When to pull power back on takeoff.

[avbug]

Regarding powerplant management and leaning: Lycoming says that it is not possible to over lean one of their engines at anything less than takeoff power. I've flown a bunch of big continentals, too, and we leaned them failrly hard(with only 3 failures in 20,000 hours). Got to keep these engines hot--until you're ready to shut them down.

What's a "big continental?" I didn't know Continental ever made any. Are you talking bout the radials? Even those were small.

Lycoming doesn't say anything about being unable to harm the engine by leanign at less than takeoff power. Less than 75% power, perhaps. But operating at takeoff power settings, especially higher manifold pressures with a mixure adjacent to lean, can damage the engine in high compression engines, thorugh detonation. Operating lean of peak, properly done, produces cooler temperatures, and does not...and lower power settings.

You don't need to keep those engines hot. You do need to control temperature change. However, leaning is really irrelevant to this topic, and isn't what was being addressed with the subject of throtle enrichment. In that case, it's a design feature to prevent detonation at higher power settings. If you've leaned for takeoff in the enrichment range and reduce power, you've leaned back too far at that point, and need to enrichen the mixture. This is applicable to carbureted engines utilizing an enrichment valve...not all do...and this isn't a function of the pressure carburetor.

You may be thinking of autorich and autolean which are entirely different functions that do apply to pressure carburetors...something with which few posters here will have had any experience.

Sounds like a throw back to the presssure carb days. Still one of the best methods around when properly set up.

What's a throw back to pressure carburetors?

If you're referring to enrichment, that's a mechanical fact for certain carburetion systems on many small carburetors used in light airplanes. It's a flat on the throttle cam which allows more fuel physically at full throttle, resulting in a richer mixture...the enrichment is purely a function of the physical position of the throttle.

I never care what the neighbors think. They bought a house next to an airport. Screw them until an official abtement procedure tells me otherwise, and even still that will almost always be a max percormance climb to a certain altitude or a lateral procedure.....NEVER A POWER REDUCTION AT LOWER THAN NORMAL ALTITUDE.

Normal altitude could be 5', it could be several hundred feet...that really depends on what's being done at any given time. You really need to start caring what the neighbors think...it's that kind of ignorance that leads to loss of flying privileges, animosity toward airports, loss of airport properties, etc. Exercising noise abatement practices is a good professional practice...even when someone isn't forcing you to do it. Doing it becasue you are a professional, rather thann having your arm twisted is...the prrofessional thing to do.

Now, pulling power back before the gear comes up (<200agl) is silly. I don't care what the airport neighbors think. They live with it and hear it all day, every day. What is 15 seconds of "tolerating" my little IO-360 gonna matter, when a 757 departed just three minutes prior?

Your cessna 185 is going to be more abrasive and annoying with supersonic prop tips than the stage III 757 for one thing...but you shouldn't be pushing your light piston single out too close to that departing 757 anyway. Do you really leave your gear down until 200 in the air? Why on earth would you do that? Positive rate, gear up. Breakaway thrust, positive rate, gear up, and any power reduction appropriate to your operation...is okay.

The point with the rental comment was that people who choose to operate more in the interest of noise and cost considerations will end up in a smoking hole. These things can be considered, of course, but "positive climb; gear up; power back" is not safe IMO. To modify an old joke, if it's being a good neighbor you're interested in: Have you ever heard the noise made by a small airplane crashing in to a house?

I have heard that sound. Have you? I also put out the burning airplane, crimped the torn and draining fuel lines by hand, and removed the battery after securing the site and pilot. What has that to do with the price of tea in china? If you're suggesting that a power reduction will result in crashing into a house, even as a joke, then you're making a ridiculous suggestion...just as you are when suggesting that making a power reuction will put someone in a smoking hole. Not so.

Correct me if I'm wrong, but don't some of the newer aircraft even tell you that full power is "okay" all the time. I seem to remember a new mooney that had that in the books.

That would really depend on the aircraft, powerplant, and the circumstance. Operationally, even where permissible, one may have no need, nor desire to run at full power all the time.

One aircraft I flew had a standard mission fuel burn of 200 gallons per hour. However, at takeoff power, burn went to 600 gallons of avgas per hour. Remaining at takeoff power was never done any more than necessary...we liked our fuel tobe available for the mission, rather than pissing away for no good reason. Reduce power when necessary, where necessary, as your mission profile dictates. Reducing after takeoff does not mean you are going to die.

I could go on for hours, but make one power change at a time(after initial climb power change), and none within 60 seconds of each other(M.P., R.P.M, Mixture) especially in a descent. Maybe we should start a new thread for this.

No basis exists for separating a throttle position change from a RPM change by one minute, nor a RPM change froma mixture change by one minute, nor a mixture change from a RPM or throttle position (manifold pressure) change by one minute...no factual basis at all You could start a thread on it, but it's a guesswork type of policy...a feel-good sort of thing with no grounding in reality. It ranks up there with oversquare myths, the myth that an engine fails at the fist power reduction, etc.

 

[KeroseneSnorter]

Dunno about the myth of engines failing at the first power reduction....but in personal experience that is when it happens the most.

2 of 3 piston engine failures were at first power reduction, 1st catastrophic with fire, second was crank failure, and 1 of 2 forced shutdowns on jet engines were at the first power reduction, technically not a failure but the problem appeared at first reduction which would have resulted in a major failure, starter generator started shucking nice chunks of metal and trying to shake the engine off the pylon (No CSD's on that model to disconnect, so shutdown was only option)

 

[Rez O. Lewshun]

Before I left the GA/recip world, I would leave the throttles full all the way up to altitude.

Why pull them back at, I'm ready to lose the engine now altitude, only to keep pushing them foward during the climb.....

 

[avbug]

I might possibly have the record among posters here and elsewhere for engine-outs...in all sorts of aircraft and under a very wide range of conditions (most of which few here will ever enter)...and I don't think a single one of them has been at the first power reduction. Or the next, or the next, or the next...

Why pull the power back...when you might be pushing it up again? For noise abatement, among other things. If you're not faced with noise issues, then you may be reducing from takeoff power to climb power.

Bottom line, set power as you need it, appropraite with the aircraft and the mission. Not really rocket science.

 

[Rez O. Lewshun]

I just read the article you linked on avweb. Dude said to keep the throttle full and adjust the RPM and/or mixture... or did I read it too fast...

 

[avbug]

Dude? What are you? Surfer from the third grade?

Must be talking about someone else. I didn't link an article. What's your point?

We departed today and immediately pulled the power back considerably to maintain our mission profile. What a sin. Perhaps we should have pushed the power to limits, told ourselves "self, screw the neighbors," and blown the purpose of the mission in favor of being a good flightinfo full-power-pilot...but we just didn't see it that way and went for the power reduction anyway.

 

[30West]

In most cases, using full power to altitude would be the most noise friendly, as it gets you the most altitude in the quickest time. Might seem counterintuitive at first, but it works.

On the DC-10 out of Brussels, we use full T/O power rather than Flex. This gets us up higher faster and actually lowers our noise footprint. If we use Flex we'll end up setting off the electronic "snitches" on the departure corridor and generate nasty grams from noise gestapo.

Fly the POH.

 

[Huggyu2]

Yes, Rez, you read it right... Avbug jumped on your case a bit too quickly this time, however Deakin's article says just that. If I remember right, he leaves the throttle full open and at about 1000' leans to 15 gph (he's flying an IO-550). He'll adjust the prop too, as required.
He dispells a bunch of techniques that most of us do regularly, showing graphs of power and heat that have me thinking about a lot of this.
He's got a slew of other articles too, so go to avweb.com and check them out.
I hope a bunch of the folks that have a lot of inline piston time (non-turbo) will read Deakin's articles, and chime in with their opinion.

 

[svcta]

Avbug, you're just my hero.

Tell me why there is no logical basis for the concept of not making more than one powerplant adjustment at once and even spacing them by a little time? M.P. adjustment= Temp change in cylinders. R.P.M. adjustment= Temp. change in cylinders. Mixture adjustment= Temp. change in cylinders.

Big is a relative term, now isn't it?(I'll hold off on the mom joke) 3 and 400 series cessnas have "big" continentals, and even the IO550s I used to tinker with on T-34s are big continentals. I know it's not big by P&W standards, but I regularly operate those, too, so I'll take the liberty.

And I've dealt with plenty of noise ababatement procedures, NONE call for power adjustement outside of normal profile(except for a few that require a reduced thrust takeoff, but that's not abnormal, either, weight permitting). If you're airplane says do that @ 5' then you just go for it. I fly jets at work when they make me go and our "mission", Ice Man, is the safety of the guy who's writing the checks in the back, then noise abatement.

Go ahead and start chopping power a a few hundred feet in you busted-a$$ rented duchess. When one of those "small" Lycomings pukes on you in the middle of the summer you will most likely end up in a neighbor's roof. I, too will ease the prop back on an R-1340 after the gear is in the well, but that's at a private airport and there's plenty of horsepower left on that particular airplane. used to do it in the twin commanders, too, as I think I mentioned, again, plenty of power. 3000 R's was go around power on those things anyway.

Pressure-carbs....it was just a little nod to the old pressure carb. Got a few hours on them myself(both wrenching and flying).....I'm totally aware of the auto-lean function.

The rest of it I'm just too disinterested to argue about, I think it's all still more than valid. Merry Christmas.

 

[avbug]

Numerous noise abatement proceedures in aircraft regard a quick climb, power reduction leveling of attitude until past noise sensors or a noise abatement area, then a return to a climb power setting. In propeller driven aircraft, this is often best accomplished by a RPM reduction, which may or may not be accompanied with a power reduction. In some aircraft, reduction of RPM just after takeoff may be accomplished for operational needs, noise abatement, or merely because it's the best power setting.

SOP in our 4Y's, for example, was breakaway thrust to become airborne, then a power and RPM reduction...the reduction was far more likely to enhance safety than any issues with the mythical but nonexistant engine-failure-with-the-first-power-reduction monster, because we were more interested in avoiding lifting a cylinder head than avoiding something that does not exist.

I do a lot of flying that doesn't climb very high...I may never climb more than a few hundred feet for the entire duration of the mission, and yes, reduction of power after takeoff, or reduction of RPM, is quite appropriate. Not uncommonly I'll back off the high RPM stops either during the takeoff roll, or just after breaking ground, while levelng at 5' to retract flaps, before climbing to 15-25' make the crosswind turn. Strange thing is, the airplane doesn't melt down, explode, or fall out of the sky because of this heretic maneuver. It may be outside the small, diminuitive box in which you operate, but it is appropriate to the mission.

Yes, mission. You fly profiles, I fly profiles. When appropriate. I am assigned sorties and missions, and they're logged accordingly. I'm paid accordingly. Perhaps you have trips, or dispatches, or rigs, or whatever you want to call them. But in every case, we each have a mission to perform, be it point to point, or some form of working operation such as utility flying. The purpose of the flight is the mission, the assignment, the duty, the plan, or whatever you desire to call it. We simply call it the mission, ice dude.

No, an 0-470, 0-520, or 0-550 isn't a big engine. A R-1340 isn't a big engine, so far as pistons go. A R-3350 or R-4360 is a big engine. Light aircooled horizontally opposed recip piston engines are small engines. As you will. Calling the engines found in a Cessna 340 or 400 series cessna "big" is worth a chuckle, though.

Go ahead and start chopping power a a few hundred feet in you busted-a$$ rented duchess.

How would you phrase that if you weren't a college graduate?

Not that you have a need to know, but I don't rent. I don't fly a dutchess, and my butt is just fine, thanks. However, if I reduce power in said airplane, your diminuitive comfort zone would have the world believing the aircraft will come raining down from the sky...when such is a ridiculous notion. Highly melodramatic, but stupid. Never the less, you're just too disinterested to care.

Folks like yourself are the reason that places like Santa Monica are so tough on noise and are rapidly becoming restricted to the rest of us. Such shortsightedness in thinking only of yourself hurts everyone. You're responsible for the damage being done to the industry, animosity toward operations at many noise sensitive airports, and limitations that we continually face as airports are closed, arrivals and departures limited, and penalties and curfews increasingly placed by communities all over. Thanks for your help!