To the youngsters reading this thread and easily impressionable think about this for a minute


It is not what you don't know that will hurt you, it is what you know that isn't so!

Still waiting for a couple of questions to be answered.

Seems to me that you are talking out of both sides of your mouth.

When professional highly experienced jet pilots have a rough running engine they go straight to the emergency check list starting with the memory items and then consulting the checklist. Sure sounds like "a by the numbers instruction sheet" designed to deal with a problem to me

So does that mean when a 100 hr PPL has a rough running engine and goes to a checklist that will ensures he methodically runs through the potential causes in a logical order without missing anything, which is exactly my response to the question posed by 500 Man in the first post, you "have to question the pilot not the problem" ?

Sorry I just don't follow your logic. :confused:

You know of all the posters who have contributed to this thread it would seem to me that the quote best applies to you....

As for answers I am still waiting for an explanation on how you seem to be the only person I have ever heard of who could get a simple horizontally opposed carburated engine to run smoothly at a true lean of peak mixture. I have personally never been able to do that, not have any of my very experienced pilot friends had any success with LOP operation on these engines.

So what is the secret ?

BPF

I am not talking out of both sides of my mouth;) We are talking about engine problems which could or could not lead to a forced landing in a single engine piston.
Obviously in a single engine piston an engine problem is more critical than in a jet as the jet will not be contemplating a forced landing into a field.
The Jet and its systems are more complex and the emergency checklist covers many other areas other than engine problems.
The fact that an engine problem in a piston single opens up the prospect of a forced landing means that the forced landing part becomes more critical.
As I posted if you have time then yes go through check lists, experiment with different settings etc but not at the expense of jeopordising the outcome of the forced landing which could be fatal if you get it wrong.
The last scenario I would want is for some pilot to be fiddling around head in books and in the aircraft with an aircraft gliding down to lower levels when he should be selecting a suitable landing area and adjusting the profile estimating winds etc as priority number one.
You cannot compare the two as other than complete fuel starvation the jet is unlikely to ever be force landed the piston single is.
Even so I see nothing wrong with a mini emergency checklist for the single piston as it could be very useful especially if it is readily at hand and actually speeds up the thought process allowing more time to carry out a successful forced landing.
Aiding decision making not hindering it is the key to the use of a checklist in such a situation.
But the best decision making is the pilot who knows every beat of his aircraft and through experience knows where the problem lies and whether it is fixable or not.

Pace

This applies to EVERYONE you included and now I think the punters might be making the judgement call for themselves. Your attempt at insults really does your argument no good at all.

I have told you repeatedly, there is not enough space to sit here and debate how it works with a bunch of flat earthers, holocaust deniers and whatever other descriptions for non believing folk there are.

Plenty of people do it around the world. I am more stunned you have never heard of it and can't accept I am telling the truth. You lot are so bigoted that you believe that everyone else should take your word as gospel and others do not deserve that privilege also.

I promise you, it works on many engines. Most can achieve a level of effective LOP operations in the most economical range 10F LOP +/- a bit if they have a "Conforming engine" strategic use of the throttle position and a scientific application of carby heat. An EMS of some sort with digital fuel flow carb temp etc is damned handy to have also. Not essential but really good to have.

Perhaps if you sucked your pride in for a bit, and realised a weekend in Ada in October was a good idea, you could learn a whole heap more. Maybe you could teach George and Walter a thing or two!

Now how about a quick answer to my questions. If you ever fly a twin and could not answer that question in the first 3 seconds of reading it.... I will not let anyone I know fly with you. I would, because I would know what we saw.

For a certified aircraft, the "gospel" is what the regulatory authority has approved. Other than simple good airmanship, there is not other gospel.

Any "others" who wish the privilege of their word also being gospel, should go through the process to create, and have approved, a modification and/or supplemental instructions. That way, pilots will know what they have as authoritative instructions with which to operate the aircraft.

For those older large radial engined aircraft which I am aware were operated LOP, 'cause I had a friend who used to do it, I'm certain that there was an approved document describing that procedure - why not so for GA aircraft?

Well some were even 25 years ago. If you really knew your stuff, you would know the exact model I refer. I am not saying you do not know stuff, but clearly there you are talking out your.. :mad: again.

As for several others, in the POH's some say do then a page later contradict. You tell me why? Its baffling to me.

As for the rest of the manuals, the manufacturers are either too lazy, too incompetent or just do not want to admit they got it wrong. Mind you I have seen an email from one prominent employee of a major manufacturer openly admit the manual writing was in fact.....very poorly written. He should know, he approved it!

It is about time you came out of the dark ages, circa mid 80's and stopped being so hard of learning.

And what is your answer to my questions?:ok:

I can't run LOP with our carb engine, and we have an EMS. Runs rough as hell.

Absolutely no argument there, but my posts on this thread are aimed at a low time pilot that is flying a rental aircraft for possibly the first time in that particular airframe. So what do advise for them ?

Not one attempt at answering a few simple questions. Very disappointing indeed. I would have thought with such a strong technical base on this forum there would have been several pages of replies.

Anyone wanna have a guess? :zzz:

Well, the only question that needs answering, as far as I'm concerned, is this one:

So by all means go ahead, Jabawocky, and answer that one, instead of pretending to be the wiseguy without actually delivering.

(The aircraft I fly most often has an induction system that's so unbalanced that the POH doesn't even have instructions for setting the "best economy" mixture. All it does is "best power" (max RPM), and all the performance tables, including cruise, are based on that. So getting that one to run LOP properly would be a major breakthrough.)

Disappointment happens Jab.

My participation on Proone is voluntary, as is my choice to not be further drawn into nonsense. I find many questions I believe to originate from the desire of a pilot to broaden their knowledge, and improve their skills. Where I can, I help. In other cases, I charge for the same service to the aviation industry, and I then often sign an STC for the modification.

Some questions on Proone I suspect are not "true", and asked in an honest spirit. I generally ignore them. Some statements on Proone I judge to be more unhelpful to new pilots than helpful to anyone, and perhaps leading the unwary pilot into troubled aircraft operation. Where I have experience, I will challenge those (as several other extremely skilled Prooners have here). The challenge not so much toward the poster, but more so everyone else sees the challenge, and takes the offending statement with a grain of salt. It is each reader's responsibility to judge the credibility of answers in their personal flying context. But, a few credible challenges could be the "red flag popping up" for those pilots who are impressionable.

For me personally, lean of peak operations pop up a lot of red flags. But, that is now well evident to readers here.

Does that answer your question about your being disappointed?

Two STC's were issued, based in part on my ground and flight detonation testing, which was done by my real time observation of cylinder pressures, measured by a piezoelectric sensor. This was my third detonation measurement system design (and the first which worked well). These tests were ultimately supervised by a national powerplant expert, and witnessed by a Transport Canada powerplant engineer, to his satisfaction. With their concurrence, and two STC's, I'm satisfied with my work. If others are not satisfied, I'm not worried.......

DAR

I am genuinely interested in your detonation data aquisistion, mainly because very few people ever go to the length to measure that properly.

Just because I challenge the comments of other matters does not mean I am taking the same challenge to this topic.

So were your pressures recorded in a digital logger at a high frequency? There is some interesting work being done considering the detonation event and the pressure waves bouncing around after the peak event. Your experience might make for good reading.

Now as for the questions I posed, which were challenging the comments about pilot education.....I am disappointed nobody bothered.

As they say, you can lead a horse to water, you cant make it enjoy the view.

Another matter altogether, but that just means a greater degree of understanding is required. Especially with students and owners.

More red flags should show up with ROP ops, as it is well known and your ICP traces would also prove this, that engine longevity reduction through mixture mismanagement is far more a problem in Rich Mixtures, than in Lean Mixtures.

And before you choke on your lunch there, remember this. Rich Mixtures are ALL settings on the rich side of peak. To a scientist and engineer, they are all rich mitres. Lean Mixtures only exist on the leaner side of peak. This is a concept most people fail to understand.

A mixture that at high temps, high ICP that can cause detonation is most likely a rich mixture., Sure at very high MP's and say 10LOP you are still in the zone, but it takes very little extra leaning to get out of the zone.

These are concepts that scientists and engineers since Lindbergh have understood, pilots have not.

Anyway back to the questions, for the educational benefit of new pilots. :ok:

Backpacker

Which engine and aircraft is it you fly? There are some combinations that will be very hard indeed.

So how far once you get to peak RPM, can you get before severe roughness sets in?

I would happily help folk who perhaps do not construct their posts with comments like "So by all means go ahead, Jabawocky, and answer that one, instead of pretending to be the wiseguy without actually delivering." And take a far more healthy and polite method of questioning.

I do not have time in my life for coming on here making false claims in the attempt to educate folk, and then having stupid debates forever and a day. You can actively engage me and learn, or stay in denial. Your choice.

To respond to your last post, I have already given you as much as a post on pprune can convey. The process of teaching is not achieved by one or two posts on pprune. Do you think you could successfully teach a student to fly to solo by a few posts on pprune? No, surely not. So the same applies here. To understand the answer for some folk requires considerably more. And when some bozo goes off half educated, and gets it all wrong, who do you want to blame.

Sorry, not going to happen.

If you are suitably equipped with knowledge and understanding, plus your aircraft equipped (makes it easier), I have already given enough info. Just for your benefit, I will give you a clue, read posts #28, #33, #46 and #65. The answers are there. Let me ask you to contemplate, Lindbergh crossing the Atlantic and the Doolittle raiders. Two famous pieces of history. Neither possible without carby engines running LOP. Your very freedom today depended upon LOP Carby engines.

Now will I give you a cookbook approach to running an engine LOP that could potentially have you do it wrong? 10F LOP at a high HP is not the same as 10LOP at 8500', so a cookbook approach will never be good. You need to understand this stuff, and I can not be sure you or any other reader understands it on a thread that is ambushed by flat earth society folk all the time.

I have given you enough to go and learn properly yourself. The rest is in front of you if you wish to embark upon the journey.

Now my questions were not that complex. What would you do in that C421 with a change in MP?

Clearly this demonstrates my point. Flying schools, hangar talk, and pprune have not educated even the very well experienced and qualified folk. I do make the assumption a few of the posters here have lots of qualification and experience. That I have no doubt. But I do have doubts about a system that has allowed a great number of people get through with poor understanding of the very thing that gets them airborne in the first place.

So just for fun, have a go at the questions, you can only gain something, never lose.:ok:

It's the Robin/Alpha R2160, with a Lycoming O-320-D2A engine. I can get it probably 25-50 RPM on the lean side of best power (max RPM), before it starts running rough. But between max RPM and 25-50 RPM lean of best power the mixture knob movement is less than two mm and there is a bit of "give" in the mixture control system, so it's pretty tough to find the "best power" mixture in the first place.

As for the rest of your comments: I visit this place to learn something, or to teach others about the areas I think I know enough about to answer their questions. Not to engage in a pop quiz where the person asking the questions already knows the answer. And not to answer rhetorical questions either.

Best power will be in the EGT range of 100 to 125 deg F rich of peak. Your 25 to 50 RPM drop will still very likely leave you on the rich side of peak although probably pretty close to peak on at least one cylinder, just exactly the place you do not want to be as operating at peak generates the highest CHT's and will stress the exhaust valves and could even result in detonation developing.

Theoretically heating the induction air should improve the vaporization of the fuel and therefore make the distribution of the fuel to air mixture to each cylinder more even, as it that unevenness which causes the engine roughness preventing LOP operation in carburated engines.

In practice I have never personally had much luck trying a bit of carb heat as I leaned. When the dust settled I did not think I was able to go appreciably leaner with the carb heat then without and still have smooth engine operation. Also I found that the Micky Mouse Cessna carb heat control made it hard to accurately set stable partial carb heat settings.

Interestingly though pilots who operate Cessna 180's with Continental O 470 engines in the Canadian North, an engine notorious for poor fuel/air distribution, find that in extreme cold weather the engine quite likes a bit of carb heat at all power settings.

The bottom line from my POV is that for the ubiquitous carburated engines found in small Cessna's/Pipers/Grummans/Robins, it is pretty hard to hurt the engine with the mixture knob. If it is running smoothly its OK. The only caveat would be low altitude, slow full power climbs with the mixture leaned.

As a general rule, all of the common simple carburated engines can and should be leaned in cruise at or below 75% power at any altitude. The flight school urban myth that it is dangerous to lean below some arbitrary altitude is wrong. In addition the engine should be leaned in a full power climb at and above the altitude specified in the aircraft POH. If no data is available then leaning above 5000 feet is a conservative practice.


A much more common problem for these engines is cylinder overheating by prolonged climbs on hot days at low speeds ( ie Vy). Even at full rich mixture damagingly high CHT's can be developed due to the lack of airflow over the engine at low speeds.

Jabowacky

Just for grins I will answer you question. One day flying a 421C I did in fact notice the MP of one engine drop an inch or so. Pulling the alternate air handle fixed the problem........but I am guessing that is not the answer you wanted to hear :E

If I was really bored I would add up the word count for all of your numerous and lengthy "it is all too hard to explain on the internet" posts. Since the concepts are not exactly rocket science, I bet that the same number of words could indeed be used to craft a post with a pretty useful description of the factors involved in leaning aircraft engines........but of course to do that you would actually have to know what you are talking about, something which you have yet to provide much evidence of.

For those interested in learning more about all aspects of aircraft engine operation I highly recommend the book by Kas Thomas "Fly the Engine"

Finally as the topic of this thread is "engine checks" and the original poster was interested in the actions to be take in the event of a loss of power/rough engine, then to get back on topic and away from feeding antipodian egos's, a poorly adjusted mixture can cause a rough running engine. The most likely cause is the mixture had been leaned for cruise and then the throttle advanced, but forgetting to enrichen the mixture first. Another scenario is that at high altitudes full rich could be so rich that the engine is choking on the excess fuel and so in this case leaning the engine is required for its smooth operation.

BPF/Back Packer

The good little O-320D2A, The exact same engine (D1A) as I use LOP and it runs smooth. We are talking about at cruise altitudes of typically above 5000' or if lower, start at a MP/RPM that is around 75% and by the time you achieve LOP you are then around 65%. Fuel flow instruments are a big help. around 27LPH is the number and it sits there all day sipping away and performing book numbers doing so.

Back to science though, BPF, we are splitting hairs here a little but best power is actually at 75-80 ROP, and the power starts dropping away at 30-40 and anything noticeable probably around 30 or less, so the fact is Back Packer is probably LOP on some and peak on some doing what he says. At 65% or there about there is no problem there at all. You are quite right about not doing this at high HP down low, but that is not what we are trying to achieve.

Your comment about operating at peak EGT and the worst place because of high CHT is false. Let me tabulate this for you for future reference and for the benefit of others. The order of peaks from Rich to Lean
1. HP peaks first 75-80F ROP
2. ICP peaks about 35-40 ROP
3. CHT peaks about 35-40 ROP and it responds directly to ICP, nothing else.
4. EGT peaks at........ 0F ROP/LOP (where else :O)
5. 1/BSFC peaks last and depends on the power setting, from 20LOP at low powers to 75-90LOP at high power.

Assuming we are at cruise powers, detonation on an O320 can not exist, and even at full power on that engine the chances of doing it are pretty hard. With Conforming fuel and a conforming engine. However, running high ICP and hence high CHT for long periods and with poor cooling gives the valves a hard time not so much from direct heat, at the valve but for stress on the cylinder head itself.

The exhaust valve is at ts hottest at 25F ROP, and it is at the same temperature when at 125ROP or 50LOP so even peak EGT the valve is cooler if you are worried about that.

Now we are onto it, ;):D the process is now working. plenty more to be discovered. It is determining the right amount of heat and the throttle plate cocking that is the key.

Back Packer, in short your engine will most likely do it, you just need to do a bunch of things right. Plugs, ignition system and chase all the induction leaks out. Again an EMS and knowing what to do helps this process big time. Maybe yours will be one that is forever a pig and not able to, but in general, most can. I have better things to do than make this stuff up.

ABSOLUTELY :ok:

Any N/A engine in a Full power climb, should be leaned every couple of thousand feet, as has been described elsewhere. A Turbo or TN engine is full rich to match full MP and leaned only when appropriate, or when doing LOP climbs, but these are not that common as the time/distance/climb is only a bit of a saving and pilots like to be lazy.

Nope, that was not the answer i was looking for. Your actions were a lucky one, although I assume you had an icing problem perhaps, and nowhere in my question did I mention anything about icing or any other influential factor. Simply with no 100% certain good reason for the MP drop, what should you do? This is not a time to mess around and plenty of people have died from this, and I personally know of two cases where the pilots did the right thing, through good engine training and survived.

SHUT THE ENGINE DOWN & DIVERT

Chances are you had some minor problem, however unless you are 100% guaranteed you know exactly what the problem is you can not be sure you have not had a exhaust leak from a failed tube/joint. This will soon and it does, start burning through all manner of things until you have a fuel fed fire that you can't stop and a wing burns off. Sounds nasty hey! From the folk I know, they thought it was too and the photos prove it.

Lastly BPF..... I am not here to prove anything knowledge wise, least of all to you. When you get your fundemental facts straight, as I have corrected above for you on just what happens with EGT/CHT and the transition from Rich to Lean, then maybe you can start the "mines bigger than yours" willy wagging.

Clearly I have stumbled into your turf on this forum, where your supposed knowledge, and I am sure the majority of it is very sound and in some areas superior to mine for sure, but now that I upset the status quo you have been biting back with cheap shots like that.

Go ahead, I am happy to bug off again to my corner of the world and let the Old Wives Tales spread around some more. But for the sake of new students and private pilots/owners how about we aim to educate them sans the OWT's. :ok:

Sorry guys I could not resist feeding the jabowacky. I think it is time to put a fork into this thread, it is definitely well done.

Well, yes, it is well done Big Pistons, but it's like a horror movie, I can't look away...

If you've ever had to lift one out of the back of a truck, they're not all that little...

However, for an engine like most carb'd opposed engines, in which getting even two, much less four (or six) cylinders within 100F EGT of each other is near impossible, how could you ever manage to lean so as to be within 20 to 70 LOP?!? Which cylinder are you measuring?, what are the other's temps while you're doing that. That even precision is not possible on your average carb'd engine.

Well, maybe this has happened, though in 35 years of flying anf maintaining light aircraft, including 8 years working in an engine overhaul shop, I have never heard of anything other than exhaust gasket, flange, or baffle damage resulting from an exahust leak. That area within the cowling, by design, does not have vulnerable fuel lines close to the exhaust, and has lots of cooling air rushing around there. I'm not saying you can't have an engine fire, but I bet an exahust leak did not cause it. Perhaps Jab has had experience with these failures, and will warn off the impressionable with stories.

My O-360 powered aircraft has cowlings which make an visual inspection of the exhaust to cylinder connection difficult during a standard preflight. The first clue I had that I had an exhaust leak, (because of the nuts falling off, and that side's exhaust dropping down 3/8") was my wife telling me that when I took off it sounded different the past few times. I investigated more deeply, and sure enough saw exhaust soot where I should not. It must have been that way for some time - no fire or other damage. I just inspected it, and did it all back up again.

Like anything leaking or falling off a plane, exahust leaks are bad, and should be repaired without delay. But, I doubt that they are a cause for an inflight diversion, if suspected during a flight, with no other abnormalities in the engine. Oh, and if I'm wrong, and you do have a fire in the engine compartment, because somehow the fuel line was burned through, pull the firewall fuel shutoff, and it will self extinguish for lack of fuel.

There are many things I would be worrying about long before I worried that an exhaust leak might cause a fire.

Pilot DAR

Exhaust failures in turbocharged engines which have resulted in catastrophic in flight fires has been an issue in the past and resulted in a AD mandating continuing exhaust system inspections for all Cessna turbocharged twins.

Failure of the tail pipe is particularly bad as it points aft towards the firewall before making a 90 degree turn down right next to the firewall. Failure at the flange out of the turbo or at the bend will result in the exhaust jet impinging directly on the firewall. The Turbocharged Lances had the same system for their turbocharged Lycoming and the same vulnerability.

The Navajo has a much superior layout of the exhaust IMO. But the bottom line is these kind of failures are invariably associated with poor, or probably non existent, maintenance of the exhaust system. Exhaust leaks at the joints will also result in tell tail soot trails on the cowling or in bad cases discoloured paint on the surface of the cowling. Any discolouration or paint blistering on the cowling is a grounding snag. Still abnormal operation of any turbocharged engine should make the pilot alert for the potential for fire.

However for your average carburated non-turbocharged engine the good news is fire risk from exhaust leaks is much much less and as you pointed out there are a lot of other more likely problems you might encounter then an exhaust leak induced fire.

The even better news is I have yet to find a case of an inflight fire where the fire did not immediately go out if the engine was shut down at the first positive indication it was on fire. All the tragic accidents I have seen reported involved the pilot keep the engine running even though it was on fire

All that being said I have a fair bit of time on twin Cessna's, including C 421's and there is no way I am going to mindlessly shut down an engine just because it shows a loss of 1 inch of MP. Do a fault check, sure but immediately shut down, probably not, well that is the difference between actual operating experience and deciding that you are the expert because you took a course....