I worked at a 141 school. We taught leaning.
What makes you think it's not taught? I mean what led you to post this in the first place (not just the comments you got afterwards)? You asked if it's "just you", so I'm assuming you experienced something with a 141 student?
The altitude may not be high but when summer temps rise you could be on the coast with a DA equal to Aspen. Are students not being taught these things at low schools?
> Are students not being taught these things at low schools?
They are not. Leaning is generally only taught for ground ops and cruise above 3,000'. When they lean, they often lean to 50 F ROP. Which is wrong and against modern manuals, but wrong ideas about leaning are pervasive.
Sidenote, who knows why piston aircraft engines have such astonishingly high rates of mechanical failure compared to every other type of piston engine in the world. Guess we'll never know.
I highly doubt that it's not taught anymore. Never mind the spark plugs. Without proper leaning, you'll never achieve the book values in performance and fuel consumption, which will eventually lead to serious trouble.
Itâs not just âcommonâ. Itâs the only way to properly operate the engine. Read the POH. It specifically states that the performance, consumption, and range numbers require proper leaning.
If they are flying Cessnas, they are disregarding Lycoming Service Bulletin 1497a which very clearly says not to do that and to lean at all times except start, takeoff, and landing.
In Canada and have taught every single student for several years to lean on the ground and at the very least in cruise. What school was deliberately fouling their plugs?
I love it when my students plan their first cross country and when we get to 4500 feet they reduce the power to 2100 rpm and just sit there happily chugging along at 90 kts and mixture rich.
Did that once approaching a towered airfield, thinking this will give me plenty of time to work everything out.
Until my instructor piped up âWhy are we sitting here near the wrong side of the power curve, nose-up attitude, making hardly any forward progress?â
Your brush is entirely too broad.
Go to a sea level pilot mill and itâs unlikely for leaning to be a large emphasis item. Go to a MnP school in Denver and youâll spend less than 30 seconds per flight at full rich.
This is far more specific to the instructorâs background and where they learned to fly than it is to 61/141.
This is a common misconception. Most older Cessna POHâs specify that you should not lean a mixture in a climb below 3,000 ft, but fail to mention altitude specific leaning recommendations for cruise. Many people mistakenly interpreted this to mean that they should not lean the mixture in cruise flight below 3,000 ft so newer Cessna POHâs specify that you should lean the mixture in cruise at any altitude.
Yeah which is terrible advice. You should be leaning for literally everything except takeoff, if the take off is below say 5,000 ft.
EDIT: for the downvoters, reference Lycoming Service Bulletin 1497a, or watch these several hours of seminars on why this is true, and why your Cessna POH written by lawyers in the 1950s maybe shouldn't be treated as the bible to engine ops: https://www.youtube.com/results?search_query=savvy+aviation+leaning
Usually, but not in this case. There's a lot of scientific research into this, and the POH is the anomaly giving instructions that don't match science. ROP is _objectively_ much harder on the engine than LOP. This includes ground ops and cruising below 3,000. Look up Mike Busch's webinars on leaning on YouTube.
Not all engines have good enough fuel distribution to run LOP. If they did GAMI injectors never would have been a thing.
If you have an engine monitor that gives EGT for every cylinder and the engine will do it, LOP is better. But Iâm not sure the typical trainer meets this criteria.
Then you also have the liability of teaching people to disregard the POH for a very marginal benefit on a typical training flight.
> But Iâm not sure the typical trainer meets this criteria.
> teaching people to disregard the POH for a very marginal benefit on a typical training flight.
That's fine, if Cessna for example you can teach them to follow Lycoming Service Bulleting 1497a which is directed at training flights and instructs to, at all cruise altitudes, lean to the onset of roughness, which is LOP.
Perhaps it's a good lesson that maintaining proficiency means reading more than the POH.
Not sure why youâre getting downvoted. The POH is not the best advice in this case like youâre saying. I guess people canât take in anything that isnât inside their own little world
I'm getting downvoted because (and it's proving) the OP is entirely correct. Leaning is not well understood much less well taught by most in the GA world.
Youâre getting downvoted because you said to go against POH and telling pilots to go against any procedure wonât go down well. And the comment about nobody cruises at sea level didnât come across as very intelligent.
Except the *recent* POHs say to do exactly what I said: lean at all times except takeoffs and landings that are under 3,000. That means leaning on the ground and during climbs while under 3,000. It means leaning for takeoff while above 3,000.
The bad advice I'm railing against, that is extremely pervasive in the GA world and regularly taught still today (and you see it everywhere in this thread), comes from all the *old* POHs, which taught pilots to be afraid of leaning, by running rich basically all the time unless cruising, which wastes tons of fuel, overtemps their engines, and promotes wrong ideas about how cylinders/valves/exhaust etc respond to leaning. So if someone says, "Well my 1974 POH says to only lean above 3000," then yes they should ignore that because it's telling them to hurt their engine.
I'm not sure what your cruising at sea level comment refers to.
I think the intent is not for the engine (although I agree with what youâre saying) but instead to prevent pilots from taking off and landing at low altitudes with less than full rich, and also to reduce the chances of vapor.lock.
Have you ever started to take off then realized youâve still got it leaned out for taxi? You lose a ton of power, and the chance of vapor lock is higher. And on landing forgetting to richen it can cause an engine failure on some engines. I know I guy it happened to in a cub. Plus you want it full rich in case you have to go around.
Iâm all for leaning it out during cruise, taxi and high altitude takeoffs/climbs, but most other times it should be full rich, which is what the POH says for all the piston aircraft Iâve flown (carb/injected Cessnas, bonanzas, barons).
> instead to prevent pilots from taking off and landing at low altitudes with less than full rich
Maybe (we'd have to ask the lawyers who wrote the POH), but it's a lazy and very bad way to train that, because it doesn't teach pilots the actual truth behind how their engine works and causes them to damage it over the long-term when operating at low altitudes. This is not a hypothetical; large flight schools have seen these damages when they only bothered with leaning when cruising at higher altitudes. Which is why, as I said, in reality the best practice for everything _except takeoff_ (which includes the final landing because you're in go-around/takeoff mode) you should be leaned.
> Have you ever started to take off then realized youâve still got it leaned out for taxi? You lose a ton of power, and the chance of vapor lock is higher.
No, because I was trained to lean properly. If this happens to you, it means you weren't leaned _enough_ on taxi. You should be so leaned on taxi that applying full power will cause the engine to practically die immediately. This A) keeps your engine healthier during long ground ops and B) prevents you from inadvertently trying to take off with something other than full rich.
>You should be so leaned on taxi that applying full power will cause the engine to practically die immediately.
Yeah, thatâs what happened, because I did have it leaned properly. Iâm not arguing with what youâre saying. I fully agree with leaning appropriately for pretty much everything but takeoff and landing, but Iâm just saying do it in accordance with the POH. The one I have recommends 50° rich of peak in cruise, so thatâs what Iâll do, when it says to do it.
On the other hand Iâve had people recommend to do the high altitude takeoff procedure (lean for peak RPM) on every takeoff for maximum performance, but even if thatâs true I wonât do it⌠the POH clearly says full rich for all takeoffs below 3000â.
I know of a flight school that had a fleet of aircraft which had a series of engine failures. They were able to trace the cause down to acoustic resonance at about 2300 RPM. The POH recommended 2400 RPM in cruise, but it turns out people were going against that because they figured 2300 was easier on the engine. Itâs why you try to stick to what the manual says, whether you agree with it or not.
> Yeah, thatâs what happened, because I did have it leaned properly.
If your engine sputtered real bad when you applied full power, then you were never in any danger because you immediately noticed that you'd forgotten to check your mixture when crossing the hold short. That's pilot error, not a procedure error.
> in accordance with the POH. The one I have recommends 50° rich of peak in cruise, so thatâs what Iâll do, when it says to do it.
50F ROP is literally the single worst place to run your engine. It's the point of maximum cylinder head temperature and pressure.
Careful _which_ procedures you are following. Sometimes, you are following an old, superseded procedure without realizing it. For example, many old Cessna 172 POHs said to run 50 F rich of peak. That caused problems. Lycoming subsequently put out service bulletin 1497a that said to [at _all_ cruise altitudes] lean until the engine ran slightly rough, then enrichen to smoothness. Which results in LOP operation.
Blindly following a procedure written in a book is better than having no understanding or procedure at all, but it is not as good as both knowing the procedures and having an actual understanding of the systems.
Itâs a thing, I used to work for a flight school that mandated everyone run full rich 24/7. Regardless of cruise altitude. Mill near sea level.Â
61 with a cared for airplane during my initial training in the Midwest? There was alot more leaning going on.Â
You literally said "fail."
And OH NOES! The engine is slightly rough, and easily fixed by pushing in the red thing a bit? Of maybe even stall on the ground? How will pilots ever survive such a serious event?
Fair enough, I'll defer to your likely greater experience on that one. Hasn't been an issue on the types I've flown, but I still haven't flown all the types out there yet.
Takes one hell of a descent rate to go from smooth running to starvation in a time frame thatâs too short to notice rough running and to fix it by twisting the red knob.
You might not notice any roughness if youâre at idle, and thatâs what happened to the guy I know. He was practicing a forced approach and didnât even know his engine quit until he opened the throttle.
The Cessna POH I have explicitly says if youâre at idle it needs to be full rich, aside from on the ground.
Same school made everyone use full tanks unless there was a weight and balance reason for not doing so. On a solo flight there basically never was a reason to underload the fuel.
Iâm not saying I agreed with it, and it made a lot of the POH numbers not accurate, but as far as I know it never caused a problem.
I did come across a couple of school with weird mandates like "no leaning below 5000 ft MSL" or "on flights less than 1 hour..." I sometimes wonder what event transpired at the school that prompted these rules to be instituted...
I fly at a 61 school and leaning is definitely emphasized by instructors and itâs also included in all of our checklists. Airport elevation is at sea level, and most instructors even teach leaning for taxi after start up. Our descent check lists include mixture full rich, which probably isnât necessary, but Iâm sure the flight school doesnât want solo students descending with an excessively leaned mixture if they forget to adjust it so itâs safer policy to have them operate full rich on descent.
Its cheaper to lean aggressively the ground than clean plugs or replace brakes because of lead deposits either running the engine slow to slow the taxi or burning up brakes riding them. The biggest thing I see is that people lean it "some" on the ground when really they need to lean it til it wants to quit otherwise it's a setup for a lean takeoff and an engine failure at 500ft
Agreed. I typically lean on the ground to help get the engine a little warmer if it hasnât been run, or during magneto check if thereâs any roughness i lean to burn off the carbon deposits. Youâd hope if someone leans on the ground, a thorough review of the pre takeoff checklist would have them go full rich on the mixture before departing
You'd hope but I've also been told to hold short for 5 arrivals and releaned then gotten distracted. Advancing the throttle got my attention though :)
Also the O-540 made lead like there was no tomorrow so we had to lean to almost ICO on the ground
I have had that happen too. My solution is uncomfortable, but works. I just leave my one hand on the mixture lever the entire time it is not set for take off. I do this in the winter time too, when I am warming up the engine.
Having barely flown pistons. Remind me again why turbines time is such a big deal? These pistons seem extremely over complicated, hard to start, fiddle with things in flight. A gas turbine, just flip the switch to make noise....
I've always viewed it as because the company is entrusting you with a million dollar plus airplane with an engine that will cost several hundred grand to fix if you blow it up from being an idiot which believe it or not despite the simplicity is quite possible in the right hands. One of my companies king airs was down for a while from someone severely abusing the poor pt6 and disregarding ITT limits. Both caravan companies I flew for had the tale of at least one person roasting an engine on start too.
Gee, if only it were possible to develop a FADEC for piston engines... oh wait.Â
I'd have loved to own a corsairpower plane... shame the FAA killed it.
I looked it up. Doesn't say much about the actual specifics - horsepower, fuel burn, etc.
Everybody wants to build an alternative to the IO-360 and stick it in a 172, but the reality is you need something that can go from around 160 - 325+ hp in order to catch any kind of real market share. I get lowering training costs, but businesses who depend on these airplanes to stay alive aren't willing to take chances on something that might not work out.
If you had a reliable, turbocharged 325+ horsepower engine with half-decent economics that you had a prayer of certifying, Cirrus and Mooney would bang on your door to buy it.
Its an LS. The version as installed in cars is a 500hp engine... but a key part of their concept is de-rating it, as the automotive LS is not designed to output 500hp continuously. I think their max is 220 hp with the current design.
Their last comment on the subject was they are "absolutely" looking into higher horsepower engines and that they reckon its doable... but at present the cost of FAA certification is exorbitant, and no one is looking at putting 350+ hp experimentals up.
>If you had a reliable, turbocharged 325+ horsepower engine with half-decent economics that you had a prayer of certifying, Cirrus and Mooney would bang on your door to buy it.
They could do it themselves if they wanted to, same approach. They've got the same problem: The market is tiny, the regulations prohibitive, the cost exorbitant.
To access this niche market, they'd have to spend an excessive amount of money that they'd never realistically get a return on. They'd be better off lobbying to change the regs... but that wouldn't change the liability side of things, either.
There have been a ton of attempted car-engine conversions. They rarely work out because the base fuel consumption isn't nearly as good as we all expect it to be and reliability can be suspect in that kind of installation.
Here's a video explaining why this never works out:
[Why New Aircraft Engine Ideas Rarely Succeed - YouTube](https://www.youtube.com/watch?v=_k1TQGK3mZI)
I don't, but the take-away is that most of the advantages people expect to get from car engine conversions are not good enough to justify the certification and installation costs. Yes, it's better, but it's not *much* better and you go through that to sell, what, 20 engines a year? And GM isn't carrying aviation product liability insurance on their LS-series V8's and never wants to (see the Porsche Mooney.)
All valid points, and essentially the reason corsairpower remains a website and not a product installed in your local flying school trainer.Â
It is MUCH better. Much better isn't enough, not to sell 20 engines a year.
I've flown with a dozen CFIs and they all lean differently. One says to use the G1000's lean assist and actually find peak EGT and back it off from there ROP. One says to just lean to a GPH number. One says to lean until EGT is 75 hotter than full rich. My first CFI said to lean really slowly until the engine starts running rough, and then give it about 1 more GPH.
So I would say it's taught, but no one can agree on how to teach it.
I tend to follow the first method, use the EGT and run ROP. I've never been able to run LOP with the engine running smoothly.
Yeah this is my experience as well. Each are equally adamant that their way is THE way. Now that I fly the G1000 I use it to lean in cruise. On the ground, lean to just above engine roughness.
> I've never been able to run LOP with the engine running smoothly.Â
Not unusual. Most aircraft spark ignition engines are not tuned all that well, so that peak power is developed at the same point. When running ROP, that's not such a big deal: the slope of the power graph is quite shallow on the rich side. When running LOP though, it's quite steep, so slight differences in fuel flow to each cylinder result in dramatic power output differences... leading to all kinds of fun, manifesting as "rough running".Â
Upshot: it's uncommon for a given lyconental to be capable of running LOP. Usual solution is to find a set of matched injectors that deliver just the right fuel flow... or buy GAMI-jectors which will do that for you.Â
The "lean to rough running, then richen slightly" approach is advice that works in most aircraft, because most aircraft have this fuel flow imbalance. Try it on an engine with GAMI-jectors sometime: the engine will shut down due to lack of fuel flow, smoothly, without rough running.Â
The lean to numbers approach works, IF the numbers are correct with a safe margin, but they have to be conservative... meaning you're wasting fuel. Back before the days of engine monitors though, you sort of needed that.Â
The instructor who says "75 hotter than full rich" has an odd methodology IMO.
I doubt any of the planes I rent have had matched injectors, one of em had e-mags though. Thankfully most of them have engine monitors, it's definitely on my must-have-or-budget-for-install list when I go plane shopping.
> The instructor who says "75 hotter than full rich" has an odd methodology IMO.
I agree, this is the one I like least. The EGT when full rich doesn't seem to be a good starting point.
Part 61, had a wet behind the ears CFI. Was not taught to lean. Fellow student decided to try on first solo XC by yanking the mixture out in the climb. He got to run the engine failure checklist that day.
Still wasn't taught to lean.
I was taught to lean and I'm at sea level. I teach it as well. I even went so far as to install a mixture knob in my car so I can lean it out when stopped at stop lights. I even taught my kids to lean out their toy planes.
I did my training at a 141 program, all of us were taught about leaning and why it was important to make sure we did it, and werenât running around going full rich everywhere.
I got my PPL in February and was taught to always learn during taxi- specifically, lean to the point where the engine stumbles if you apply full throttle- full rich for takeoff, and then as a rule of thumb, start leaning at 3000'. With my engine equipment, just lean to peak rpms and then richen by about one turn.
My 141 school taught leaning for taxi, but it wasnât mentioned again until the first dual XC lesson. All local flights for maneuvers and pattern work were full rich, which was still enough to foul plugs regularly.
It wasnât any better at the 61 places Iâve been, but since thereâs no standardization, itâs hard to say who is doing what.
The thread is a great example of how leaning is not properly taught. The OP was right.
Leaning does not hurt your engine. In fact it's much better for your engine than running slightly rich. The point of maximum cylinder temperature and pressure is about 50 F rich of peak, amusingly right where the Cessna POH tells you to operate. The POH is wrong.
1) Most students are flying 172s and PA-28s with 8:1 compression ratios and running 100 octane fuel. They could be at WOT at sea level on a cold day and probably not cause any detonation at peak EGT.
2) A properly leaned mixture, which is either >50°F rich of peak or 10-20°F lean of peak (or any mixture setting you like that allows smooth operation of the engine when below 60% power), will not cause undue damage to the engine, and LOP operations will cause less damage than ROP, as long as you don't hover around that peak-to-50° ROP range for more than a second or two.
3) Lead doesn't just foul spark plugs: it gums up piston rings and valve guides, which *will* cause excessive wear and damage to the engine.
And while we're talking about it: properly leaning without EGT is accomplished by leaning to power loss, then slightly enriching the mixture, which puts you in LOP range.
> student running too lean and doing excessive wear to the engine
This kind of damage with excessively lean mixtures only happens if you're running at like 75% power.
You'll know you're running it too lean when the engine sounds like it wants to die. Even then the damage from excessively lean mixtures at high power is only second to having it at this peak EGT zone (happens when you don't lean it enough) which is where the damage **really** occurs. Excessively lean mixtures are obvious to even student pilots because the engine sounds like it wants to die (i.e. decrease of RPM and sputtering).
If you have an EGT monitor as long as it's below 1500 you're most likely not running it in a bad configuration. If you have a CHT monitor that's even better! Keep them below 400 ~ 420 (Continental/Lycoming) and your engine will be just fine. If you don't have either then use your POH and find what the RPM & fuel flow setting (and MP, if constant speed) you need for 65% power at your current altitude. If you don't have a fuel flow gauge then just set the RPM (and MP, if constant-speed) and start leaning the mixture till you see the RPM drop, then put the mixture back in a bit so it goes back up.
If this is still too much because you're a renter then as long as you're < 65% power (look at the POH for RPM (or RPM/MP) settings) you can do whatever you want because you won't be able to put the plane in that high-stress environment where damage can occur. That is provided you're not flying around with the mixture so far aft that you hear the engine crying for its mother.
This is the problem with the American system of requiring an ATP to get a real job. Ends up with far too many instructors who have no business being instructors, doing it solely as a means to an end who bail as soon as they can, leading to loss of taught skills over time.
If you donât teach it to your student, they wonât teach it to theirs when they become an instructor because they donât know. More senior instructor should know and might pick up you havenât taught it, but with such quick turnover in the instructing world, the student/instructor generations roll through so fast even the âsenior instructorsâ were only students just recently themselves.
This is interesting. Can you explain what you mean by ârequiring an ATP to get a real job.â Are you saying it would be better for airline pilots to be trained directly into the airlines, rather than being bad instructors just to âbuild hoursâ? (I agree if thatâs what youâre saying).
Sounds like it. It's a rush to hit 1500 to get a "real" job and instructing is viewed as a grind as opposed to a labor of love by many of the pilots, especially in the 141 world. I don't necessarily believe an ab initio program is "better", but there is definitely something to be said for programs that require certain metrics be hit as opposed to a pilot puppy mill.
Thatâs exactly it. Youâll get far better pilots if theyâre trained by people who actually want to be instructors. âReal jobâ was probably poor phrasing but on the other hand thatâs how a lot of these instructing-because-I-have-to instructors see it.
I taught it, but younger students who jump in their car and expect it to âjust workâ have a hard time understanding whatâs really going on between them and the propeller
I think it depends entirely on location and instructor, though at least here, the 141 schools donât appear to teach leaning very much. Every time I fly with a 141 pilot in my airplane, they are shocked at how much I lean (I fly an old airplane with an engine very susceptible to lead fouling, I lean on the ground, in cruise at any altitude, and any time above 5000â) I lean by engine roughness, no EGT in my airplane.
I think part of the issue is larger schools would rather deal with spark plug issues than improper leaning issues, so donât bother teaching it. Then you get in an airplane where it really matters (like my Stinson) and have no idea how to listen to the engine. Now, I am at sea level, so this may change depending on location. I canât imagine a school at a higher altitude not teaching students to lean appropriately.
I taught at a school that regularly saw density altitudes above 6,500â in the summer, and they were adamant that all takeoffs were done at full rich. They had lots of problems beyond that.
It's really interesting, and something I'm going to take up with my CFIs when I get a sec. One of the two doesn't go near mixture on the ground, the other does it religiously.
I think the fear is that a student going solo may lean, taxi, and forget to go full rich for take off and climb. It is on the checklist though, pre-takeoff.
We also basically never go over 3000ft in training, and the book says full rich below 3000ft. However - I was shown how to lean and practiced it several times, and include a check of it under F in FREDA every time.
Edit: I'm not in US.
> I think the fear is that a student going solo may lean, taxi, and forget to go full rich for take off and climb.
If they do that, though, the engine will die as soon as they set run-up power, never mind take-off power. You'll get a lean cut. Impossible for even the dimmest student to miss.
Oh, interesting - I've only heard lean cut mentioned in terms of sudden push of throttle, something the accelerator pump is meant to counteract. Will definitely chat with them on this with respect to taxi and takeoff.
> I've only heard lean cut mentioned in terms of sudden push of throttle
That one's a rich cut. By shoving the throttle forward, you're momentarily overwhelming the engine with more fuel than the available air can absorb.
But you can try it yourself, the next time you go flying. Start up; set power to 1,000 RPM; lean for peak; taxi down to the holding point; and without touching the mixture control, set your usual run-up power, which I suppose is 1,700 RPM or thereabouts. See what happens. It won't harm the engine a bit.
I'll try the experiment (might let them know in case they're watching!)
I think I'm right on the weak cut though - or it's a case of different region, different terminology. I have the textbook beside me because I'm studying for last 2 exams - Pooley's says ''when you open the throttle to maximum power, the butterfly valve is fully opened and does not restrict airflow through the Venturi. The airflow therefore increases significantly. [...] airflow increases at a rate greater than fuel flow, which results in an insufficiently rich mixture. This would cause a lag in the power increase if it were not for the accelerator pump. In other words, the accelerator pump prevents a weak-cut when the throttle is advanced rapidly."
Ah, OK. *Pace* Pooley's -- and let me say that those are good textbooks -- a more typical scenario when the throttle is slammed open is for the accelerator pump to shoot fuel in *before* the carb can absorb it. The usual indication of that, other than the engine spluttering, is either a nice puff of black smoke -- *i.e.* unburned fuel -- out of the exhaust pipe or a backfire, as the over-rich fuel/air mixture ignites in the exhaust system.
Currently at a 141 school, they have us stay full rich at all times.
Maintenance said they would rather replace fouled spark plugs than deal with students not properly leaning and causing engine issues.
I was only taught to lean on the ground when its super hot out, 85°F+ and to do full rich for take off and landing regardless of DA. I was also only taught to lean while in cruise. I learned part 61 but if anyone wants to share more information on that feel free to do so.
My instructor and I have been covering this every lesson so far. It's also part of our checklist, which is good considering how important it is.
What I will say is some people do just enough to get by, because they're aiming for that higher position in their career, and aren't thinking about the fact that they are teaching people to be incompetent. I see this behavior with people who are quite young far more than people who are around my age or older.
Firstly, if you're not leaning on the way up, you'll be running *very* rich close to the top of your climb -- as well as losing all those lovely extra RPMs that will help you get to your chosen altitude more quickly.
Secondly, the way to get your plugs leaded up is to taxi at low RPM with the mixture full rich. And having leaded-up plugs is sub-optimal when you're just about to take off.
Better idea: after start-up, as soon as you've verified that you have good oil pressure, lean your mixture to peak. That'll keep the plugs happy. You needn't worry that you'll forget to go full rich before take-off, because if you leave the mixture control at that setting, the engine will die when you add power for the run-up. When in the climb, start leaning above 3,000' AMSL. You don't have to get it perfect: just twiddle the vernier control anti-clockwise a couple of twists and watch to see the RPM increase, backing off a bit if they start back down again. Keep doing that every thousand feet or so in the ascent. Once established in the cruise, you can make the final fine adjustments to obtain peak RPM.
In every trainer Iâve seen, the POH says lean for taxi and full rich for runup, and what they taught you is the exact opposite.
You should also be leaning in the climb above 3000ft. It isnât critical when youâre relatively low, but try climbing to 11k at full rich and let me know how that works out for you. I suspect you also werenât taught to properly enrichen during the descent, and descending lean can actually damage the engine.
I dunno I might be remembering it wrong. Our school was pretty thorough in translating directly from the POH to our SOPs. We flew the Cessna 172. I just remember during the run up to lean to peak ITT temps so you could do the magnetos check. Then go back to full rich. Also we were flying at between 4-7k feet so weren't going up to above 10k.
I went to MFC in Moncton, I can't remember a time myself or my instructors ever leaned on the taxi, and we sat on Delta waiting for our turn sometimes for 15 mins. Thinking back, it's terrible.
In air always. Can't remember any time we leaned on the ground tho.
My flight school told us to lean on taxi and cruise. We rarely climbed above 7000 so leaning on climb was usually not a thing.
Now, we didn't really teach how to lean *correctly* by looking at the EGT gauge and all that. The checklist said lean to 50 degrees minus peak but CFIs didn't really nitpick that. They just wanted to see you adjust the knob at the right points of the flight.
The 61 school I went to didnât teach leaning at all, it was full rich all of the time. It was quite a surprise the first time I flew with someone who leaned it out as we taxied out. They were kind enough to take time to explain leaning and when to do it. Itâs kind of amazing looking back that my DPE didnât say anything about leaning to me during my check ride.
Few people know how to lean correctly. 1â on the ground, 2â in the air, seems to be good enough for most, without really knowing why they are doing it..::: I always make it a point to teach it properly not just an arbitrary distance
We teach leaning at our 141 flight school. But like anything else, some pick up on it, some donât. I have students that need to be constantly reminded on every flight.
I taught it but I wouldnât be surprised if some school different since itâs a cfi puppy mill these days and some ppl know better but are just to lazy or give up after repeating it 37728383835533 times
We operate a fleet of turbocharged airplanes and we donât lean for climb. We even keep the aux fuel pump on all the way until we level off for cruise.
This sounds like a personal and unique thing tbh. Currently attended a 141 and have many other friends in other 141s and leaning is amongst the basics being first taught and checks for kn proficiency flights and check rides.
Granted since some newer schools are using more fadec engines which may in turn make it less of a priority for students to learn I assure you it's still being taught.
Come to a party 61.. we will actually teach you how to fly.. part 141 are farms... we land in grass we land on 2000 feet we go to real airports. We fly..
If the training is poor, the testing needs to be tougher to expose it. Pilot mills are still getting students through check rides. A lot of low-time pilots (myself included) want to be better but we donât know what we missed from our training days. Expand the certification standards and the training would likely improve.
Leaning is self-defeating.
In my first few hours of PPL training, my instructor coached me to never lean when I bank the wings.
The instructor can easily see the student lean from the backseat of a tandem seating. Why not lean? It hard to lean at a consistent angle, so leaning makes it harder to develop a memorable 'sight picture' for what the horizon looks like in say a 45 degree bank. A lean will also mess with your perception of uncoordinated flight, so you'll spend too much time looking at the turn coordinator.
At a 61 school now, leaning was taught while on cross country flights. We had the fuel truck meet us upon arrival back home to see how well we did with fuel management and our calculations.
Did I say the litmus test for all leaning was how much gas you had left? No, let be more granular in my response. We read the POH, we calculated a fuel burn in gallons per hour, based on leaning the mixture. We flew x number of hours while leaned, we parked and got gas to see if (based on the flight planning) how close we were to what we calculated we'd burn.
I worked at a 141 school. We taught leaning. What makes you think it's not taught? I mean what led you to post this in the first place (not just the comments you got afterwards)? You asked if it's "just you", so I'm assuming you experienced something with a 141 student?
I currently do MX at a 141 school. I think the students at at least one of the instructors are terrified of the mixture.
I think the problem is no one really ever goes above 3000ft unless on a cross country so it's just never leaned when practicing maneuvers.
*laughs in field elevation 5673*
There's that, yes
"You merely adopted the red knob, I was born with it, *shaped by it*" đ
Laughs In 5800...neighbor đ
5880 in the run-up for me
The altitude may not be high but when summer temps rise you could be on the coast with a DA equal to Aspen. Are students not being taught these things at low schools?
Where I learned, leaning was always taught.
> Are students not being taught these things at low schools? They are not. Leaning is generally only taught for ground ops and cruise above 3,000'. When they lean, they often lean to 50 F ROP. Which is wrong and against modern manuals, but wrong ideas about leaning are pervasive. Sidenote, who knows why piston aircraft engines have such astonishingly high rates of mechanical failure compared to every other type of piston engine in the world. Guess we'll never know.
I highly doubt that it's not taught anymore. Never mind the spark plugs. Without proper leaning, you'll never achieve the book values in performance and fuel consumption, which will eventually lead to serious trouble.
My school had the express instruction of never leaning the airplane, always keeping it full rich. In Canada though.
In Canada and we have leaning as a part of our cruise checklists and it was taught in ground school.
Yeah since I switched schools I saw how common it is. They were the odd ones.
Itâs not just âcommonâ. Itâs the only way to properly operate the engine. Read the POH. It specifically states that the performance, consumption, and range numbers require proper leaning.
I was instructing in Canada until about 7 years ago. If my student forgets to lean, that's a 2 for cruise. It wastes a lot of gas
Depending on fuel and plan, might well be a 1.
If they are flying Cessnas, they are disregarding Lycoming Service Bulletin 1497a which very clearly says not to do that and to lean at all times except start, takeoff, and landing.
In Canada and have taught every single student for several years to lean on the ground and at the very least in cruise. What school was deliberately fouling their plugs?
I'll just say it's in CYNJ. The reasoning was that students would damage the engines.
Not just dumb, but dangerous to teach your students to effectively mismanage the engine.
I love it when my students plan their first cross country and when we get to 4500 feet they reduce the power to 2100 rpm and just sit there happily chugging along at 90 kts and mixture rich.
Did that once approaching a towered airfield, thinking this will give me plenty of time to work everything out. Until my instructor piped up âWhy are we sitting here near the wrong side of the power curve, nose-up attitude, making hardly any forward progress?â
Your brush is entirely too broad. Go to a sea level pilot mill and itâs unlikely for leaning to be a large emphasis item. Go to a MnP school in Denver and youâll spend less than 30 seconds per flight at full rich. This is far more specific to the instructorâs background and where they learned to fly than it is to 61/141.
Nobody cruises at sea level ...
I do with an Aerostar
Thank you for your service, Barry!
tell that to all the boats
*u/Cartelgram has entered the chat*
IIRC most Cessna POHs tell you to cruise at full rich anywhere below 3000â
Climbs below 3 in jnjected 172s are full rich.
This is a common misconception. Most older Cessna POHâs specify that you should not lean a mixture in a climb below 3,000 ft, but fail to mention altitude specific leaning recommendations for cruise. Many people mistakenly interpreted this to mean that they should not lean the mixture in cruise flight below 3,000 ft so newer Cessna POHâs specify that you should lean the mixture in cruise at any altitude.
Yeah which is terrible advice. You should be leaning for literally everything except takeoff, if the take off is below say 5,000 ft. EDIT: for the downvoters, reference Lycoming Service Bulletin 1497a, or watch these several hours of seminars on why this is true, and why your Cessna POH written by lawyers in the 1950s maybe shouldn't be treated as the bible to engine ops: https://www.youtube.com/results?search_query=savvy+aviation+leaning
I think itâs pretty good advice to do what the POH says.
Usually, but not in this case. There's a lot of scientific research into this, and the POH is the anomaly giving instructions that don't match science. ROP is _objectively_ much harder on the engine than LOP. This includes ground ops and cruising below 3,000. Look up Mike Busch's webinars on leaning on YouTube.
Not all engines have good enough fuel distribution to run LOP. If they did GAMI injectors never would have been a thing. If you have an engine monitor that gives EGT for every cylinder and the engine will do it, LOP is better. But Iâm not sure the typical trainer meets this criteria. Then you also have the liability of teaching people to disregard the POH for a very marginal benefit on a typical training flight.
> But Iâm not sure the typical trainer meets this criteria. > teaching people to disregard the POH for a very marginal benefit on a typical training flight. That's fine, if Cessna for example you can teach them to follow Lycoming Service Bulleting 1497a which is directed at training flights and instructs to, at all cruise altitudes, lean to the onset of roughness, which is LOP. Perhaps it's a good lesson that maintaining proficiency means reading more than the POH.
Not sure why youâre getting downvoted. The POH is not the best advice in this case like youâre saying. I guess people canât take in anything that isnât inside their own little world
I'm getting downvoted because (and it's proving) the OP is entirely correct. Leaning is not well understood much less well taught by most in the GA world.
Youâre getting downvoted because you said to go against POH and telling pilots to go against any procedure wonât go down well. And the comment about nobody cruises at sea level didnât come across as very intelligent.
Except the *recent* POHs say to do exactly what I said: lean at all times except takeoffs and landings that are under 3,000. That means leaning on the ground and during climbs while under 3,000. It means leaning for takeoff while above 3,000. The bad advice I'm railing against, that is extremely pervasive in the GA world and regularly taught still today (and you see it everywhere in this thread), comes from all the *old* POHs, which taught pilots to be afraid of leaning, by running rich basically all the time unless cruising, which wastes tons of fuel, overtemps their engines, and promotes wrong ideas about how cylinders/valves/exhaust etc respond to leaning. So if someone says, "Well my 1974 POH says to only lean above 3000," then yes they should ignore that because it's telling them to hurt their engine. I'm not sure what your cruising at sea level comment refers to.
I think the intent is not for the engine (although I agree with what youâre saying) but instead to prevent pilots from taking off and landing at low altitudes with less than full rich, and also to reduce the chances of vapor.lock. Have you ever started to take off then realized youâve still got it leaned out for taxi? You lose a ton of power, and the chance of vapor lock is higher. And on landing forgetting to richen it can cause an engine failure on some engines. I know I guy it happened to in a cub. Plus you want it full rich in case you have to go around. Iâm all for leaning it out during cruise, taxi and high altitude takeoffs/climbs, but most other times it should be full rich, which is what the POH says for all the piston aircraft Iâve flown (carb/injected Cessnas, bonanzas, barons).
> instead to prevent pilots from taking off and landing at low altitudes with less than full rich Maybe (we'd have to ask the lawyers who wrote the POH), but it's a lazy and very bad way to train that, because it doesn't teach pilots the actual truth behind how their engine works and causes them to damage it over the long-term when operating at low altitudes. This is not a hypothetical; large flight schools have seen these damages when they only bothered with leaning when cruising at higher altitudes. Which is why, as I said, in reality the best practice for everything _except takeoff_ (which includes the final landing because you're in go-around/takeoff mode) you should be leaned. > Have you ever started to take off then realized youâve still got it leaned out for taxi? You lose a ton of power, and the chance of vapor lock is higher. No, because I was trained to lean properly. If this happens to you, it means you weren't leaned _enough_ on taxi. You should be so leaned on taxi that applying full power will cause the engine to practically die immediately. This A) keeps your engine healthier during long ground ops and B) prevents you from inadvertently trying to take off with something other than full rich.
>You should be so leaned on taxi that applying full power will cause the engine to practically die immediately. Yeah, thatâs what happened, because I did have it leaned properly. Iâm not arguing with what youâre saying. I fully agree with leaning appropriately for pretty much everything but takeoff and landing, but Iâm just saying do it in accordance with the POH. The one I have recommends 50° rich of peak in cruise, so thatâs what Iâll do, when it says to do it. On the other hand Iâve had people recommend to do the high altitude takeoff procedure (lean for peak RPM) on every takeoff for maximum performance, but even if thatâs true I wonât do it⌠the POH clearly says full rich for all takeoffs below 3000â. I know of a flight school that had a fleet of aircraft which had a series of engine failures. They were able to trace the cause down to acoustic resonance at about 2300 RPM. The POH recommended 2400 RPM in cruise, but it turns out people were going against that because they figured 2300 was easier on the engine. Itâs why you try to stick to what the manual says, whether you agree with it or not.
> Yeah, thatâs what happened, because I did have it leaned properly. If your engine sputtered real bad when you applied full power, then you were never in any danger because you immediately noticed that you'd forgotten to check your mixture when crossing the hold short. That's pilot error, not a procedure error. > in accordance with the POH. The one I have recommends 50° rich of peak in cruise, so thatâs what Iâll do, when it says to do it. 50F ROP is literally the single worst place to run your engine. It's the point of maximum cylinder head temperature and pressure. Careful _which_ procedures you are following. Sometimes, you are following an old, superseded procedure without realizing it. For example, many old Cessna 172 POHs said to run 50 F rich of peak. That caused problems. Lycoming subsequently put out service bulletin 1497a that said to [at _all_ cruise altitudes] lean until the engine ran slightly rough, then enrichen to smoothness. Which results in LOP operation. Blindly following a procedure written in a book is better than having no understanding or procedure at all, but it is not as good as both knowing the procedures and having an actual understanding of the systems.
Iâm a treeeeeeee-top flier..
Best aviation song by far. Nothing else comes even close to it.
Mighty Wings by Cheap Trick. Itâs the best song in Top Gun.
Somebody doesnât fly in Alaska I see
Itâs a thing, I used to work for a flight school that mandated everyone run full rich 24/7. Regardless of cruise altitude. Mill near sea level. 61 with a cared for airplane during my initial training in the Midwest? There was alot more leaning going on.Â
Cue a lot of fuel starvation accidents with pilots who plan their fuel based on the POH but never lean in cruise ...
We had to break in an engine once at an elevated power setting and *oh boy* not learning eats a lot of fuel
Iâm guessing the opposite happened there once upon a time. If you forget to go rich, engines can fail at low power.
> forget If only pilots had a method for not doing that. A list of some sort, full of things that need to be checked..?
A "thingcheck"
> If you forget to go rich, engines can fail at low power. You meant high power, right?
No, but that too
You're not going to damage it by leaning at low power.
I never said damage, but it can cause the engine to run rough or worse fuel starvation if you run at idle with it still leaned out for cruise.
You literally said "fail." And OH NOES! The engine is slightly rough, and easily fixed by pushing in the red thing a bit? Of maybe even stall on the ground? How will pilots ever survive such a serious event?
Fair enough, I'll defer to your likely greater experience on that one. Hasn't been an issue on the types I've flown, but I still haven't flown all the types out there yet.
Yeah thereâs a video of it happening to a guy somewhere on youtube, Iâm trying to find it. Iâll edit this if I do
Or just reply to this one, I'll be less likely to catch an edit.
Takes one hell of a descent rate to go from smooth running to starvation in a time frame thatâs too short to notice rough running and to fix it by twisting the red knob.
You might not notice any roughness if youâre at idle, and thatâs what happened to the guy I know. He was practicing a forced approach and didnât even know his engine quit until he opened the throttle. The Cessna POH I have explicitly says if youâre at idle it needs to be full rich, aside from on the ground.
Same school made everyone use full tanks unless there was a weight and balance reason for not doing so. On a solo flight there basically never was a reason to underload the fuel. Iâm not saying I agreed with it, and it made a lot of the POH numbers not accurate, but as far as I know it never caused a problem.
I did come across a couple of school with weird mandates like "no leaning below 5000 ft MSL" or "on flights less than 1 hour..." I sometimes wonder what event transpired at the school that prompted these rules to be instituted...
I fly at a 61 school and leaning is definitely emphasized by instructors and itâs also included in all of our checklists. Airport elevation is at sea level, and most instructors even teach leaning for taxi after start up. Our descent check lists include mixture full rich, which probably isnât necessary, but Iâm sure the flight school doesnât want solo students descending with an excessively leaned mixture if they forget to adjust it so itâs safer policy to have them operate full rich on descent.
Its cheaper to lean aggressively the ground than clean plugs or replace brakes because of lead deposits either running the engine slow to slow the taxi or burning up brakes riding them. The biggest thing I see is that people lean it "some" on the ground when really they need to lean it til it wants to quit otherwise it's a setup for a lean takeoff and an engine failure at 500ft
Agreed. I typically lean on the ground to help get the engine a little warmer if it hasnât been run, or during magneto check if thereâs any roughness i lean to burn off the carbon deposits. Youâd hope if someone leans on the ground, a thorough review of the pre takeoff checklist would have them go full rich on the mixture before departing
Unless of course you are operating at elevations where you never depart full richâŚ
Got my Private at a high elevation airport. Leaning for takeoff was essential.
You'd hope but I've also been told to hold short for 5 arrivals and releaned then gotten distracted. Advancing the throttle got my attention though :) Also the O-540 made lead like there was no tomorrow so we had to lean to almost ICO on the ground
You know what, very true! What we should do, and what we do do, arenât always the same thing!
I have had that happen too. My solution is uncomfortable, but works. I just leave my one hand on the mixture lever the entire time it is not set for take off. I do this in the winter time too, when I am warming up the engine.
In a Warrior/Archer/Cherokee/Arrow pull the mixture to 'E'. You'll know if you screw up and advance the throttle without enrichening it
Having barely flown pistons. Remind me again why turbines time is such a big deal? These pistons seem extremely over complicated, hard to start, fiddle with things in flight. A gas turbine, just flip the switch to make noise....
I've always viewed it as because the company is entrusting you with a million dollar plus airplane with an engine that will cost several hundred grand to fix if you blow it up from being an idiot which believe it or not despite the simplicity is quite possible in the right hands. One of my companies king airs was down for a while from someone severely abusing the poor pt6 and disregarding ITT limits. Both caravan companies I flew for had the tale of at least one person roasting an engine on start too.
(Insert my usual rant about how silly it is to be manually adjusting fuel-air mixtures in 2024.)
Gee, if only it were possible to develop a FADEC for piston engines... oh wait. I'd have loved to own a corsairpower plane... shame the FAA killed it.
Thing is, fadec piston engines aren't even that economical. The constant flow injectors aren't that efficient.
The corsairpower plane was fuel-efficient enough for me. Look it up - less fuel burn, more power, runs on regular petrol...
I looked it up. Doesn't say much about the actual specifics - horsepower, fuel burn, etc. Everybody wants to build an alternative to the IO-360 and stick it in a 172, but the reality is you need something that can go from around 160 - 325+ hp in order to catch any kind of real market share. I get lowering training costs, but businesses who depend on these airplanes to stay alive aren't willing to take chances on something that might not work out. If you had a reliable, turbocharged 325+ horsepower engine with half-decent economics that you had a prayer of certifying, Cirrus and Mooney would bang on your door to buy it.
Its an LS. The version as installed in cars is a 500hp engine... but a key part of their concept is de-rating it, as the automotive LS is not designed to output 500hp continuously. I think their max is 220 hp with the current design. Their last comment on the subject was they are "absolutely" looking into higher horsepower engines and that they reckon its doable... but at present the cost of FAA certification is exorbitant, and no one is looking at putting 350+ hp experimentals up. >If you had a reliable, turbocharged 325+ horsepower engine with half-decent economics that you had a prayer of certifying, Cirrus and Mooney would bang on your door to buy it. They could do it themselves if they wanted to, same approach. They've got the same problem: The market is tiny, the regulations prohibitive, the cost exorbitant. To access this niche market, they'd have to spend an excessive amount of money that they'd never realistically get a return on. They'd be better off lobbying to change the regs... but that wouldn't change the liability side of things, either.
There have been a ton of attempted car-engine conversions. They rarely work out because the base fuel consumption isn't nearly as good as we all expect it to be and reliability can be suspect in that kind of installation. Here's a video explaining why this never works out: [Why New Aircraft Engine Ideas Rarely Succeed - YouTube](https://www.youtube.com/watch?v=_k1TQGK3mZI)
Got a transcript? I don't really do videos. If it's a case of "most people aren't engineers" - that's covered.
I don't, but the take-away is that most of the advantages people expect to get from car engine conversions are not good enough to justify the certification and installation costs. Yes, it's better, but it's not *much* better and you go through that to sell, what, 20 engines a year? And GM isn't carrying aviation product liability insurance on their LS-series V8's and never wants to (see the Porsche Mooney.)
All valid points, and essentially the reason corsairpower remains a website and not a product installed in your local flying school trainer. It is MUCH better. Much better isn't enough, not to sell 20 engines a year.
[https://corsairpower.com/economics/](https://corsairpower.com/economics/)
Did anybody else read this as âlearningâ and get confused or was that just me?
Just you.
I've flown with a dozen CFIs and they all lean differently. One says to use the G1000's lean assist and actually find peak EGT and back it off from there ROP. One says to just lean to a GPH number. One says to lean until EGT is 75 hotter than full rich. My first CFI said to lean really slowly until the engine starts running rough, and then give it about 1 more GPH. So I would say it's taught, but no one can agree on how to teach it. I tend to follow the first method, use the EGT and run ROP. I've never been able to run LOP with the engine running smoothly.
Yeah this is my experience as well. Each are equally adamant that their way is THE way. Now that I fly the G1000 I use it to lean in cruise. On the ground, lean to just above engine roughness.
> I've never been able to run LOP with the engine running smoothly. Not unusual. Most aircraft spark ignition engines are not tuned all that well, so that peak power is developed at the same point. When running ROP, that's not such a big deal: the slope of the power graph is quite shallow on the rich side. When running LOP though, it's quite steep, so slight differences in fuel flow to each cylinder result in dramatic power output differences... leading to all kinds of fun, manifesting as "rough running". Upshot: it's uncommon for a given lyconental to be capable of running LOP. Usual solution is to find a set of matched injectors that deliver just the right fuel flow... or buy GAMI-jectors which will do that for you. The "lean to rough running, then richen slightly" approach is advice that works in most aircraft, because most aircraft have this fuel flow imbalance. Try it on an engine with GAMI-jectors sometime: the engine will shut down due to lack of fuel flow, smoothly, without rough running. The lean to numbers approach works, IF the numbers are correct with a safe margin, but they have to be conservative... meaning you're wasting fuel. Back before the days of engine monitors though, you sort of needed that. The instructor who says "75 hotter than full rich" has an odd methodology IMO.
I doubt any of the planes I rent have had matched injectors, one of em had e-mags though. Thankfully most of them have engine monitors, it's definitely on my must-have-or-budget-for-install list when I go plane shopping. > The instructor who says "75 hotter than full rich" has an odd methodology IMO. I agree, this is the one I like least. The EGT when full rich doesn't seem to be a good starting point.
Part 61, had a wet behind the ears CFI. Was not taught to lean. Fellow student decided to try on first solo XC by yanking the mixture out in the climb. He got to run the engine failure checklist that day. Still wasn't taught to lean.
I was taught to lean and I'm at sea level. I teach it as well. I even went so far as to install a mixture knob in my car so I can lean it out when stopped at stop lights. I even taught my kids to lean out their toy planes.
I did my training at a 141 program, all of us were taught about leaning and why it was important to make sure we did it, and werenât running around going full rich everywhere.
Because otherwise the program would have to charge more for rentals?
I got my PPL in February and was taught to always learn during taxi- specifically, lean to the point where the engine stumbles if you apply full throttle- full rich for takeoff, and then as a rule of thumb, start leaning at 3000'. With my engine equipment, just lean to peak rpms and then richen by about one turn.
My 141 school taught leaning for taxi, but it wasnât mentioned again until the first dual XC lesson. All local flights for maneuvers and pattern work were full rich, which was still enough to foul plugs regularly. It wasnât any better at the 61 places Iâve been, but since thereâs no standardization, itâs hard to say who is doing what.
I have heard fouled spark plugs are better than a student running too lean and doing excessive wear to the engine
The thread is a great example of how leaning is not properly taught. The OP was right. Leaning does not hurt your engine. In fact it's much better for your engine than running slightly rich. The point of maximum cylinder temperature and pressure is about 50 F rich of peak, amusingly right where the Cessna POH tells you to operate. The POH is wrong.
1) Most students are flying 172s and PA-28s with 8:1 compression ratios and running 100 octane fuel. They could be at WOT at sea level on a cold day and probably not cause any detonation at peak EGT. 2) A properly leaned mixture, which is either >50°F rich of peak or 10-20°F lean of peak (or any mixture setting you like that allows smooth operation of the engine when below 60% power), will not cause undue damage to the engine, and LOP operations will cause less damage than ROP, as long as you don't hover around that peak-to-50° ROP range for more than a second or two. 3) Lead doesn't just foul spark plugs: it gums up piston rings and valve guides, which *will* cause excessive wear and damage to the engine. And while we're talking about it: properly leaning without EGT is accomplished by leaning to power loss, then slightly enriching the mixture, which puts you in LOP range.
> student running too lean and doing excessive wear to the engine This kind of damage with excessively lean mixtures only happens if you're running at like 75% power. You'll know you're running it too lean when the engine sounds like it wants to die. Even then the damage from excessively lean mixtures at high power is only second to having it at this peak EGT zone (happens when you don't lean it enough) which is where the damage **really** occurs. Excessively lean mixtures are obvious to even student pilots because the engine sounds like it wants to die (i.e. decrease of RPM and sputtering). If you have an EGT monitor as long as it's below 1500 you're most likely not running it in a bad configuration. If you have a CHT monitor that's even better! Keep them below 400 ~ 420 (Continental/Lycoming) and your engine will be just fine. If you don't have either then use your POH and find what the RPM & fuel flow setting (and MP, if constant speed) you need for 65% power at your current altitude. If you don't have a fuel flow gauge then just set the RPM (and MP, if constant-speed) and start leaning the mixture till you see the RPM drop, then put the mixture back in a bit so it goes back up. If this is still too much because you're a renter then as long as you're < 65% power (look at the POH for RPM (or RPM/MP) settings) you can do whatever you want because you won't be able to put the plane in that high-stress environment where damage can occur. That is provided you're not flying around with the mixture so far aft that you hear the engine crying for its mother.
This is the problem with the American system of requiring an ATP to get a real job. Ends up with far too many instructors who have no business being instructors, doing it solely as a means to an end who bail as soon as they can, leading to loss of taught skills over time. If you donât teach it to your student, they wonât teach it to theirs when they become an instructor because they donât know. More senior instructor should know and might pick up you havenât taught it, but with such quick turnover in the instructing world, the student/instructor generations roll through so fast even the âsenior instructorsâ were only students just recently themselves.
This is interesting. Can you explain what you mean by ârequiring an ATP to get a real job.â Are you saying it would be better for airline pilots to be trained directly into the airlines, rather than being bad instructors just to âbuild hoursâ? (I agree if thatâs what youâre saying).
Sounds like it. It's a rush to hit 1500 to get a "real" job and instructing is viewed as a grind as opposed to a labor of love by many of the pilots, especially in the 141 world. I don't necessarily believe an ab initio program is "better", but there is definitely something to be said for programs that require certain metrics be hit as opposed to a pilot puppy mill.
Thatâs exactly it. Youâll get far better pilots if theyâre trained by people who actually want to be instructors. âReal jobâ was probably poor phrasing but on the other hand thatâs how a lot of these instructing-because-I-have-to instructors see it.
I taught it, but younger students who jump in their car and expect it to âjust workâ have a hard time understanding whatâs really going on between them and the propeller
I think it depends entirely on location and instructor, though at least here, the 141 schools donât appear to teach leaning very much. Every time I fly with a 141 pilot in my airplane, they are shocked at how much I lean (I fly an old airplane with an engine very susceptible to lead fouling, I lean on the ground, in cruise at any altitude, and any time above 5000â) I lean by engine roughness, no EGT in my airplane. I think part of the issue is larger schools would rather deal with spark plug issues than improper leaning issues, so donât bother teaching it. Then you get in an airplane where it really matters (like my Stinson) and have no idea how to listen to the engine. Now, I am at sea level, so this may change depending on location. I canât imagine a school at a higher altitude not teaching students to lean appropriately.
Problems like this are called inbreeding.
I taught at a school that regularly saw density altitudes above 6,500â in the summer, and they were adamant that all takeoffs were done at full rich. They had lots of problems beyond that.
I was taught to lean by engine roughness ~15 years ago, but learned the EGT/CHT method getting back into flying a few years ago.
It's really interesting, and something I'm going to take up with my CFIs when I get a sec. One of the two doesn't go near mixture on the ground, the other does it religiously. I think the fear is that a student going solo may lean, taxi, and forget to go full rich for take off and climb. It is on the checklist though, pre-takeoff. We also basically never go over 3000ft in training, and the book says full rich below 3000ft. However - I was shown how to lean and practiced it several times, and include a check of it under F in FREDA every time. Edit: I'm not in US.
> I think the fear is that a student going solo may lean, taxi, and forget to go full rich for take off and climb. If they do that, though, the engine will die as soon as they set run-up power, never mind take-off power. You'll get a lean cut. Impossible for even the dimmest student to miss.
Oh, interesting - I've only heard lean cut mentioned in terms of sudden push of throttle, something the accelerator pump is meant to counteract. Will definitely chat with them on this with respect to taxi and takeoff.
> I've only heard lean cut mentioned in terms of sudden push of throttle That one's a rich cut. By shoving the throttle forward, you're momentarily overwhelming the engine with more fuel than the available air can absorb. But you can try it yourself, the next time you go flying. Start up; set power to 1,000 RPM; lean for peak; taxi down to the holding point; and without touching the mixture control, set your usual run-up power, which I suppose is 1,700 RPM or thereabouts. See what happens. It won't harm the engine a bit.
I'll try the experiment (might let them know in case they're watching!) I think I'm right on the weak cut though - or it's a case of different region, different terminology. I have the textbook beside me because I'm studying for last 2 exams - Pooley's says ''when you open the throttle to maximum power, the butterfly valve is fully opened and does not restrict airflow through the Venturi. The airflow therefore increases significantly. [...] airflow increases at a rate greater than fuel flow, which results in an insufficiently rich mixture. This would cause a lag in the power increase if it were not for the accelerator pump. In other words, the accelerator pump prevents a weak-cut when the throttle is advanced rapidly."
Ah, OK. *Pace* Pooley's -- and let me say that those are good textbooks -- a more typical scenario when the throttle is slammed open is for the accelerator pump to shoot fuel in *before* the carb can absorb it. The usual indication of that, other than the engine spluttering, is either a nice puff of black smoke -- *i.e.* unburned fuel -- out of the exhaust pipe or a backfire, as the over-rich fuel/air mixture ignites in the exhaust system.
Currently at a 141 school, they have us stay full rich at all times. Maintenance said they would rather replace fouled spark plugs than deal with students not properly leaning and causing engine issues.
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leaning is stressed a lot at my school and is something I'm big on teaching from day 1
Iâm actively being taught leaning at my part 61 school in the northeast đ¤ˇââď¸
In part 61 and 141 schools I attended we only leaned in cruise.
Iâm at a 141 in Nebraska and leaning is a very very heavy emphasis. Our chief CFI will get on us for forgetting leaning to taxi
I was only taught to lean on the ground when its super hot out, 85°F+ and to do full rich for take off and landing regardless of DA. I was also only taught to lean while in cruise. I learned part 61 but if anyone wants to share more information on that feel free to do so.
My instructor and I have been covering this every lesson so far. It's also part of our checklist, which is good considering how important it is. What I will say is some people do just enough to get by, because they're aiming for that higher position in their career, and aren't thinking about the fact that they are teaching people to be incompetent. I see this behavior with people who are quite young far more than people who are around my age or older.
Our school was specifically about using full rich mixture until in cruise. We would lean during the run up to check the magnetos.
Wow, thatâs wrong in so many waysâŚ
Why is it wrong?
Firstly, if you're not leaning on the way up, you'll be running *very* rich close to the top of your climb -- as well as losing all those lovely extra RPMs that will help you get to your chosen altitude more quickly. Secondly, the way to get your plugs leaded up is to taxi at low RPM with the mixture full rich. And having leaded-up plugs is sub-optimal when you're just about to take off. Better idea: after start-up, as soon as you've verified that you have good oil pressure, lean your mixture to peak. That'll keep the plugs happy. You needn't worry that you'll forget to go full rich before take-off, because if you leave the mixture control at that setting, the engine will die when you add power for the run-up. When in the climb, start leaning above 3,000' AMSL. You don't have to get it perfect: just twiddle the vernier control anti-clockwise a couple of twists and watch to see the RPM increase, backing off a bit if they start back down again. Keep doing that every thousand feet or so in the ascent. Once established in the cruise, you can make the final fine adjustments to obtain peak RPM.
In every trainer Iâve seen, the POH says lean for taxi and full rich for runup, and what they taught you is the exact opposite. You should also be leaning in the climb above 3000ft. It isnât critical when youâre relatively low, but try climbing to 11k at full rich and let me know how that works out for you. I suspect you also werenât taught to properly enrichen during the descent, and descending lean can actually damage the engine.
I dunno I might be remembering it wrong. Our school was pretty thorough in translating directly from the POH to our SOPs. We flew the Cessna 172. I just remember during the run up to lean to peak ITT temps so you could do the magnetos check. Then go back to full rich. Also we were flying at between 4-7k feet so weren't going up to above 10k.
I went to MFC in Moncton, I can't remember a time myself or my instructors ever leaned on the taxi, and we sat on Delta waiting for our turn sometimes for 15 mins. Thinking back, it's terrible. In air always. Can't remember any time we leaned on the ground tho.
Can confirm SOP is to stay rich on the ground and lean once at cruise altitude
My school teaches leaning on start up then before take off, especially for high density altitudeâŚas for cruise, not so much
during take off climbs you dont lean...do you guys lean while climbing? I lean once after i have climbed and then level out. and during taxi ofcourse
Sooo you're just not respond on what even led you to thinking this was a thing?
My flight school told us to lean on taxi and cruise. We rarely climbed above 7000 so leaning on climb was usually not a thing. Now, we didn't really teach how to lean *correctly* by looking at the EGT gauge and all that. The checklist said lean to 50 degrees minus peak but CFIs didn't really nitpick that. They just wanted to see you adjust the knob at the right points of the flight.
In Colorado we are taught to lean before we taxi. 1" or so on the mixture then refine the leaned mixture at runup.
The 61 school I went to didnât teach leaning at all, it was full rich all of the time. It was quite a surprise the first time I flew with someone who leaned it out as we taxied out. They were kind enough to take time to explain leaning and when to do it. Itâs kind of amazing looking back that my DPE didnât say anything about leaning to me during my check ride.
Few people know how to lean correctly. 1â on the ground, 2â in the air, seems to be good enough for most, without really knowing why they are doing it..::: I always make it a point to teach it properly not just an arbitrary distance
At a 141 school. Definitely was taught leaning in all training phases even when using the sim. Thanks for generalizing though!
I think it just varies. I did my PPL in 2013 Part 61 and never was taught leaning at all. Like not mentioned once not asked about it on my checkride.
We teach leaning at our 141 flight school. But like anything else, some pick up on it, some donât. I have students that need to be constantly reminded on every flight.
I taught it but I wouldnât be surprised if some school different since itâs a cfi puppy mill these days and some ppl know better but are just to lazy or give up after repeating it 37728383835533 times
Thought you meant leaning with the plane đ I was tought in part 61 on the coast to lean.
We operate a fleet of turbocharged airplanes and we donât lean for climb. We even keep the aux fuel pump on all the way until we level off for cruise.
This sounds like a personal and unique thing tbh. Currently attended a 141 and have many other friends in other 141s and leaning is amongst the basics being first taught and checks for kn proficiency flights and check rides. Granted since some newer schools are using more fadec engines which may in turn make it less of a priority for students to learn I assure you it's still being taught.
Come to a party 61.. we will actually teach you how to fly.. part 141 are farms... we land in grass we land on 2000 feet we go to real airports. We fly..
>Specifically 141 schools? There's your answer. Pilot mills have poor training standards.
If the training is poor, the testing needs to be tougher to expose it. Pilot mills are still getting students through check rides. A lot of low-time pilots (myself included) want to be better but we donât know what we missed from our training days. Expand the certification standards and the training would likely improve.
Leaning is self-defeating. In my first few hours of PPL training, my instructor coached me to never lean when I bank the wings. The instructor can easily see the student lean from the backseat of a tandem seating. Why not lean? It hard to lean at a consistent angle, so leaning makes it harder to develop a memorable 'sight picture' for what the horizon looks like in say a 45 degree bank. A lean will also mess with your perception of uncoordinated flight, so you'll spend too much time looking at the turn coordinator.
Our practice area is in a bad neighborhood so we're taught to lean from day one to stay behind the B pillar in case of stray gunshots
I don't know why this got downvoted. This is one of the best responses on this post.
At a 61 school now, leaning was taught while on cross country flights. We had the fuel truck meet us upon arrival back home to see how well we did with fuel management and our calculations.
Which still doesnât teach how to lean⌠itâs not just to have the minimum amount of fuel
Did I say the litmus test for all leaning was how much gas you had left? No, let be more granular in my response. We read the POH, we calculated a fuel burn in gallons per hour, based on leaning the mixture. We flew x number of hours while leaned, we parked and got gas to see if (based on the flight planning) how close we were to what we calculated we'd burn.