Took off on one mag accidentally - did I hurt my engine?

[PaulMillner]

Sure. But did they try one mag at full throttle?

Sure, I do that every flight, as part of my LOP cruise mag check... much more demanding of the ignition system than the pre-takeoff checks. On one mag, the EGTs go up, and if you wait a minute, the CHTs come down.

Paul

 

[Dan Thomas]

Sure, I do that every flight, as part of my LOP cruise mag check... much more demanding of the ignition system than the pre-takeoff checks. On one mag, the EGTs go up, and if you wait a minute, the CHTs come down.

Paul

But full throttle at sea level is a lot different than full throttle at cruise altitudes unless the engines is at least turbonormalized. Detonation requires cylinder pressures that are unachievable at altitude in an NA engine.

 

[Magman]

I’ve had folks that cite one occurrence as a reason to discredit techniques and phenomenons.

Don’t reset mag timing to factory spec is one. Never, ever take a cylinder off for repair is another.

Detonation is in the same boat. Some understand and believe and others say it won’t happen.

There are previously mentioned factors that favor detonation occurring.

The prudent pilot will strive to understand detonation and its control .

Ignoring it will not make it go away.

Removal or addition of some of the possible factors can change your whole day.

You bet your engine and potentially your life on this.


There are times when supposedly knowledgeable people provide erroneous information

or are misunderstood.

 

[Dan Thomas]

The prudent pilot will strive to understand detonation and its control .

The aviation textbooks are woefully inadequate on detonation.

Operating within POH/AFM stipulations will keep you well clear of detonation. But only a tiny percentage of pilots ever consult it, and many don't even have one for their airplane.

 

[Magman]

Many folks do not realize how close they are to entering the “ Realm of Detonation”.

Fortunately many of them are flying low compression engines with fuel octane well above the certification figure.

Examples :

Allowable mag drop is determined with detonation in mind. A dead plug MAY cause that one cylinder to
detonate.


Adjusting the. Prop Control to Full Increase on short final is preparing for a possible go- around.
Failure to do so may result in high BMEP on the go.


Few people would beat on their cylinders with a hammer, yet some will inadvertently do it with the Throttle.

 

[PaulMillner]

But full throttle at sea level is a lot different than full throttle at cruise altitudes unless the engines is at least turbonormalized. Detonation requires cylinder pressures that are unachievable at altitude in an NA engine.

Mine is turbonormalized, Dan... and switching to one mag effectively retards the timing, and cools the engine... even at full throttle.

Paul

 

[Joepilotmsp]

Not only did you hurt the engine, you ruined the whole airplane! Being the swell guy I am, I’ll take it off your hands out of the kindness of my heart. You’ll just need to cover fuel, food, entertainment and lodging while I take it on a few week cross country to see just how much money I’ll be losing, you know helping you out so much..

All seriousness aside, you’re most likely fine. So long as EGT didn’t redline and she weren’t knocking like a PO’ed landlord wanting three months past due rent. Wouldn’t make a habit out of it though. As others pointed out, the “both” position is there for a reason. Not sure how this happened.

 

[Eric Pauley]

Allowable mag drop is determined with detonation in mind. A dead plug MAY cause that one cylinder to detonate.

Source?

As Paul said, a dead plug (as opposed to damaged) should effectively retard timing. Should this not improve detonation margin?

Adjusting the. Prop Control to Full Increase on short final is preparing for a possible go- around.
Failure to do so may result in high BMEP on the go.

My engine is approved for continuous ops up to 5" oversquare at all MAPs. Why would it be any different during go around?

 

[Magman]

Source? Too numerous to list. Numerous Tech Manuals, videos from mfg. USAF FE training materials, numerous hours watching 112 plugs on “ Chinese Television “.

I suggest you gain an understanding of the phenomenon rather than discredit the existence.

With 1 plug inoperative the flame front take longer to move across the bore. This extra time allows compression and recompression of the unburned charge. Finally the remaining portion explodes. The high temps and pressures can severely damage cylinders.

With dual ignition the flame front starts from both sides and being of less duration does not allow
recompression/auto- ignition EXPLOSION to take occur . Note detonation is an explosion and not normal burning.

To my knowledge you have not stated your engine type. All engines have parameters that you can exceed at your
peril. What is allowable on yours does not mean ALL. So yours is restricted to 5 in OS. Why not 6, 7, 10 or 20?
There are a lot of different engines with different limits. I previously named some of the factors that cause
the phenomenon. These engine are not always perfect. ie An Economizer that is not adjusted properly can result in a Lean mixture at high power settings. All bets off on limits at that point.

These engines will take a lot of abuse but are not immune. 100LL provides an additional margin for engines designed to run on 73 or 80/87 octane. Contaminating proper fuel with lower octane products such as jet diesel or some mo-gas
can wreck some but be tolerated by others.

You are aware of the ADs regarding “ misfueling” ?

 

[Dan Thomas]

As Paul said, a dead plug (as opposed to damaged) should effectively retard timing. Should this not improve detonation margin?

If you Google "detonation in aircraft engines" you'll find plenty of explanations of detonation, but they're all inadequate. As I said earlier, twice, the fuel molecules are complex, detonation-resistant hydrocarbons that can break down into easily autoignitable molecules that don't wait for the normal flame front to reach them. The heat and pressure ahead of the flame front cause the breakdowns, and then the whole remaining unburnt fuel combines explosively with the oxygen. Normal flame front speeds are about 100 feet per second; detonation can produce speeds of around 5000 fps, and the pressures can damage the engine.

In the old days, crude oil was heated and vaporized and the various fractions condensed at different levels in the cooling tower and drawn off. Gasoline was a mix of a few of these fractions, and tetraethyl lead was added to control detonation. These days the oil is dismantled into more basic molecules, as I understand it, using catalysts and so on, and then there's a reassembly process to create detonation-resistant fuels. That's where unleaded Mogas comes from. Aviation gasolines are made in the same refinery, so are going though the same processes. Less TEL is necessary and we get 100LL with 2 grams of it per gallon instead of the 4 per gallon of the old 100/130 green stuff. 80/87 had 0.5.

Auto engines have variable timing, and almost since the introduction of ECUs have had knock sensors that tell the ECU to retard the timing and increase the mixture to stop it. In the old days we had to be careful not to "lug" the engine or we'd get that knock.

Now, it takes time for that big aircraft cylinder to burn. The engine is also running at lower RPM that the typical auto engine when it's working hard. Both of those increase the time it takes for the fuel molecules to break down into stuff that spontaneously ignites instead of waiting for the flame front. Another factor is heat; these things are aircooled and get pretty hot. Yet another factor is fixed timing, which sets the mix off at the same time regardless of whether the engine is a redline or in a low-RPM cruise, and with a CS prop we can get the MP way up at lower RPM, which raises the cylinder pressures and temperatures toward detonation points.

So, theoretically, a dead plug makes that cylinder burn slower, which leaves more time for molecular breakdown and detonation. The one saving factor is the lower CHT that results from a dead plug, and that lower temp will work against detonation.

And like I said before: Fly that engine as per the POH. It was drawn up by the engine and airframe manufacturers to make for safe flight. There's also some advice from the manufacturers on LOP operations, which don't show up in older POHs. Both Lyc and Cont have Engine Operator's Manuals available online.

 

[Eric Pauley]

Source? Too numerous to list. Numerous Tech Manuals, videos from mfg. USAF FE training materials, numerous hours watching 112 plugs on “ Chinese Television “.

Can you link one? I don't necessarily doubt this explanation but am struggling to find a single written source to back it up. To clarify, specifically wondering about a dead plug. Of course damaged plugs can cause hot spots/detonation (see link above).

 

[Pinecone]

With a single flame front, the pressures and temperatures are less. Combustion is slower. In most cases, less chance of detonation.

 

[Dan Thomas]

Amazing how the untrained and inexperienced know so much about aircraft engine and airframe stuff, to the point they diss the opinions and knowledge of those with the training and experience.

Preconceived notions, or ideas picked up from the wrong people, are the hardest thing for any instructor to deal with. Of the Seven Larning Factors, this one is the biggest:

9. PRIMACY - Present new knowledge or skills correctly the first time. (Teach it right the first time.)

(a) When students are presented with new knowledge or skills, the first impression received is almost unshakeable. This means that what you teach must be correct the first time. Students may forget the details of lessons, but will retain an overall image of the skill or knowledge for a long time. Frequently you will be required to perform manoeuvres in the aircraft before a student has had the necessary background training. You must perform those manoeuvres correctly or the student may imitate any errors you make. For example, before the exercise on cross-wind landings, you and your student are required to land in a cross-wind. Any poor example shown at this time would have to be "unlearned" when the exercise came up in a subsequent lesson.

This has to do with flight training, but I found the same phenomenon at work among some students in my college teaching on Aircraft Systems.

 

[Eric Pauley]

Amazing how the untrained and inexperienced know so much about aircraft engine and airframe stuff, to the point they diss the opinions and knowledge of those with the training and experience.

Preconceived notions, or ideas picked up from the wrong people, are the hardest thing for any instructor to deal with. Of the Seven Larning Factors, this one is the biggest:

9. PRIMACY - Present new knowledge or skills correctly the first time. (Teach it right the first time.)

(a) When students are presented with new knowledge or skills, the first impression received is almost unshakeable. This means that what you teach must be correct the first time. Students may forget the details of lessons, but will retain an overall image of the skill or knowledge for a long time. Frequently you will be required to perform manoeuvres in the aircraft before a student has had the necessary background training. You must perform those manoeuvres correctly or the student may imitate any errors you make. For example, before the exercise on cross-wind landings, you and your student are required to land in a cross-wind. Any poor example shown at this time would have to be "unlearned" when the exercise came up in a subsequent lesson.

This has to do with flight training, but I found the same phenomenon at work among some students in my college teaching on Aircraft Systems.

Asking for evidence of claims is not the same as dissing. 1. Make claim, 2. Provide Evidence. Simple.

 

[Eric Pauley]

Amazing how the untrained and inexperienced know so much about aircraft engine and airframe stuff, to the point they diss the opinions and knowledge of those with the training and experience.

Maybe you are right, but it’s hard to trust you without data/evidence when other things you’ve said clearly go against what people with far more credibility have said.

https://www.advancedpilot.com/articles.php?action=article&articleid=1838

“For optimum service life, Lycoming suggests operating 50 degrees rich of peak EGT or TIT.”

This was (and in many cases is) the manufacturer recommended leaning method. You’re telling me to follow it. Not good for credibility.

 

[Dan Thomas]

Maybe you are right, but it’s hard to trust you without data/evidence when other things you’ve said clearly go against what people with far more credibility have said.

https://www.advancedpilot.com/articles.php?action=article&articleid=1838

“For optimum service life, Lycoming suggests operating 50 degrees rich of peak EGT or TIT.”

This was (and in many cases is) the manufacturer recommended leaning method. You’re telling me to follow it. Not good for credibility.

A ten-year-old article that was already at least 8 years out of date when it was written. From the IO-360 Operator's Manual:

Does that look like Lycoming is recommending that you operate 50 degrees rich of peak? Nope. Looks to me like peak to 100° LOP is fine.

And from that same manual:

The manual is dated 2005, eight years before that article. https://www.lycoming.com/sites/default/files/attachments/O-HO-IO-HIO-AIO%20%26%20TIO-360%20Oper%20Manual%2060297-12.pdf

 

[Eric Pauley]

Indeed, eventually the people who questioned the status quo got the status quo changed. With evidence!

 

[Eric Pauley]

Still waiting for that link about single spark plug causing detonation, btw.

 

[Dan Thomas]

Indeed, eventually the people who questioned the status quo got the status quo changed. With evidence!

And you trust these guys to keep you up to date with old articles like that, wrong when they were written! How did they manage to write an article and had an eight-year retroactive effect on the manufacturer's recommendations?

Sometimes we DO get them to change stuff. Like the famously unreliable Champion sparkplugs with their spring-loaded internal resistor that made so much trouble for so many years. Auburn made plugs with molded-in resistors that never failed. Those plugs would run 800 hours and were replaced only due to erosion. I used a lot of them in the flight school airplanes. Then Champion bought the company and shut them down. Tempest/Unison came out with a monolithic-resistor plug that I started using, and we kept beefing about the failure rates of the Champions until finally, very quietly, in about 2015, Champion used that Auburn technology that they had owned for maybe ten years already and fixed their problem.

They went from this:

To this, with no announcement:

Nowhere do they admit that the fired-in resistor is a fix of any sort.

 

[Eric Pauley]

And you trust these guys to keep you up to date with old articles like that, wrong when they were written! How did they manage to write an article and had an eight-year retroactive effect on the manufacturer's recommendations?

The article was written in 2001 and retracted for political reasons. The link is a retrospective. I'd ask if you read beyond the third sentence, but it's literally in the third sentence.

 

[Dan Thomas]

Asking for evidence of claims is not the same as dissing. 1. Make claim, 2. Provide Evidence. Simple.

Still waiting for that link about single spark plug causing detonation, btw.

OK. You find a source of proof that a dead plug reduces the chances of detonation.

 

[Eric Pauley]

OK. You find a source of proof that a dead plug reduces the chances of detonation.

Should this not improve detonation margin?

Luckily for me I don't have to because I'm asking a question not making a claim. That being said I trust Paul more than you or Magman so he gets a pass without links.

 

[Magman]

Still waiting for that link about single spark plug causing detonation, btw.

Eric

There are quite a few folks on this and other forums that endeavor to share their hard acquired expertise with others.

Many of us are well too aware of the consequences of operating outside of proven criteria. We all have other activities

in life and are not here just to serve you. Since my last post on this board I returned a couple aircraft to service. These

were folks with long term relationships that want to get their aircraft in the air again. You may not be aware but this is

not something that is taken lightly. Until you are in a situation where you sign your name and put a lot on the line this is

likely lost on you. I could care less about your trust and impatience with me for not providing a link as rapidly as you

“ needed”.

Since in this situation you are the student I’ll give you some sources for your “ Research Project”.


“ Cyclone Combustion” is a very old b&w transfer of a 16 mm film. It is very well animated to provide an in- depth

understanding of the phenomenon.


Insight. The folks that produce the GEM - Graphic Engine Monitor will provide a vid that addresses this as well.


Sky Ranch Engineering Manual - Schwaner - is a good source.

Jeppesen A & P Powerplant textbook is another source.

AC 65-12A - FAA Powerplant Handbook is also useful.

Aircraft Maintenance Foundation - Reciprocating Engine Textbook is another.

Aircraft Powerplants - Bent - McKinley is a good read.

ASA. Powerplant textbook - Dale Crane is a valued reference book.

ASA General textbook - Dale Crane is highly recommended.


I’ve given you enough sources . Are you capable of producing a Report AFTER checking them out?

The clock starts now.

 

[Eric Pauley]

A single source (rather than a list of every book in existence with "detonation" in it) would have sufficed, so long as it's actually accessible to be inspected. Thanks to the magic of the Internet, though, here's a line for 65-12A that appears to be where you're coming from:

When only one spark plug is
firing in a cylinder, the charge is not consumed as
quickly as it would be if both plugs were firing.
This factor causes the peak pressure of combustion
to occur later on the power stroke. If the peak
pressure occurs later than normal, a loss of power
in that cylinder results. However, the power loss
from a single cylinder becomes a minor factor when
the effect of a longer burning time is considered.
A longer burning time overheats the affected cylin-
der, causing detonation, possible pre-ignition, and
perhaps permanent damage to the cylinder.

This book was written 52 years ago so it's unclear that this effect actually leads to lower detonation margins in practice. The proposed cause->effect chain is long and ignores other follow-on effects from single-plug operation (i.e., that the peak pressure is likely actually lower, in addition to being later).


There's also this from Sky Ranch:

Dual ignition sources speed up the combustion process and reduce the amount of the end gases as much as possible by spreading the flame front from two directions

I see where you're coming from in both cases, but given these were both written before there was any advanced instrumentation of combustion chambers I'm concerned about whether these insights actually hold. Neither source holds to this claim very strongly other than an aside mention and does not seem to consider all effects in play.

See an example pressure chart from GAMI (ignore the LOP part that's not important here):

Peak pressure is occuring after TDC even in rich operation. So delay in peak pressure will naturally lead to lower peak pressure because of cylinder geometry. This is not considered in either source.

I appreciate you taking the time to write such a thorough reply, though I fail to see how you reach the conclusion that "student" is some sort of putdown. I decided to do academic research instead of taking marching orders in industry because I enjoy the pursuit of knowledge based on evidence.

 

[Bell206]

I decided to do academic research instead of taking marching orders in industry because I enjoy the pursuit of knowledge based on evidence.

Unfortunately, you'll find in the aviation industry not all "knowledge" is learned from written evidence. Questioning the lack of evidence is normal but you'll find there is not always a convenient FAR or other specific hard document to answer or prove a point. Take the definition of airworthy. Until 2005 there was no regulatory definition of airworthy. The definition was implied by many for years but there was no hard copy to prove it. Since definition of airworthy wasn't important enough to document for so many years, neither were a number of other important facts especially on the maintenance/airworthiness side. It is what it is.

 

[Dan Thomas]

The article was written in 2001 and retracted for political reasons. The link is a retrospective. I'd ask if you read beyond the third sentence, but it's literally in the third sentence.

I saw that. And the question I still ask: Why did they publish an article that condemned Lycoming long after they had updated their operator's manuals? That is NOT honest journalism. They didn't even reference the 2005 manual, or any Lycoming updated manual or Service Letter.

And they're still using the old 75% cruise power figure for leaning. That was updated a long time ago, too. From the old Lycoming Key Reprints Flyer:

65%, not 75%. So that article is not fair to Lycoming or Continental or anyone else. The writer did not do his homework.

Lycoming has hundreds of documents, and every one of them has to pass a team of lawyers before its update is published. That's not Lycoming's fault; it's the fault of every greedy plaintiff that seeks to put the blame for their mistakes elsewhere, or wants a bunch of money, or both. That litigious attitude has driven up the costs of everything for everybody. The money that funds the vast legal industry comes from somewhere, and that's your wallet.

And every time they update a manual, they have to test the advice, of course. That takes time. The old advice has been working well, and the stats prove it. Pilot error is responsible for between 75 and 80% of failures, maintenance for a few more. Catastrophic structural engine failure is rare, and often due to poor maintenance practices. A few will blow up because the pilot has been mismanaging them. Some quit because the owner is just plain cheap.

https://www.aviationsafetymagazine.com/features/why-engines-fail/

https://www.avweb.com/flight-safety/accidents-ntsb/why-engines-quit-failures-are-avoidable/

There are plenty of articles like this. "Unknown cause of failure" is a common factor, and the investigators will often admit that they suspect carb Ice, since the engine was carbureted, the atmospheric conditions were conducive to carb ice, the carb heat control was found in the closed position, and there was absolutely nothing else wrong with the engine or the fuel system or anything else. In the flight school I found that getting the students to learn about carb ice and understand it was difficult. They often thought it was a wintertime thing, and we see that mistaken idea on POA all the time. One of our graduates got a job as a pipeline patrol pilot, and he heard a distress call from a commercial student in a 172 from another flight school when he was flying in the foothills of the Rockies. The guy's engine had quit and he was going down and gave a rough location. Our grad went looking for him and found him and orbited until a rescue helicopter got there. Spring time. He landed in a snowmelt-fed creek, got wet. In the mountains. And he was wearing shorts and sneakers and a t-shirt, didn't even have a jacket. We never let our students fly like that. He's lucky our grad found him, or hypothermia would have killed him by the time he was missed and someone went looking.

At any rate: the guy had pulled carb heat when the engine got rough, and it got rougher so he turned it off. A common mistake due to ignorance. The investigators helicoptered the airplane out, replaced the bent prop, and started it. It ran fine. Carb ice, but of course the ice was long gone by the time the investigators got to it. No evidence, no crime.

Poor training is a big factor, and poor study habits is another. It seems that few people are curious anymore, and they learn only as much as they need to to pass the exams.

 

[Eric Pauley]

Poor training is a big factor, and poor study habits is another. It seems that few people are curious anymore, and they learn only as much as they need to to pass the exams.

Very well-put. I like to think I'd remember to expect worsening roughness from carb heat (it's written all over the place and Piper AFMs clearly state to wait after applying heat). Not trusting myself on this was one reason to pick an IO engine.

The carb heat issue reminds me of Kahneman's "Thinking Fast and Slow" (Nice idea but not the best book). Pilot response to carb icing is an example of fast thinking leading to increased risk. As pilots we should try to eliminate as much fast thinking as possible by doing slow thinking. Developing and following checklists/memory items are a prime example.

I agree that the Lycoming blame game is extreme in that article. There's a difference between questioning existing/unsubstantiated wisdom (which I believe is a very good thing) and demonizing the source of that wisdom (something I try to avoid but am undoubtedly guilty of).

 

[Dan Thomas]

A single source (rather than a list of every book in existence with "detonation" in it) would have sufficed, so long as it's actually accessible to be inspected. Thanks to the magic of the Internet, though, here's a line for 65-12A that appears to be where you're coming from:

This book was written 52 years ago so it's unclear that this effect actually leads to lower detonation margins in practice. The proposed cause->effect chain is long and ignores other follow-on effects from single-plug operation (i.e., that the peak pressure is likely actually lower, in addition to being later).

I knew I'd read that somewhere, but it was a long time ago. I read a lot, sometimes a couple hundred books a year, but not many texts anymore. Being retired lets me read what I want to read. I was looking for the chemical breakdown factors in detonation, and found a few lengthy papers on the subject. There doesn't seem to be anything simple and understandable on that subject available to the pilot or mechanic. Like I said, the textbooks are woefully inadequate on detonation. They will cover the physics of carb ice, but not the chemistry of detonation.

Slow or late burns are dangerous. Not only can they give more time for detonation, if other factors are also present, they damage stuff. A couple of other mechanics were struggling to get a TSIO-540 to run and produce full power. They couldn't get it past about 1700 RPM at full throttle. I kept telling them to check that timing again, but they kept telling me that they had already reset it. Finally, they had it outside, dark already, and fired it up. Cowling off. The exhaust system was running red-hot even at 1700 and flame was coming out of the stacks. "Timing," I yelled at them. "It's way late. Check it again." They finally checked the timing and found it after TDC instead of 20° before. One of them had misread the mag timer's lights. They reclocked the mags and the engine worked normally.

 

[Dan Thomas]

I agree that the Lycoming blame game is extreme in that article. There's a difference between questioning existing/unsubstantiated wisdom (which I believe is a very good thing) and demonizing the source of that wisdom (something I try to avoid but am undoubtedly guilty of).

Lycoming has a reputation to protect and a huge liability threat hanging over them all the time. Guys like John Deakin and Mike Busch don't have that threat to deal with, so they can spout off on stuff on which they might very well be wrong. There is no shortage of experts seeking to make money by "correcting" everyone else. YouTube is a classic source of aviation misinformation.

 

[Magman]

A single peek at any multi - faceted item is not enough. Detonation is such an
item. Each author tries to present their view of the phenomenon. Ever hear of the blind men and the elephant ?

My belief is the biggest strides in recip technology were made in the WW2 era.
After that the focus went to turbines. While there is “ advanced instrumentation” for analysis today don’t underestimate the “Old School” either.

50+ years ago there were test engines with glass cylinders to observe combustion .

Transport Aircraft had Ignition Analyzers on board that permitted observing every single spark plug in flight. Engine Analyzers added other parameters.

Some aircraft had BMEP/Torque Meters to permit an indication of how much power the engine was actually producing.

A skilled FE could monitor and determine the health of an engine in- flight during the b&w tv era!

It would be really good if someone could put “Cyclone Combustion “ on- line.
While ancient; it provides the best insight into detonation I’ve ever seen. I did donate a copy to the Glenn Curtiss Museum in Hammondsport. So there are at least 2 in existence.

My intention was that “ Student “ was used in that you are a Student of the
Combustion process. I have no way of knowing what you do with your life.

We are all students in some respects. While I did have a Sinclair computer ages ago I have huge gaps in that department. I relied on my “ graphite rod that was cellulose enclosed and digitally manipulated with a rubber corrective device”.

Students that are motivated often learn more when furnished less information .
This makes them pursue sources of information that is more beneficial. Seems to have worked in your case.

If Detonation fascinates you checking out ADI. ( Anti Detonation Injection ) may be
worth your time.

 

[Sundancer]

I sort of thought of mags as primitive generators, probably butt simple. Anyway, they either were working OK, or not. If not, I'd write it up. Then I "helped" our club A&P at KFME rebuild a mag. Oh. . .there are a LOT of moving parts in there, plenty of them plastic-looking thingy's, and the design and engineering looked pretty darn crude.

My next club had replaced one mag with electronic ignition. More power, better fuel economy, plug life, and no failures.

 

[Magman]

Yet! Just about everything has some “ growing pains”.

 

[Dan Thomas]

Then I "helped" our club A&P at KFME rebuild a mag. Oh. . .there are a LOT of moving parts in there, plenty of them plastic-looking thingy's, and the design and engineering looked pretty darn crude.

A LOT of moving parts? Like the rotor, the points, a gear on the rotor that turns with it, and which turns the distributor gear? A total of three moving parts? Or maybe it was a dual Bendix mag with five moving parts?

Sure, they're primitive. They've been around for 150 years or so. But they are not complicated. At all. The engine has far more moving parts in it, even a "primitive" aircraft engine. A lawnmower is far more complicated than a magneto. A toaster has as many moving parts as a mag.

 

[Magman]

Isn’t there a scoop that takes money from your bank account?

 

[RyanB]

My next club had replaced one mag with electronic ignition. More power, better fuel economy, plug life, and no failures.

Some club plane (C172) came up here a number of weeks back with an electronic mag. It failed on them and was found during the run-up before heading home. They definitely can fail, as can all of this stuff, but that aside, I wouldn’t want one.

 

[Dan Thomas]

Some club plane (C172) came up here a number of weeks back with an electronic mag. It failed on them and was found during the run-up before heading home. They definitely can fail, as can all of this stuff, but that aside, I wouldn’t want one.

Yup. We're hearing complaints of failing electronic mags right here on POA. A magneto's robust construction lets it get shaken and heated. Electronic stuff does not like that at all. And that engine is shaking hard, all the time, and aircooled engines get mighty hot, too.

 

[Sundancer]

I liked the electronic ignition system - improves power and fuel efficiency for sure. But EIS failure rates as opposed to mags? I couldn't say.

 

[Sundancer]

A LOT of moving parts? Like the rotor, the points, a gear on the rotor that turns with it, and which turns the distributor gear? A total of three moving parts? Or maybe it was a dual Bendix mag with five moving parts?

Sure, they're primitive. They've been around for 150 years or so. But they are not complicated. At all. The engine has far more moving parts in it, even a "primitive" aircraft engine. A lawnmower is far more complicated than a magneto. A toaster has as many moving parts as a mag.

Not an A&P, don't play one on TV - but that mag was full off itt-bitty plastic pieces - lot's and lot's of pieces, moving or not. My understanding of EIS (and it's a VERY sketchy understanding) is an EIS "adapts" ignition to the conditions/demands on the engine, changing it on the fly. A mag does not. I couldn't say which is more rerliable or has a better MTBF - no clue. If they are anywhere near the same, I'd replace a mag with an EIS after having flown with one.

 

[Dan Thomas]

Not an A&P, don't play one on TV - but that mag was full off itt-bitty plastic pieces - lot's and lot's of pieces, moving or not. My understanding of EIS (and it's a VERY sketchy understanding) is an EIS "adapts" ignition to the conditions/demands on the engine, changing it on the fly. A mag does not. I couldn't say which is more rerliable or has a better MTBF - no clue. If they are anywhere near the same, I'd replace a mag with an EIS after having flown with one.

This is a Slick magneto, apart:

Almost all of that stuff is metal. The distributor housing, bearing support, gears, coil wrap and points cam are plastic for reasons of electrical insulation. What would you suggest instead? Metal will not work.

The electronic mag will be full of plastic as well, for the same reasons. Ever done any electronic building or repair? Ever looked at the schematic for a simple AM-FM radio? Here's one:

Every resistor, capacitor, transistor, wire, coil, and IC is mostly plastic. That electronic mag will be full of plastic stuff. Real tiny plastic stuff. I am not surprised that SureFly and others are encountering problems. As I said elsewhere in another thread, the car manufacturers do not put their electronics on the engine. Just a few sensors, whatever is absolutely necessary, is on that vibrating, hot engine. They learned a long time ago to keep the sensitive stuff somewhere else, and I am baffled why Surefly didn't do the same. I predict that they will eventually have to do it.

 

[Bell206]

I couldn't say which is more rerliable or has a better MTBF - no clue. If they are anywhere near the same, I'd replace a mag with an EIS after having flown with one.

If you research the failure data you'll find of all the components on your typical opposed engine the magnetos are the most reliable items. Even the mags that do fail, most are operator induced from lack of performing recommended maintenance or addressing OEM upgrades. As long as the engine turns a good mag will give spark. EIS on the other hand requires an external electrical source to provide the same. And since the electrical system is the most neglected system on a private aircraft I doubt any inherent reliability from EIS will be noted in the big picture.