Lean of Peak Operations

[LAINC]

Running Lean of Peak at altitude what mixture adjustments do you make before/in descent & as well prior to landing? Pro's vs Con's?... and any tips appreciated.

[crazy_aviator]

When not in cruise, suggest using book value. Its not good to loose an engine on approach because you forgot to richen the mixtures upon descent

[ahramin]

I add a couple twists before top of descent, a couple more twists during descent, then full rich at 1000' during the before landing checks (I'm at sea level).

Not very scientific I know, but I think the important thing is small adjustments, not full rich at top of descent. In other words, keep the mixture in descent where it would be if you were cruising at that altitude.

[182-SS]

It isn’t necessary to go full rich on approach and landing. I would definitely go rich of peak and book values will work, but I do not go full rich for landing. I will give a few twists rich and check my fuel flow and temps. Its only necessary to richen if your leaned way out for higher altitude cruise. Reasoning behind leaving it leaned is your plugs are less likely to foul if you stay leaned rather than a full rich approach like the instructors tell the flight students. On the event of a go around she’ll run fine if its leaned out, just remember to check your CHT’s and richen a bit on climb, this is the real reason to run full rich on take off, fuel is used for cooling of the cylinders.
I lean aggressively on taxi too to prevent fouling.

[LAINC]

Still doesn't seem to be that many guys that even know about running LOP. Why is it so slow to catch on? Especially commercial... The savings are huge! Fuel and maintenance.

[ahramin]

It isn’t necessary to go full rich on approach and landing.

Not sure what type of plane you are flying 182, but my C-182 manual says

(2) Check mixture "Full Rich" (full in).

Same for C-150

(2) Mixture -- RICH.

Same for C-210.

If you have book values for your aircraft though, obviously that is what you would use.

[Shiny Side Up]

Still doesn't seem to be that many guys that even know about running LOP. Why is it so slow to catch on? Especially commercial... The savings are huge! Fuel and maintenance.

All depends on what the manufacturer reccomend on what installations. I know afew fellows who swear by lean of peak operations despite TCM reccomending otherwise for that aircraft. They're been replacing a lot of cylinders on that thing. Another guy I know runs same model of airplane by the book adn never has problems. Suffice to say, LOP operations aren't for every plane despite what some of the rags would have you believe.

[Colonel Sanders]

The engine doesn't give a sh1t about the
stoichiometric ratio. What it cares about is
the temps.

Metal lasts longer if you keep it cooler.

Rather than memorizing a bunch of junk
written by salesmen and marketing guys
in suits, if you understand the engineering
fundamentals (e.g. above) pretty quickly
you figure out what keeps your engine
happy.

You checklist types, that don't understand
your aircraft, do a lot of damage. I know
a checklist type that just trashed a very
expensive engine due to fundamentally not
understanding how it operated.

[LAINC]

Both Continental and Lycoming have changed their tune on this topic. They both support LOP operations, obviously not in carb engines but fuel injected engines set up properly. Continental has even developed their own balanced fuel flow injectors that come stock now so it isnt necessary to install GAMI injectors to run LOP. I'm currently running LOP on an IO-550 w/ GAMI's in a Cessna 206 after going through too many cylinders ROP. 550's in the 206 are notorious for high running temps ROP and most guys I know are running them at 18 gph plus just to keep temps reasonable. I get 12.5-13 now and temps are around 50 degrees cooler. By no means a professional in this area but I am loving the savings and sure seems to be maintenance friendly so far.

[Colonel Sanders]

If you keep the CHT's and EGT's low, the engine
will last longer than if you keep the CHT's and EGT's
high.

Again, I'm not sure how this got so complicated.

[LAINC]

I agree but you'd b amazed how many people would argue with you on LOP operations

[LAINC]

Sanders u may be right about stoichiometric ratio's too but what im looking for here is tips or ideas to be tossed around concerning LOP operations. You make it sound like its as simple as hot vs cold when in reality there is much more to it than that when running LOP.... such as avoiding power settings in the "RED BOX" and ramrodding the mixture when in LOP.....so yes this is a little more complicated than you make it sound especially for those totally unfamiliar with LOP. Contributions to the subject are welcome though

[Edo]

What engine instruments are you using? From what i have read your had better have balanced injectors AND good engine instruments.

[Cat Driver]

What engine instruments are you using? From what i have read your had better have balanced injectors AND good engine instruments.

Or lots of money.

[LAINC]

EDM 700

[182-SS]

It isn’t necessary to go full rich on approach and landing.

Not sure what type of plane you are flying 182, but my C-182 manual says

(2) Check mixture "Full Rich" (full in).

Same for C-150

(2) Mixture -- RICH.

Same for C-210.

If you have book values for your aircraft though, obviously that is what you would use.

Sounds like a “checklist type” comment
Lean of peak isn’t book values is it.... as stated above continental and lycoming are only just changing their tune regarding lean of peak operations

I am lucky enough to have an old timer as a piloting and mechanical mentor instead of the kids teaching kids back when I was in flight school (pilot since the 40s as well as being an AME and formerly owning a Cessna dealership/service centre) has been running LOP since the 50’s you just need to know how to do it. His engines have always made it to TBO and I can assure you that he wasn’t running “book numbers”

Book numbers are important, they are great, how much runway do I need on a 30 degree day at 4500’ altitude strip. You run your machine where it and you are happy. Book values are a great reference and some machines perform optimal at them, many don’t however. My machine will run lean of peak at 14.1gph, I know of some 550’s that will do around 12.5-13 as stated in another comment, depends on your engine, some make a little more HP than others therefore a bit thirstier.

The funny thing about LOP is that everyone is so worried about the EGT, forget your EGT and worry about your CHT, that’s what matters, (well dont forget it but you know what I mean, swich your focus) Find the article that mike Busch writes in Cirrus Pilot magazine, Voume 5, Number 4 july/aug 2010.

I wasn’t going to buy into the AVCANADA forum syndrome of making comments back like this but for some reason…….

[iflyforpie]

What engine instruments are you using? From what i have read your had better have balanced injectors AND good engine instruments.

Or lots of money.

And lots of money.

As an AME, I love engine analyzers on private aircraft. Between damage from overzealous leaning (got to pay for those instruments somehow), chasing bad probes, and changing jugs because the readings aren't all lining up, they are a good money maker.

[ahramin]

182, yes there is far more to understand than what's on the checklist.

If you are going to deviate from the checklist you'd better understand it all though. Why do you suppose they have full rich in the before landing checklist?

[LAINC]

Ok once again kids I'm not looking for naysayer comments with no real knowledge on the topic, or those who want to fight about stuff unrelated to the topic. U want to fight go start your own thread or go educate yourself a bit on the topic and we can have a real discussion. If you have something to contribute as a few already have welcome to the thread and thank you for posting.

[Colonel Sanders]

Why do you suppose the have full rich in the before landing checklist?

So "Checklist Pilots" like you can crack the cylinder heads.

Call TCM if you don't believe me.

I'm pissed at you "checklist pilots". One of you just trashed
a perfectly good - and very expensive - engine, because you
think that a checklist is a substitute for brains.

Lord save us from white shirts and gold bars

[LAINC]

Hey sanders did you read my last post? Your last post is exactly what I was talking about....take your crybaby ass elsewhere and go start a thread about how to hijack and make pointless comments in other peoples threads. Or even start one bout your hate for the checklist types.....once again LEAN OF PEAK is the topic folks.

[Cat Driver]

Great attitude lainc.

Can't wait to learn from you.

[LAINC]

I'm pretty sure I started this thread and made it pretty clear what I was and wasn't looking for here. You don't respect me I'm sure not going to respect u. I came on here to start a discussion and hopefully learn something here pretty sure I made that clear too cat. From your posts on here you arnt exactly contributing anything either if you have something valid to say go ahead I'm all ears but I'm not seeing that from you either don't waste my time or anyone else who actually came on here to learn something.

[Edo]

when in cruise running LOP how much of an altitude tolerance to you have before resetting the mixture? Need and extra 500' to clear the tops do you run same settings or go back to ROP for the climb and reset?

[LAINC]

I have been giving myself 500 ft either way to make it easy. Its not so much a problem when you are descending it will just begin to run rough eventually and you'll have address it. In the climb however you risk having the mixture creep back toward peak EGT that's bad news especially at higher power settings. This is in the "RED BOX" and you can certainly do damage to your engine. If I'm going to to climb to gain any significant alt. I'll go back to ROP and climb. You have to be careful to not just ramrod the mixture back in without reducing power first or you risk detonation. I slowly pull my power back to 19-20 inches and then slowly advance the mixture. This way your not firing a whole shit load of cold fuel into the cylinder all at once....could also shock cool you engine. I use the same procedure in the descent for landing although i do not have a checklist for any of this its just what i do lol! Remember all my research into LOP operation, and hands on experience for that matter is with the IO-550. Many of the principles are applicable across the board though.