Need some Serious brain power on this problem! HELP!

[Austintatious]

OK, I have wracked my brain for a few weeks on this and we still have not resolved an issue with a bad mag check.

Here's the story.  One of my Rockets has a Surefly mag installed on the RIGHT.   About 2 weeks ago while the other owner was flying it, The TIT and Cyl #5 went hot During flight.  He called me afterwards wondering what I thought might be going on.  I told him to go do a runup/mag check.  Sure enough the mag check was bad when running on only the RIGHT mag (surefly) and Number 5 went cold.

We started simple by removing and cleaning/gapping the plugs and injector for number 5.   This did not help.

We then inspected the plug wires, which have been installed for only around 80 hours.  They looked good, but for good measure we replaced the number 5 wire since we had one handy as we had purchased 2 surefly mags and wire sets, one for each of the two rockets we own.  We have not yet installed the surefly in ship number 2.   Replacing the number 5 wire did not help.

The next move was to replace the surefly mag itself as we didnt know what else could possibly be going on.  When we replaced the surefly mag, the issue went away.  We were a bit surprised and sent the surefly back for warranty repair.

All was good for about 4 flights / 4 hours.  Surefly called us and told us that there was nothing wrong with the mag we had sent them, it tested out properly.  Which we were left questioning as replacing it had resolved the issue.....

Then the same thing happened again in flight.  Only this time it was number 5 AND number 2.  A mag check confirmed that when running on the RIGHT (surefly) mag, number 5 and 2 were going cold.

 

I had the idea that the P leads might be backwards and it is the conventional mag that is misbehaving... we were able to verify that this is not the case.   We are now stuck and have no idea what could be going on.  The only thing we can think to try is to take out ALL spark plugs, clean and gap them.  We can also replace the entire wiring harness for the RIGHT/surefly mag. since we have a replacement on hand.  If this does not work, we can reinstall the conventional mag on the right and see if the problem remains.

 

NOTE:  the bad mag check seems to only happen after the engine is thoroughly heat soaked... if the run up is done on a "just warm enough" engine, the mag checks good.

 

If anyone has any ideas on what could be going on, please help, nobody  can seem to figure out what is happening.  It is unlikely that it is a problem with the Surefly mags, unless we got incredibly unlucky and got 2 of them with the same subtle defect that would cause this and not be detectable on a bench test.  I suppose it it possible that the heat could be effecting the sureflys and that causes issues when installed but not on the bench... that still seems unlikely because the aircraft has flown a lot on the surefly and there were no issues.  We have been very happy with the surefly and at this point blaming it does not seem reasonable, but it is the common denominator.

Edited July 5, 2022 by Austintatious

[EricJ]

Do I understand correctly that the surefly was installed both times when the problem occurred?

It appears to be not unusual that a surefly tests good on the factory test bench but misbehaves in the airplane.   This is not the first time I've heard of or seen this.    A local overheating case was cured by permanently replacing the surefly with the original Bendix mag. 

If the problem goes away when the surefly is removed that's likely the problem, even if it tests good on the factory test bench.

[N201MKTurbo]

I have no idea how a Surefly mag works. Well I might have a few ideas, but I've never seen a technical description of how it works, or a exploded view of what's inside. This leaves us with a black box that is apparently failing. I wouldn't expect much help, because nobody knows any more than you do.

I'm familiar with the Surefly problem @EricJ is talking about. Couldn't make the Surefly work reliably. put the MAG back on and everything worked just fine.

 

[Will.iam]

Are you on a 28v system and what version of surefly do you have? Neighbor had version one and transient voltage spikes were causing the surefly to misbehave enough to effect prop governor speed. Version 2 of surefly fixed his problem on the right engine (he has a twin with surefly on each engine) left one was fine throughout all of this. Then 2 months later left engine started acting up. And he got it replaced with version 2 surefly. Point is verify you have version 2 or demand replacement if you don’t and have a 28v system. Version one does strange things on 28v but is fine on 14v systems. 

[Austintatious]

  On 7/5/2022 at 3:19 PM, Will.iam said:

Are you on a 28v system and what version of surefly do you have? Neighbor had version one and transient voltage spikes were causing the surefly to misbehave enough to effect prop governor speed. Version 2 of surefly fixed his problem on the right engine (he has a twin with surefly on each engine) left one was fine throughout all of this. Then 2 months later left engine started acting up. And he got it replaced with version 2 surefly. Point is verify you have version 2 or demand replacement if you don’t and have a 28v system. Version one does strange things on 28v but is fine on 14v systems. 

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14 volt system.  It is a Rev A model.

Edited July 5, 2022 by Austintatious

[Austintatious]

  On 7/5/2022 at 3:05 PM, EricJ said:

Do I understand correctly that the surefly was installed both times when the problem occurred?

It appears to be not unusual that a surefly tests good on the factory test bench but misbehaves in the airplane.   This is not the first time I've heard of or seen this.    A local overheating case was cured by permanently replacing the surefly with the original Bendix mag. 

If the problem goes away when the surefly is removed that's likely the problem, even if it tests good on the factory test bench.

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Yes, the problem happened with 2 different sureflys.

The bold section disturbs me greatly.

[kortopates]

You should be able to determine if you have the earlier Surefly system that needs the voltage regulator service kit added for 24V installs with a call to surefly. But if you do, you should install the service kit.
That said though, your symptoms of misfire on specific cylinders is not consistent with the random re-boots that the original surefly was experiencing in 24V installations before adding the voltage regulator service kit which does entirely resolve that issue.
Furthermore, a mag doesn’t typically cause issues with just one or two plugs unless the issue is at the cap to mag interface. The mag usually causes symptoms (e.g. weak spark) on all the plugs it’s firing.


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[MikeOH]

Heat plus electronics = Problems

If it was me I’d put the tractor mag back in and go fly in the heat. If the issue doesn’t come back after a reasonable number of hours (based on how long you’ve seen it take to appear X 4), then I think you have your answer.

[Guest]

Long live the magneto!  We’ve just installed a second Surefly on an SR22.  Bets that they will find nothing wrong with it?

Clarence

[M20F]

  On 7/5/2022 at 9:44 PM, M20Doc said:

Long live the magneto!  We’ve just installed a second Surefly on an SR22.  Bets that they will find nothing wrong with it?

Clarence

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While I love old things one would think somebody would have figured it out for GA at this point.  The first thing I did on my MGB project was ditch the points. 
 

Hope springs eternal. 

[Austintatious]

UPDate:

We spoke with Surefly and they are saying it sounds like a harness issue.  We went with the Maggie harness on their suggestion.  We have a second, brand new harness at the ready so we are going to swap them out.  Surefly is also sending us a test harness that we can also try to see if this resolves the issue.

If that doesn't work, we will probably go back to the old tractor mag and then try to figure out what to do with TWO surefly mags we bought.

[N201MKTurbo]

  On 7/6/2022 at 2:09 PM, Austintatious said:

UPDate:

We spoke with Surefly and they are saying it sounds like a harness issue.  We went with the Maggie harness on their suggestion.  We have a second, brand new harness at the ready so we are going to swap them out.  Surefly is also sending us a test harness that we can also try to see if this resolves the issue.

If that doesn't work, we will probably go back to the old tractor mag and then try to figure out what to do with TWO surefly mags we bought.

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I have installed two Maggie harnesses lately. It is a rare combination of the highest quality and lowest price.

[takair]

Easy thing to do would be to swap plugs top to bottom and see what happens. Cracked plug can cause strange issues. Cleaning and gapping likely would not correct it but can make it worse. 

[Austintatious]

  On 7/6/2022 at 4:38 PM, takair said:

Easy thing to do would be to swap plugs top to bottom and see what happens. Cracked plug can cause strange issues. Cleaning and gapping likely would not correct it but can make it worse. 

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Thank you, yes we did do exactly that with no change... though I failed to mention that in the first post

 

[Igor_U]

What spark plugs do you have? Years ago, I had similar issue in 2 flights before annual spark plug would go off line. It turned out 6 out of 8 Champion spark plugs had much higher resistance than specified. We replaced all with Tempest plugs and problem went away. My new engine came with Champions, though...

[Igor_U]

  On 7/5/2022 at 3:34 PM, Austintatious said:

It appears to be not unusual that a surefly tests good on the factory test bench but misbehaves in the airplane.   This is not the first time I've heard of or seen this.    A local overheating case was cured by permanently replacing the surefly with the original Bendix mag. 

The bold section disturbs me greatly.

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yeah, disturbs me as well since I have Surefly installed on left mag side. It is working great, though and would not like to go back as I removed SoS and associated wiring and sold Left magneto.

[KSMooniac]

I agree with Igor... What kind of plugs are you running, and did you measure resistance? If they're champions, I'd their throw them all in the trash and install Tempest.

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[Austintatious]

  On 7/6/2022 at 4:49 PM, Igor_U said:

What spark plugs do you have? Years ago, I had similar issue in 2 flights before annual spark plug would go off line. It turned out 6 out of 8 Champion spark plugs had much higher resistance than specified. We replaced all with Tempest plugs and problem went away. My new engine came with Champions, though...

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Tempest plugs

 

[KSMooniac]

  On 7/6/2022 at 5:41 PM, Austintatious said:

Tempest plugs

 

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Well, dang!  There goes my easy answer.  Have you measured the resistance of them?  I did have a couple of their fine wires go out-of-spec over the last couple years after 1000+ hours on them.

[Will.iam]

I had a tempest plug die on me in the first few months. Had less than 50 hours on it! But other than that haven’t had an issue with tempest plugs. I went with maggie harnesses when i had the surefly installed and overhauled the other mag. Haven’t had any other issues going on 9 months since install. 

[Will.iam]

  On 7/5/2022 at 3:32 PM, Austintatious said:

14 volt system.  It is a Rev A model.

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Then you will not have the reboot problem like the 28v system causes. I would think if it’s working cold but acts up once the engine is heated up that one of the circuit boards has a weak solder joint that with heat expansion is causing an open. If this is reproducible on the ground then you could take a can of compressed air and flip it upside down to spray the liquid out onto the surefly housing will quickly drop the temp. We used to do that on circuit boards to test for weak solder joints. 

[Jblanton]

I finally found on mine that the conductor springs were not long enough on my new slick style harness cap.  look for burning where springs contact SIM.  Maggie harness fixed my problem.

[Ragsf15e]

  On 7/7/2022 at 12:05 PM, Jblanton said:

I finally found on mine that the conductor springs were not long enough on my new slick style harness cap.  look for burning where springs contact SIM.  Maggie harness fixed my problem.

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I just read another thread about a rough running SF and it was exactly the same reason.  Short springs corroded quickly. A better quality harness fixed it.

[chriscalandro]

Solid nope from me. 

[Austintatious]

Update.

Surefly offered to send us back the mag we sent them, as it had checked out OK on the bench, OR to send us a different overhauled mag REV 2.

We opted with the REV 2 replacement and installed it alone with a new harness.  The problem has gone away.  We will of course be watching it closely. 

Also upon close examination, the harness we replaced had absolutely no signs of any malfunction or damage/wear that might have caused the issue.

I guess we will see.  If we have the trouble again, the old Mag will be going back on the aircraft.