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  #21  
Old 02-24-2014, 03:09 PM
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RV10inOz RV10inOz is offline
 
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You have explained why the EGT may have been randomly high in two ways. The first being a connection issue. The second being a fouled plug. Both of these are valid for EGT excursions.

The CHT excursion is still not explained. Perhaps it was a connector issue, but normally they drop not skyrocket. But a failed probe can do anything I guess.

By the way a fouled plug will not give you a CHT rise, it will give you a drop in CHT along with a rise in EGT.

I would also caution you in selecting a higher heat range plug. Better ground leaning practices would be a good start, not using full rich on descent and landing or when taxiing.

Did you manage to get that data file?
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  #22  
Old 02-24-2014, 03:33 PM
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Quote:
Originally Posted by Toobuilder View Post
This reminds me that we are both blessed and cursed by the information available today. After all, these engines flew for decades with essentially zero health information available to the pilot. Yet when presented with information that is essentially impossible in the real world, we are inclined to believe it. Not saying that the OP did anything wrong by shutting down with 420/1750 temps displayed - just mentioning that you can't believe everything you see.

Runups were a lot easier when we only had oil pressure and oil temp to look at, weren't they?
Michael, there is only one statement in your post that is true. We are blessed by the available information today. The rest of your post is possibly dangerous to the untrained eye. Until you know how many peoples lives have been saved by an engine monitor and knowing what it was telling you, it is easy to make your assessment. Believe me, an inop EMS is a NOGO item for those of us who know better.

For a start, if you (and you should) have an EMS, it helps understanding what it is telling you. 99% of pilots are dogs watching TV. Simple as that. All the threads on VAF prove this. Don't feel like it is just VAF, same on Mooneyspace, Cirrus COPA, Beechtalk although the %age there is way better and by a long margin, pprune, the Cessna pilots association. Despite this, having an EMS and not knowing what it is telling you but taking action to not fly, investigate and seek help is far better than just blasting off.

I have had people with one CHT only tell me that they had a preignition event in a C172, and fortunately they had the probe on that cylinder, and he amazingly noticed the needle moving up quickly, he made the right call and even though it was trashed he made it. Had he had the probe on another cylinder, he would have been so far off the coast he would have been swimming in a section of coast known for the worlds apex predator. Then of course I compare this to all the data files APS have collected over the years where EMS's have saved the day.

I did a short lecture at an AOPA safety conference in the nations capital recently and used one real life scenario, we play back the JPI in real time, displaying everything, and paint the scenario as it happened. Out of a lecture room with 60-70 pilots, safety folk, ATSB and CASA folk.......how many survivors? I exclude the two past APS students coz they know the answer, but we killed every single one of them and their wives and kids in the back seat. All of them. I even had one guy telling me if we just switched that mag off it would save them.....sorry....it will not help. He and his family died twice!

So you can hopefully see why I am passionate about these things, when you have coached round the world pilot Ryan Campbell, and realise what can give you a bad day, when you have lived on the sidelines to the Whyalla crash and subsequent ballsup of an ATSB report and you know folk who have been a part of the Cessna twin exhaust AD, and how some lives are saved and others not, it becomes a very real thing.

If your EMS is telling you something....Believe it until proven otherwise!!

Now lets look back at the good old days, A&P's had plenty of work to do and parts and labour were cheap. Well not so, but lets assume so. Runups today are far better because if you always fly your plane and you do a mag check at TOD on the way in, your runup is already done. Better to find the bug today on descent than next Monday morning when you have a meeting to attend and you are at the runway end. Besides knowing what was wrong it is a direct hit on exactly the plug not just one of twelve.

What happens if you have two faulty plugs, and the old mag drop is about the same on each mag. You take off, but a LOP high power mag check will find this long before it is a problem found later and likely not doing an old rpm drop check.

Yes the old days were great. But in terms of an EMS, today is far better.

I hope you do not feel like I am picking on you or starting a fight, this is not the intention, but for those others reading this thread and easily (because it is convenient) take the view who cares about the EMS, the truth needs to be told. I was thinking over a beer I could tell you more....but it would take a carton or two

Cheers!
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  #23  
Old 02-24-2014, 03:33 PM
glider4 glider4 is offline
 
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Default Follow-up question

I'm still learning a lot about engine management so forgive me is this is a dumb question.
In a dual ignition system, if, in one cylinder, one plug is firing and one is firing inconsistently, wouldn't the CHT tend to rise when there was just one spark per cycle instead of two? I understand that if I was just on Left or Right "mag" and not on Both that CHT would drop when the single spark stopped sparking in one cylinder.
My local engine guru who saw the #4 plugs before cleaning thought this could explain the higher CHT during the run up. During my taxi to the run up area it was full rich at low RPM.
Also, he said it was not unusual to get some moderate levels of carbon fouling, especially in the lower plugs, during the first several hours of operation in a brand new engine until the rings seated. I spent today cleaning all the other plugs. They were all somewhat carbon fouled.
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  #24  
Old 02-24-2014, 04:14 PM
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Toobuilder Toobuilder is offline
 
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Yes, David, EMS are a good thing. And I also understand you are passionate (and have a financial interest) about it.

However, the point is, even by your own admission, this event is impossible. You said: "If the CHT went from 230 to 420 in a few seconds.....then this is a probe issue or something else. You just can't do that short of setting off an atomic weapon in there..."

So we have become slaves to numbers on the screen. On the balance, more info is better, but only if it is right. If pointing out this neutral observation constitues blasphemy or spreading "dangerous information" then so be it. Better start gathering up the firewood and hay bales... It certainly won't be the last time.
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  #25  
Old 02-24-2014, 04:33 PM
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TangoPapa TangoPapa is offline
 
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Default EGT CHT VIDEO

Quote:
Originally Posted by glider4 View Post
I'm still learning a lot about engine management so forgive me is this is a dumb question.
In a dual ignition system, if, in one cylinder, one plug is firing and one is firing inconsistently, wouldn't the CHT tend to rise when there was just one spark per cycle instead of two? I understand that if I was just on Left or Right "mag" and not on Both that CHT would drop when the single spark stopped sparking in one cylinder.
My local engine guru who saw the #4 plugs before cleaning thought this could explain the higher CHT during the run up. During my taxi to the run up area it was full rich at low RPM.
Also, he said it was not unusual to get some moderate levels of carbon fouling, especially in the lower plugs, during the first several hours of operation in a brand new engine until the rings seated. I spent today cleaning all the other plugs. They were all somewhat carbon fouled.
Watch this video presented by mike Busch on CHT,EGT and how they relate.
http://www.eaavideo.org/video.aspx?v=1316946190001
It will help you with your questions.
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Last edited by TangoPapa : 02-24-2014 at 07:24 PM.
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  #26  
Old 02-24-2014, 05:42 PM
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RV10inOz RV10inOz is offline
 
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Quote:
Originally Posted by Toobuilder View Post
Yes, David, EMS are a good thing. And I also understand you are passionate (and have a financial interest) about it.

However, the point is, even by your own admission, this event is impossible. You said: "If the CHT went from 230 to 420 in a few seconds.....then this is a probe issue or something else. You just can't do that short of setting off an atomic weapon in there..."

So we have become slaves to numbers on the screen. On the balance, more info is better, but only if it is right. If pointing out this neutral observation constitues blasphemy or spreading "dangerous information" then so be it. Better start gathering up the firewood and hay bales... It certainly won't be the last time.
Michael, if and only IF the event went from 230-420 in a couple of seconds, then yes it is impossible....but so far we do not have proof of that, it is not a data file in the guys memory, so what do you do? What if you are flying along and you see it.....just assume it is a bad probe? What about if you have your alarm set at 500dF (which is stupid but many do) and you see 480? Is it a bad probe? What do you do?

I agree, more info is better but only if it is right......but how can you tell? If you can't, you need to assume the worst and hope for the best, or be able to diagnose it on the spot. This is where 99% of pilots fall down. And some problems are not easy to find the exact fault in flight even with a lot of knowledge. This is why a data file is so valuable. Most folk do not study them on regular occasions or just prior to doing maintenance or an annual. And they should. This can be the payback time. Most do not get it.

Lets say you are flying a turbocharged plane, and for no good reason you have lost a couple of inches of MP. Do you just say....ohhh must have bumped the throttle and just push it forward and reset say 32"? No other data available and you can't diagnose that in the air........until it is too late.

Your NTSB has lots of dead people to verify this one.

By the way Michael, I am calling you out on this one (And I also understand you are passionate (and have a financial interest) about it.), and if this is the first time for you and I am confusing you with others I apologise, but it needs putting to bed. If you or anyone else anywhere else in the world does a live or online APS course.......I do not see one cent. Not one. Is that OK?

This notion that because a business unit is set up (which it has to be) and I am passionate about it, I must be making a fortune from it, is one of the most irritating aspects of the human condition. If and I say IF the course costs were sent to me 100% ....so what? I bet not one of the students would begrudge it. I am yet to meet a person who says afterwards they paid too much and many say too little or one recently, "where were you guys 20 years ago when I started out as a commercial operator and engineer" (A&P). Also RV8 builder/owner and a fleet of piston twins.

Why is it that Mike Busch who makes it his business, and wilfully plugs his SAVVY business in all his articles does not cop this stick? And I do support Mike in plugging his maintenance planning business, because nobody else will and he gives away much for free. (By the way he attended APS THREE times and learned most of what he teaches from there). George Braly, John Deakin and Walter Atkinson have given away so much for free, and contributed so much to GA safety that is taken for granted, and they too have been accused of similar things. The small amount of pocket money made over the years amounts to cents per hour. But they still do it because they enjoy it, and most appreciate it.

As for APS -Oz......still not drawn a cent (residual leftovers are reinvested), in fact it has cost me thousands, the AOPA safety seminar last week cost me in after tax (non deducted) dollars about $2500 plus a day of work and all my weekend.

I am sorry that in trying to help and educate I have to be this defensive, but it gets right up my nose when the kind of comments about having a commercial interest are made in such a way to discredit the facts and are likely to be revered by others yet are completely false. I sure don't see Stein, Don at Airflow, Dynon, or others who have a significant financial interest get pasted.....and nor should they. All I ask is the same respect.
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  #27  
Old 02-24-2014, 05:45 PM
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I also noted that someone posted that the various EMS manufacturers manuals are a good source for diagnostic advice.

Well.......that might apply to the instruments features etc, but most have some very poor and some completely wrong information contained in them.

But how can you tell?

I reckon there is far more and better advice here on VAF than there is in many of those manuals.
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  #28  
Old 02-26-2014, 07:52 AM
6 Gun 6 Gun is offline
 
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Smile EMS

I like having an engine EMS in my RV but to tell you the truth I don't have a problem getting in any plane that does not have any engine EMS AND FLY IT ANYWHERE and lean it out till it runs rough and enrich it a little till it runs smoothly worked since the beginning and works just as good today in most planes that are used for training and the majority of the GA fleet.
Bob
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  #29  
Old 02-26-2014, 03:11 PM
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RV10inOz RV10inOz is offline
 
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That is fine Bob, and still many do. And for a VFR jolly in the local area I will jump in the Cub or a mates RV6 no problem. But I will not fly them IFR in IMC or at night.

My question to you is what kind of car do you drive? If it is a 1950's Chevy Impala with no seat belts, my argument is going to be shot down now, but you could. I bet 99.9% of us prefer a 2013 model and wear their seat belts.


As a follow up, to the OPs problems, the data shows some connector problems and some plug fouling from taxiing too rich.

Data, Data, Data. It can tell you a lot more than just a number.
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The two best investments you can make, by any financial test, an EMS and APS!
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  #30  
Old 02-27-2014, 07:44 AM
Allen Barrett Allen Barrett is offline
 
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Quote:
Originally Posted by RV10inOz View Post
This will be a partially blocked injector or intake leak. To test it run it with the high EGT and lean the engine and if that cylinder peaks long before the others and then starts going cold and rough running it is a blockage in the injector or a massive intake leak leaning that cylinder out.

It will not be a failed plug. That will give higher EGT but lower CHT.

If you have an engine monitor, and you should, send me the data file.

This is yet another reason why I suggest you guys do an APS class. They pay for themselves in this one area alone.

Agree with David on this. You have a clogged nozzle. A fouled plug would give an EGT rise, but a lower CHT reading.
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