Questions about mixture leaning

[RyanB]

I found out about the RED FIN elsewhere as a variation of the RED BOX, the idea that operation within the box will be harmful to the engine.

If you consider all of the slopping leaning practices that students do in flight school aircraft (a lot of which routinely operate within the red box), yet still make TBO and beyond.

 

[WannFly]

If you consider all of the slopping leaning practices that students do in flight school aircraft (a lot of which routinely operate within the red box), yet still make TBO and beyond.

Way beyond, the local flight school once told me their average TBO time is somewhere between 3200- 3800 hrs. And those planes gets a used way more than any owner would ever do. Think the only thing that matters is how much you let the engine sit. These things are built to stand abuse.

 

[Ryan F.]

Flight school airplanes... flying every day is the best way to keep an engine happy. It more than makes up for all of the operational practices which are considered "hard" on an engine... though just imagine how long a gently flown engine could make it if it was flown every day.

Personal aircraft which fly 100-150 hours per year need their engines to be managed more carefully to approach this sort of flight hour longevity.

 

[gfinn12]

That’s why on some of our checklists it says “as req’d.” For example engine anti ice. Under certain conditions it will be on and other times it will be off. Some items are not always required.

Hey do you have the rest of this MD88 checklist? If so can you post it?

 

[Crashnburn]

Mixture simply regulates how much fuel goes into the engine for a given amount of air (basically). If you aren't changing altitude (or rather, the air density isn't changing), the only real reason you'd have to adjust mixture when changing power is to manage engine temps

For climb, I usually leave it full rich until around 3K-5K and start to lean for better performance, careful to watch temps
For descent, I usually leave the red knob alone for a while until the engine seems rough.. I always go full rich though by around 3K in the club Archer and Skyhawk though

PS, I know pilots (myself included) tend to be control freaks, but honestly, given how poor most CFIs are at teaching engine management it really would be nice to have the plane regulate its own mixture. This, by the way, doesn't have to be fancy electronic technology.. the Twin Bonanza mechanically managed its own mixture as does the Antonov AN-2 (yes, the big Soviet biplane), and I'm sure many others. How many engines have been damaged or killed by incorrect mixture technique. Just let an engineer figure it out and have the engine manage itself

Continental had FADEC on their Liberty XL but pilots didn’t like it because they thought they could manage the engine better. Last I heard the Continental IO240F was no longer supported.

 

[brcase]

Continental had FADEC on their Liberty XL but pilots didn’t like it because they thought they could manage the engine better. Last I heard the Continental IO240F was no longer supported.

Continental either missed a great opportunity here, or didn't believe the Fadec was any better than pilots either. IMO, All they would have had to do is significantly extend the warranty or better yet the TBO of the engines equipped with FADEC to make them sell. Seems like adding a few hundred more hours to an engine that is continuously care for by the computer would have been an easy thing to do. Convincing the FAA might have been a harder sell for a TBO increase, but the FAA doesn't regulate the engine warranty. The problem was they tried to sell the Fadec as an increased cost feature with no reasonable expectation that there would be any return on the investment.

 

[MRC01]

Do whatever your instructor wants you to do regarding leaning. First, you need to make him/her happy in order to succeed in attaining your certificate. Second, it's not your plane, and its health is his/her responsibility.

True, so long as what the instructor requests does not contradict the POH or engine operating manual.

... When you own your own plane readdress the leaning issue. It may vary from plane to plane and engine to engine. In my normally aspirated Piper Warrior, I lean aggressively on the ground. So much so, that if the throttle is advanced the engine will stumble. This is as insurance against taking off too lean. Generally, I take off full rich, then lean above 3000 MSL/DA (ish). At cruise, I lean as the POH suggests -- lean to roughness, then enrichen to smoothness.

Leaning is simple for most certified common lower performance aircraft engines like the O-320, O-360 and similar Continentals. Essentially, it boils down to 1 simple rule: any time you are below 70% power, lean it. Even at sea level. This is especially true during ground operations where the power output is so low you can lean it aggressively almost to the cut-off. It will keep the plugs and valves clean, save fuel, reduce the chance of carb icing, and reduce emissions.

The term "lean it" can mean 2 things:

1. For level cruise flight, just rich of rough. Lean until the engine gets a bit rough, then enrich just enough for it to smooth out. In level flight there is plenty of airflow through the cowling so you're not worried about cooling.

2. For max power at high density altitude, lean to peak RPM, then enrich a few turns from there. This is to put the engine on the rich side of peak power, as a little extra fuel promotes cooling. Especially when climbing where there is less cooling airflow through the cowling.

 

[Pinecone]

1) Everything forward for take off and go around can kill you. That is fine a low DA, but high DA that plan significantly reduces the power from the engine.

2) CFIs teach what they know/have learned. Many/Most are not and have not been aircraft owners and have not learned about leaning and protecting their engine. Their CFI was not knowledgeable about leaning, and their CFI before that. And what they know is probably wrong from a long line of CFIs spouting old wive's tails that they learned.