Walter Atkinson

How can operating LOP where internal cylinder pressures are lower, heat is lower, and the combustion chamber is cleaner be worse than operating at 50dF ROP where the OEMs have recommended and heat and pressure are the highest with a dirty combustion chamber? The enemies of metal are heat, pressure and frictional wear--all worse ROP than they are LOP. How do you burn something up when you are running it cooler? Just doesn't pass the smell test, much less data collection. If you can't screw it up as recommended ROP, how can you screw it up worse, LOP in a safer regimen?

As the King of Siam said, "Tis a puzzlement."

****What an engineer would do is to run the engine in a controlled experiment, collect data on the internal runnings, temps, pressures etc. Compare this to the materials, construction of the unit and come up with whether it is more damaging one way or another. This data could then be put into practice and measure the outcomes of operational use from trends and condition monitoring.****

That's what we've been doing for over 15 years! Then we've gone the step further and done it in hundreds of engines in flying machines. Guess what? Conveniently, the data is all the same.

27/09

How can you be sure all cylinders are LOP just by what EGT you see on one cylinder?

Actually I disagree. I would think the average Lycoming is far more conforming than your average blonde, otherwise the FAA might have something to say.

Because these engines are being produced to a "conformance standard" (for want of a better term) I thinks it's entirely reasonable to expect there is data on how good or bad the F/A ratio spread is. As you rightly pointed out the average doesn't tell you anything about the engine you are flying but it will give you some confidence (or not) on whether or not you have a good chance of running LOP in an aircraft without the need to find out an optimum carb temp etc..

The reason for my question is most of the pilots I know fly behind Lycomings, and in many cases not always the same aircraft. None of these aircraft have any EMS systems fitted. On this thread and others like it we keep hearing about the benefits of LOP. I don't dispute those benefits. However I did question the practicality of running LOP for many pilots flying behind a 4 cylinder Lycoming.

When I asked how how practical is LOP for the average pilot flying a C172 or PA28 or anyone flying a four cylinder Lycoming.

Walter said
Which to me says it's not practical, yet John Deacons says

Which is it?


Are you and Dexta talking about the same model of engine here?




In an earlier post
Does this apply so much to Lycoming engines. On another site I've read that because of the way the Lycoming induction system is set up there is a natural heating of the carb and application of carb heat has no effect in at least some installations. In other words the Lycoming induction system lends itself to naturally aid vapourisation unlike in a Continental set up where there is no natural heating of the induction system.

Brian Abraham

Well, I could show you the flight manuals and training notes (helos - from Flight Safety) and the only parameters talked about are, in the order of your listing, fuel flow, rotor RPM, N1, N2 (missing from your list) and ITT. Not a wf to be seen anywhere.

No Hoper

Brian
In helos we have
NR rotor RPM and
N2 (power turbine) RPM on same indicator for reasons you would be aware
N1 Compressor RPM
Wf fuel flow
Pc compressor discharge pressure
Px modified Pc for governor regulating
Py modified Px
But enough.
There just NP on turboprop engines as no need to match needles

yr right

Heat is irrelevant 50 below or above. As you lean out the burn is slower this is what is the cause effect on an exhaust valve. Notice that the inlet dosent get damaged at all. The gas flow past the valve going on to extreme lean conditions passes the valve and over heats it. Much like if you get a piece of steel and heat it with a oxy set. Get the metal hot and move the tip around so the heat is not in one place. As you move the tip around the past steel cools. Now place that heat at the edge. What happens it starts to burn the edge. This is the same as what happens to the valve. The colour is very different to a normal valve. Once the valve damaged it will not repair itself. So are burnt valve mine and everyone else imagination. I think not. Also remember that the engine is. at its most stressed on takeoff. Dose the valve burn at this position if it is in good condition no why because the mixture is by manufactures settings is on the rich side of sinc may be they can tell us why that is. Just like they said that the whallya engine was ok cause it was rich enough. It was rich enough until the engine went to full power then it wasn't.
This week I place a plug I placed a plug in the over as I was changing a gear for a starter adaptor. I got the plug hot and I then dropped it into a bucket of room temp water. Gee guess what happen the ceramic cracked.

This myth that if you run lop you will get all your troubles gone is just that. We ran rop we never had a problem in fact we had very little problems at all with our engine. They all made o/h with expect one which had a blower bearing failure that caused that engine to be removed. We done more take off and landings a day than most of you would do in a year. Yet we looked after our engines and airframes.

Now if you won't to run lop do it I'm not telling you what to do. Let's see what tcm have to say I don't know what they have planed. But if you experiment
With lop be prepared to put your hand in your pockets for engine repairs. As I said earlier this is a saving of a few dollars an hour. Expect a bill from $1000 a cly min if you screw it up.

Now they will come back with data distrusting what I have said they have a financial interest in that I have not. I see what I see. Funny they don't acknowledge the work that tcm have put in to provide better reliable engine components. They call there stuff sience we'll what works on paper dosent always work in real life.

They said light was the fastest thing in the known universe then oh we may be wrong the giant collider in France has maybe proven that not to be true. Where dose this leave us now.
Leaves me in the place I started. Leaves you the pilot to decide what you won't to do. People here called me all sorts of stuff yet don't know simple terms parts etc. At the end of the day will it worry me in what you do not really with the exception that if you have an accident I really don't won't to be called into an inquest. If the cly has a damaged valve and until there is documentation to say it's ok ( which I doubt will ever come ) they will be removed and repaired not at my cost but yours.

Cheers

43Inches

So the fuel burns hotter and longer when LOP causing valves to erode and pistons melt? But the cylinder pressure is lower CHT and EGT is cooler? Where does peak cylinder pressure, power and temperature occur again?

yr right

Fuel burns slower so instead of the fuel being burnt in the chamber it burn is continued outside the chamber and past the valve and into the exhaust. This is a fact. If you don't believe this why do we have burnt valve. Maybe the burnt valve fairy sneaks in and dose it.

Cheers

43Inches

So what happens when your mixture is ROP? If rich to cool the engine can this not lead to buildups on the valve and seat and what would this do to valve life. What is the burn rate of fuel that is richer than the correct fuel/air for combustion.

Ethel the Aardvark

I think the majority of pro posters here are bums down in experimental category aircraft. A quite different breed of pilots.
They would most likely have all the multiple egt and cht sensors. Pilot would be soul operator and has a vested interest in flying his aircraft non commercially to obtain cheapest cost per mile.
However a commercial operator with their fleet of 210 or 206/7 type aircraft with a bunch of newbie 200 hr pilots who don't ultimately care about engine life or costs are expected to change engine control procedures, some even can't work out how to operate the cowl flap handle. I can't see it happening anytime soon.
Good luck

yr right

Speed is irelavant if the burn is contained in the chamber as the valve is closed. Same as the inlet. It made of a different material but as it's no open to the gas flow it dose not get effected.
When the exhaust valve opens it gets all hot gas if it still burning as it passes the valve it burns it. Not that hard really. And if you get a carbon under the seat it can cause it to burn as we'll as in correct lift timing of the cam (not meaning an aircraft engine).
Don't believe me about flame front. What happens when you do a mag check. These are big bore engines

So do you own your own aircraft.
Cheers.

yr right

We'll I think you have a lot of truth in what you have said Ethel. I said before it dosent matter what you give someone if the don't look after it it will break. Unless you are like mick who I continuely said well done you are dancing on a dangerous curve. I've it won't worry me or any other lame. We will continue to do what we do.
It will not be hurting my pocket.

Cheers

Weheka

So to sum it all up then, it would be fair to say that you think everything Walter, John, Jabba etc has to say about LOP vs ROP, using their advise on correct procedures, equipment etc, is total bollocks and all you will end up with is so many burnt, destroyed cylinders, covering the hangar floor, you will be tripping over them?

Is that what you think in a nut shell, because it's all a bit confusing?

Sometimes you say LOP has been around for ages and it's well known, and other times you say it's crap and no one should attempt it?

yr right

The average pilot will destroy an engine. This is fact. When lop in the earlier days the flight engineer watch with eagle eyes his instrument and make adjustments as required. Mick is a long way and I mean a long way above and beyond what people are on this post. He trends tends and trends. I don't know hot his operation and can only go on what I have been told on this forum.
I have also said if you wish to do it and it's in the poh go do it I don't care but give the maintenance shop pirour knowegle about what you going to do.
I wa ask do I recommend it or my thoughts I have done that. I see and lots others lame see the same results as I do.

Your $$$$$
Fuel is the cheapest single thing you can put in your aircraft. So what do you save over an hour how many hours a year you flying most private don't fly more than a 100 hours a year

Cheers

No Hoper

Sitting by the pool sipping beers and assessing the weight and distribution thereof on three blonde backpackers. Mmmmm one is more top heavy but has attracted most attention. Go figure
Have we discovered the near perfect machine with LOP and all those clys flying in close formation.
Low BMEP, low fuel burn and very little heat losses
And this is at full noise or so posters here say
A few more experiments and we are going to have to defuell after every flight

43Inches

So at what temp lean of peak will this combustion not be contained within the cylinder. The reduction in mixture burn rate would be progressive so at what temp will it start to erode the exhaust valve. Will this happen any temp leaner than best power or leaner than peak or leaner again say 50 LOP.

You have made a statement that the slower mixture burn at LOP makes it combust beyond the valve opening but the mixture with ROP the slower burn does not exit?

I have owned and managed piston aircraft in the past but not now, maybe in the future.

Creampuff

Now that right there's hilariously funny.

And I know the majority of anti posters are trolls!

yr right

I'm guessing that cream puff believes in Santa the tooth fairy and climate change because he was told they all true.
Sorry for not being a sheep and at least putting a balance view on this post. Maybe they from mother Russia were you weren't allowed to have a view out side of the state.
If I'm a troll for doing that so be. But I'm a better person than you will ever be.

I didn't know that you were allowed to say anything against these people selling you all stuff. And they own the post. All you can say is we have the data I've got a hangar full of data

Cheers

Weheka

Either you have a very good operation with all your engines going to TBO, or you have cylinders from stuffed engines scattered all over the floor, i.e. "Iv'e got hangar full of data."

Still a bit confusing as to what you are trying to say?

Mick Stuped

Ethel,
Love the handle, wish I could have been around the night that you came up with Ethel the ardvark. Love it.

LOP can be done very successful in an operational environment. Training is all important. I agree new pilots can be a bit of a trial. But really I don't think a lot of management or in company check and training fully understand enough of basic parameters that is needed to have sweet running engine. This results in line pilots perpetuating bad operational habits. Have seen bean counters insist a company go LOP, flight management put it into practise without knowing even if the engines online could run LOP. Pilots thought it was simple missed some important indicators through not understanding and no EMS installed and were not lean enough. Company returned to ROP because bean counters could not see a benefit but from talking to a pilot who came to work for us from them their engines ran so rough they couldn't get to peak let alone LOP. So I can understand why not many of us run LOP.

When a newbie comes to us looking for a job, with ink still wet on their new licence have just been bombarded by so many new things in training that they are a bit in the learning overload mode and really just want to fly, feeling they now know it all. We realise that it is up to us to guide them slowly to LOP through show and tell.

What seems to work for us is we run our own engine management induction separate to flight and operational induction and try to simply explain what's happening when they touch the red knob, not get to bogged down in science to much. This includes time with the HAMC and on the floor with our LAME. EMS is very important to this as generally, gen Y is very good at digital but crap at analogue. We start them ICUS with learning to read and lean via EMS. Then when they can show us what happens to CHT and EGT when they lean in flight we then get them to do the big slow mixture pull. And then check where they are with EGT and CHT Compared to leaning via EMS another light switch moment. Then we get them to run 40 degrees ROP as they were taught and compare CHT and EGT to 40 degrees LOP and ask them to explain why they think the difference. Man do you see the light switches come on. Demo is the best teacher with the use of an EDM.

We encourage questions and we like them to sit with us after their first few solo flights and go through the their own flight data from startup to shutdown and explain what they have done and how they operated the aircraft. If they can see they have done the right thing it gives them confidence. From my experience newbies really want to do the right thing. They bend over backwards to try and get it right. They just need better training when it comes to engine management as the current pilot training syllabus has some major gaps. Don't blame the student, blame the educator.

Sometimes I do feel experts can be to close to their passion they have studied for so long that they forget that most of us are just trying to catch up with the basics of engine management and feel ashamed to ask basic stupid questions that they must have heard thousands of times. For this I really feel that we as an industry really need to focus the attitude to correcting the training establishment, the syllabus, and the authors of the text books.

As we all know change moves slow in this industry, however it is changing, least we are now getting newbies that have used an EMS and have heard if LOP. I am just surprised, as ever that engine management is such a low priority in training but can be such an important part of keeping you up there both safely and economically.

Weheka

Mick and 43inchs have put it in a nut shell. I really don't see what the argument is about when the above statement is the simple truth of the matter.