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Dual Pmags, or surefly+pmag

RV74ME

Well Known Member
I currently have a slick mag on left, pmag on right. Considering replacing the slick with either surefly or another pmag.

From what I understand, the big difference in the two is that the surefly isn’t self powered like the pmag. Am I missing anything else? Can I use auto plugs with surefly?
 
Surely uses slick harness and NOT auto plugs, but massive plugs. If me, I’d go pmag both
 
I just went through the whole decision tree on electronic ignitions for aircraft. I built my first EI for a 1971 Toyota Corolla almost 50 years ago!

For various reasons, I ended up with my second choice, dual PMags on my new engine. My first choice was SDS, but I didn't want my whole engine dependent on a complicated electrical system. Since I an an EE, this is a pretty damning statement about my confidence in switches, relays, batteries, magnetic pickups and alternators... all of which have failed at some point when flying.

I wanted to eliminate as many electromechanical and electrochemical devices as possible in my critical ignition system (and/or fuel injection system), and reduce complexity and minimize connections. This led me to either PMags or conventional Mags. Since Mags have their share of reliability problems and the history of PMags showed a lot of teething problems as well, this was a tough decision.

We’ll see if I made the right choice.

VV
 
Dual pMags - the only thing I’d put on an RV. After ~1000 flawless hours on two RVs they have proven themselves reliable while providing measurable gains in cruise efficiency. AND I don’t have to mess with cleaning those over priced aviation plugs like I did on the RV-10 (but it now sports the new six cylinder pMag so the new owner is happy).

Carl
 
+1 for Vlittles comment.

My 3B is dual pmag with carb, simplicity & reliability.
My R4 is SDS ignition ( two batteries ) and AFP injection (two fuel pumps ) Again, simplicity and reliability.
 
Properly installed, two P-mags is by far the best option. Why mix technologies - the chance of both failing is almost un-heard of.
 
Properly installed, two P-mags is by far the best option. Why mix technologies - the chance of both failing is almost un-heard of.

Claiming that anything is clearly the best is a bit much. If you’re looking to truly optimize efficiency, something from SDS might be your choice. If you think you could find yourself with a dead battery one day, retaining an impulse coupled Mag is a good idea. There are dozens of combinations and to say one is clearly the best is a stretch.

Identify the mission and the desired results and pick systems to match.
 
Properly installed, two P-mags is by far the best option. Why mix technologies - the chance of both failing is almost un-heard of.

I was rather amused to learn (a recent thread) a P-mag could be failed simply by disconnecting a ground wire.
 
I was rather amused to learn (a recent thread) a P-mag could be failed simply by disconnecting a ground wire.

But of course anything electrical will fail simply by disconnecting a ground wire. Two P-mags each with their own ground wire (and every other wire needed to operate including plug wires, connectors and spark plugs), independent of each other, controllable/selectable and the engine capable of running well on just one or the other is some of why I chose dual P-mags for my RV7A. I also like the advance timing curve. Would do it again in a heartbeat. Make informed choices and understand your systems.

Bevan
 
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P-Mags

Dual P-Mags for over 1865 Hrs. I have found them to be more reliable than standard mags, and definitely a better ignition system than a Mag. So far, I'm still running massive aviation plugs, but that will change to auto plugs if I have any more ignition wires fail, as that harness isn't available from EMAG anymore.
 
I was rather amused to learn (a recent thread) a P-mag could be failed simply by disconnecting a ground wire.

Not exactly correct. Here is the blurb from the pMag install manual for wiring:
1. “1” connects directly to a nearby engine case ground using 18 gauge wire. Note: You cannot rely on the ignition’s mechanical attachment to the engine to provide ground. Aluminum anodizing acts as an electrical insulator, so the clamp connection to the anodized flange will not be a reliable ground.

So while I always provide a close engine case ground to the pMag, this tells me that both that ground and the pMag case to engine ground must be bad for the pMag to not work. I offer that if a magneto case to engine ground failed it too would stop working.

Carl
 
I currently have a slick mag on left, pmag on right. Considering replacing the slick with either surefly or another pmag.

From what I understand, the big difference in the two is that the surefly isn’t self powered like the pmag. Am I missing anything else? Can I use auto plugs with surefly?

I would be interested hearing why RV74ME wants to change from the Slick mag.

Are you looking for Added reliability? Added redundancy? Added performance? Or preceive that newer must be better, & have cash burning a hole in your pocket?

Added reliability - how? 2 ignitions is to afford redundancy in case one of them pack it in. PMag/Slick fills this requirement - cost zip.

Added Redundancy - unless you figure how to add a third ignition to your engine, changing to a different type or brand ignition gains you nothing.

Added performance - by changing the Slick for another PMag, is the only way to gain a slight incremental performance gain by synchronizing your advance curves so top & bottom plugs are firing at the same time. The Pmag/Slick combo you currently have in effect has the engine running on the PMag in cruise (advance timing) and the Slick firing slightly later effectively just along for the ride - filling the role as being Redundant. By mismatching other brand ignitions would have same effect of having slightly differing advance curves, performance wise you gain nothing over the PMag/Slick option. Only 'other brand option' would be by using SDS CPi ignition that could be programmed to mimic the PMag advance curve.

So the question comes back to why do you want to change?
 
Have you ever flown around a thunderstorm and wondered what would happen to your all electric airplane if you got zapped by a lightning bolt :eek:
 
Thanks all, some great points made. Nothing wrong with my current slick, but i have seen two slick failures...one of them made me think the engine was coming apart. That and i dont see the point in paying $500-$700 every 500 hrs. for overhaul when I’ve been very happy with my pmag. Just didnt know if going with surefly gained any real advantage over the pmag. There is no right or wrong, but definitely leaning towards swapping slick with 200 hrs on it (while still has decent value) for some form of electronic ignition.
 
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Have you ever flown around a thunderstorm and wondered what would happen to your all electric airplane if you got zapped by a lightning bolt :eek:

Have taken a documented strike on a composite homebuilt with one LSE ignition and one Slick while IFR/IMC, and more ice than I ever want to see on my airplane.

The LSE, as well as the panel mounted com, LORAN, and NAV122 and electric engine instruments (tach/OP/OT/EGT/CHT) went tango uniform . The Alcor fuel flow continued to work, but the whisky compass took a 45* deviation

The lone Slick, O-320 and gyros continued to work perfectly - had they not I might have had to see what ditching in Lake Pontchartrain was like.

30 years later, I still fly that plane with one LSE and one non-impulse Slick
 
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Have you ever flown around a thunderstorm and wondered what would happen to your all electric airplane if you got zapped by a lightning bolt :eek:

If my plane gets hit by lightning, I’ve got all kinds of unwanted problems. A bigger fear would be welded control surface hinges. For the sake of argument, is a dual Pmag equipped airplane considered “all electric” when a regular mag equipped airplane is not?
 
... Can I use auto plugs with surefly?

https://www.surefly.aero/faq

Can I use automotive spark plugs with a SIM?
The SIM is compatible with all automotive and aviation spark plugs. SureFly’s FAA STC’s do not grant permission to use automotive spark plugs in FAA certified engines. You may only use spark plugs FAA-approved for your application.

I've got two pmags which I like (so far), but if you are worried about a common "bug" hitting both pmags at the same time, the surefly seems like an option. Looks like a solid product, but I've seen many cases where in an effort to make things more resilient they actually become less resilient. This might be one of those cases, since you need to "learn" two different types of ignitions, make sure that they are both working optimally, etc.

If your concern is a massive electrical problem on your aircraft or EMP or lightning, then you have no choice but to stick with traditional mags.
 
If my plane gets hit by lightning, I’ve got all kinds of unwanted problems. A bigger fear would be welded control surface hinges. For the sake of argument, is a dual Pmag equipped airplane considered “all electric” when a regular mag equipped airplane is not?

In context of this discussion, YES. WHile the Pmag has it's own power source to insulate itself from loss of electrical source issues on the airframe, it is still a microprocessor based piece of electronics and would expect it to fail just like all of the other electonic, microprocessor based systems in your aircraft from over voltage, tansient spikes like a lightning strike, etc.

A mag has NO modern electronic components (chips, capacitors, resistors, etc.) and therefore quite unlikely to fail from a lightning strike.

Larry
 
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I have dual PMags. Love the way they start and the ease of auto-plugs. Mag drop is half of what my dual slicks have. One time my voltage reg crapped out and lost battery. Dual PMags kept on producing power until I Idled down after landing....at which time they both stopped since my battery was dead.

those that are running one slick.....The PMags have their own timing curve while the slick is fixed. Not a big concern but would think there is something else to consider.
 
A mag has NO modern electronic components (chips, capacitors, resistors, etc.) and therefore quite unlikely to fail from a lightning strike.

Larry
Ok so still possible. I guess it boils down to his level of risk tolerance for his airplane in such an unlikely event.

:cool:
 
Funny that it took 14 post to actually attempt to define the "mission" the OP was trying to enhance. Post #17 seems to indicate "reliability" is the focus, so my vote would be SDS CPI - no moving parts, no maintenance. Same architecture as Pmag (flying magnets, automotive coil, proprietary control module), but without the downside of having it all mounted in a tight package on a hot engine with whirring gears and shafts.
 
Funny that it took 14 post to actually attempt to define the "mission" the OP was trying to enhance. Post #17 seems to indicate "reliability" is the focus, so my vote would be SDS CPI - no moving parts, no maintenance. Same architecture as Pmag (flying magnets, automotive coil, proprietary control module), but without the downside of having it all mounted in a tight package on a hot engine with whirring gears and shafts.

I’m certain the sps is a great product, but I really don’t want to add another piece of equipment to my panel. As far as reliability goes, I think they are ALL reliable and all have their pros/cons.

At this stage of the game, I am very comfortable going with dual electronic ignition. But was mainly trying to figure out if there was any distinct advantage of “diversifying” (surefly+pmag) or just going dual pmags. Like I said, I’m happy with the one pmag I have now. Just didn’t know if I was missing something.
 
...mainly trying to figure out if there was any distinct advantage of “diversifying” (surefly+pmag) or just going dual pmags.

Probably not. Over time, the various human operators will arguably be the least reliable items in the loop, so keeping all factors the same for both ignitions is desirable.
 
I’m certain the sps is a great product, but I really don’t want to add another piece of equipment to my panel...

There is no requirement to add anthing to the panel with SDS. Dont want/need to look at the programmer? Fine, hide it under the panel somewhere. Its about the size of a pack of cigarettes and perfectly happy as an "install and forget" system.
 
Ok so still possible. I guess it boils down to his level of risk tolerance for his airplane in such an unlikely event.

Yes, very unlikely but it did happen to me, and I may be alive today because I elected to have a single LSE.

14,000', icing, over water, IMC, St Elmos Fire inside the cockpit - it would not have have been a good time to lose both ignition systems. But, I will allow it was not a good time to be airborne - period.
 
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All this talk of lightening taking out an electronic ignition has me scratching my head. How do airliners harden their electronic systems against a lightening strike? Electronic engine control started in the 80s, and full FADEC is common now. We don't hear about airliners falling out of the sky after lightening strikes and the FADEC computers getting fried.
 
But, I will allow it was not a good time to be airborne - period.
No amount of redundancy will prevent bad decision making.

THANKS for sharing your experience. It takes guts to admit this kind of mistake and I am glad it worked out for you.

:cool:
 
All this talk of lightening taking out an electronic ignition has me scratching my head. How do airliners harden their electronic systems against a lightening strike? Electronic engine control started in the 80s, and full FADEC is common now. We don't hear about airliners falling out of the sky after lightening strikes and the FADEC computers getting fried.

Not a double EE, but pretty confident that many things can be done to the airframe and the electronics to deal with lightning suppression. Decades ago I was in the telecom business and all of the equipment was designed with suppressors and various other methods for protecting electronic components from surges due to lightning. As many know, lightning frequently hits free hanging electrical distribution wires and telephone wires, as in many areas they are the highest point accessible to an earth ground.

I am confident that surviving lightning strikes is a design goal for boeing and it's avionics and engine suppliers, but don't know how much is in the electronics vs the airframe grounding system. I am equally confident that it is NOT a design goal for the pmag folks, or any of the GA EI suppliers.

I still believe that the best way to keep the prop spinning after a lightning strike is to have a traditional FI or carb and at least one traditional mag, assuming you think this a realistic threat for you.
 
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SNIP

I am confident that surviving lightning strikes is a design goal for boeing and it's avionics and engine suppliers. I am equally confident that it is NOT a design goal for the pmag folks.

I suspect this is not a design goal for Garmin either.

Perhaps some data would provide insight as to if this is a problem or not. How many people flying pMag lost an ignition due to lighting strike?

Carl
 
I suspect this is not a design goal for Garmin either.
Carl

Agreed. I would expect ANY experimental EFIS to have a high likelihood of failure following a lightning strike. That said, if anyone took on effort to minimize it, it would be garmin, as they may have some of this as legacy from their work in the certified world. Though unsure if the TSO requirements include surviving lightning. I tend to doubt it.
 
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Have you ever flown around a thunderstorm and wondered what would happen to your all electric airplane if you got zapped by a lightning bolt :eek:

On an aluminum aircraft? Likely nothing at all -- perhaps a slight disturbance to the compass &/or magnetometer as the magnetic flux density changes during the stroke...

Again, on an aluminum skinned aircraft, what happens to the hinge points on un-bonded control surfaces -- that's a concern.
 
All this talk of lightening taking out an electronic ignition has me scratching my head. How do airliners harden their electronic systems against a lightening strike? Electronic engine control started in the 80s, and full FADEC is common now. We don't hear about airliners falling out of the sky after lightening strikes and the FADEC computers getting fried.

I'd like to echo the above response and add that a fiberglass long-eze has a fuselage is a resistor not conductor to current flow. An Aluminum or Steel tube fuselage is a conductor. Thats a big difference when getting struck, or operating in that realm. Damage is pretty limited in a ship thats also a conductor.

I hope this thread doesn't stray from too much towards risk and engineering of lightening strike protection.
 
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Lightning strikes are the least of my worries. 30+ years and 20k hours flying airplanes has given me a healthy respect for thunderstorms, so I keep my distance.
 
“ Much consideration has been given to the LSE electronic ignition system's susceptibility to lightning strikes, static discharge and single event upsets. This environment is unique to aircraft and composite airplanes in particular. Critical microprocessor applications in the aerospace industry such as in space shuttle guidance computers or X31 electronic flight control systems, use three or more processors and a voting system which automatically selects the most accurate system.

As a result of investigating this potential problem, LSE decided to design discrete electronic components instead of using a much cheaper microprocessor. Using good grounding techniques and quality shielded wires for all connections, this system can be protected to a similar level as a magneto. As of today a conservatively estimated 90,000 hours have been flown in experimental aircraft using one or two LSE electronic ignition systems. There have been no reported problems from lightning strikes, static discharge, or EMI. One Glasair using one LSE CDI system and a magneto reported a lightning strike which failed two radios and a transponder without effecting the electronic ignition system.”

So there you go. At least one EI vendor has considered this issue. I am not necessarily agreeing with Klaus, but at least he considered it during design.

Anyone searched the accident reports to gather actual data?
VV
 
Lightning strikes are the least of my worries. 30+ years and 20k hours flying airplanes has given me a healthy respect for thunderstorms, so I keep my distance.

I'm building a VFR plane, but many people want IFR capability. As much as people get into inadvertent icing, people will also get struck by lightning. Not sure there's any RVs with weather radar, and we don't all have access to data link weather. Lightening detectors are marginal at best, and aren't very common either.

Anyway, back on topic. I'd install two of the same EIs. Operational simplicity.
 
All this talk of lightening taking out an electronic ignition has me scratching my head. How do airliners harden their electronic systems against a lightening strike? Electronic engine control started in the 80s, and full FADEC is common now. We don't hear about airliners falling out of the sky after lightening strikes and the FADEC computers getting fried.
I can assure you the standards and regulations for lightning protection are far more extensive for Air Transport Category planes. The FADEC besides having redundancy, they are shielded and power protected extensively. Can't compare them.

In general like a car a metal airplane, you and systems are in a metal envelope to route electrical charge, It enters and exits all on the outside of the envelope. Still there is a risk taking out any electronic device in a car or plane with a direct strike, especially if power supply. I have been hit a few times. Only once in a light plane, a piston twin, and a few times in a Jet. The former I had to clean my shorts and it caused some burn marks in fiberglass fairings and blew nav light lens off one wing. In the jet sometimes I did not know the plane was hit, but there were burn marks in gear doors or radome that were not there on previous walk around. There was convective activity in the area. Of ten jets are hit and no one knows. Sometimes planes induce a strike. Once there is a differential charge in cloud and you fly though the cloud, you can trigger a strike. So VFR it is unlikely you will be hit unless you are really unlucky to be between a cloud to cloud or cloud to ground strike. Of course stay clear of convective activity. if you see lightning go way around (50 miles), turn around or land. Planes have been hit flying next to a build up. Worse is if downwind of a cell and hail comes out the top and rains down on you even in clear air, VFR. So downwind of cell is more risk. Not to mention wind shear. Nothing to mess with in any plane small or large.
 
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