider subscribing to the engine monitoring service if this doesn't get resolved though. 

A, forgive as I might not remember the precise sequence of events since it was almost 3 weeks ago now but I think I did the run-up like this... RPM set at 2000 RPM, MP at about 19", mags BOTH, L, R, L, R. 

I appreciate the suggestions about taking more time to do the run-up. I didn't think about the time intervals during data collection, I actually have an Insight G3 and not a JPI which records dats at 1 second intervals and not 6 like the JPI.

I won't be able to conduct another test because my A&P already removed the dual mag and is going to ship it back to Aero Accessories on Monday. I will definitely report the finding. I'm keeping my fingers crossed. Thank you all for your insight so far.

[MB65E]

Since you already have the mag off, and the way the graph looks it appears that 2 cylinders follow eachother, and the other 2 do not follow the first 2. Based on that I hope it's in the mag. 

I would run it with the inspected mag. Then if it continues I'd swap 1 and 4 plugs and see if it follows. 

I'm courious if it's in the plugs. 

-Matt

[carusoam]

The advantage of following the 

Both, mag1, both, mag2, both routine...

(I used mag1&2 here because they are interchangeable in order.... it doesn't matter which one you test first or second)

On one mag, while you are watching the rpm drop, there is a correlating EGT rise.

on both mags, the rpms return and the correlating EGTs all fall back in line.

Skipping the both step in between just muddies the data.  Rpm drop would become rpm stays down...EGT rise, would be EGT stays high... the bump is probably an artifact of the ignition switch itself, as it goes from mag1 only to mag2 only....

The G3 is really cool for doing the mag drop sequence, especially if you have FF and rpm connected through it.

1) It does the math for you.  Calculates the actual rpm drop...

2) For LOP, it includes the FF at peak of each cylinder.  Essentially does a gami spread each time you use it.  Smaller Gami spreads are better....

When you get the mag back.  Get ready to take a video of it working as expected! 

Best regards,

-a-

[NotarPilot]

17 hours ago, carusoam said:

The advantage of following the 

Both, mag1, both, mag2, both routine...

(I used mag1&2 here because they are interchangeable in order.... it doesn't matter which one you test first or second)

On one mag, while you are watching the rpm drop, there is a correlating EGT rise.

on both mags, the rpms return and the correlating EGTs all fall back in line.

Skipping the both step in between just muddies the data.  Rpm drop would become rpm stays down...EGT rise, would be EGT stays high... the bump is probably an artifact of the ignition switch itself, as it goes from mag1 only to mag2 only....

The G3 is really cool for doing the mag drop sequence, especially if you have FF and rpm connected through it.

1) It does the math for you.  Calculates the actual rpm drop...

2) For LOP, it includes the FF at peak of each cylinder.  Essentially does a gami spread each time you use it.  Smaller Gami spreads are better....

When you get the mag back.  Get ready to take a video of it working as expected! 

Best regards,

-a-

A, I'm hoping they find something amiss in the mag so we can get it fixed. I have FF hooked up on my Insight but the guy who installed it wasn't able to get the RPM function to work and it's been on my list of things to get done by someone else. I might get it done next month at the annual since I'm going to a new shop.

[NotarPilot]

Good news, my plane is back up and running. Apparently the mag shop discovered a plastic cam follower partially melted which wasn't allowing he points to open or close properly (sorry, can't remember which he said). The plastic may have melted due to an improper ground wire. Being that the P-leads were also replaced that should fix that. During my run up today the RPM barely dropped when I checked each mag by itself so it seems to be running better than it was before where I saw a little bit more of a RPM drop during mag checks.  Thanks again for your help and suggestions.

[N201MKTurbo]

Mine did the same thing about 80 hours out of overhaul. I had to reset the points on the ramp of a non-home airport with borrowed tools. You can reset the points and internal timing without removing the mag...

[Guest]

1 hour ago, NotarPilot said:

Good news, my plane is back up and running. Apparently the mag shop discovered a plastic cam follower partially melted which wasn't allowing he points to open or close properly (sorry, can't remember which he said). The plastic may have melted due to an improper ground wire. Being that the P-leads were also replaced that should fix that. During my run up today the RPM barely dropped when I checked each mag by itself so it seems to be running better than it was before where I saw a little bit more of a RPM drop during mag checks.  Thanks again for your help and suggestions.

The plastic cam inside Slick magnetos is famous for failing.  It's one of the improvements that Champion made to the Slick line when they off shored parts manufacturer.

Clarence

[carusoam]

Plastics are typically horrible in hot ozonated (O3) environments.  They get brittle and fail. They also may get brown in color appearing to have been cooked... crack propagation is a typical means of spreading a crack that starts at the surface...

Post a Photo if you can... 

Best regards,

-a-

[NotarPilot]

That's good to know for future reference.

[N201MKTurbo]

I think the cam followers on the points are nylon. One of the toughest plastics ever made.

[Guest]

It depends on magneto brand.  Slick has a plastic cam and a metal tab on the points.  TCM Bendix has a metal cam and a lubricated plastic arm on the points.

Clarence

[carusoam]

Nylon is great and has fantastic impact strength, until it ages in a hot ozone environment.

Corvette owners and firebird owners upgrade the headlight door drive system to brass after the first round of nylon gears give up.

Pain in the butt to get access to the gears too.

Best regards,

-a-

[NotarPilot]

Holy crap! These mags must have a personal vendetta against me. Issue was resolved then returned, same thing. My mechanic replaced the capacitors and they worked fine for two weeks. I did probably 10-12 flights all with run-ups and no issues. Today I do a run up, left mag and no rpm drop and no EGT rise. Switch to the right mag and rpm starts to drop like it's gonna quit but doesn't run rough. I switch to both and the RPM returns to 2,000. Try left again, same thing, no drop and no EGT rise. When I switched to the right I let the engine quit and it did. What the hell?

So far the ignition switch has been replaced with a brand new one, P-leads have both been replaced, the capacitors in the mag have been replaced and the mag was also sent back and the plastic cam followers in the dual mag have been replaced too. Any suggestions?

[carusoam]

Observations and logic of a PP:

1) Both mags on: best conditions observed...  (though, not as good as it should be)

2) Left mag on: conditions didn't change...  (This means the right mag wasn't helping in the first place.)

3) Proof comes when you switch to right mag and it still doesn't want to work.  But, the left mag isn't there to support it.

4) Left mag is behaving well.  Right mag needs some help...

5) Run down the list of connections from the ignition switch to the P-lead.  See if you can get the Right mag to behave.

6) Check in with your mechanic and let him know what you are seeing.

7) Tell us some detail about running on the right mag only.  Does it just quit when you turn the switch?  Or does it continue to struggle before dying?

8) If it is dead, the engine will just quit.  If it's timing just slipped (this happens often when mags get OH'd...)

9) Based on this tree of logic.  I would bet checking the timing of the right mag is in order...

10) Mags don't have a memory.  They can't hold a grudge or have a vendetta.  But, they can misbehave!

A reason why some people prefer not to swap out both mags at the same time.  This is a known form of infant mortality or strong illness...

I have learned this from people on MS.

Good luck.  

Best regards,

-a-

[Marauder]

Holy crap! These mags must have a personal vendetta against me. Issue was resolved then returned, same thing. My mechanic replaced the capacitors and they worked fine for two weeks. I did probably 10-12 flights all with run-ups and no issues. Today I do a run up, left mag and no rpm drop and no EGT rise. Switch to the right mag and rpm starts to drop like it's gonna quit but doesn't run rough. I switch to both and the RPM returns to 2,000. Try left again, same thing, no drop and no EGT rise. When I switched to the right I let the engine quit and it did. What the hell?
So far the ignition switch has been replaced with a brand new one, P-leads have both been replaced, the capacitors in the mag have been replaced and the mag was also sent back and the plastic cam followers in the dual mag have been replaced too. Any suggestions?

Wow Steve! You do have bad mojo going on with those mags. I haven't read through the entire thread too closely. Who did the mag work? Wondering if they keep missing something.


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[SpeedyJoe]

11 hours ago, NotarPilot said:

[...] Today I do a run up, left mag and no rpm drop and no EGT rise.[...]

NO rpm drop when running on just one mag is a red flag to me already. Either the other isn't doing anything or something with the switch / the leads is wrong and doesn't kill the other mag. 

If I were you I would consider the electronic magneto at this point, discussed on another thread. Once my magnetos are up for overhaul / give me any trouble, I will be replacing one of them.

[Guest]

4 hours ago, SpeedyJoe said:

NO rpm drop when running on just one mag is a red flag to me already. Either the other isn't doing anything or something with the switch / the leads is wrong and doesn't kill the other mag. 

If I were you I would consider the electronic magneto at this point, discussed on another thread. Once my magnetos are up for overhaul / give me any trouble, I will be replacing one of them.

I don't think electronic ignition is an option for the OP, he has a D3000 dual magneto.

Clarence

[NotarPilot]

Thanks for the response -a- I wasn't thinking of some of those things you mentioned, during my frustration (Forest through the trees) eh.

Chris, the mags were inspected by Aero Accessories in Van Nuys. 

SpeedyJoe, at this point I would love to go to an E-mag system at this point. I don't think I'd care about the cost at this point. I just want my reliable Mooney back. She's hardly given me any problems in almost 5 years of ownership. Now she's been AOG more in 2 months than flyable.

[Guest]

9 hours ago, NotarPilot said:

Thanks for the response -a- I wasn't thinking of some of those things you mentioned, during my frustration (Forest through the trees) eh.

Chris, the mags were inspected by Aero Accessories in Van Nuys. 

SpeedyJoe, at this point I would love to go to an E-mag system at this point. I don't think I'd care about the cost at this point. I just want my reliable Mooney back. She's hardly given me any problems in almost 5 years of ownership. Now she's been AOG more in 2 months than flyable.

I don't know if it has an STC, but this guy has a replacement for the D3000 magneto.

http://www.flyefii.com/products/ignition-systems/

Clarence

[N201MKTurbo]

People like to toute the benefits of electronic ignition by saying we can get more power and better mileage.  That is bull, our engines operate in a very narrow RPM range and fixed timing is fine. 

I would love to get rid of the points and the gears that spin the magnet in our magnetos. What could fail? A bearing?

[NotarPilot]

1 hour ago, M20Doc said:

I don't know if it has an STC, but this guy has a replacement for the D3000 magneto.

http://www.flyefii.com/products/ignition-systems/

Clarence

I doubt it since there's no mention of an STC on his website but I will call tomorrow just to ask.