Commercial Pilots who don't know about piston engines
That Lycoming advice has eff all to do with the actual powerplant., it is simply trying to stop one from taking-off with a leaned mixture.
And as for cooling the engine with full-rich during the taxi., who the bleep actually needs to operate an engine at high power, for prolonged periods, at low ground speeds. ? (LAMEs excluded)
And as for cooling the engine with full-rich during the taxi., who the bleep actually needs to operate an engine at high power, for prolonged periods, at low ground speeds. ? (LAMEs excluded)
Last edited by KittyKatKaper; 4th Mar 2016 at 02:18.
Join Date: Jul 2007
Location: in the classroom of life
Age: 55
Posts: 6,864
Likes: 0
Received 1 Like
on
1 Post
A2
You are correct in your statement about the small variation on the rich side of the peak where there is a rise in HP peaking at around 75-80 ROP. And yes when very rich it falls off a touch as the mixture moves ThetaPP out a fair bit.
You will no doubt appreciate in practical terms for the pilot in flight, splitting atoms is not relevant, and the small difference <1~1.5% is not a practical thing for pilots to be contemplating. We teach the whole thing in class but for practical application purposes what Walter describes is correct.
Cloudee,
Let me copy paste and highlight the OWT's, the BS and the spin produced by Lycoming to cover their butts from "loss of face".
You are correct in your statement about the small variation on the rich side of the peak where there is a rise in HP peaking at around 75-80 ROP. And yes when very rich it falls off a touch as the mixture moves ThetaPP out a fair bit.
You will no doubt appreciate in practical terms for the pilot in flight, splitting atoms is not relevant, and the small difference <1~1.5% is not a practical thing for pilots to be contemplating. We teach the whole thing in class but for practical application purposes what Walter describes is correct.
Cloudee,
Let me copy paste and highlight the OWT's, the BS and the spin produced by Lycoming to cover their butts from "loss of face".
To Lean or Not to Lean While You Taxi
Aviation is full of tribal knowledge from pilots, both past and present. One trick that often comes up, usually in the early part of your flying career is, “you should lean the engine while on the ground to prevent spark plugs from lead fouling.” In theory, this seems like a completely logical method. Less fuel equals less lead deposits in my spark plugs. So why do Lycoming Engines’ Operators Manuals recommend different?
Is there a better way? Not surprisingly, Mother Nature throws more unexpected factors into the situation, and while you might feel better trying, you can’t fool Mother Nature. No you can't and when operating as per Lycoming I always had far more Pb deposits, who are they trying to kid here?
WHY SHOULDN'T I LEAN DURING TAXI?
To start, Lycoming Engines’ Operators Manuals clearly instruct the pilot to keep the mixture at full rich during ground operations and engine run-up. By leaning on the ground, you may not entirely eliminate the problem of spark plug fouling. While you’re introducing less lead into the system, you are also reducing the cooling effects of the fuel. COMPLETE BS, at any power the combustion curves applyYour airplane’s cooling package is not designed for prolonged periods of zero airspeed operations. Of course, we have the propeller wash, but it isn’t the same as having airspeed blowing over your air cooled Lycoming Engine. Leaving the mixture rich helps cool your engine since you don’t have that airspeed yet. Supporting a myth by telling the truth…clever trick
Taxi and take-off can be a busy time for a pilot, especially if you are at a busy airport. Imagine you are at a complicated international airport. You’ve leaned your mixture to try to prevent the engine from fouling up. The tower is yelling at everyone, (Really??)making things stressful. There are jets all around you with engines big enough to suck up your entire airplane. (Sounds like a Greenpeace or PETA commercial- Are you scared yet?) You are given a challenging departure procedure and you are trying to brief yourself. Before you know it they give you a clearance to take-off-- not in 2 seconds, but right now. You start your take-off roll and realize the engine seems weaker than normal. Maybe it’s even got a little vibration to it. But you are committed now, and you’re running out of runway. Because of the heavy workload, you may have forgotten to push the mixture back to full rich, and it is negatively affecting the engine’s power for takeoff and climb. This happens more than you might think. (Only if they are poorly trained, Line up and go in a LYCOMING is simple, boost pump on mixture rich and GO!!!!Add to this that Lycoming’s Service Instruction 1094 recommends take-off be conducted at the full rich setting when at density altitudes below 5,000 feet; above 5,000 feet density altitude may require some leaning to achieve acceptable power and smooth operation. Complete myths designed to scare you. The APS method does everything it should and nothing it shouldn't. Do it right and the engine will stumble and almost quit…..you will push the red knob in GUARANTEED
WELL THEN, WHAT SHOULD I DO?
Make sure your mechanic is doing all of the proper spark plug maintenance. Lycoming Engines recommends spark plugs by part number in our Service Instruction 1042. It may be a good idea to check your plugs to make sure previous owners or mechanics installed the correct part numbers. Also, the spark plugs should be cleaned, gapped, and rotated at least every 100 hours of operation. If you are operating Champion spark plugs, information on those procedures can be found on their website here: Aviation Service Manual.
Ensure that your carburetor or fuel injection servo have the idle settings correctly adjusted. A proper idle set up will help reduce the possibility of lead collecting in the cylinders and spark plugs.
Your mechanic should run the aircraft until the engine oil temperature is up to the normal operating temperature before making any of the following adjustments:
Idle Speed - Increase the throttle to roughly 1,700 RPM and rapidly reduce it back to idle. Generally the airframe manuals recommend the idle speed be set between 600 RPM and 700 RPM. If it is outside the specification, it should be adjusted using the idle stop screw.
Idle Mixture - While at idle, slowly pull the mixture lever back to idle cut-off. You should notice a slight rise in engine RPM before it shuts off. Lycoming Engines recommends a rise of 10-25 RPM. If there is no rise, the engine is too lean and needs to be richened slightly. If it rises more, the engine is getting too much fuel and needs to be leaned.ALL GOOD ADVICE
4. Study the figure to the left. Lead fouling is greatly affected by the temperature of the gasses inside the cylinder. How can we take advantage of this? Shortly after you start your engine and have positive oil pressure, increase your throttle setting to obtain an engine speed between 1,000 RPM and 1,200 RPM. This will allow enough heat to be generated to properly scavenge lead from the cylinders. Anything less and the temperatures inside the cylinder will cool enough to form lead and carbon deposits, even if the engine is leaned. 1000 RPM is enough, think noise and stone damage
5. Just prior to engine shut down, increase the throttle setting to about 1,800 RPM. Operate here for 15 to 20 seconds. Reduce the throttle back to 1,000 RPM to 1,200 RPM and immediately shut down the engine using the mixture control. This will ensure the engine gets properly scavenged of lead just before shut down. Bad idea, heat the engine up to achieve what? Make a lot of noise, rotating props are best not where people are around….and I never found doing or not doing this made any difference, nor do thousands of others.
FINAL THOUGHTS
Don’t be afraid to question procedures that aren’t found in the Pilot’s Operating Handbook (POH). Poor practices which then become bad habits may have been passed down from pilot to pilot for generations; leaning during ground operations is one example. Always refer to the aircraft’s POH for the approved practices or operation instructions. If someone recommends something different than the POH, ask them to provide approved data to allow you to operate the aircraft using their method. Don't be afraid to question your POH, much of what is written in them is not scientifically correct, is misleading or contradictory to the engineering data in the same manual……so Be a critical thinker. Just because it is a POH does not mean it is correct, approved BS is BS all the same.
Aviation is full of tribal knowledge from pilots, both past and present. One trick that often comes up, usually in the early part of your flying career is, “you should lean the engine while on the ground to prevent spark plugs from lead fouling.” In theory, this seems like a completely logical method. Less fuel equals less lead deposits in my spark plugs. So why do Lycoming Engines’ Operators Manuals recommend different?
Is there a better way? Not surprisingly, Mother Nature throws more unexpected factors into the situation, and while you might feel better trying, you can’t fool Mother Nature. No you can't and when operating as per Lycoming I always had far more Pb deposits, who are they trying to kid here?
WHY SHOULDN'T I LEAN DURING TAXI?
To start, Lycoming Engines’ Operators Manuals clearly instruct the pilot to keep the mixture at full rich during ground operations and engine run-up. By leaning on the ground, you may not entirely eliminate the problem of spark plug fouling. While you’re introducing less lead into the system, you are also reducing the cooling effects of the fuel. COMPLETE BS, at any power the combustion curves applyYour airplane’s cooling package is not designed for prolonged periods of zero airspeed operations. Of course, we have the propeller wash, but it isn’t the same as having airspeed blowing over your air cooled Lycoming Engine. Leaving the mixture rich helps cool your engine since you don’t have that airspeed yet. Supporting a myth by telling the truth…clever trick
Taxi and take-off can be a busy time for a pilot, especially if you are at a busy airport. Imagine you are at a complicated international airport. You’ve leaned your mixture to try to prevent the engine from fouling up. The tower is yelling at everyone, (Really??)making things stressful. There are jets all around you with engines big enough to suck up your entire airplane. (Sounds like a Greenpeace or PETA commercial- Are you scared yet?) You are given a challenging departure procedure and you are trying to brief yourself. Before you know it they give you a clearance to take-off-- not in 2 seconds, but right now. You start your take-off roll and realize the engine seems weaker than normal. Maybe it’s even got a little vibration to it. But you are committed now, and you’re running out of runway. Because of the heavy workload, you may have forgotten to push the mixture back to full rich, and it is negatively affecting the engine’s power for takeoff and climb. This happens more than you might think. (Only if they are poorly trained, Line up and go in a LYCOMING is simple, boost pump on mixture rich and GO!!!!Add to this that Lycoming’s Service Instruction 1094 recommends take-off be conducted at the full rich setting when at density altitudes below 5,000 feet; above 5,000 feet density altitude may require some leaning to achieve acceptable power and smooth operation. Complete myths designed to scare you. The APS method does everything it should and nothing it shouldn't. Do it right and the engine will stumble and almost quit…..you will push the red knob in GUARANTEED
WELL THEN, WHAT SHOULD I DO?
Make sure your mechanic is doing all of the proper spark plug maintenance. Lycoming Engines recommends spark plugs by part number in our Service Instruction 1042. It may be a good idea to check your plugs to make sure previous owners or mechanics installed the correct part numbers. Also, the spark plugs should be cleaned, gapped, and rotated at least every 100 hours of operation. If you are operating Champion spark plugs, information on those procedures can be found on their website here: Aviation Service Manual.
Ensure that your carburetor or fuel injection servo have the idle settings correctly adjusted. A proper idle set up will help reduce the possibility of lead collecting in the cylinders and spark plugs.
Your mechanic should run the aircraft until the engine oil temperature is up to the normal operating temperature before making any of the following adjustments:
Idle Speed - Increase the throttle to roughly 1,700 RPM and rapidly reduce it back to idle. Generally the airframe manuals recommend the idle speed be set between 600 RPM and 700 RPM. If it is outside the specification, it should be adjusted using the idle stop screw.
Idle Mixture - While at idle, slowly pull the mixture lever back to idle cut-off. You should notice a slight rise in engine RPM before it shuts off. Lycoming Engines recommends a rise of 10-25 RPM. If there is no rise, the engine is too lean and needs to be richened slightly. If it rises more, the engine is getting too much fuel and needs to be leaned.ALL GOOD ADVICE
4. Study the figure to the left. Lead fouling is greatly affected by the temperature of the gasses inside the cylinder. How can we take advantage of this? Shortly after you start your engine and have positive oil pressure, increase your throttle setting to obtain an engine speed between 1,000 RPM and 1,200 RPM. This will allow enough heat to be generated to properly scavenge lead from the cylinders. Anything less and the temperatures inside the cylinder will cool enough to form lead and carbon deposits, even if the engine is leaned. 1000 RPM is enough, think noise and stone damage
5. Just prior to engine shut down, increase the throttle setting to about 1,800 RPM. Operate here for 15 to 20 seconds. Reduce the throttle back to 1,000 RPM to 1,200 RPM and immediately shut down the engine using the mixture control. This will ensure the engine gets properly scavenged of lead just before shut down. Bad idea, heat the engine up to achieve what? Make a lot of noise, rotating props are best not where people are around….and I never found doing or not doing this made any difference, nor do thousands of others.
FINAL THOUGHTS
Don’t be afraid to question procedures that aren’t found in the Pilot’s Operating Handbook (POH). Poor practices which then become bad habits may have been passed down from pilot to pilot for generations; leaning during ground operations is one example. Always refer to the aircraft’s POH for the approved practices or operation instructions. If someone recommends something different than the POH, ask them to provide approved data to allow you to operate the aircraft using their method. Don't be afraid to question your POH, much of what is written in them is not scientifically correct, is misleading or contradictory to the engineering data in the same manual……so Be a critical thinker. Just because it is a POH does not mean it is correct, approved BS is BS all the same.
Join Date: Apr 2013
Location: Vail, Colorado, USA
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
***
If someone recommends something different than the POH, ask them to provide approved data to allow you to operate the aircraft using their method.
***
This from Lycoming?????
"allow you to operate..." That's ridiculous. The POH "allows you to operate" anywhere you choose, unless it's in the LIMITATIONS section. The rest is nothing more than a "recommendation."
No one on the face of this earth has offered more hard data to pilots, mechanics, and OEM representatives than the teachers at Advanced Pilot Seminars. "Approved data?" What the heck is that? Because the FAA has stamped it as "approved" has nothing to do with it's scientific validity.
Over a decade ago, I asked Lycoming to provide data to back up some of their statements. I'm still waiting. Nada, Nunca, NOTHING. Why would someone not show their supporting data--unless they don't have any. Some of Lycoming's recommendations don't even agree with their own published data. Go figure?
If someone recommends something different than the POH, ask them to provide approved data to allow you to operate the aircraft using their method.
***
This from Lycoming?????
"allow you to operate..." That's ridiculous. The POH "allows you to operate" anywhere you choose, unless it's in the LIMITATIONS section. The rest is nothing more than a "recommendation."
No one on the face of this earth has offered more hard data to pilots, mechanics, and OEM representatives than the teachers at Advanced Pilot Seminars. "Approved data?" What the heck is that? Because the FAA has stamped it as "approved" has nothing to do with it's scientific validity.
Over a decade ago, I asked Lycoming to provide data to back up some of their statements. I'm still waiting. Nada, Nunca, NOTHING. Why would someone not show their supporting data--unless they don't have any. Some of Lycoming's recommendations don't even agree with their own published data. Go figure?
The content of that Lycoming document is a crack up. If I didn't know that many of our US brothers and sisters don't 'do irony' too well, I'd guess Lycoming had run a competition to see who could:
(1) use as many words as possible to state: "Make sure you set mixture to full rich before taking off (unless DA requires some leaning) and make sure you maintain your spark plugs properly", and
(2) squeeze in as much unsupported codswallop as possible.
Go to 1,800 RPM for 15 to 20 seconds to "ensure the engine gets properly scavenged of lead just before shut down." I'm hoping that's the product of comic genius rather than abject ignorance.
(1) use as many words as possible to state: "Make sure you set mixture to full rich before taking off (unless DA requires some leaning) and make sure you maintain your spark plugs properly", and
(2) squeeze in as much unsupported codswallop as possible.
Go to 1,800 RPM for 15 to 20 seconds to "ensure the engine gets properly scavenged of lead just before shut down." I'm hoping that's the product of comic genius rather than abject ignorance.
Last edited by Lead Balloon; 4th Mar 2016 at 22:59. Reason: Fixed typos - laughing too much the first time
Join Date: Dec 2000
Location: Sydney NSW Australia
Posts: 3,051
Likes: 0
Received 0 Likes
on
0 Posts
ensure the engine is probably scavenged of lead just before shut down
how does running at a certain RPM buring the same leaded fuel scavange the lead byproducs of previous combustion using the same fuel, when chemicals added to the Tetraethyl lead compond are designed to scavange the lead before it can be deposited during combustion, turning into lead bromide so it passes out with the exhaust.. (which freezez at 370deg C, hence leaves the light grey residue in the exhaust pipe)
I wonder if its a co-incidence that car engines became far more reliable once the fuels they used stopped producing a corrosive carcenogenic compound of lead during combustion?
Last edited by Ultralights; 4th Mar 2016 at 22:23.
Whatever it is, just imagine how bad it will be if it's not properly scavenged before shutdown. 
Join Date: Jul 2007
Location: in the classroom of life
Age: 55
Posts: 6,864
Likes: 0
Received 1 Like
on
1 Post
What does this tell you……….. It is worth a few minutes to watch, even if you do not see the parallel.
Margaret Heffernan: Dare to disagree | TED Talk | TED.com
Thanks WA
Margaret Heffernan: Dare to disagree | TED Talk | TED.com
Thanks WA
As usual, Margaret Heffernan makes a lot of very good sense.
(I believe always keeping a very open mind to be rather wise.)
I've been flying VFR GA with someone on PPRuNe for more than 30 years. I check just about everything that person does and have never been unprepared to question anything that I was doubtful or unhappy with. I suppose that's now known as good CRM.
The properly (IO520) engine monitored aircraft with Gami Injectors runs LOP in the cruise. I'm happy about that because it is logical to do so.
(I believe always keeping a very open mind to be rather wise.)
I've been flying VFR GA with someone on PPRuNe for more than 30 years. I check just about everything that person does and have never been unprepared to question anything that I was doubtful or unhappy with. I suppose that's now known as good CRM.
The properly (IO520) engine monitored aircraft with Gami Injectors runs LOP in the cruise. I'm happy about that because it is logical to do so.
Join Date: Jul 2005
Location: Queensland
Posts: 686
Likes: 0
Received 0 Likes
on
0 Posts
Jabba
Your clip doesn't relate to aviation. My 21 year old 600hour instructor knew more about how to run big bore air cooled aircraft engines than all the data backed, test cell experienced experts in the world. I have to believe him because he had the flight manual written by the sales team to back him up so it must be right. Those people getting double TBO using data based information are just plain lucky and any day now their planes will plummet to the ground.
Your clip doesn't relate to aviation. My 21 year old 600hour instructor knew more about how to run big bore air cooled aircraft engines than all the data backed, test cell experienced experts in the world. I have to believe him because he had the flight manual written by the sales team to back him up so it must be right. Those people getting double TBO using data based information are just plain lucky and any day now their planes will plummet to the ground.
I purchased a Turbo Encabulator to properly scavenge the lead from my engine, thanks Gerry.
I switch it on during the 5 minute period in which I 'cool' my turbo after each flight.
I switch it on during the 5 minute period in which I 'cool' my turbo after each flight.
"Those people getting double TBO using data based information are just plain lucky and any day now their planes will plummet to the ground."
Or perhaps worse into the sea, Rutan? I just so worry for that young family orbiting at 500' near Anna Bay that Dick has warned us of...
Or perhaps worse into the sea, Rutan? I just so worry for that young family orbiting at 500' near Anna Bay that Dick has warned us of...
Join Date: Apr 2013
Location: Vail, Colorado, USA
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
Jabba
Your clip doesn't relate to aviation. My 21 year old 600hour instructor knew more about how to run big bore air cooled aircraft engines than all the data backed, test cell experienced experts in the world. I have to believe him because he had the flight manual written by the sales team to back him up so it must be right. Those people getting double TBO using data based information are just plain lucky and any day now their planes will plummet to the ground.
Your clip doesn't relate to aviation. My 21 year old 600hour instructor knew more about how to run big bore air cooled aircraft engines than all the data backed, test cell experienced experts in the world. I have to believe him because he had the flight manual written by the sales team to back him up so it must be right. Those people getting double TBO using data based information are just plain lucky and any day now their planes will plummet to the ground.
Or, is he just another person with an unsupported opinion.
As for the video Jabba posted, it does apply to aviation in a BIG way. Open data and information not being recognized for what it is, or how to use it, while the old-schooled among us hang on to the way they've always done things in the face of the data. If you don't see that, well, you're missing the point.
It is worth noting that "a delusion is holding to an unsupported belief in the face of hard data to the contrary."
Each must decide for themselves how they will approach knowledge.
Join Date: Feb 2000
Location: Alaska, PNG, etc.
Age: 60
Posts: 1,550
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Apr 2013
Location: Vail, Colorado, USA
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Jul 2005
Location: Queensland
Posts: 686
Likes: 0
Received 0 Likes
on
0 Posts
Walter
A X A posted
He is correct and I'll risk outing myself here when I tell you that you and I have met and chatted at an Australian APS. I learned to fly in 72 ( well started then. I'm still learning) When I asked my instructor how leaning hurt the engine he said the excess oxygen rusted out exhausts. I asked how just a few molecules of oxygen could do that. He didn't know - it just did. Then I asked how come diesel trucks didn't burn out their exhausts because diesels always have an excess of oxygen in their exhausts. He said they must have different metal in their exhaust systems. He also said leaning even further caused rough running due to lean misfire.
Only in the 90s did I learn the real reasons for these problems and then at the APS the whole picture was explained with great clarity.
The reason for the sarcasm was that people who won't look at data or are too lazy to try and understand it really annoy me. When hard data contradicts what they were taught they appear to prefer the unsubstantiated information given to them by someone just parroting whatever they were taught.
My father in law and a good friend both died of stomach ulcers even though the cause and cure had been discovered by then. It took 20-25 years before the medical generally accepted the data. How many people died a miserable death because doctors were too stubborn or to lazy to to critically examine the new data as it became available?
How many aircraft engines life will be shortened because some pilots don't understand the data?
A X A posted
. I'm pretty sure that RutanAround was being ironic
Only in the 90s did I learn the real reasons for these problems and then at the APS the whole picture was explained with great clarity.
The reason for the sarcasm was that people who won't look at data or are too lazy to try and understand it really annoy me. When hard data contradicts what they were taught they appear to prefer the unsubstantiated information given to them by someone just parroting whatever they were taught.
My father in law and a good friend both died of stomach ulcers even though the cause and cure had been discovered by then. It took 20-25 years before the medical generally accepted the data. How many people died a miserable death because doctors were too stubborn or to lazy to to critically examine the new data as it became available?
How many aircraft engines life will be shortened because some pilots don't understand the data?
Join Date: Apr 2013
Location: Vail, Colorado, USA
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
The issues in longevity are two-fold: 1) controlling heat, and 2) controlling pressure. Both of these are moderated when LOP. The difference between heat and pressure at Best power and at 50dF LOP are significant. Very significant. Two engines, one ROP and one LOP AT THE SAME HP, will have the LOP engine running much cooler and under far less stress.
An optimal LOP setting (NA) results in a loss of only about 3 knots TAS for a savings of 3 gph in a 285-300 HP engine. That's a 20% fuel savings for a 2% loss of airspeed. If you are losing more speed than that, you are leaner than optimal. If you take one vector from ATC, you've eaten up that speed difference! Turbos are different. They can actually produce more HP LOP than ROP if one is controlling CHTs. That means that I can go faster on less fuel and have the engine operate under less stress.
It may be worthwhile to ask, "if Lycoming really felt that their 'approved' ROP methodology was best, why is their new FADEC-type engine set up to run LOP?"
There are well over 400 million flight hours of hard data which supports the above comments.
Join Date: Apr 2013
Location: Vail, Colorado, USA
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
In certain circumstances, it can, but it won't be by much. Increasing MP results in higher combustion temps and a slightly faster flame front speed. The faster flame front results in an earlier thetaPP and lower EGT/TIT, but again, it's not much--might even be "not enough to notice" since the temperature of combustion went up slightly. Again, this is not related to engine longevity.