A Little Gem from CASA Experts

[LeadSled]

Folks,
From a new AWB:

AIRWORTHINESS BULLETIN
AWB 85-023 Issue 1 – 3 April 2018
Piston Engine Spark Plug Insulator Cracking

Fuel Management - Lean-of-peak operation where precise control over the engine's performance cannot be assured is to be avoided to negate the possibility of detonation. For appropriate fuel leaning practices refer to the aircraft POH (pilot's operating handbook) or AFM (aircraft flight manual), as applicable, for specific instructions.

And we are supposed to take CASA seriously???

Tootle pip!!

[lo_lyf]

That is pure gold. I thought we got passed this and the enlightenment was starting to spread... guess I was wrong.

[gerry111]

Yep. 50F ROP cruise is still their idea of perfection. :ugh:

Where's Jaba and the APS guys?

[Lead Balloon]

To quote the Spodman once again: May Jesus pee in a bucket. What are these wombats on?

A complete misunderstanding of what causes detonation.

A complete misunderstanding of what caused the cracked spark-plug insulators.

Apparently the spark-plugs on engines fitted to aircraft with POHs that deal with LOP operations ‘know’ they’re fitted to those engines and aircraft, and therefore ‘know’ not to crack. Not so when the spark-plugs are fitted to the same engine fitted to an aircraft without a POH that deals with LOP.

Complete muppets. :ugh:

[Checklist Charlie]

I do wish CAsA would stick to doing what they know best, whatever that maybe.

CC

[Eddie Dean]

Fuel Management - Lean-of-peak operation(missing comma) where precise control over the engine's performance cannot be assured (missing comma) is to be avoided to negate the possibility of detonation.

Perhaps that is what was meant to be said?????

[kaz3g]

It was released on 1 April!

[Lead Balloon]

It’s dated 3 April: https://www.casa.gov.au/file/197511/download?token=7BkVew_q

If it’s an attempted late April Fool’s joke, it ain’t funny.

Muppets.

[andrewr]

For appropriate fuel leaning practices refer to the aircraft POH (pilot's operating handbook) or AFM (aircraft flight manual), as applicable, for specific instructions.

Perish the thought! What a ridiculous suggestion.

[Lead Balloon]

Sadly, it is an objectively risky suggestion in the case of POHs and AFMs that enshrine the sort of hogwash repeated in the AWB.

The primary causes of spark plug insulator cracking?

(1) LAMEs dropping plugs then surreptitiously refitting rather than replacing them.

(2) Manufacturing defects.

To the extent that the way in which an engine is run may cause insulator cracking, (3) would be running the engine RICH OF PEAK, but not far enough rich of peak.

But an evidence-based regulatory system should be run on the basis of folklore. It must be the fault of pilots running engines LOP. FFS. :ugh:

[andrewr]

You are obviously an APS convert.

What I have learnt since I first read the Deakin articles about 15 year ago:
1) APS don't know as much as they think they know.
2) Engine manufacturers know a lot more than APS give them credit for.

In a disagreement between the engine manufacturers and APS I give the benefit of the doubt to engine manufacturers.

What causes detonation? How about:
1) Heat
2) Time

Detonation is definitely associated with insulator cracking, but APS do have a tendency to put anything that doesn't fit their narrative down to LAMEs dropping plugs or manufacturing defects.

[Lead Balloon]

The laws of physics and the causes of problems aren’t about being a “convert” or the “benefit of the doubt” (and more fool you and your wallet in giving the benefit of the doubt to engine manufacturers).

You’ve identified “heat” as a (or is it “the”?) cause of detonation. OK then, on your superior knowledge:

1. At what mixture setting is cylinder head temperature at its highest?

2. At what mixture setting is exhaust gas temperature highest? Is it lean of peak, or rich of peak?

[andrewr]

APS have a few problems here and there with the laws of physics (and chemistry).

I said heat and TIME. If you understand a little of how tetra ethyl lead suppresses knock you will see where time comes into it.

At what mixture setting is cylinder head temperature at its highest?

That is the wrong question. The right question is "Under what conditions are unburnt gases exposed to the most heat for the longest time?"

The answer is: when combustion is slow, because you have heat from the already burnt gases acting on unburnt gases. Very lean mixture makes it worse because uneven mixing can give you very lean spots that are very slow to burn.

Cylinder head and valve temperature can contribute, but they are far from the only factor.

[Lead Balloon]

Under what conditions are unburnt gases exposed to the most heat for the longest time?Well that’s a relief.

You’re completely bonkers.

[andrewr]

Whatever you say.

If you're interested in information from people other than APS, here is a good article:
Engine Basics: Detonation and Pre-Ignition by Allen W. Cline (http://www.contactmagazine.com/Issue54/EngineBasics.html)

I would wager that Allen Cline has done a lot more detonation testing with more instrumentation and under a greater variety of conditions than George Braly and co.

[Lead Balloon]

Again, if the article at the link is what you’re citing as authority for the proposition that running an engine LOP is the (or even a) cause of spark-plug insulator cracking, you’re completely bonkers.

[gerry111]

At risk of calling out the popcorn, I suggest a truce between andrewr and Lead Balloon.

For those that don't have an engine monitor and prefer to run 50F ROP, I say good on you. For those that appropriately run LOP, I say good on you too.

But personally, I'm a fan of the science that tells me that running LOP in the cruise can be a very good idea.

[outnabout]

Dammit, Gerry, I was just organising the deck chair and the esky, getting ready for the show.

[Connedrod]

Never let the turth get in the way. Even when they proven wrong they never give up. They just delete the thread. When they dont even know or understand the combustion temperatures very between rich and lean and which way the thoose changes go. Prove them wrong and hey presto thread deleted.

But the greatest one was when 70% lop is the same as 70%rop..
Wtf anyone knows that a reduction of airspeed running lop is greater than running rop. Therefore it cant be the same not even close.

Any way run it i dont care keeps me in employment. 😁

[Eddie Dean]

(1) LAMEs dropping plugs then surreptitiously refitting rather than replacing them. You just made this up, admit it now.

[Lead Balloon]

You just made this up, admit it now.I didn’t make it up.

I’ve just been through the usual cycle of working out what damage and defects have been inflicted on my aircraft during annual maintenance. This year was pretty good compared to others.

Only four loose washers and one loose lockwire offcut found in the engine bay. The ‘good’ news is that I don’t think the washers were left off anything important but were rather dropped and ignored because - well I suppose it might be inconvenient to try to find them. A missing adel clamp from one of the fuel hoses meant it was rubbing against the engine crankcase. But it’s only a fuel hose.

And they always set a special, hard-to-find trap. This year it was the pilot’s seat not being engaged on one of the rails. They nearly got me, because when I sat on the seat and adjusted it fore and aft it felt normal: two of the rails were engaged and the third anchor was pressed against the top of the third rail due to my weight. Luckily I had to taxi to get fuel, first, and discovered the seat was off the third rail through sheer luck while embarking a second time.

But all round a pretty ‘good’ outcome compared with some previous years.

People who do this quality of work would never, never accidentally drop a spark plug and surreptitiously refit it. :rolleyes:

[rutan around]

Andrewr just one question. Have you ever been to an APS seminar?

[Eddie Dean]

I didn’t make it up.

I’ve just been through the usual cycle of working out what damage and defects have been inflicted on my aircraft during annual maintenance. This year was pretty good compared to others.

Only four loose washers and one loose lockwire offcut found in the engine bay. The ‘good’ news is that I don’t think the washers were left off anything important but were rather dropped and ignored because - well I suppose it might be inconvenient to try to find them. A missing adel clamp from one of the fuel hoses meant it was rubbing against the engine crankcase. But it’s only a fuel hose.

And they always set a special, hard-to-find trap. This year it was the pilot’s seat not being engaged on one of the rails. They nearly got me, because when I sat on the seat and adjusted it fore and aft it felt normal: two of the rails were engaged and the third anchor was pressed against the top of the third rail due to my weight. Luckily I had to taxi to get fuel, first, and discovered the seat was off the third rail through sheer luck while embarking a second time.

But all round a pretty ‘good’ outcome compared with some previous years.

People who do this quality of work would never, never accidentally drop a spark plug and surreptitiously refit it. :rolleyes:Anecdotal evidence, as impressive as your's may be, could still be made up.

The obvious answer, if the lack of quality control is true, would be to change service provider.

Whilst there is no doubt that spark plugs have been dropped and damaged, I struggle with the concept that the said plug would not have been replaced. It would behoove the mechanic to sell you a new one, considering that you would have no idea when it had been damaged.

To be honest, I would agree that there are indeed some dodgy workshops operating in the GA environment, and in fact have rolled my swag twice due to disagreements with the practices in outback workshops.

On your comment in a recently closed thread, I see your bet and raise you a carton of beer.:ok:

[andrewr]

How much information have you read about detonation, mixture etc. that did NOT originate from APS? It is always wise to gather information from multiple sources. There are a few critical areas (particularly chemistry) where they get things very wrong. Even references to "the laws of physics" when everything they are referring to is chemistry.

I have no doubt many people run their engine LOP without problems. However, the APS attitude where if you DO have problems it means the mechanic dropped a plug, or it was a manufacturing defect, or you simply weren't doing it right concerns me.

They claim science, but I have never seen anything from them that actually looks like science. As far as I know none of them have science qualifications.

(If you're wondering what real science might look like, try some of the NACA reports. They have detailed descriptions of the tests that were done, exactly what was measured and how, the results, conclusions etc. Enough information that someone else could re-run the experiment to verify the result.)

[Lead Balloon]

Anecdotal evidence, as impressive as your's may be, could still be made up.

The obvious answer, if the lack of quality control is true, would be to change service provider.

Whilst there is no doubt that spark plugs have been dropped and damaged, I struggle with the concept that the said plug would not have been replaced. It would behoove the mechanic to sell you a new one, considering that you would have no idea when it had been damaged.

To be honest, I would agree that there are indeed some dodgy workshops operating in the GA environment, and in fact have rolled my swag twice due to disagreements with the practices in outback workshops.

On your comment in a recently closed thread, I see your bet and raise you a carton of beer.:ok:It’s not “anectdotal”. It’s fact. Witnessed. My post-maintenance pre-flight inspections and test flights are always carried out these days accompanied by another person. I do that precisely because of the pervading folklore - manifested in your post and the AWB - that LAMEs never make mistakes.

I have changed LAMEs. The one I use now seems less mistake-prone than the one I used previously.

The other pervading folklore is that plug manufacturers never produce a defective product, and nor do engine manufacturers.

If I ran my engine in accordance with the POH, I’d be giving the engine the hardest pounding I could give it. Unnecessarily. There’s a reason POHs say these things: Back in the heyday of GA, it was a speed race between the brands and a couple of knots on the competion was a key marketing advantage. So what if the engine was getting the hardest pounding it could get? The chump who purchased it had deep pockets and any damage done was always their fault.

[andrewr]

Andrewr just one question. Have you ever been to an APS seminar?

No I haven't. And they probably don't want me, because I would keep interrupting with questions every time they said something questionable. For example:

"Peak EGT is the worst place to run your engine."

Why?

Every mixture vs fuel efficiency chart shows peak EGT corresponds very closely to mixture for best efficiency. If the engine designer cares about fuel efficiency, this is exactly where he wants the engine to run in cruise. If the engine manufacturer says you can run there in cruise why would you doubt them?

"But the heat..."

Engines are designed to burn fuel and get hot. It's what they do. As long as the cooling is adequate you will be fine. And if the engine gets too hot running at the settings it was designed for, you have a cooling problem.

"But it will last longer if it's cooler..."

Evidence please. How much longer? How did you measure it?

[Lead Balloon]

Who said “peak EGT is the worst place to run your engine”?

I ran my engine at peak EGT on Monday, because that happened to be the ‘best’ setting for the altitude and range requirements.

You do understand that the data prove that at peak EGT the CHTs are cooler than at around 25C ROP?

[Eddie Dean]

I do that precisely because of the pervading folklore - manifested in your post and the AWB - that LAMEs never make mistakes.You are either being purposely obtuse or cannot read and comprehend basic English. No where has it been said or implied that LAMEs do not make mistakes.

I would counsel you to read the AWB in its entirety and not concentrate on the spark plug issue. Most of the advice given in the AWB is very sound and should be followed to ensure the longevity of your engine.

If you have the correct equipment to follow the APS LOP method, by all means do so as long as you are comfortable with it and do all that APS teach.

[Lead Balloon]

The day that I have to rely on a CASA AWB as the source of any wisdom is the day I give it away. To the extent that the content is accurate, it will have been based on primary sources that are available directly anyway. I prefer the primary sources.

[Eddie Dean]

The day that I have to rely on a CASA AWB as the source of any wisdom is the day I give it away. To the extent that the content is accurate, it will have been based on primary sources that are available directly anyway. I prefer the primary sources.Therein lies the dichotomy, you are willing to use the AWB to pursue your vitriolic agenda against CASA and LAMEs but not as a source for correct maintenance.

[Lead Balloon]

I don’t think you meant “dichotomy”.

And guess what: It’s a free country and I’m allowed to criticise anyone I like. Especially when the criticism is based on fact. I’m allowed to use whatever sources I like for “correct maintenance”, just as CASA does in its AWBs.

[rutan around]

andrewr who has never been to an APS says that they say:


"Peak EGT is the worst place to run your engine."

I have been to one of their seminars and they have never said that. Careful they don't sue you.

They probably would love to have you attend one of their seminars. It would be greatly to your benefit and also to aviation in general if it stopped you presenting demonstrably incorrect information tangled up with random bits and pieces of fact.

[Eddie Dean]

I don’t think you meant “dichotomy”.Fair enough; it was the closest I could get, out here at the station kitchen.

If, like you, my machine was coming out of a servicing with a plug with cracked ceramic or any other physical damage which had showed when I taxied to the fuel bowser (righteous indignation moment), my suggestion would be: negotiate to have the rest replaced with known good ones, preferably new, but seconds would do as long had atleast as much time in service remaining as mine.

If your near Cable Beach any time this season, PM for a sherbet, could talk over beers looking out to the Indian Ocean.

[roundsounds]

Surely that’s already addressed by the General Competency Rule?
https://www.casa.gov.au/file/131276/download?token=kzbe519K

[Lead Balloon]

andrewr: I will pay for your place to attend the next APS seminar delivered in Australia. PM me when the next one’s advertised, if you’re available to attend.

[LeadSled]

Folks,
Once again, the anti-LOP troglodytes are out in force, again! All those airlines, over years of "big pistons" had it all wrong!! Pratt & Whitney and Curtis Wright had it all wrong.

Our semi-illiterate mate Connedrod, has chucked his two bob's worth in --- Rod, for your information, at a given HP output, the aircraft performance will be the same, the only difference at, say 65% power, ROP and 65% power, LOP is the fuel flow -- unless you have invented ROP/HP and LOP/HP.

As for the whole document, it is a simplistic "teaching you to suck eggs" effort.

Amazingly, I did know you are supposed to get all the blast cleaning material out after I have cleaned a plug --- and I would hope every LAME, indeed every first year apprentice (if there is still such a thing), knows.

I do highly recommend the small Champion book and card for reading plug condition. And please use a recommended tool to adjust gap, not as I saw quite recently, a plug clamped in a vice, and the "adjustment" being "achieved" with a hammer and cold chisel.

Engine manufacturer's manuals for particular engines are a far more reliable guide to the engine capability, than an AFM/POH for reasons made obvious (marketing edge) in a previous post.

Tootle pip!!

PS: Eddie, our mate Lead Balloon is actually very well qualified in the aero MRO field, I hope he doesn't mind me letting the cat out of the bag.

[Eddie Dean]

I do highly recommend the small Champion book and card for reading plug condition. And please use a recommended tool to adjust gap, not as I saw quite recently, a plug clamped in a vice, and the "adjustment" being "achieved" with a hammer and cold chisel. Such sound advice too, is a great tool for troubleshooting engine condition. For those that want to modernise their thinking on piston engine maintenance there are many resources available on the internet, APS being only one source.

As for the other, I'd be requesting he can't work on my machine, unless under direct supervision. That being my obligations as an owner in CASA regulations.
I always make sure to be shown the disassembled filter and strained engine oil from the engine and ensure that both engine screens and the main oil filter are serviced and inspected. CASA AWB 85-014 shows very good reasons to do so.

[tio540]

Does APS represent me in court when I get a $50 million lawsuit, following an accident, and the lawyers subpoena trend sheets operating contrary to the manufacturers POH?

Maybe I get a $250 refund.

[Lead Balloon]

Put this Supplement in your POH, and the engine magically knows that it’s OK to run LOP: http://www.gami.com/gamijectors/afms%20-%20gamijectors%20rev%20ir.pdf

Then the documents subpoenaed by the lawyers won’t disclose operations contrary to the POH.

[tio540]

So I save $15 per hour in fuel, but the lawyers get your house.

[Lead Balloon]

From first-hand experience: The lawyers are going to get your house if you have an engine failure running your engine/s on folklore, in accordance with the POH or otherwise. The only difference is whether you have a provable cross-claim against the publishers of folklore in the POH. That argument will cost you your house, anyway.

I envy you your blissful ignorance.

[lo_lyf]

A friend of mine works at Katherine Aviation where they operate 210s and Barons lean of peak with GAMIs fitted. Apparently it's all part of their SOPs/in their operations manual. CASA must have signed off on this right?

[tio540]

Lead Balloon

The POH is not folklore, but a legal document. The defence that a dentist at APS gave me operational engine management guidelines, not accredited by CASA, or the manufacturer, means you will end up enjoying the bliss of a trailer park, as you say.

[tio540]

A friend of mine works at Katherine Aviation where they operate 210s and Barons lean of peak with GAMIs fitted. Apparently it's all part of their SOPs/in their operations manual. CASA must have signed off on this right?

Not actually correct, CASA do not approve Operations Manuals, they merely accept them.

[Lead Balloon]

You’re obviously sure of your opinion, tio540. Those reading PPRuNe will rely on it. :ok:

[tio540]

I am all for a robust discussion.

The PA31-350 POH actually permits LOP, one of three options for leaning, so here we might even agree. However, the actual Lycoming engine manufacturer does not approve LOP.

The Continental service bulletin cites engine longevity as an issue when describing LOP, and recommends this only in extreme long range operations, and only occasionally.

I should add I have absolutely no engineering quals, and am usually wrong with most things.

[oggers]

Leadballoon

A complete misunderstanding of what caused the cracked spark-plug insulators.

In your opinion. Now for the facts:

If the engine has detonated visual signs like broken spark plug porcelains or broken ground electrodes are dead giveaways and call for further examination or engine disassembly. Engine Basics: Detonation and Pre-Ignition by Allen W. Cline (http://www.contactmagazine.com/Issue54/EngineBasics.html)

The typical cracked core nose condition shown may be caused by improper cleaning or gapping procedures and by detonation. Champion Aerospace Aviation Service Manual

Detonation is an explosion of the combustion charge in an uncontrolled sudden manner. This condition may damage the spark plug electrodes or crack the insulator nose as well as destroy the engine if permitted to continue. Tempest Aviation Spark Plugs

It is a fact that detonation causes cracked insulators. It is also a fact that running lean of peak at high power puts an engine inside its certified detonation envelope. Note I am not saying LOP causes detonation, I am saying LOP at high power can cause detonation, for instance when a pilot forgets to set the mixture full rich before take off or go-around on a hot day.

[Lead Balloon]

I wish I’d said that.

Oh wait, I did, or most of it to the extent it’s accurate:To the extent that the way in which an engine is run may cause insulator cracking, (3) would be running the engine RICH OF PEAK, but not far enough rich of peak.I listed the top 3 causes, not the only causes.

The most efficient way to punish an engine is to run it ROP, but not far enough ROP. As I said, the surest way to cause detonation in my engine is to run it where the POH says to run it.

You can also punish an engine if don’t you run it far enough LOP. But you will never be giving it as good a thrashing as you could ROP.

[Lead Balloon]

Note I am not saying LOP causes detonation, I am saying LOP at high power can cause detonation, for instance when a pilot forgets to set the mixture full rich before take off or go-around on a hot day.On my engine the throttle is left full from the start of the take off roll to joining the circuit at the destination. From the top of descent to the shut down the mixture control is at whatever the cruise setting was - usually LOP. (Sometimes I’ll have to give it twist or two richer, but I’ll be on the lean side of peak all the way down.)

Walk me through how I’d get detonation if I went to full throttle to go around, without touching the mixture. Note that the engine would in that case be set precisely where it was set when I arrived in the circuit. And I can see on the engine monitor that the CHTs are lovely and cool.

I might not have as much power as I could safely draw from the engine if I leave the mixture LOP, which is why I would as SOP go full rich. But note I’m not going full rich to avoid detonation LOP, but rather to get more power at a safe mixture.

And not I’m not setting the mixture to get maximum power - around 25C ROP - as that would be the mixture that would maximise the likelihood of .... detonation, particularly if I’ve forgotten to set the prop to maximum RPM.

[andrewr]

Who said “peak EGT is the worst place to run your engine”?

My mistake, it is 50 ROP they describe as the worst place to run an engine. But peak is generally in their "Red Box".

It doesn't change the fact that this is where all engine designers intend the engine to run. What evidence do you have that it is bad?

You keep using words like "punishing" and "thrashing". These are just words, not evidence.

[Lead Balloon]

But peak is generally in their “Red Box”.Again, a misrepresentation. As I said earlier, I ran at peak EGT during a flight on Monday. At 9,500’, normally aspirated, peak EGT ain’t in no ‘Red Box’.

Tell you what: Next time you take off around sea level on an ISA day with a big bore piston engine, lean the mixture so that you’re getting the maximum possible power out of the engine. (Hint: That’s a setting ROP.) And for good measure to perpetuate another OWT, pull the RPM back to 2,500. If you don’t believe you’re “punishing” and “thrashing” the engine at that setting, it won’t take long for you to see the evidence to the contrary.

Will you take up my offer to pay for your seat at the next APS in Australia?

(PS: You need to take care to include the unit of measurements in the numbers you quote. It’s 50F.)

[andrewr]

That's why I said "generally" not "always".

Will you take up my offer to pay for your seat at the next APS in Australia?

That is a generous offer. Yes, I would be happy to.

[Lead Balloon]

Great. PM me when you make the booking, and I’ll arrange payment to APS.

[andrewr]

(PS: You need to take care to include the unit of measurements in the numbers you quote. It’s 50F.)

Fair point, although I can only recall F being used in these discussions, with the exception of your posts.

As I said, the surest way to cause detonation in my engine is to run it where the POH says to run it.

How did you determine that?

[Lead Balloon]

From first-hand observation of measurements taken from a piston aero engine in a test cell.

Indeed, those measurements indicate that many big bore piston engines run in a state of mild detonation at settings that are uncontroversial from any perspective.

[Connedrod]

What size bore ?

For the edrumergated there is a great difference between a opposed engine used in ga and the large radials used in a time since past. While they both suck push bang blow thats basically where it starts and finishes.
The airlines did not invent running lop btw. It was used by the millitary mostly to cross the pond to the UK for delivery. In fact there is a great book on it were they were running lop and had to go to rop to make it.

There are no free rides everthing has its costs.

[Lead Balloon]

While they both suck push bang blow thats basically where it starts and finishes.And it doesn’t go any further so far as the effect of mixture control is concerned. Varying the fuel/air ratio of what’s sucked into a cylinder that’s fitted to a radial engine has the same effect as varying the fuel/air ratio of what’s sucked into a cylinder that’s fitted to a horizontally opposed engine.

Or maybe the laws of chemistry and physics mean the fuel/air being sucked into a cylinder fitted to a radial engine combusts differently than if it’s being sucked into a cylinder fitted to a horizontally opposed engine. Maybe the compression is squashier or the spark sparkier? Hmmmm....But what happens when the aircraft to which the radial engine is fitted goes into a vertical climb or dive and the engine effectively becomes horizontally opposed? Does the fuel/air being sucked into the pistons ‘know’ to behave differently? Remarkable technology.

Walk us unedgumicated through it, Rod.

[Lookleft]

Page 180 in Fate is the Hunter makes reference to boffins getting the crews to operate at reduced RPM and MP so I imagine that operating LOP was part of it. EK Gann found that it was bollocks in practise, but then again what would he know.

[Connedrod]

How about this. Why dont you tell us why the radial and the opposed egines are the same. Now im sure younknow why this is as your an expert at all things and done the aps course and then i will respond to your comments. So back to you. Let see what you come up with. Im not holding my breath while i wait but as you also believe that a rich mixture burns slower than a lean mixture i dont hold much faith in you getting much right but who knows you may supprise

Waiting in suspense

[gerry111]

Perhaps Lead Balloon is a complete idiot when it comes to his IO-520 engine management, Connedrod and andrewr?

But somehow, he manages to do a lot of GA flying and remarkably stays alive!

[Lead Balloon]

Why dont you tell us why the radial and the opposed egines are the same.What I said was that varying the fuel/air ratio of what’s sucked into a cylinder that’s fitted to a radial engine has the same effect as varying the fuel/air ratio of what’s sucked into a cylinder that’s fitted to a horizontally opposed engine.

The reason is simple: The laws of physics are the same everywhere.

andrewr described my offer to pay for his spot on an APS course as “generous”. My motivation is pure self-interest.

The fewer people there are in GA perpetuating myths, intuition-based folklore, 60s marketing-hype, mule-stupid ‘wisdom’ and other mumbo-jumbo, the safer my wallet and I will be.

[rutan around]

andrewr described my offer to pay for his spot on an APS course as “generous”. My motivation is pure self-interest.

The fewer people there are in GA perpetuating myths, intuition-based folklore, 60s marketing-hype, mule-stupid ‘wisdom’ and other mumbo-jumbo, the safer my wallet and I will be. Absolutely spot on.:ok:

[rutan around]

Page 180 in Fate is the Hunter makes reference to boffins getting the crews to operate at reduced RPM and MP so I imagine that operating LOP was part of it. EK Gann found that it was bollocks in practise, but then again what would he know. I haven't read Fate is the Hunter yet. (It's on my "to do" list) however I have read a number of articles about how Charles Lindbergh demonstrated lean of peak operation to greatly extend the range of navy aircraft operating in the Pacific.

I wondered why quite a number of pilots rejected the method until I read their reason for refusing to use it. It turns out it was because they were operating in an active war zone and were on high alert as soon as they were airborne even when the target of the day was a considerable distance away.

They weren't interested in stuffing around with mixtures when they needed instant power to escape a nasty situation or press on with an attack when they spotted a stray enemy aircraft.

The average GA aircraft doesn't have the Navy's wartime problems so it makes sense to run your engine where it's happy, cool and giving you the best bang for your buck in the fuel and maintenance department.

[andrewr]

Next time you take off around sea level on an ISA day with a big bore piston engine, lean the mixture so that you’re getting the maximum possible power out of the engine.

My first post in this thread was in support of following the flight manual, so let's keep it to settings approved by the POH.

What about 24" MP, 2400 RPM - about 70% power on an IO-360 - at peak EGT as approved by the Lycoming manual. Thrashing or punishing?

There are settings in the manual that I would consider punishing, e.g. 2000 RPM at 26" MP (about 60%). If you are looking for detonation, you won't necessarily find it at maximum RPM and full power. You are more likely to find it at these lower RPM and power settings along the "Limiting manifold pressure for continuous operation" line.

[rutan around]

Andrewr this is a genuine question. Do you own your own aircraft or do you fly someone else's?

[Lead Balloon]

What about 24" MP, 2400 RPM - about 70% power on an IO-360 - at peak EGT as approved by the Lycoming manual. Thrashing or punishing?Neither, provided all cylinders are at peak. However, you could move to thrash or punish territory if you were to change the mixture to around 25C ROP. If you have an all-cylinder engine monitor, you will see it before your very eyes.

What’s the fetish with “as approved by the Lycoming manual”? Is 24.734” MP and 2,355 RPM “approved”?

If you are looking for detonation, you won't necessarily find it at maximum RPM and full power. Correct. That’s one of the reasons why reducing RPM to 2,500 after take off, IAW the OWT, increases risk. It has the effect of reducing thetaPPP. I.e. it moves the peak pressure point closer to TDC.

This is also why the AWB highlighting LOP operations and not the operations that are more likely to cause problems is mumbo-jumbo.

[T]he "Limiting manifold pressure for continuous operation" line.What an interesting line. I’ve never heard of it.

As I said in an earlier post, my SOP is wide open throttle from the commencement of the take off roll until entering the circuit at my destination. In other words, the MP is continuously as high as it could possibly be. In cruise I just set the RPM to wherever the engine feels smooth - it’s interesting to note how this varies with different propellers - I imagine it has something to do with resonance and other esoteric issues. I haven’t a clue what the POH says about RPM and MP, and I’m not inclined to waste my time reading it. My SOPs are based on science and the evidence of the instruments in front of me.

[megan]

I have read a number of articles about how Charles Lindbergh demonstrated lean of peak operation to greatly extend the range of navy aircraft operating in the PacificIt wasn't LOP he introduced. Normal squadron practice was to fly at 2,200 to 2,400 RPM with mixture auto rich. Lindbergh introduced the practise of 1,600 RPM and auto lean.

2,300 RPM was the change over point for auto lean/auto rich operation according to the manual. Lean allowed a max of 34.5", rich 38" at 2,300. The manuals provide data for auto lean cruise, so wonder why the squadron didn't use it?

[Lookleft]

Just out of interest I had a look at the AP website and I noted that the staff were people who happened to be pilots. Other than the ex 747 pilot the other two are from non-aviation backgrounds. I would have expected some engineering background. I noticed that two of them flew for the CAF. I wonder what that organisation uses as their SOP for mixture control? I also noticed that there are no upcoming courses.

I don't have an opinion one way or the other on the issue of LOP or ROP but I have learnt from experience that wandering off the reservation in terms of POH puts one in test pilot territory. I have never subscribed to the theory "Its ok everyone does it this way" when its not stated in the manual.

[rutan around]

I would have expected some engineering background.Just like I expected the POH in my 210 to be written by engineers and expected my brand new IO520 designed by engineers to have all 6 cylinders put out pretty equal power whatever the mixture. Luckily 3 non engineers sorted out both problems and saved me a bucket of $$$$$$$.

PS The engineers actually recognized the problems but were not funded to fix them. I wonder how many extra engines that shiny pants decision sold for their company.

[dhavillandpilot]

This thread has some interesting theories and pontification a from so called experts: mostly flying other people's aircraft.

We operate an aircraft with GTISO 520 engines. Our SOPs are simple 55% power setting and slightly rich. Fuel is cheap but an overhaul is expensive.

[gerry111]

This thread has some interesting theories and pontification a from so called experts: mostly flying other people's aircraft.

We operate an aircraft with GTISO 520 engines. Our SOPs are simple 55% power setting and slightly rich. Fuel is cheap but an overhaul is expensive.

I reckon that 'rutan around' and 'Lead Balloon' fly their own single engine aircraft which are both fitted with IO-520 engines. What about you, 'andrewr'?

[oggers]

As I said, the surest way to cause detonation in my engine is to run it where the POH says to run it.

From first-hand observation of measurements taken from a piston aero engine in a test cell.

Indeed, those measurements indicate that many big bore piston engines run in a state of mild detonation at settings that are uncontroversial from any perspective.

...hmm. Certification of the engine requires the manufacturer to demonstrate that the engine can be run detonation free at the leanest fuel flow approved for each power setting in its manual, up to 103ºF and down to sea level. At leaner settings the engine may detonate up to so-called limiting detonation but those settings are, by definition, not recommended. In this buffer range, the fuel must be able to be reduced by 12% from recommended before limiting detonation occurs.

Therefore, a conforming engine run at the manufacturer's recommended settings (and fuel octane rating) is proven not to detonate. The flip side is that at the most critical recommended settings you do not have to stray far from the strictly controlled conditions of the test in order to induce incipient detonation to a class of APS delegates.

Understanding the certification requirement may also help people understand why the manufacturers do not recommend running lean of peak, even though they acknowledge it is perfectly feasible with the correct equipment. The engines were simply not tested for it as originally certified. Now, GAMI must know this as they finally did get an STC in 2015, and as per their website:

GAMIjector® and turboGAMIjector® fuel injectors, when properly tuned using the GAMI Lean Test procedures and with the aid of an every-cylinder EGT/CHT engine monitor, will allow the engine to operate in a wider range of fuel/air mixture settings than originally available when the Aircraft Flight Manual or Pilot Operating Handbook was first published

Nonetheless, the fact remains that a conforming engine is proven not to detonate when run at the settings recommended.

[Connedrod]

Poeple pushing the lop line really are only going of the aps course and indoctrination of that. When they dont even know that difference between flame front speeds between rich and lean and push push push the wrong answer proven wrong will not addmit they were wrong and then delete a complete thread to cover their tracks.
When a person cant even tell the difference between a radial and a opposed engine. Wow he flys a io520 so that makes him an expert on the whole engine in the aviation fleet.

They say 75% rop is the same as 75% lop how so how much harder is the lop engine working to maintain that power.

They continue to claim lower exhaust temperatures but dont understand that the lower power settings that they are achieving is mainly because all the energy is is not used due to the slower burn rate of the lean mixture. So now energy is lost because its exiting past the exhaust valve. This is why you have burnt valves. This is why you have exhaust leakage on a leak rate test. This is why we check it iaw ad eng 4 and why both major manufacturers say you must do tnis check with zero leakage. To get around this the cult say this is not required and dismiss it. Totally agaist the AD.
Real world environment has shown and proven not only to myself but ask just about lame the same question what the results are from extreme leaning. Thier answer it not your fault its what you all been learnt from trade school etc and manuals. Wtf you think we all dumb sheep. We see feel smell whats going on we can make or own decessions and assessment on maintenance.

Fact is the leaner the mixture the slower tbe flame front burn rate is. With this the mixture is still emiting energy to the exhaust valve on opening where as in a richer mixture the energy is wholly consumed in the chamber, and even though it my be hotter it is NOT burning the valve because its engry is already been consumed.

They say running rop you will damage your engine and running lop ypu will not. Nothing could be further from the truth. 99% off engines in GA in aust do not run lop. So were are all these damaged engines then.
Go ask any lame that looked after a late model plastic fantastic with an io550 in it with lean assit and ask them what they have found over the years.

The other state they mention is it was proven by the airlines running the large radials running lop how they extended there engine o/h life from the millitary version. Wtf . Really. Not.
This is a play on words. Commercial avaition could never operate on millitary o/h periods. The P&w 985/ 1340 for example had an millitary o/h life by memerory of approx 300 hours, ( wil try and locate the 1st issue book i have on it to confrim) now its up to 1200 hours in cilivian life. Millitary have a zero expence rule where commercial well we have to pay so we make things last.
For the most part aps plays on words dyno testing is not reworld testing and never will be.

Cavite emptor i think it is let the byer be were.

[Connedrod]

And with these late model plastic aircraft with first life engines we dont see many if ever clyinder head cracking we do see exhaust valve destress and a lot off it.

Both lyc and cont have put alot of work on to their engines of late. While they may retain the outward appearance they are made of better materials than past engines. When you do your o/h replace the cylinders with new.
I recently was talking to a frim tnat they done two o/h with 2nd life cylinders and had failures at periodic inspection since they replace them all with new and get a full run out the engine till next o/h.
So who here has ever detenated an aviation engine. The last one i know off was across the spencer gulf in the chieftan because he didnt push the red knob first. And before a certain individuals say but the crank was cracked on that engine the crank did not fail so tnat is tottaly irrelevant. It failed because it was to lean and went into self destruct mode period. The evidence is quite clear on this fact.

If you ever get to have a look at an aircraft crank rod bearings they are extremely lagre for the power they produce against a cars of the same power.
Manufacturers make them like this for a reason and produce a manual for the engine for the same reason.

Isf aps is so good why dont they start producing their own manuals our even get their courses and manuals for operating engines approved. Just like everyone else has too.

[rutan around]

:ugh::ugh::ugh::ugh::ugh::ugh::ugh::ugh::ugh::ugh:

[Lead Balloon]

Nonetheless, the fact remains that a conforming engine is proven not to detonate when run at the settings recommended.Nonetheless, the fact remains that conforming engines have been proven to detonate when run at some of the settings recommended.

Could you walk us through the test equipment used and cite the data produced by the engine manufacturers during certification mid-last century to "prove" that a conforming engine never detonates at any of the recommended settings? A very sophisticated test cell used contemporarily proves otherwise.

When GAMI obtained the STC and corresponding POH supplement for LOP operations from the FAA, how did all those engines (like mine) fitted with GAMIjectors that had been run LOP for years before suddenly 'know' that it was 'safe' to do so?

Why have I never had a plug with a cracked ceramic insulator (at least not after I've run it - I make damned sure they aren't fitted with defects)? I've had a few fail at altitude and quite a few defective new out of the packet, but no cracked insulators.

This thread has some interesting theories and pontification a from so called experts: mostly flying other people's aircraft.Could you identify the posters who fly other people's aircraft? For my part, it's my engine. My life depends on it.

We operate an aircraft with GTISO 520 engines. Our SOPs are simple 55% power setting and slightly rich. Fuel is cheap but an overhaul is expensive.So why have my engines gone hundreds of hours past TBO when run on "interesting theories" rather than your evidently scientifically-based "55% power setting and slightly rich"?

Oggers mentioned certification. My engine is certified to run at maximum rated power, continuously, to TBO. Whether it will do that in fact depends on the quality of manufacture (sadly deteriorating) the quality of maintenance (can be variable) and the nut behind the wheel operating it in accordance with the laws of physics, hopefully supplemented by input from an engine monitor, rather than POH-enshrined and regulator-perpetuated folklore.

[andrewr]

Or maybe the laws of chemistry and physics mean the fuel/air being sucked into a cylinder fitted to a radial engine combusts differently than if it’s being sucked into a cylinder fitted to a horizontally opposed engine.

Of course there are variations in how the fuel/air combusts in different engines. Differences in bore, stroke, compression ratio, piston speed, head design, piston design, manifold pressure, spark timing, spark plug location all affect combustion and in particular influence the likelihood of detonation.

The fact that different Lycoming engines use different timing is evidence that there are differences even between engines that appear very similar.

The assertion that all engines are the same is one of the those statements that just fall apart if you look at the evidence.

Maybe the compression is squashier

The flow of gas inside the cylinder during compression is influenced by cylinder and head design, and is a very important factor in engine design. It directly influences the likelihood of detonation. So yes, it certainly could be different.

or the spark sparkier?

I read some notes on operating the big radial engines. Part of the leaning procedures was to advance the timing to improve valve life. Maybe they were the earliest victims of the OWT about LOP causing valve problems? Or maybe there is something there?

In any case yes the spark was certainly earlier running LOP.

I reread one of John Deakin's columns where he was describing a Lycoming engine where Lycoming had approved operation LOP. One interesting tidbit was that the timing was advanced compared to engines where LOP operation was not approved.

Many engines run LOP, but I don't know of any engines with variable spark timing that would not advance the spark when running LOP.

[Lead Balloon]

And all of that can happen whether the engine is radial or horizontally opposed.

Do you own the aircraft you fly? Does it have an engine monitor?

[andrewr]

Neither, provided all cylinders are at peak. However, you could move to thrash or punish territory if you were to change the mixture to around 25C ROP.


Punishing? Really? This is exactly the range where engine manufacturers design the engine to be run. I don't understand this idea that aircraft engines are light, powerful, reliable, efficient, wonders of engineering and the designers are incompetent and don't know what they are doing.

What’s the fetish with “as approved by the Lycoming manual”? Is 24.734” MP and 2,355 RPM “approved”?

It was leaning at that power setting I was referring to, not the power setting itself. As opposed to your example, where the manual tells you to run full rich. The RPM and MP was simply chosen because it's corresponded approximately to 70%, was in the middle of the power chart, and the numbers were easy to follow.

24.734” MP and 2,355 RPM is fine, but harder to read off the chart.

What an interesting line. I’ve never heard of it.

It's on the Lycoming power charts.

[andrewr]

Just like I expected the POH in my 210 to be written by engineers and expected my brand new IO520 designed by engineers to have all 6 cylinders put out pretty equal power whatever the mixture. Luckily 3 non engineers sorted out both problems and saved me a bucket of $$$$$$$.

Or they convinced you there is a problem with a perfectly good engine.

I hate to burst your bubble, but on the lean side of peak power i.e. if you lean at all, power is more dependent on fuel quantity than air. So if the airflows to each cylinder are uneven it doesn't matter much.

A bit more air moves you further from peak power mixture, a bit less air moves you closer to peak power mixture. If the fuel flows are even the power from each cylinder will be reasonably even.

If you make the mixtures the same, the power from each cylinder will be uneven, matching the uneven airflow. But you can get leaner overall before the first cylinder gets too lean to run.

[Lead Balloon]

The scenario you gave was:What about 24" MP, 2400 RPM - about 70% power on an IO-360 - at peak EGT as approved by the Lycoming manual.I said that if you enriched the mixture to around 25C ROP, you could move to thrash or punish territory. It is certainly the worst place to set the mixture if you're interested in engine longevity.This is exactly the range where engine manufacturers design the engine to be run. I don't understand this idea that aircraft engines are light, powerful, reliable, efficient, wonders of engineering and the designers are incompetent and don't know what they are doing.It is indeed patently clear you don't understand. What's worse, you won't understand.

I pity the wallet of the poor bastard who owns the aircraft you fly.

[andrewr]

I said that if you enriched the mixture to around 25C ROP, you could move to thrash or punish territory. It is certainly the worst place to set the mixture if you're interested in engine longevity.

It's where the engine designers designed the engine to run! What evidence do you have that this affects engine longevity, assuming you observe the other engine limits e.g. CHT?

I suggest you do not attach a data logger to your car. It will do your head in to see what mixtures it runs, and when you are most likely to see knock detected.

[rutan around]

If the fuel flows are even the power from each cylinder will be reasonably even.

That's the whole problem with IO520 engines as they come out of the factory.The bloody fuel supply to the cylinders is all over the place. THAT is what GAMI injectors rectified. More reading by you required.

[andrewr]

That's the whole problem with IO520 engines as they come out of the factory.The bloody fuel supply to the cylinders is all over the place. THAT is what GAMI injectors rectified. More reading by you required.

My understanding was that the injectors were matched from the factory to flow the same amount of fuel.

The GAMI lean test matches the injectors so the EGTs of all cylinders peak at the same time i.e. matches the mixture. That's perfect if you have equal airflow to each cylinder. If you don't then equal fuel flow is better (more even power) than matching EGT.

Am I incorrect?

If the injectors don't flow the same amount of fuel then maybe they need to be matched - but by fuel flow, not EGT.

(The proviso of course that there may be inequalities by design, it is quite possible that there are reasons fuel flows don't match. So any adjustment needs to be according to and within tolerances allowed by maintenance documentation.)

[IFEZ]

Genuine question here LB - Are you suggesting that Cessna are telling their aircraft owners to run their engines 50deg ROP to deliberately reduce the potential life of their engines..? Or that there have been no advancements in the companies engineering knowledge in the last 50 years..?


The reason I ask is that the POH in the latest C182T with all the bells & whistles including lean assist etc is still recommending leaning to 50deg ROP like all the older models. Are they in denial or do they genuinely believe this is the best way to treat their engines..? (Presumably backed up by exhaustive testing and maintenance records).

[Lead Balloon]

As I said before, for the marketing departments a few knots on the competition makes a difference. They want you to achieve the cruise speeds and fuel consumption figures in the glossy brochures.

The data prove that at a mixture of around 50F ROP you're giving the engine the hardest thrashing you can give it. Many engines tolerate the abuse. Some don't. If you're interested in maximising the longevity of an engine, it's better to sacrifice some fuel efficiency by going further ROP, or better still to sacrifice a few knots in return for greater efficiency by running LOP.

The reason aircraft manufactures and engine manufacturers and maintainers don't really care is because everyone knows what causes any and all engine problems: Pilots.

[megan]

All my piston leaning experience was simply putting the lever to auto lean, so excuse my ignorance. One method of leaning is leaning to the point of roughness (misfiring cylinder because it's too lean), so if you enrichen to the point of removing roughness would that particular cylinder not be running LOP? I notice reading FAA safety information they give the impression of giving their imprimatur to LOP, with the caveat of having proper instrumentation and calibrated yearly.

[andrewr]

If you're interested in maximising the longevity of an engine, it's better to sacrifice some fuel efficiency by going further ROP, or better still to sacrifice a few knots in return for greater efficiency by running LOP.

What evidence do you have that this improves longevity? By how much?

According to one of John Deakin's articles, Lycoming said they have collected data that indicates more problems with engines run LOP.

Deakin's conclusion was that Lycoming didn't know what they were talking about and it was because the pilots weren't doing it right.

But Lycoming are in the best position to collect that data. What evidence is there that they don't understand the data they are collecting? Alternatively, would they really lie?

If Lycoming really wanted to sell more engines or parts they could just reduce the TBO, or require mandatory replacement of certain parts like Rotax with their 5 year rubber & fuel pump replacements.

And I have already given my opinion on the APS attitude that if you DO have problems when following their recommendations it must be the pilot's fault.

[Lead Balloon]

Hi Megan: The "roughness" is not caused by "misfiring". It's caused by different amounts of power being produced by the individual engines - each cylinder - bolted to the same crankshaft.

When you plot the power output of a cylinder against mixture, you see that the curve is 'steeper' on the lean side of peak. That means that smaller changes in mixture on the lean side cause greater changes in power than the same change in mixture on the rich side. That's why trying to run LOP highlights the extent to which engines come 'out of the box' with poorly balanced fuel/air across cylinders. Running ROP 'hides' the imbalance. That's also why successful LOP operations usually entail testing and swapping injectors (on injected engines) to get all of the cylinders close to each other on the lean curve. For those who achieve the nirvana of perfect balance, there is no 'lean missfire'. As the mixture is leaned on the lean side, each cylinder produces progressively less - but the same - power output, until the mixture is so lean that it can't sustain combustion and all cylinders simply cease to produce power.

andrew: Please save your questions for the APS.

[andrewr]

It is indeed patently clear you don't understand.

You are correct.

When I first read John Deakin's articles on Avweb 15 or so years ago, I was convinced LOP was good and I was happy.

But I was good at physics and chemistry at school, and Deakin posted a couple of things where the physics and chemistry were obviously wrong. I didn't understand. So I did some reading from other sources.

Since then I have read all the Deakin articles, various NACA reports, articles by Lycoming, other engine designers, engine tuners, information about the big radials, talked to a guy who does engine management system consulting for various manufacturers and race teams, and basically anything else I can get my hands on. It's a subject that interests me.

There is a lot out there from a lot of different sources that contradicts what APS have in their public materials.

That's one reason why I asked (unanswered) what sources other than APS have you used for your information?

On the other hand I have found nothing apart from the Deakin & APS information that contradicts what is in the engine manuals.

My conclusion is that yes, I don't understand. What I do know however is that it is a very complex subject, much more complex than APS indicate.

I certainly don't understand enough to be confident ignoring the manufacturers recommendations. From what I have seen of APS I doubt they could change that.

andrew: Please save your questions for the APS.

Will they answer them, or just give an answer like "Well it stands to reason, cooler is better"

Do they actually have real data gathered from engines in the field, with at least a basic level of correction for uncontrolled variables?

[Lead Balloon]

No. APS just make it up. Based on their amateur intuition. They do not have access to the most sophisticated piston aero engine test cell on the planet and they do not show videos of the actual measurements taken in that cell during a real engine run in which fundamental variables like timing and mixture are varied. And even if they did show those videos, the measurements would be faked because - well, what interest would they have revealing the real measurements.

Alas, I think my first call was the correct one.

[Connedrod]

Just about any engine can run past tbo. Running lop will not and never will make it go padt tbo any more than running rop.

[andrewr]

"Engines in the field" is different to engines in a test cell. The test cell can't tell you whether what is measured results in greater longevity in service or how much.

the most sophisticated piston aero engine test cell on the planet

Who told you that? I haven't done a survey, but this sounds like marketing fluff rather than true facts.

The guy who consults to the auto engine manufacturers and race teams told me that this stuff is well enough understood that test cells are not used as much anymore by manufacturers. Most of it can be modeled by computer. The test cells are mostly used to validate the important data points.

[Bend alot]

I think the horizontally opposed vs radial question may have been interoperated wrongly?


If the question was in relation to the difference in size and stroke of a HO vs a big radial, then the difference is in the time/s the spark are set and changes in valve overlap and use of gearboxes. These are all based on the combustion burn rate in design stage and not normally pilot adjustable.

[rutan around]

Andrew

If the injectors don't flow the same amount of fuel then maybe they need to be matched - but by fuel flow, not EGT.Before I or anyone else take the time and effort to explain the induction and fuel injection system used in IO 520 aircraft engines please let us know whether or not you know roughly how it works. If you do know give us a brief rundown of how the fuel and air end up in the cylinders ready for compression. It is very important you understand this because not understanding makes you say silly things which later will embarrass you.

[Bend alot]

Fuel flow increases on most IO-520 when a nozzle is partially or fully blocked.

[Eddie Dean]

Fuel flow increases on most IO-520 when a nozzle is partially or fully blocked.Or Perhaps not the fuel flow its self, one could say it "indicates" due to the mode of operation.

[airag]

Oh dear .... all this on a 1940 technology , low compression , glorified VW industrial engine !

Andrewr I wouldn't bother ... these guys have been cult members pushing this barrow for awhile .... clearly they know best and pilots have been destroying engines prematurely for 70 years...

[Connedrod]

So leadie as you fail to provide an answer to the previous questions what about this two.

What is cause for an opposed engine for the uneven breathing of each cylinder make it easy for you as you an expert on the io520 we will use this engine

Now
What is the change that gami make to even out fuel flow and what is the difference between them an a cont nozzles

Ok 2 basic simple questions im sure your able to find an answer too.

Then will go back to a radil of large scale to to opposed ga engine.

[Tankengine]

It is over 30years since I flew an injected twin.
My flying now is in carbureted engines with no EGT indication.
I lean until rough, richen until smooth, the richen another centimetre of throttle movement or so.
What am I doing wrong?, or at least how can I improve things? :hmm:

[Lead Balloon]

For those who only believe what manufacturers say...

From the Textron Lycoming article “‘Experts’ Are Everywhere to Help You” (their pub number SSP700):... The newly discovered method of operating on the lean side of peak exhaust gas temperature has been known since Charles Lindbergh employed it to navigate the Atlantic Ocean and Max Conrad established distance records in his Comanche. This procedure was employed on large supercharged and turbocharged radial engines effectively during the era of large transport aircraft such as the Lockheed Constellation and Douglas D-6. ...

Lycoming is in complete agreement that it is possible to operate an engine on the lean side of peak TIT.. It is done on engines in our well-instrumented Experimental Test laboratory every day. There is nothing detrimental in operating an engine in this manner. ...Having agreed that the facts are the facts - no other choice really, unless they wanted to look as stupid as some posters on PPRuNe - Lycoming went on to express this opinion: But you need proper instrumentation and GA pilots are too distracted doing other stuff to do it safely. Thousand of pilots flying aircraft with engine monitors and proper education have proved this opinion to be wrong.

From the Continental Aircraft Engine Maintenance And Operator’s Manual for Models IO-550A, B, C and G, Form X30565 FAA Approved August 1990, para 13-2:[b]CRUISE CONTROL BY E.G.T.

If exhaust gas temperature indicator is used as an aid to leaning proceed as follows:

1. Adjust RPM for desired cruise setting

2. Slowly move mixture control toward “lean” while observing E.G.T. gage. Note position on the instrument where the needle “peaks” or starts to drop as mixture is leaned further.

3. The maximum recommended cruise setting is 235 BHP at 2500 RPM and 25.0 In. Hg. MAP with mixture set at 25F rich or lean of peak E.G.T. At cruise settings below 65% engine may be operated at peak E.G.T.Although there’s a range of nonsensical aspects to that recommendation, I note that the recommendation includes a setting that dare not speak its name, with my bolding.

A Lycoming publication titled “More On Cylinder Head Temperature” says this:Although [the specified temperatures] are minimum and maximum limits, the pilot should operate the engine at more reasonable temperatures in order to achieve the expected overhaul life of the powerplant. In our many years of building engines, the engines have benefited during continuous operation by keeping CHT below 400F in order to achieve best life and wear of the powerplant. In general, it would be normal all year operations, in climb and cruise to see head temperatures in the range of 350F to 435F.Let’s assume the proposition that keeping CHT below 400F is good for engine longevity. At what mixture setting will CHT be highest, all other variables unchanged:

1. 40F ROP.
2. Peak.
3. 40F LOP.

Answer: 1.

But maybe the manufacturers’ views on running engines LOP and the effects of temperature on engine longevity should be ignored, like the data?

[rutan around]

Oh dear .... all this on a 1940 technology , low compression , glorified VW industrial engine !

Andrewr I wouldn't bother ... these guys have been cult members pushing this barrow for awhile .... clearly they know best and pilots have been destroying engines prematurely for 70 years... Airag don't discourage Andrew from learning. He stated earlier that he wanted to do that.

All 4 stroke engines are very similar in that they all suck,compress, bang and blow. Inside the engine there are many variables such as stroke, valve position number and size, piston top shape and number of rings. Also there are many different internal head shapes. This lists some of the variations.

Outside the cylinder it becomes even more interesting. I guarantee the fuel and air induction system in your beloved VW is nothing like the IO520. the same applies to the ignition system.

You could be the worlds greatest expert on VW engines but that would not help you sort out why factory new IO520s run rough at lean mixture settings. The reason is quite simple and logical for those who want to learn but you must understand how that particular engine, and many like it, recieve the air and fuel.

[Connedrod]

Once again you cant answer a simple basic questions that are asked of your self. Ypu done an aps course and now ypur an instant expert on sfa. You can quote all you like thats because you dont have any knowledge at all on aircraft engines bar your skills at being able to find quotes on the net. You have zero skill level in maintaining or actually what how and why things happen within the engine and the interaction of all the components that make the engine work.
Basically your a paid up member of the aps troll net work or clut you can choose either of both as you fit both requirements.
So answer the question btw you also were one of the lot tbat didnt know the burn rate of a lean mixture before the thread was deleted strange that.

[Connedrod]

Or Perhaps not the fuel flow its self, one could say it "indicates" due to the mode of operation.

Well actully it dose not increase this is a misnomer. Although the indication on some wf gauges that read px indicate a higher wf due to the higher px in the system due to the resiction.

[oggers]

LB

You have repeated a few times that the manufacturers recommend running the engine at the absolute worst mixture setting. But you keep overlooking the important caveat that they recommend full rich at power settings above 75% and only recommend leaning to best power at 75% or below where they have demonstrated to the FAA that the engine will not detonate with that mixture. Misrepresenting the manufacturers advice may play well with the APS audience but it does not invalidate the true recommendations of the manufacturer.:ok:

[Lead Balloon]

Setting the mixture to around 25C ROP is the worst setting for a piston aero-engine whatever the power setting. It will produce the highest CHT possible for that power.

Given the choice of a 74% power setting with a CHT of X and a 74% power setting with CHT less than X, I choose the latter.

Detonation is not the only thing that is detrimental to engine longevity. So is heat. The manufacturers say so. :ok:

[Connedrod]

LB

You have repeated a few times that the manufacturers recommend running the engine at the absolute worst mixture setting. But you keep overlooking the important caveat that they recommend full rich at power settings above 75% and only recommend leaning to best power at 75% or below where they have demonstrated to the FAA that the engine will not detonate with that mixture. Misrepresenting the manufacturers advice may play well with the APS audience but it does not invalidate the true recommendations of the manufacturer.:ok:


Thats all aps do. The convert data so it favours their own interest, example engine overhaul periods. They quote millitary hours then say but the airlines ran lop and increased the overhaul hours. This while an increase in commercial aviation often happens it was in no way related to running lop. The millitary ran lop as well. Its happening now if you purchase from the manufacturer you get more hours o your engine overhaul life.
If your say anything the bully get you banned and try and discredit. They basically are just trolls pushing their own views and they do the above if you dont follow.
And when they proven wrong and then again and again they get the whole thread to cover their tracks. They will never admit the are incorrect.
Its not your fault you were trained incorrectly. Wtf. What you think i and others dont have a brain and can think out side the square. Gid give me some credit for being able to think for my self.
So here tgh e answer go do the aps course become a complete expert.
Funning the guy running it wife works and checks thst all things are above board for the mines and overs. When he was asked if she found that an org was running lop outside of the poh would she allow her cilents to fly in that aircraft. Answer was NO.
For the record btw.
I have never said not to run lop. Check all my comments, what i have said is facts on what i know and seen as an lame with 40 years experience working daily on such aircraft.
If one aps course is greater than my 40 years experience and makes a pilot after doing it more experienced than myself ill give it away.

[Connedrod]

How about answering my question thanx leadie or cant you ?

[Aussie Bob]

Yr Right, Conartist or whatever pseudonym your going under today, your arrogance is quite clear. Here is a question for you: Have you done an APS course?

It is OK I already know the answer, so here is another: if you haven’t done a course, how it it you profess to know what they teach?

I for one actually like your input here in this forum but your know all arrogance and poor grasp of the English launguage are disappointing. It is after all a pilots forum, not an engineers “I know everything” wonderwall.

[rutan around]

Rod said in post 103
Once again you cant answer a simple basic questions that are asked of your self.Rod, to whom are you addressing this statement?

[Lead Balloon]

Rod: Stick to tuning the piano. Leave the playing to the experts.

One of the reasons APS has detractors is that engine monitors and pilot education have exposed the variable quality of engine manufacture and maintenance.

The effort and cost it takes to get F/A mixtures balanced across cylinders shows how poorly balanced it is off the production line. Many new, certified and quality stamped cylinders need to be set up properly by the few remaining competent experts before fitment. Bushings made of cheese. Spark plug suppressors made of unicorn farts...

I can tell, on the first flight after maintenance, whether timing advance has been fiddled with and set correctly. Some engineers don’t like it when you say: “As a consequence of a change in CHTs and and in-air mag check, I can tell that you’ve advanced the timing on right magneto too far.”

Blocked injectors usually happen just after maintenance. Engineers don’t like it when you say: “The injector on 4 is blocked as a consequence of contamination introduced during your maintenance.”

[Connedrod]

Rod said in post 103
Rod, to whom are you addressing this statement?

I was refering to leadie. But he is obviously unable to answer the basic questions that was asked of him. So anyone may answer.
As this is a free forum leadie im free to be on tnis forum. If you dont like it please feel free to leave.

Have i done the aps course no i havent. My use of language is not the best but my knowledge is far greater than yours in regrads to aviation maintenance.

So you are saying that due to the fact i havent done the aps cult course that my qualifications and knowledge is of no use.
Please remind me of the approved aps course you obviously are suggesting i go and do..

[Connedrod]

Just wondering how good some of you would be trying to fix an aircraft engine if it wasnt equipped with a engine management computer/instrument.
Just athought as 95% of ga aircraft arnt equipped with them
.

[Connedrod]

So once again thoose tnat are unable to prove me giving incorrect infromation go onto the personal attact mode, gee how would have thought that would happen and if i bite back they go run an hide and get me banned.

[Lumps]

aps cult course that my qualifications and knowledge is of no use

If it wasn't for anti-factual APS trolls conflating their experience with knowledge I'd have given up on pprune ages ago.

[Aussie Bob]

So you are saying that due to the fact i havent done the aps cult course that my qualifications and knowledge is of no use.
Please remind me of the approved aps course you obviously are suggesting i go and do..

Rod, I am not saying that at all, it is just that you wrote this:

Thats all aps do. The convert data so it favours their own interest, example engine overhaul periods. They quote millitary hours then say but the airlines ran lop and increased the overhaul hours. This while an increase in commercial aviation often happens it was in no way related to running lop. The millitary ran lop as well. Its happening now if you purchase from the manufacturer you get more hours o your engine overhaul life.

So I ask, how do you know what they teach when you haven't done the course? I didn't see this when I did the course. So come on, answer the question, how do you know what they teach when you haven't done the course?

Your problem and the reason you get banned and keep changing your user name is that you seem to come on here to slang out other people. People have different opinions and if your only response is ridicule and contempt then it is not surprising you get banned and need a new user name.

Let's see, yr right, band a lot, con rod and more, how about a few manners and some understanding of differing opinions and you may actually get some of the respect you think you deserve.

[Bend alot]

It is over 30years since I flew an injected twin.
My flying now is in carbureted engines with no EGT indication.
I lean until rough, richen until smooth, the richen another centimetre of throttle movement or so.
What am I doing wrong?, or at least how can I improve things? :hmm:


Your using the wrong lever - use the red one, not the black one.

[Bend alot]

One of the reasons APS has detractors is that engine monitors and pilot education have exposed the variable quality of engine manufacture and maintenance.

The effort and cost it takes to get F/A mixtures balanced across cylinders shows how poorly balanced it is off the production line. Many new, certified and quality stamped cylinders need to be set up properly by the few remaining competent experts before fitment. Bushings made of cheese. Spark plug suppressors made of unicorn farts...

I can tell, on the first flight after maintenance, whether timing advance has been fiddled with and set correctly. Some engineers don’t like it when you say: “As a consequence of a change in CHTs and and in-air mag check, I can tell that you’ve advanced the timing on right magneto too far.”

Blocked injectors usually happen just after maintenance. Engineers don’t like it when you say: “The injector on 4 is blocked as a consequence of contamination introduced during your maintenance.”


Many new, certified and quality stamped cylinders need to be set up properly by the few remaining competent experts before fitment. Bushings made of cheese. Spark plug suppressors made of unicorn farts...


Can you explain what is set up before fitment?


I can tell, on the first flight after maintenance, whether timing advance has been fiddled with and set correctly. Some engineers don’t like it when you say: “As a consequence of a change in CHTs and and in-air mag check, I can tell that you’ve advanced the timing on right magneto too far.”


Is within tolerance too far? If my memory serves me correctly there is a tolerance of magneto to engine timing and also a tolerance of the internal magneto timing and considering there are two units - the total variation can be rather large, but certainly not defiantly "too far". In my honest opinion I believe you can not tell what you stated above, but that there is a change in indication most likely cause by a timing adjustment.


Blocked injectors usually happen just after maintenance. Engineers don’t like it when you say: “The injector on 4 is blocked as a consequence of contamination introduced during your maintenance.


I have known far more injectors to become blocked between servicing than just after maintenance, probably a ratio of 10 or 20 to 1!


Now if the nozzle has become blocked due to maintenance, it would be because the nozzle has been removed - just a random guess unless you have filter less aircraft and flow divider. Simply request at your expense to have the stainless fuel supply lines removed and cleaned when nozzles are removed if it is a common event for you.

A response to another post about LAME's dropping Spark Plugs - often that HT lead end ceramic breaks out in full, not seen it crack the other end.

[Connedrod]

So bob
Its ok to have a dig at myself and i can include yourself in that. But if i have a go back thats not ok. And if you take the time to actully look at what is said about me its a dam site worse than what i have ever said. Btw im never been bend a lot or band a lot for the record.

As for comments about the aps course ive been going on what has been posted on this forum and tne lies that have been quoted on here by aps. So if anyone to blame about comments ive made please quote correct statements that arnt lies miss truths etc, then there will not be any thing to comment about. But if lies incorrect statements or miss truths are quoted expect to be quized and pulled up about them. How about that. And maybe we will not have another thread removed because they been wrong.

[Bend alot]

FYI.




TCM IO520 engine - magnetoto engine timing 20 degrees BTC +/- 1 degree.


Bendix 1200 - E gap timing 15 degrees +/- 2 degrees


Bendix 1200 - points gap 0.016 +/- 0.003 thou.


Champion - RHB32E gap 0.016 - 0.021.


So one magneto can be 19 deg TDC, E gap 13 deg, point gap 0.013& spark plug gap 0.016.


The other mag 21 deg TDC, E gap 17 deg, point gap 0.019& plug gap 0.021.

[Connedrod]

FYI.




TCM IO520 engine - magnetoto engine timing 20 degrees BTC +/- 1 degree.


Bendix 1200 - E gap timing 15 degrees +/- 2 degrees


Bendix 1200 - points gap 0.016 +/- 0.003 thou.


Champion - RHB32E gap 0.016 - 0.021.


So one magneto can be 19 deg TDC, E gap 13 deg, point gap 0.013& spark plug gap 0.016.


The other mag 21 deg TDC, E gap 17 deg, point gap 0.019& plug gap 0.021.



Come on now wtf wouldthe manufacture know about timing on their engines.
Cont for some time now fit their engines with matched nozzles as stanard.
I laugh on pages on this forum the expects dont even know how the magnetos actually work. But they coment its a degree out. I wonder how good they be with out that instrument on their low power tractor engine.
When someone ask why leadie dosnt change maintenance facilities i tnink that answer is quite obvious.

[oggers]

Could you identify the posters who fly other people's aircraft? For my part, it's my engine. My life depends on it.

Every pilot’s life depends on it. It doesn’t change the facts. But I’ll rmatch your life and raise it by the 6 other pilots and hundreds of pax our company moves each and every day of the week your chosen metric for the value of opinion is the human cost of being wrong.

So why have my engines gone hundreds of hours past TBO when run on "interesting theories" rather than your evidently scientifically-based "55% power setting and slightly rich"?

Nobody is saying the only way to get an engine to TBO is to run “slightly rich at 55% power”. The question is whether running lean at high power will cause detonation. The hard facts are the manufacturer has demonstrated to the certifying authority that the engine does not detonate at the recommended power and mixture settings. At some point above those power settings the engine will begin to detonate if you lean far enough. And yes, I do know that if you lean even further it may stop detonating, but that is because the power would begin to drop again.

Oggers mentioned certification. My engine is certified to run at maximum rated power, continuously, to TBO.

Your engine is NOT certified to make TBO at any setting. The TBO is a recommendation for private ops and a limit for commercial ops. There is nothing in the certification that requires the engine to make TBO if run continuously at 100% of max rated power and it is bizarre that any pilot would hold such an opinion.

[Bend alot]

The FYI above was to highlight the great allowable variation in engine timing that is not "too far advanced"


The adjustable variables above will shift those little bars around a lot on that round gauge.


But to make the statement implying the LAME has timed the engine wrong is made by an uneducated person on such topic, but happily bags out maintenance staff.

My opinion of the engine monitoring systems and balanced or Gammi injectors is they are great, but not always useful.


* In trouble shooting - they may isolate a cylinder but many times via wiring error be the wrong cylinder.


* They do not in any way shape or form indicate anything other than temperature of a cylinder - not a reason why it is different to others by a small or large amount.


* Extend an engine TBO. They have zero effect on wear on cams and con rod bearings also little to no effect on cylinder wall and valve wear. A top overhaul with new cylinders will give a better break down report for engine extensions than anything else.


But for private ops and on condition engines they can save the owner/s lots on fuel and reduce cylinder related maintenance costs. Just don't tell me the timing was too far advanced unless you can prove it is!

[Lead Balloon]

LB: Many new, certified and quality stamped cylinders need to be set up properly by the few remaining competent experts before fitment. Bushings made of cheese. Spark plug suppressors made of unicorn farts...

BAL: Can you explain what is set up before fitment?What I know is that there are an increasing number of valve guide problems with Continental cylinders, whether they’re on ‘new’ or overhauled engines. An increasing number of frustrated owners take their ‘new’ or overhauled engine to experts who have a process using Prussian Blue to get the correct print on the valve stem tip. Those experts are increasingly frustrated at the ‘quality’ of what they are seeing.

If you are drawing a distinction between before and after fitment and I got that wrong, well done! It proves nothing I say is true and there is no problem with quality control.

LB: I can tell, on the first flight after maintenance, whether timing advance has been fiddled with and set correctly. Some engineers don’t like it when you say: “As a consequence of a change in CHTs and and in-air mag check, I can tell that you’ve advanced the timing on right magneto too far.”

BAL: Is within tolerance too far? If my memory serves me correctly there is a tolerance of magneto to engine timing and also a tolerance of the internal magneto timing and considering there are two units - the total variation can be rather large, but certainly not defiantly "too far". In my honest opinion I believe you can not tell what you stated above, but that there is a change in indication most likely cause by a timing adjustment.Is within tolerance too far? Errrm, I’ll make a wild guess and say within tolerance is not too far.

“In my honest opinion I believe you can not tell what you stated above, but that there is a change in indication most likely cause by timing adjustment”. It just goes to show that you have zero experience as a pilot flying behind these engines.

Out of maintenance the CHTs were 15C higher on climb-out than normal. That put CHTs above that magic number Lycoming got about right in the information I quoted earlier. A temperature I’d never been before. Mag check shows all plugs working but big differences between mags.

The timing of one of the mags had been advanced too far (and out of tolerance - 25 degrees instead of 22). The engineer probably used a mechanical protractor rather than the accurate equipment used by the Timing Fairy to confirm the problem.

For your education, the reason advancing the timing increases CHT is because in reduces thetaPPP - i.e. brings the peak pressure point closer to top dead centre. A bit like leaning the mixture to 25C ROP.

LB: Blocked injectors usually happen just after maintenance. Engineers don’t like it when you say: “The injector on 4 is blocked as a consequence of contamination introduced during your maintenance.

BAL: I have known far more injectors to become blocked between servicing than just after maintenance, probably a ratio of 10 or 20 to 1!

Now if the nozzle has become blocked due to maintenance, it would be because the nozzle has been removed - just a random guess unless you have filter less aircraft and flow divider. Simply request at your expense to have the stainless fuel supply lines removed and cleaned when nozzles are removed if it is a common event for you.
Yours is very small sample.

I’m talking about the experience across thousands of aircraft. Yours is a very small sample.

“Now if the nozzle has become blocked due to maintenance, it would be because the nozzle has been removed - just a random guess...”. Brilliant guess.

“Simply request at your expense to have the stainless fuel supply lines removed and cleaned when nozzles are removed...”. Spoken like a true engineer! Your fiddling (for which I’m paying) introduces the crud that causes the defect, and your solution is to ‘up-sell’ more fiddling.

I think I’ve mentioned this in other threads. I would offer various engineers many thousands of dollars not to inflict a range of counter-productive maintenance on my aircraft, if I weren’t committing what’s probably a crime under the civil aviation law. Bleeding money to reduce risk is better than bleeding money to buy risk.

Just as a matter of interest, have you ever seen any engine or engine component that’s ‘new’ or out of overhaul that’s had a defect? Just once? Or are you observing perfection?

Have you ever made a mistake during maintenance that wasn’t picked up and ended up causing an in-air problem. Just once? Or have you achieved perfection?

I’ve made a number of mistakes during maintenance that weren’t picked up and ended up causing an in-air problem. When you’ve worked at it for a long time and you’re not perfect, it’s bound to happen occasionally. That’s why I know what really goes on inside maintenance hangars. But it’s also why I don’t rain down legal hellfire and brimstone every time one of these mistakes is made on my aircraft. I could do it, but I empathise with the people who’ve made the mistakes.

[A Squared]

Page 180 in Fate is the Hunter makes reference to boffins getting the crews to operate at reduced RPM and MP so I imagine that operating LOP was part of it. EK Gann found that it was bollocks in practise, but then again what would he know.


Well, frankly, not much. Gann also believed in the myth of getting an airplane "One the step". His tale of south American mechanics sabotaging his airplane by putting water in the oil, which resulted in (according to him) the steam pressure blowing the oil filler caps off of his oil tanks is indicative of an embarrassing lack of systems knowledge.

Gann was a great story teller, but not particularly knowledgeable about technical matters.

[Tankengine]

Your using the wrong lever - use the red one, not the black one.

Quite correct:ouch:

However, nobody here (from old-school lame to APS expert) seems to want to tell me what to do with the red lever if I don’t have an EGT gauge on a carburetted engine!:ugh:
You know, like probably 75% of GA aircraft! (Unless they have improved remarkably in the last few years);)

[A Squared]

Quite correct:ouch:

However, nobody here (from old-school lame to APS expert) seems to want to tell me what to do with the red lever if I don’t have an EGT gauge on a carburetted engine!:ugh:
You know, like probably 75% of GA aircraft! (Unless they have improved remarkably in the last few years);)

I think you're mistaken there. I haven't been to an APS seminar, but I have read a quite a bit of Deakin's articles and as I recall, the advice was generally don't attempt LOP operations with an uninstrumented carburated engine. I don't know if that's still what they are recommending.

[Lead Balloon]

The question is whether running lean at high power will cause detonation. The hard facts are the manufacturer has demonstrated to the certifying authority that the engine does not detonate at the recommended power and mixture settings. At some point above those power settings the engine will begin to detonate if you lean far enough. And yes, I do know that if you lean even further it may stop detonating, but that is because the power would begin to drop again.

Oggers

All mixtures are ‘lean’.

Running 25C rich of peak is ‘leaner’ than running 100C rich of peak.

Running 25C rich of of peak at high power is more likely to cause detonation than running 25C lean of peak at high power.

THAT IS WHY THE CAUSAL CONNECTION BETWEEN DETONATION AND LEAN OF PEAK OPERATIONS DRAWN BY THE AWB IS UTTER BOLLOCKS. The mixture settings that will always create the greatest risk of detonation are rich of peak.

Do you know what mixture settings were used on the Whyalla Airlines aircraft?

Your engine is NOT certified to make TBO at any setting.No ****? I’ll write that down somewhere. What I actually said was: My engine is certified to run at maximum rated power, continuously, to TBO.That statement is true.

You need to understand (or forgot to note) the meaning of “maximum rated power”.

I could, if I were stupid enough, drag more than the maximum rated power out of my engine by leaning the mixture to around 25C rich of peak after take off at sea level on an ISA day with full throttle and maximum RPM. However, I’m not that stupid.

And as I said, contemporary measurements show that some certified engines detonate at recommended power and mixture settings.

[Lookleft]

Gann was a great story teller, but not particularly knowledgeable about technical matters.

And you know this because........?

[Lookleft]

Just as a matter of interest for those who haven't looked at the website, these are the credentials for the "staff" of APS.

...a retired JAL 747 Captain with over 39,000 flight hours. He holds the ATP, CFII, and MEI, Instructor Certificates and has extensive radial and flat engine experience. He has flown everything from Piper Colts in South America to WWII war birds. He flew for Air America in the 60's and wrote a monthly column for AvWeb. John has done all the flying we dreamed of doing, although he downplays it as "having just survived." He was a Commemorative Air Force pilot on the C-46, B-24, B-29, T-6, Bearcat and Zero. He owned a V-tail Bonanza with GAMIjector set #1......

....passion for aviation began in high school but her flight training was delayed by college basketball, marriage, and raising a family. After her two-decade delay, she attended APS as a student pilot and realized her life-long passion a short time later. She joined APS in 2008 and has flown a variety of GA aircraft. She owns a Bonanza and a C-170 and routinely cruises her carbureted Cessna LOP. While a ski instructor on Vail Mountain, she awoke one morning and said, "No more snow. Let's find an aviation community somewhere warm and move.".....

....is a retired general dentist with over 4700 hours flight time. He holds the ATP, CFII, MEI, and A&P Certificates and is a published author of novels and professional articles on dentistry and aviation. Walter did his first landings in a C-172 on the beach at Chandelier Island south of Gulfport, MS, and has had a Bush Pilot mentality ever since. He has been a Commemorative Air Force pilot on the C-46, C-47, and B-24 and has radial and flat engine experience. He had GAMIjector set #3 on his Bonanza and is now the current owner of a 1969 E33A Bonanza.

BTW LB APS offer online courses so would you be willing to pay for andrewr to sign up for that?

[Bend alot]

** = my reply


What I know is that there are an increasing number of valve guide problems with Continental cylinders, whether they’re on ‘new’ or overhauled engines. An increasing number of frustrated owners take their ‘new’ or overhauled engine to experts who have a process using Prussian Blue to get the correct print on the valve stem tip. Those experts are increasingly frustrated at the ‘quality’ of what they are seeing.


** Yes certainly some years ago there was massive TCM cylinder issues, closely followed by Superior and from memory a bit latter Lycoming too - but in recent years say last 4 or 5 nothing, but I am not current.

If you are drawing a distinction between before and after fitment and I got that wrong, well done! It proves nothing I say is true and there is no problem with quality control.


** Yes was confused as your fitment comment - yes all cylinder manufactures and engine manufactures have had quality issues over the years.

Is within tolerance too far? Errrm, I’ll make a wild guess and say within tolerance is not too far.

“In my honest opinion I believe you can not tell what you stated above, but that there is a change in indication most likely cause by timing adjustment”. It just goes to show that you have zero experience as a pilot flying behind these engines.

Out of maintenance the CHTs were 15C higher on climb-out than normal. That put CHTs above that magic number Lycoming got about right in the information I quoted earlier. A temperature I’d never been before. Mag check shows all plugs working but big differences between mags.


** I have not closely followed this thread but thought we were talking TCM IO520 - my fault but again not current with your engine.

The timing of one of the mags had been advanced too far (and out of tolerance - 25 degrees instead of 22). The engineer probably used a mechanical protractor rather than the accurate equipment used by the Timing Fairy to confirm the problem.


** Interested as to your knowing the 25 degrees and not 22, did they allow you to be present? Normally owners/pilots are not allowed to oversee such work in many places (that just an interest question). I personally have never seen a mechanical protractor in about 35 years and a number of countries. There was the plate on the pulley on the rear of IO520 TCM that had timing marks but that was removed years back. If it is a Lyco it would be the line on the fly wheel matched to the dot on the starter. This can be hard due propeller blade and cowling arrangements on some craft.

For your education, the reason advancing the timing increases CHT is because in reduces thetaPPP - i.e. brings the peak pressure point closer to top dead centre. A bit like leaning the mixture to 25C ROP.


** that can be changed by spark plug gap and E gap timing.


Yours is very small sample.

I’m talking about the experience across thousands of aircraft. Yours is a very small sample.


** Correct I have only worked on a thousand or so piston aircraft tail numbers

“Now if the nozzle has become blocked due to maintenance, it would be because the nozzle has been removed - just a random guess...”. Brilliant guess.

“Simply request at your expense to have the stainless fuel supply lines removed and cleaned when nozzles are removed...”. Spoken like a true engineer! Your fiddling (for which I’m paying) introduces the crud that causes the defect, and your solution is to ‘up-sell’ more fiddling.

I think I’ve mentioned this in other threads. I would offer various engineers many thousands of dollars not to inflict a range of counter-productive maintenance on my aircraft, if I weren’t committing what’s probably a crime under the civil aviation law. Bleeding money to reduce risk is better than bleeding money to buy risk.


** Think fuel nozzle cleaning on TCM was called up at 3 or 500 hour intervals - just apply to CASA for a dispensation. Will send bank details later.

Just as a matter of interest, have you ever seen any engine or engine component that’s ‘new’ or out of overhaul that’s had a defect? Just once? Or are you observing perfection?


** Yes plenty.

Have you ever made a mistake during maintenance that wasn’t picked up and ended up causing an in-air problem. Just once? Or have you achieved perfection?

** A reverse elevator trim due twisted cable - Darwin around 1995 on a C206 a nose gear issue on a 210. There are others but very minor.

I’ve made a number of mistakes during maintenance that weren’t picked up and ended up causing an in-air problem. When you’ve worked at it for a long time and you’re not perfect, it’s bound to happen occasionally. That’s why I know what really goes on inside maintenance hangars. But it’s also why I don’t rain down legal hellfire and brimstone every time one of these mistakes is made on my aircraft. I could do it, but I empathise with the people who’ve made the mistakes.


** I assume since 1985 counts as a long time?

[A Squared]

And you know this because........?

I just gave you 2 examples from his writing of badly flawed technical knowledge.

Your position seems to be that Gann is a technical expert because he wrote some books whcih a lot of people have read.

[Lead Balloon]

Normally owners/pilots are not allowed to oversee such work in many places...And we all know why that is, don’t we. ;)

I told you how I knew the magneto to engine advance: The Timing Fairy told me. ;) This is your cue to say the problem never happened. ;)

And are you sure about your 20 degree +/- 1 BTC magneto to engine figure for all IO520s? Really sure?

[Bend alot]

And we all know why that is, don’t we. ;)

I told you how I knew the magneto to engine advance: The Timing Fairy told me. ;) This is your cue to say the problem never happened. ;)

And are you sure about your 20 degree +/- 1 BTC magneto to engine figure for all IO520s? Really sure?

Yep am sure that is TCM tolerance on all engines "unless otherwise noted"

You certainly are a operator I would not like to want to need - believing in fairy's and all.

Most workshops don't allow persons that are not staff in them, think mostly that the believe in mechanical protractor devices used on engine timing.


So talk straight to me or bugger off - I don't care.

[Eddie Dean]

And are you sure about your 20 degree +/- 1 BTC magneto to engine figure for all IO520s?Not IAW MSB94-8D. This SB will also tell you about using the Time Rite device, which in my opinion is the onliest way to time a piston engine in an aeroplane, rotor craft engines of course, have their own arrangement.
Although LB you may consider the whole MSB documentation old wives tales, and only to be followed if one feels like it.
And we all know why that is, don’t we. ;)Why would that be? Because I do not know. Sign on the workshop wall here denotes charge out rate as $100 if we do the job, $130 an hour if you stay and watch, $150 an hour if you stay and help.

[Lead Balloon]

Band and Rod, meet Eddie.

Eddie knows what he’s talking about, at least in so far as the magneto to engine advance setting on an IO520 is concerned.

Heck: I think it’s even stamped on a plate riveted to the crankcase...

Edited because Eddie edited his:

No Eddie. I don’t consider the “whole MSB documentation old wives tales”. I only consider the bits that are old wives’ tales to be old wives’ tales. By the way, do you know why TCM issued an MSB specifying that the magneto to engine advance be changed from 20 to 22 on IO520s?

I’d be more than happy to stay and watch at $130 an hour, because it would get done more efficiently, correctly and at less cost than at $100 an hour.

[Lookleft]

I just gave you 2 examples from his writing of badly flawed technical knowledge.

No you gave me your opinion. 'Being on the step" was something I was hearing from very experienced pilots when I was a very junior Metro F/O. A bit like this thread, one person's myth is another person's experience. As for the oil cap incident I have no idea whether its bollocks or not maybe someone else can comment but I have no reason to believe it wasn't as described. Someone who flew radial piston engine aircraft for so long I think would have picked up a thing or two about how they worked. I would suggest E K Gann has more technical knowledge than someone who flies a desk and has done a 3 day seminar on piston engine operation.:D

[Eddie Dean]

LL - Being on the step" was something I was hearing from very experienced pilots when I was a very junior Metro F/O. Is this float plane "on the step" or some other sort?

[Bend alot]

Band and Rod, meet Eddie.

Eddie knows what he’s talking about, at least in so far as the magneto to engine advance setting on an IO520 is concerned.

Heck: I think it’s even stamped on a plate riveted to the crankcase...



"Stamped" well it is a Chinese fake then!

Happy to discuss any maintenance stuff with Eddie or Rod or yourself, but keep it factual not fairy based assumptions of a short course watching a gauge! any corrosion on joints corrections for your gauge readings?

[Connedrod]

Band and Rod, meet Eddie.

Eddie knows what he’s talking about, at least in so far as the magneto to engine advance setting on an IO520 is concerned.

Heck: I think it’s even stamped on a plate riveted to the crankcase...

Think you need to be drug tested.
Ffs a timerite is only one of many ways to time a mag. Wtf would you know what when ive done them,
How about practice what you prech and let thoose that know do their jobs while you go get some piano lessons.

And whist useing a time rite getting tdc to set it up still leaves a possiblity for an inaccurate setting. Btw the only way to do mags on a radial is ? Btw trick ? This sort some out

Its also noted know one has answered the questions ive as or old leadie cause he cant.

[Connedrod]

I wonder that they so intent on sayiong it was 15 deg hotter etc but when were these edm last cal done ?

[Lead Balloon]

BTW LB APS offer online courses so would you be willing to pay for andrewr to sign up for that?No.

Andrew won’t be satisfied - and I won’t be getting value for money - unless Andrew has the opportunity to ask questions of, and point out all the flaws in the data presented by, the presenters. It may be that he is successfull, in which case I will have learned something new and important.

[Lead Balloon]

Is this float plane "on the step" or some other sort?Being “on the step” was just another ubiquitous pilot’s OWT. Very rare these days, but there’s the occasional outbreak. A bit like measles...

[Lookleft]

So information presented online isn't as valid as that presented in a seminar format? Online content from universities and Ted talks (and APS)are a complete waste of time?

The internet version of "Engine Management Made Easy" is a detailed, multi-media, online course reflecting nearly all of the aspects of the live class. It is designed for all levels of pilot experience, from the private pilot to the ATP and covers basic piston engine theory from the basics through advanced concepts. You will see all of the same material as seen in the live class including the engine runs on the Carl Goulet Memorial Engine Test Facility at GAMI and the in-flight videos shown in class. The APS class has always been a firehose of information over 2 1/2 intense days in the classroom. One advantage to the online course is that you may proceed at your own pace. For a more detailed overview of the material, see the description of the curriculum to the live class.

So what would andrewr not understand about what you are talking about from the online content?:=

[Tankengine]

I think you're mistaken there. I haven't been to an APS seminar, but I have read a quite a bit of Deakin's articles and as I recall, the advice was generally don't attempt LOP operations with an uninstrumented carburated engine. I don't know if that's still what they are recommending.

How can I be mistaken?:confused:
I am asking a question!:ugh:

[Lead Balloon]

So information presented online isn't as valid as that presented in a seminar format? Online content from universities and Ted talks (and APS)are a complete waste of time?



So what would andrewr not understand about what you are talking about from the online content?:=The online content has been presented on PPRuNe and Andrew doesn’t accept it.

You and he seem to take the view that too many others in aviation do: It’s up to someone else to spend their time and money to cure you of your ignorance.

[Bend alot]

Andrew take the course and ask lots of questions - it will certainly be of great benefit for you.


It is also admirable of the other member to pay the course cost.


But it is not the be all and end all of engine operation, but certainly a tool you can use.

[Eddie Dean]

do you know why TCM issued an MSB specifying that the magneto to engine advance be changed from 20 to 22 on IO520s?No, I do not know. Elucidate please.

[Lookleft]

And Aussie Bob talked about arrogance! If you think that what you have put on this thread is equivalent to online content then you are more arrogant than even AB can imagine!

You and he seem to take the view that too many others in aviation do: It’s up to someone else to spend their time and money to cure you of your ignorance.


You were the one that made the grand and magnanimous offer of paying for andrewr to attend an APS seminar when it was presented in Australia. According to their website they have no seminars on offer in the States or here. They will however take your money and put your name on a list to assess if there is sufficient interest! Their website is offering an online equivalent yet you are now saying that it wouldn't satisfy andrewr ( have you asked him?) and its content is on Pprune. The more I see posted on this thread the more I agree with those who suggest that APS is equivalent to a cult.

[tio540]

Setting the mixture to around 25C ROP is the worst setting for a piston aero-engine whatever the power setting. It will produce the highest CHT possible for that power.

Given the choice of a 74% power setting with a CHT of X and a 74% power setting with CHT less than X, I choose the latter.

Detonation is not the only thing that is detrimental to engine longevity. So is heat. The manufacturers say so. :ok:

On the attached chart, the CHT does not peak at 25 degrees C ROP.

[Lead Balloon]

Eddie

You will almost certainly be surprised to learn that it wasn’t to make the engines more reliable.

Which of these IO520s at sea level on an ISA day, RPM set to 2,700, mixture set to full rich and throttle set to maximum will deliver more power:

1. The one with magneto to engine advance set to 20 degrees.

2. The one with magneto to engine advance set to 22 degrees.

[Lead Balloon]

And Aussie Bob talked about arrogance! If you think that what you have put on this thread is equivalent to online content then you are more arrogant than even AB can imagine!I didn’t say “this thread”.

Your new found prejudice means you haven’t been keeping up with the very, very long and multiple threads on this subject, in which andrewr has been an active contributor.

[Lead Balloon]

On the attached chart, the CHT does not peak at 25 degrees C ROP.Are you sure you have your units of measurement correct? Sure?

And you do know what the word “around” means, don’t you?

[Bend alot]

What aircraft operate at sea level?

[Bend alot]

And we all know why that is, don’t we. ;)

I told you how I knew the magneto to engine advance: The Timing Fairy told me. ;) This is your cue to say the problem never happened. ;)

And are you sure about your 20 degree +/- 1 BTC magneto to engine figure for all IO520s? Really sure?



"Sure" and "Really sure"


Do I need to bold it?

[tio540]

Are you sure you have your units of measurement correct? Sure?

And you do know what the word “around” means, don’t you?

Lead Balloon, you say previously that your LOP operation is backed up with science, and a test cell. In the chart I provided, at any mixture setting richer than peak EGT, the CHT reduces. Correct, or not.

[Bend alot]

Sorry take it back it is 22 degrees on the 520 - as said not current


http://www.tcmlink.com/pdf2/msb94-8d.pdf

[Lookleft]

Your new found prejudice means you haven’t been keeping up with the very, very long and multiple threads on this subject, in which andrewr has been an active contributor.

No prejudice just checking what the APS website states. I don't imagine that the multiple threads are very different to this one, this is already up to page 8. andrewr is also not the only APS sceptic, of note the other sceptics seem to be engineers who have probably had a lot more experience dealing with engines than you have. If the complete online content from APS is on pprune then I suggest that someone owes APS $375 plus whatever costs a good lawyer can extract for plagiarism and the theft of intellectual property, I understand the Yanks are big on that at the moment. I also note that those in the pro-APS camp don't want to make any comment on the bio's that have been posted. Like I have stated I haven't flown piston engine aircraft for a long time and have no opinion on the merits of LOP and ROP but I do know BS when I see it and it is usually accompanied by denigration of those offering a difference of opinion.

[Lead Balloon]

tsi540: Not correct.

If you enrich the mixture from peak EGT, the CHT will increase - repeat increase - until the mixture is about 25C rich of peak. After that, enriching the mixture will result in a decrease in CHT.

I don’t know what picture you’re trying to post, but if it has CHT and EGT curves that peak at the same point (e.g. like those in the EDM manuals) they are bull****. All you need to do is plot EGT against CHT in a real aircraft in the real world on a real flight. (I’m always struck by the irony of my love and dependence of the EDM in my aircraft but contempt for some of the OWT in the EDM manuals, which OWTs have been proved as OWTs as a consequence of measurements on the EDM...)

[Lead Balloon]

I don't imagine that the multiple threads are very different to this one, this is already up to page 8. andrewr is also not the only APS sceptic, of note the other sceptics seem to be engineers who have probably had a lot more experience dealing with engines than you have.What you imagine is not correct. There are many more threads of substantially greater length than this one.

“Probably” have more experience? You do a lot of speculation, Lookleft.

Let’s make it easy:

I have no clue what I’m talking about and nobody should take seriously anything I say.

Just quote the above in any thread in which I post and you can relax and get on with whatever it is that you do.

[Lead Balloon]

What aircraft operate at sea level?Aircraft that operate at sea level.

As you have no experience as a pilot, you’d not be aware that it’s possible to be operating at sea level so far as the engine is concerned, even though it’s higher than sea level. Indeed, it’s possible to be operating below sea level so far as an engine is concerned, and that’s where it’s particularly important to keep within the parameters in the engine limitations section of the flight manual/POH.

[Lookleft]

I have no clue what I’m talking about and nobody should take seriously anything I say.

Finally you and I can agree on something!:ok:

There are many more threads of substantially greater length than this one.

So what! I can start a thread on 'that year" and it will still have the same stuff in it.

“Probably” have more experience?

Yep, unless you want to post your CV. From what I can tell you were a lawyer from CASA If you have any engineering qualifications then I will defer to your experience. If you don't then the "probably" becomes a "definitely".

[tio540]

tsi540: Not correct.

If you enrich the mixture from peak EGT, the CHT will increase - repeat increase - until the mixture is about 25C rich of peak. After that, enriching the mixture will result in a decrease in CHT.

I don’t know what picture you’re trying to post, but if it has CHT and EGT curves that peak at the same point (e.g. like those in the EDM manuals) they are bull****. All you need to do is plot EGT against CHT in a real aircraft in the real world on a real flight. (I’m always struck by the irony of my love and dependence of the EDM in my aircraft but contempt for some of the OWT in the EDM manuals, which OWTs have been proved as OWTs as a consequence of measurements on the EDM...)


So where the manufacturer states, 50 deg C, 100 deg C, and 125 deg C rich, the CHT is not at peak, and longevity does not suffer, however fuel consumption does?

[Car RAMROD]

According to their website they have no seminars on offer in the States or here.

Quite possibly because they are going through the courts in the USA at the moment. Internal issues it seems.

[Lead Balloon]

Finally you and I can agree on something!:ok:



So what! I can start a thread on 'that year" and it will still have the same stuff in it.



Yep, unless you want to post your CV. From what I can tell you were a lawyer from CASA If you have any engineering qualifications then I will defer to your experience. If you don't then the "probably" becomes a "definitely".Engineering I do well. Law is a retirement hobby and I’m getting OK at it. However, there are other things I’m really good at that you’ll see when we meet. :ok:

[Lead Balloon]

So where the manufacturer states, 50 deg C, 100 deg C, and 125 deg C rich, the CHT is not at peak, and longevity does not suffer, however fuel consumption does?Errrm, at post #150 you said “On the attached chart, the CHT does not peak at 25 degrees C ROP.”

We’re still waiting for the chart that you posted to be released by the PPRuNe gods.

I agree that CHT does not peak at 50C or 100 or 125 C rich of peak. I said CHT peaks around 25C rich of peak EGT. Are you :confused:

[lo_lyf]

We ought to be grateful that yr_right/connedrod is the voice for the perpetuation of the old wives tales. There is a much greater number of people who solely read these forums rather than post, many of which are newcomers to the industry. Hopefully the coherent, well structured posts containing DATA from the sled and balloon might might motivate those readers to be curious, ask questions, read some pelican perch(as a start) and then draw their own conclusions. Team OWT is doing itself a disservice with its verbal diarrhoea.

Where's Jabawocky these days? Chocky frogs need dishing out!

[Lead Balloon]

You make the most important point: Find the data and rely on the data.

Don’t rely on what APS or anyone else says, except to the extent that their assertions are supported by data.

Jabba’s busy doing some good work that will result in a revision of the AWB.

[Lead Balloon]

Good news, tio540, your images have been released by the PPRuNe gods.

I’m pleased to say that my guess was correct. The images are of the EGT/CHT plots in many EDM manuals.

To the extent that those plots show that EGT and CHT ‘track’ each other always, they are bull****.

CHT ‘tracks’ EGT while mixture is being leaned from rich of peak towards peak. Then something interesting and counter-intuitive happens, approaching and passing peak EGT. From around 25C rich of peak, CHT peaks then starts to decrease as mixture is leaned further. As a consequence, the CHT at peak EGT is lower than CHT is around 25C rich of peak.

As I noted in earlier posts, this outcome is, despite the plots in EDM’s manuals and ironically, observed on every EDM (and other engine monitor) that takes measurements on real engines in the real world.

[tio540]

Good news, tio540, your images have been released by the PPRuNe gods.

I’m pleased to say that my guess was correct. The images are of the EGT/CHT plots in many EDM manuals.

To the extent that those plots show that EGT and CHT ‘track’ each other always, they are bull****.

CHT ‘tracks’ EGT while mixture is being leaned from rich of peak towards peak. Then something interesting and counter-intuitive happens, approaching and passing peak EGT. From around 25C rich of peak, CHT peaks then starts to decrease as mixture is leaned further. As a consequence, the CHT at peak EGT is lower than CHT is around 25C rich of peak.

As I noted in earlier posts, this outcome is, despite the plots in EDM’s manuals and ironically, observed on every EDM (and other engine monitor) that takes measurements on real engines in the real world.

Okay, with my limited experience, I only recall one POH specifiying 25 degrees C ROP, all the rest varied between 50 deg C to 125 deg C ROP. So you disagree with EDM, and many manufacturers avoid the 25 deg C ROP. Then you agree with the manufacturers, mostly anyway.

[Lead Balloon]

I “agree” that the worst place to run your engine is at an EGT of around 25C rich of peak. That’s because it’s the mixture around which your CHT will be maximum and you’ll be giving your engine the hardest (and unnecessarily hardest) beating that you can give it.

I don’t “agree” or “disagree” with EDM, other than to say that their EGT/CHT charts are crap to the extent that they falsely represent CHT and EGT as ‘tracking’ each other always. There’s some other folklore in the EDM manual but I ignore it.

I don’t “agree” or “disagree” with engine manufacturers, except to the extent that some of their publications contain crap.

But whatever the facts and the bull****, doing piston engine management properly depends on you having an all cylinder engine monitor and you knowing what it’s telling you and why, and what if anything can and should be done about it.

[A Squared]

Someone who flew radial piston engine aircraft for so long I think would have picked up a thing or two about how they worked.

As it turns out, I flew the DC-6 for 8 years. All 3 seats.


As for the oil cap incident I have no idea whether its bollocks or not maybe someone else can comment but I have no reason to believe it wasn't as described. Someone who flew radial piston engine aircraft for so long I think would have picked up a thing or two about how they worked.

It is bollocks. Oil systems are vented, Oil tanks are vented. They have to be, a sealed system would rupture due to expansion of the oil as it heated or from crank case blowby.

'Being on the step" was something I was hearing from very experienced pilots when I was a very junior Metro F/O.

No doubt. it's a persistent myth. THere's also a fair number who believe in the downwind turn. Nonetheless it's a myth there's no technical basis for it, nor has it ever been verifiably demonstrated under repeatable conditions.

[A Squared]

How can I be mistaken?:confused:
I am asking a question!:ugh:

Sorry, I thought that was more of a rhetorical question.

[Connedrod]

[QUOTE=lo_lyf;10111148]We ought to be grateful that yr_right/connedrod is the voice for the perpetuation of the old wives tales. There is a much greater number of people who solely read these forums rather than post, many of which are newcomers to the industry. Hopefully the coherent, well structured posts containing DATA from the sled and balloon might might motivate those readers to be curious, ask questions, read some pelican perch(as a start) and then draw their own conclusions. Team OWT is doing itself a disservice with its verbal diarrhoea.


Its one thing to run with theory but real world engineering dose not run on theory but with what is acutely and accurately occurred and shown.
What you and others do not understand and cannt be told or shown is what the exhaust gas is doing. The energy of the gas has not all been exhausted in the chamber and as it exiting past the valve it is still burning and as such damages the valve. This is not theory but fact. You can run all the dnyo runs you can wish for but the prove is the exhaust valve.
I dont no anyone or operator that run 25 deg rop. Normal is 75
Rop.
I will say it again. They stated that as you lean the mixture the burns faster than a rich mixture. Tbis is incorrect statement in fact it is reverse. If they get this basic rule wrong what else have they got wrong as it seams pently as i have shown.
Because i and others dont agree with the statements made at an UNAPPROVED course dose not mean we are wrong and dont have the right to have an opinion.

Where dose it say on any manual that you can spilt the magneto timing. Btw this isnt something that aps has found its been known well before they ever thought of it. So why is this happening why dose it work i guess leadie you wont answers this question as you havent answered any others i guess because you cant.

[oggers]

Given the choice of a 74% power setting with a CHT of X and a 74% power setting with CHT less than X, I choose the latter.

Detonation is not the only thing that is detrimental to engine longevity. So is heat. The manufacturers say so. :ok:

We all know too much heat is detrimental to the engine. However, we are talking about a heat engine here so the thermodynamic efficiency increases with temperature. If the materials could take it we would run them hotter. It is always a compromise. It is too simplistic to say that colder is better. You could run at rich best power and get the same CHT as if leaned to BSFC but more power and a cooler exhaust valve. There are no free lunches.

[A Squared]

Where dose it say on any manual that you can spilt the magneto timing.

Really hard to read your fragmented gibberish, so not 100 percent sure I follow what you're asking but just as a single example the magneto timing for a Continental o-300 is 26 degrees BTDC for the right magneto and 28 Degrees BTDC for the left magneto. That is from the Type Certificate Data Sheet.

[Connedrod]

Really hard to read your fragmented gibberish, so not 100 percent sure I follow what you're asking but just as a single example the magneto timing for a Continental o-300 is 26 degrees BTDC for the right magneto and 28 Degrees BTDC for the left magneto. That is from the Type Certificate Data Sheet.

Yes that is one engine. Were dose it say it for example a io520 ?
Gibberish or dont you understand whats happening with the engine chamber ?
Btw the engine manufacture holds the type cert for the engine however the airframe manufacture takes control of the engine when fitted into their airframe and as such their data for the engine takes precedence over the engine manufacture.

[A Squared]

Just as a matter of interest for those who haven't looked at the website, these are the credentials for the "staff" of APS.


And yet, you're holding up Ernest Gann as a technical expert merely because he wrote some popular books.

Detecting irony is not your strong suite, is it?

[Connedrod]

We all know too much heat is detrimental to the engine. However, we are talking about a heat engine here so the thermodynamic efficiency increases with temperature. If the materials could take it we would run them hotter. It is always a compromise. It is too simplistic to say that colder is better. You could run at rich best power and get the same CHT as if leaned to BSFC but more power and a cooler exhaust valve. There are no free lunches.

There is this thing they call it cowl flaps i do believe not fitted to all aircraft though. Most problems with cylinder cracking is due to the use of older cylinders being reused after an o/h. Thus said they are far more susceptible to cracking due to the Parthenon known as fatigue. To be honest i cant remember the last time i had to change one on a 1st life for cracking. But more than i can count on plastic aircraft with burnt valves useing lean assist.

[A Squared]

Is this float plane "on the step" or some other sort?

Yeah, it was those rare float equipped metroliners. :E

If that's a serious question, there is a myth that you can get an airplane in flight "On the step" in a similar way that a boat or floatplane will get "on the step" and that once "on the step" the airplane will cruise at a higher airspeed with the same power. Yeah, it is complete nonsense. In order to do that, there necessarily must be a reversal in the drag vs. airspeed curve. Yet in 70 something years of pretty extensive empirical testing in wind tunnels and such, nobody has ever observed this reversal of the drag curve. So, the question is how is it that this "step" can be reliably detected by the hundred dollar hamburger crew with the low resolution analog airspeed indicators in the panel of their bugsmasher, but all the aerodynamics and all the aeronautical engineers in all the research institutions and air-frame manufacturers around the world have not been able to detect this "step"? It just seems unlikely, doesn't it?

Yes, a boat or a floatplane will "get on the step" and once on the step it is in fact possible to cruise at a higher speed with less power than at a speed below "the step". The reason for this is that the boat is operating within two fluid mediums, sir and water, one of whcih (water) has far greater drag. when a boat is traveling slowly, it is in displacement mode, that is to move ahead, it must move all the water displaced by the hull aside or beneath the hull. That takes power, because compared to air, water is dense and viscous and hard to move. As a boat hull reaches a certain speed the boat begins "planing" where hydrodynamic forces will lift the hull out of the water, so that the boat is being supported primarily by the hydrodynamic forces rather than the buoyancy of the hull. With a float-plane, obviously, some of the weight is being supported by lift on the wings. This is easy to observe in a hydroplane; virtually none of the hull is in the water, it's skimming across the surface. This reduces drag in two ways: first, the hull is no longer displacing much water as it moves, and second because less of the hull is in the water, there is less skin friction from the water. The portion of the hull that has been lifted out of the water is now moving through air, whcih creates far less form drag and skin friction.

In short, a boat gets "on the step" because in planing mode, most of it is lifted out of the water which is creating the vast majority of the total drag.

There is no equivalent effect with an airplane in flight. The airplane is moving through a single fluid medium, air. It is not lifted out of anything as a boat is when planing, the entire aircraft remains submerged completely in that single medium.

[oggers]

LB

I could, if I were stupid enough, drag more than the maximum rated power out of my engine by leaning the mixture to around 25C rich of peak after take off at sea level on an ISA day with full throttle and maximum RPM. However, I’m not that stupid.

You said the engine is certified to run at max rated power continuously to TBO. Again, no it isn’t. It seems you didn’t read my post. The information is freely available from the FAA. A TBO in terms of the certification process, is a recommendation for private pilots and a limit for commercial ops. Either way the engine is not ‘certified’ to make the TBO at rated power or any other power. It is implied that the engine will make TBO if run at the “recommended power setting for maximum service life” - eg 65% for Lycoming.

Your point that “all mixtures are lean”: go on then, explain why in your opinion a full rich mixture is lean, or for that matter why any mixture richer than stoichiometric is ‘lean’.....

[Sunfish]

A Squared: There is no equivalent effect with an airplane in flight. The airplane is moving through a single fluid medium, air. It is not lifted out of anything as a boat is when planing, the entire aircraft remains submerged completely in that single medium.

Yes, but....., there are second order effects due to control loads and out of balance forces that need to be trimmed out, and the control reactions vary with speed. These can, in my opinion, even be felt on the humble C172.

To put that another way, the elevator and trim tabs have their own L/D curves which are independent of the wing. It is not inconceivable, at least to me, that at some points there is a mismatch and also a "sweet spot" where you are at maximum L/D and get a few extra knots or whatever its called that is termed being "on the step" because it cannot be achieved below a certain speed.

[A Squared]

A Squared:

Yes, but....., there are second order effects due to control loads and out of balance forces that need to be trimmed out, and the control reactions vary with speed. These can, in my opinion, even be felt on the humble C172.

To put that another way, the elevator and trim tabs have their own L/D curves which are independent of the wing. It is not inconceivable, at least to me, that at some points there is a mismatch and also a "sweet spot" where you are at maximum L/D and get a few extra knots or whatever its called that is termed being "on the step" because it cannot be achieved below a certain speed.


Well, yes. if you're holding a lot of control force against a lot of trim force you may be adding extra drag. That isn't what is being claimed by the "on the step" advocates.

[Connedrod]

The fuel mixture is set to a rich setting by the manufacturer settings at the idle position. Its different for the two manufacturers this places the engine fuel system to a rich mixture in all modes of operations unless the mixture is controled via the mixture lever or an automatic belows.

The step on a float plane is this. The float in the sitting position will take the full weight of the aircraft across the whole of the hull. The step approx 2/3 down the hull is waisted toward the rear. When the airspeed is great enough the rear 1/3 is free of the water surface thus reducing drag. Thats the only step other than thoose used to enter or exit the aircraft.

For thoose that think i and others are agaist running lop consider why that is. We have absolutely nothing to gain. We not trying to sell you a thing. The advice giving is what we see.

[Lead Balloon]

We all know too much heat is detrimental to the engine. However, we are talking about a heat engine here so the thermodynamic efficiency increases with temperature. If the materials could take it we would run them hotter. It is always a compromise. It is too simplistic to say that colder is better. You could run at rich best power and get the same CHT as if leaned to BSFC but more power and a cooler exhaust valve. There are no free lunches.And he who hesitates is lost and look before you leap. Meanwhile back in the real world..

You want to run an engine at 74% power. What mixture do you set, by reference to peak EGT?

Real world numbers please.

You said the engine is certified to run at max rated power continuously to TBO. Again, no it isn’t. It seems you didn’t read my post. The information is freely available from the FAA. A TBO in terms of the certification process, is a recommendation for private pilots and a limit for commercial ops. Either way the engine is not ‘certified’ to make the TBO at rated power or any other power. It is implied that the engine will make TBO if run at the “recommended power setting for maximum service life” - eg 65% for Lycoming.It “is implied”? Such an important concept is “implied”? I think not. We’ll have to agree to disagree on this point until I track down the primary certification materials.

Your point that “all mixtures are lean”: go on then, explain why in your opinion a full rich mixture is lean, or for that matter why any mixture richer than stoichiometric is ‘lean’.....”Full rich” is just where the mixture is adjusted. It could be adjusted even richer, although it would eventually get to the point it would be too rich to sustain combustion.

“Full Rich” isn’t “pure fuel”, is it? Full Rich is just the point on the lean curve that has been chosen as the mixture you get when the control is set there.

To put this another way, “full rich” is still leaner of a mixture that could sustain combustion, albeit very inefficiently.

By the way, at what mixture do you maximise the risk of detonation, all other variables like RPM, timing and manifold pressure being equal? A straight answer please.

And also by the way and as you will know, this has all been discussed before on PPRuNe, many times. For late-comers like Lookleft, here’s one example: https://www.pprune.org/pacific-general-aviation-questions/573902-commercial-pilots-who-don-t-know-about-piston-engines.html

It’s a more technically detailed discussion than this thread.

[djpil]

The POH is not folklore, but a legal document.Only part of it is FAA approved as the AFM. And if one has installed stuff per an STC then that AFM Supplement is now part of the AFM/POH.

[megan]

Flying on the step. This article seems to back up what I was told many years ago, a procedure used when power was marginal. The author is David F. Rogers, PhD, ATP, Professor of Aerospace Engineering (Emeritus), and has a page of articles at Prof Rogers (http://www.nar-associates.com/technical-flying/technical-flying.html)

http://www.nar-associates.com/technical-flying/step/step_wide_screen.pdf

[A Squared]

Flying on the step. This article seems to back up what I was told many years ago, a procedure used when power was marginal. The author is David F. Rogers, PhD, ATP, Professor of Aerospace Engineering (Emeritus), and has a page of articles at Prof Rogers (http://www.nar-associates.com/technical-flying/technical-flying.html)

http://www.nar-associates.com/technical-flying/step/step_wide_screen.pdf

That is not what the "on the step" folks claim.

[Lookleft]

And also by the way and as you will know, this has all been discussed before on PPRuNe, many times. For late-comers like Lookleft, here’s one example: https://www.pprune.org/pacific-general-aviation-questions/pacific-gener...n-engines.html

Thanks for the reference LB,I particularly liked this post from gerry111

I suspect that 'Lead Balloon' may be a rather junior aeromodeller, perhaps flying his first Enya 15 powered model aircraft?

So he'd have no idea of how an IO520 engine in a family owned Bonanza would operate? Things like how to run the engine at its most efficient leisure. And how to keep his life and that of his pax safe?

Clearly, he doesn't have a clue..


There is also this one from your good mate Aussie Bob:I reccomend the course, either online or with Jabba. For most pilots, there is heaps to learn.

Maybe you and he could go halves in the online course for andrewr?

Like I said I could start a thread about "that Year" and it would have the same stuff. Your 18 page reference is just this thread repeating itself. It once again seems to be those who are pro APS and those who think its rubbish.

Thanks for the reference megan, Not quite an OWT afterall. In the Metro it was as described. Climbing a little bit higher above the required altitude then accelerating before reducing the power. This is what E K Gann was talking about. If you don't want to accept it thats your perogative. It does not mean that your point of view is more relevant and mine is less relevant. A bit like the LOP ROP debate.:ok:

[sagesau]

Glad I drive a vehicle with a diesel engine in it

[Tankengine]

Sorry, I thought that was more of a rhetorical question.

I notice that none of you “experts” will even answer a simple question.:hmm:

[Connedrod]

And he who hesitates is lost and look before you leap. Meanwhile back in the real world..

You want to run an engine at 74% power. What mixture do you set, by reference to peak EGT?

Real world numbers please.

It “is implied”? Such an important concept is “implied”? I think not. We’ll have to agree to disagree on this point until I track down the primary certification materials.

”Full rich” is just where the mixture is adjusted. It could be adjusted even richer, although it would eventually get to the point it would be too rich to sustain combustion.

“Full Rich” isn’t “pure fuel”, is it? Full Rich is just the point on the lean curve that has been chosen as the mixture you get when the control is set there.

To put this another way, “full rich” is still leaner of a mixture that could sustain combustion, albeit very inefficiently.

By the way, at what mixture do you maximise the risk of detonation, all other variables like RPM, timing and manifold pressure being equal? A straight answer please.

And also by the way and as you will know, this has all been discussed before on PPRuNe, many times. For late-comers like Lookleft, here’s one example: https://www.pprune.org/pacific-general-aviation-questions/573902-commercial-pilots-who-don-t-know-about-piston-engines.html

It’s a more technically detailed discussion than this thread.

Your irrational logic is grasping at frictional facts that arnt there.
Damp test required.

[A Squared]

Thanks for the reference megan, Not quite an OWT afterall. In the Metro it was as described. Climbing a little bit higher above the required altitude then accelerating before reducing the power. This is what E K Gann was talking about.

Yes, it's an Old wives tale. Megan's article is something completely different than the "on the step" myth. Everyone with a private pilots' license knows (or should know anyway) that there is a minimum and maximum speed for a given power setting, with the minimum being below the minimum drag point on the drag vs airspeed curve. It would be theoretically possible to place yourself on the back side of the power curve and stay there. In reality, not particularly likely, airspeed is unstable there and will tend not to remain, the general tendency will be to slow further, and whcih point you will likely begin descending. However if you are just a few knots faster than that minimum, and you smoothly hold that altitude and power setting, your airspeed will increase and it will continue increasing until you reach the maximum airspeed for the power setting. Certainly if you climb at the best rate of climb airspeed or faster (and why on earth would you climb slower?) level off and set cruise power you will accelerate to the maximum airspeed. Regardless the claim of the "step climb" myth is not that there is a minimum and maximum airspeed for a given power setting. Again, that's private pilot stuff. The Step climb theory is that there is a third, higher airspeed, faster than the maximum, which can be achieved by accelerating past the maximum airspeed.

I would hope for your own sake that when flying your metro, that you weren't climbing slower than best climb and then further slowing up so much that you were finding yourself wallowing on the back side of the power curve. That would be some pretty poor airmanship.

Edit: the author of megan's article has a very poor understanding of what's going on. he refers to the U-2's operational limits as being the same as the minimum and maximum airspeed on the power required curve. It was nothing of the sort. The so called "Coffin Corner" of the U-2 was because the stall speed and the critical mach number (above whcih the airplane might tuck into an unrecoverable dive) came together as altitude increased. It had absolutely nothing to do with minimum and maximum air speeds on a power required curve.

[LeadSled]

On the step
Folks,
A bit off thread, but some large aircraft, particularly early model B747, exhibited a marked "on the step" characteristic.
It was finally tracked down the boundary layer adhesion characteristics.
In short, in decreasing speed to a steady Mach No., the boundary layer produced less drag than accelerating to the same Mach No. The difference in power settings and fuel flow was quite measurable.
As for the case with very sub-sonic light aircraft, I am not getting unto the argument, other than to say that an aerodynamic explanation was given in the text books most of use used in the '50's/60's, and some types certainly exhibited the characteristics as described.
Tootle pip!!

[Lookleft]

other than to say that an aerodynamic explanation was given in the text books most of use used in the '50's/60's, and some types certainly exhibited the characteristics as described.
Tootle pip!!

So my turn in opinion ping pong, from the above it can be taken that it is not an OWT. Out of interest A2, what are your credentials that you can just dismiss out of hand everyone else's experience and knowledge?:confused:

[Lead Balloon]

Hi again, oggers.

On the certification issue, FAR 33:19, headed “Durability”, said this in 1965:Engine design and construction must minimise the development of an unsafe condition of the engine between overhaul periods.(I think the current FAR 33:19 still starts with that sentence.)

FAR 33.7 deals with engine operating limitations.

I’ve always interpreted these provisions, and their predecessors prior to the advent of the FARs, as having the effect that the durability standard required the engine to make it to TBO, provided the engine was operated within the established limitations, which limitations end up in the “Limitations” section of the AFM.

Otherwise, the standard and the certification are a bit of a nonsense.

It just so happens that there is no limitation in my AFM as to how long the engine may be operated at maximum rated power, and it just so happens that I can operate the engine at maximum rated power without exceeding any of the limitations such as CHT, oil temperature etc.

Indeed, I anticipate that my engine would last longer if it were operated continuously, rather than started and stopped every few hours. Cold starts are when most engine wear and tear is inflicted.

On the mixture front, I note TCM SID97-3E. It deals with fuel adjustment procedures for TCM engines. It provides for, among other things, fuel system adjustment values.

For e.g an IO-520-B the SID specifies full power fuel flows of 23.2 to 24.9 US gallons per hour. That’s a range of 1.7 US gallons per hour.

I note this because one engine adjusted in accordance with the SID can have a full power fuel flow of 24.9 US gallons per hour, another can have a full power fuel flow of 23.2 US gallons per hour, yet both have mixtures set to “full rich”. The “full rich” setting on the second engine is leaner than the “full rich” setting on the first engine.

Both engines could be set up to have full power fuel flow of 25 US gallons per hour - out of specification - but that would still be a leaner “full rich” mixture than if the full power fuel flow was set out of spec to 25.1 US gallons per hour.

When convenient:You want to run an engine at 74% power. What mixture do you set, by reference to peak EGT?

Real world numbers please.

[A]t what mixture do you maximise the risk of detonation, all other variables like RPM, timing and manifold pressure being equal? A straight answer please. You’re the one flying all the precious passengers around each day. You must be setting the mixture somewhere, and doing so to avoid detonation?

[De_flieger]

Opinion ping pong sounds like fun, LL...out of curiosity I had a search through the ebook of Fate Is The Hunter to find the exact phrase and see how he described getting "onto the step". It turns out to be very similar to the way my training captains described and demonstrated it to me, and how I've seen it done many times (aircraft type - larger than Metro, smaller than 747). Maybe some aircraft don't do it, maybe some do but to a degree that it isn't evident or a worthwhile technique, but there's definitely one or two types out there that is is a usable technique worth knowing about. Nothing to do with floatplanes though!

[Aussie Bob]

So I owned this early model 172, 6 cylinder Continental, 145HP @ 2600 RPM. From the placard on the engine: 145 HP @ 2600 135 HP @ 2500 etc. No rocket science required to work out that 100 RPM = 10 HP

So .... You could easily get 100 knots at 2500 RPM. The problem was if you pitched the nose up slightly the speed would rapidly decay to around 90 - 95. At the same time, the RPM would also drop to around 2450 so the horsepower decayed by about 5. The angle of attack also increased to maintain the same altitude with less speed and less HP.

Some experts here tell me that there is no such thing as a "step". In a perfect world perhaps there isn't but my 172 sure exhibited exactly what Ernie and a heap of others talk about. To get 100 knots it required a bit of finesse, 90 - 95 was easy but I guess in fact it had no "step". You blokes told me so.

[Connedrod]

So I owned this early model 172, 6 cylinder Continental, 145HP @ 2600 RPM. From the placard on the engine: 145 HP @ 2600 135 HP @ 2500 etc. No rocket science required to work out that 100 RPM = 10 HP

So .... You could easily get 100 knots at 2500 RPM. The problem was if you pitched the nose up slightly the speed would rapidly decay to around 90 - 95. At the same time, the RPM would also drop to around 2450 so the horsepower decayed by about 5. The angle of attack also increased to maintain the same altitude with less speed and less HP.

Some experts here tell me that there is no such thing as a "step". In a perfect world perhaps there isn't but my 172 sure exhibited exactly what Ernie and a heap of others talk about. To get 100 knots it required a bit of finesse, 90 - 95 was easy but I guess in fact it had no "step". You blokes told me so.


Would it be fare to say that you have placed the aircraft into the correct trim position ?
Just as a matter of interest what dose the flight manual say inrgrads to the profromance of the aircraft in question ?

[megan]

What our long departed and much admired 411A had to say.Having flown DC-3's, DC-6's and Lockheed Constellations in the past, can say that ALL of these aircraft were climbed slightly high (100-200 feet), then descended slowly to the desired cruise altitude, while maintaining climb power.

Once level at altitude, reduce to cruise power (approximately 50% BHP) and adjust mixture to autolean, close cowl flaps and oil shutters as needed...presto, time for coffee.

ANY other method of level off at the desired cruise altitude took MUCH longer to reach the desired cruise speed, simply because these aircraft, as well as many older turboprops (F.27/FH227's for example) did not have excess power at higher altitudes, unlike many turbofan powered aircraft today.

What Exactly Is, "Flying On The Step"? - Airliners.net (http://www.airliners.net/forum/viewtopic.php?t=739005)

Where does lack of excess power put you on the drag curve?

Talking of the U-2, did you know in the cruise the power was at idle.

[Connedrod]

Talking of the U-2, did you know in the cruise the power was at idle.[/QUOTE]

Are you really sure.
Sl 14.7 psi
70000 feet 0.6 psi

I dont think the engine is at idle. It maybe making idle power at 70000feet but it most certainly would not be at the idle setting one would think. Maybe it turning at 2000rpm though.

[megan]

Flight manual.With the P-37 engine an altitude will eventually be reached during the cruise climb where the engine is operating at idle RPM, the exhaust gas temperature is up to the rnaxirnum, and the aircraft is still climbing. When this condition occurs, prompt action must be taken to prevent over temperature operation of the engine. Initially, the condition may be corrected merely by allowing the aircraft speed to increase while maintaining constant altitude. When the speed has increased to a point within 5 knots of the needle, aerodynamic drag should be added. The initial drag is created by using the variable speed brake or extending the landing gear. As the aircraft descends, engine power is increased to maintain engine operation at maximum limitations. Eventually, the aircraft will cease descent and again begin a cruise climb. When the aircraft again reaches the altitude of limiting conditions, the remaining drag devices will be used.

The P- 31 engine will normally never reach an altitude where idle RPM is encountered. However, maximum altitude is limited to the point where maximum exhaust gas temperature is reached and power cannot be further reduced without dropping below the minimum engine pressure ratio limit. The corrective procedure is the same as outlined above for the P·37 engine.

[A Squared]

What our long departed and much admired 411A had to say. Having flown DC-3's, DC-6's and Lockheed Constellations in the past, can say that ALL of these aircraft were climbed slightly high (100-200 feet), then descended slowly to the desired cruise altitude, while maintaining climb power.

Once level at altitude, reduce to cruise power (approximately 50% BHP) and adjust mixture to autolean, close cowl flaps and oil shutters as needed...presto, time for coffee.

ANY other method of level off at the desired cruise altitude took MUCH longer to reach the desired cruise speed, simply because these aircraft, as well as many older turboprops (F.27/FH227's for example) did not have excess power at higher altitudes, unlike many turbofan powered aircraft today.

What Exactly Is, "Flying On The Step"? - Airliners.net (http://www.airliners.net/forum/viewtopic.php?t=739005)


You really need to read that more carefully.

Focus on this part. ANY other method of level off at the desired cruise altitude took MUCH longer to reach the desired cruise speed

Notice that he says that it take longer to reach *the* desired cruise speed. Notice that he does *not* say that it allowed you to achieve and maintain a higher cruise speed.

Yes, if you leave in climb power, and/or dive slightly, you will achieve the maximum cruise airspeed sooner than if you level off and immediately set cruise power, and wait for it to build. When I was a flight engineer on the DC-6 I used to occasionally fly with a captain who would do that. Yeah, it took a long, long time to gradually accelerate to your cruising speed. And it was a real pain, because as an engineer, it really dragged out the time that you had to be constantly adjusting the cowl flaps and oil cooler door flaps to keep all your temps in line as airspeed soooooowly built. But for all that, eventually, you did reach the same cruising airspeed that you'd reach if you left in climb power and accelerated to slightly above it before setting cruise power.

Once again, the "step climb theory" is the theory that by accelerating to a higher airspeed by diving or using climb power or both, you can you maintain a cruise airspeed higher than the *maximum* cruise airspeed you would get if you just accelerated to cruise airspeed with a lower power in level flight.

[Connedrod]

Flight manual.

As i said.
The egine is not in idle. The engine has reached it critical engine operating limit. The power lever is not in idle. The power lever is forward of the idle position. The engine if it was in the idle positon would flame out. This is a totally different to what yo stated.
The engine has the same thrust as at idle, it is not in idle.

You dont seem to understand this.

[De_flieger]

Looks like megan's found the same flight manual as me... later in the piece it goes on to say An altitude will sometimes be reached where the minimum fuel flow setting equals that required for maximum exhaust gas temperature. This is called "minflow". In this case, retarding the throttle to idle will not change the power conditionThe minimum fuel flow is an engine characteristic, not a pilot setting, so reducing the power lever at that point will not affect the power produced, the power lever may be back at idle or at some small increment forward of the stop. The manual goes on to say that the power lever can be brought back to the idle position for descent regardless of altitude - so it won't cause a flameout. The power lever may well be in the idle position. That's just what the flight manual says.

[Connedrod]

The min wf is set by the fcu compututing system. This will set max fuel per alt and position. Once again the engine is in its max crictal alt. The compututing section in the fcu will not be able to provide any more fuel. This is not as stated at idle. What it means is the engine is at its lowest self substaining level. Its not in the idle position in the compututing secting and there fore not in idle.

[A Squared]

So my turn in opinion ping pong, from the above it can be taken that it is not an OWT.

Not really. the "above" is nothing more than a completely unsubstantiated claim by an anonymous person on an internet forum that some texts had an "aerodynamic explanation". That's it. If that, in your mind is proof of anything, I think we've found the problem here. You have no idea what constitutes proof of anything. Until we have the information allegedly printed in those alleged texts, we really have nothing. The fact that you're jumping up and down and clapping your hands and saying "Well now we have proof!!!" is really kind of laughable. I have no idea what "texts" Lead Sled is referring to, nor what sort of "aerodynamic explanation" ... and neither do you. His description is pretty short on detail. A little story about people on internet forums claiming certain sources say certain things. A while back I was involved in a discussion on another aviation forum about certain point of dispute. The guy with whom I was debating posted: "well a few years ago "publication XXX" tested such and such and their results found blah, blah" Of course "Blah blah" was exactly his side of the debate. Unbeknownst to him, I was on the staff of publication XXX when they did the said testing, in fact I was pretty thoroughly involved in that testing. The thing is, the results of the testing did not show "blah, blah" Not only did it not show "Blah, blah" the testing we performed did not even examine the question at hand or measure anything which would even shed any light on that question. Yet here he was, quoting that publication as a definitive source that proved his point. Now, I know the guy in question by reputation, and I don't believe that he was being intentionally dishonest. I think that as a result of flawed memory and confirmation bias, he genuinely believed that the article in question really did have test results whcih proved his point. But, it most assuredly did not. Similarly, with LS's vague claim about what some text from half a century ago said, without actually seeing what the text really *did* say, we don't really know, now do we? I'm a "show me guy". (For those in the US, yeah, I was born in Missouri.) You want to claim that some source or another says something? Cool, show me. I'll read it and we'll see what it really says and then we can discuss that.

I could be convinced that there is some effect out there which allows you to cruise at a measurable higher speed than your normal maximum cruising speed with the same power setting. It will take more than "some pilot said this is true" or "this guy who wrote some really popular aviation books said it was true" or "some guy on an internet forum claims he had a text half a century ago that explained this". What it would take is actual data, measured by some reputable and verifiable entity, together with some coherent explanation in aerodynamic terms of the nature of the phenomenon. So far that has been lacking here.

[Connedrod]

In other words lest say idle n1 was 55%
One would imagine for n1 at 70000feet in this example would be 101% maxed out
Clearly the engine is not idle.

The crical thing now would be the itt or egt etc temp as the flow of air to fuel ratio will be the limiting factor. To stop this exceeding the temp they will have to drop of fuel which would put the engine below min fuel and therefore flame out.

[A Squared]

So I owned this early model 172, 6 cylinder Continental, 145HP @ 2600 RPM. From the placard on the engine: 145 HP @ 2600 135 HP @ 2500 etc. No rocket science required to work out that 100 RPM = 10 HP

Ummm, actually the O-300 developed 145 hp a 2700 rpm, but I'm sure you remember all the other details correctly.

[De_flieger]

One would imagine for n1 at 70000feet in this example would be 101% maxed out
Clearly the engine is not idle. Connedrod, you keep saying things like "one would imagine" and "one would think", but they are contradicted by a reliable reference, the operating handbook for the aircraft.
This is not as stated at idle. What it means is the engine is at its lowest self substaining level. Its not in the idle position in the compututing secting and there fore not in idle. The flight manual says otherwise. According to the manual the power lever is either on or near the idle stop, reducing it onto the stop if not already there will not achieve a reduction in power and the fuel flow, EPR, NG and power being produced are all at their minimum levels. Sounds like idle to me.

[Connedrod]

Connedrod, you keep saying things like "one would imagine" and "one would think", but they are contradicted by a reliable reference, the operating handbook for the aircraft.
The flight manual says otherwise. According to the manual the power lever is either on or near the idle stop, reducing it onto the stop if not already there will not achieve a reduction in power and the fuel flow, EPR, NG and power being produced are all at their minimum levels. Sounds like idle to me.

I say imagine because i dont have the detail figues.

Are you saying n1 at idle at sl is the same n1 at 70000feet

[Lookleft]

That's it. If that, in your mind is proof of anything, I think we've found the problem here. You have no idea what constitutes proof of anything. Until we have the information allegedly printed in those alleged texts, we really have nothing.

The same is valid for your (and LB) assertion that the step is an OWT. As I asked before, what are your credentials and evidence that the step does not exist?

As far as anonymous person's on the interent is concerned here is prof Dave Rogers bio:


Dave Rogers is an airline transport rated pilot. He owns and flys a 1969 E33A Beech Bonanza. He has over 2300 flight hours and has been flying off and on for over 40 years. He was the chief pilot for the Naval Academy's flight test engineeing course. He habitually flys transcontinental, to Alaska, and to the Canadian High Arctic including as far north as Alert at 82 degrees 30 minutes. He has also flown across the North Atlantic in a single engine aircraft and thoughout the Carribean and the Bahamas.

Dr. Rogers is a graduate of Rensselaer Polytechnic Institute where he obtained his Bachelor of Aeronautical Engineering, Master of Science in Aeronautical Engineering and Doctor of Philosphy in Aeronatical and Astronautical Engineering degrees.

Professor Rogers was one of the original faculty who established the Aerospace Engineering Department at the U.S. Naval Academy in 1964. He has both an experimental and a theoretical research background. He has research interests in the areas of general aviation flight testing, hypersonic viscous flow, boundary layer theory, computational fluid mechanics, flight dynamics, highly interactive computer graphics, computer aided design and manufacturing, numerical control and computer aided education. He recently retired as Professor of Aerospace Engineering and Director of Aeronautics after 39 years of service. He has been honored with the title of Professor Emeritus. During his tenure he also served as Director of the Fluids Laboratories and head of the supercomputing group in addition to his professorial duties.

Dr. Rogers is the author of five textbooks including An Introduction to NURBS, With Historical Perspective; Laminar Flow Analysis, Mathematical Elements for Computer Graphics, Procedural Elements for Computer Graphics, and Computer Aided Heat Transfer Analysis. He is also the co-editor of four books from the State-of-the-Art Series on Computer Graphics and the Proceedings of ICCAS 82 - the International Conference on Computer Automation of Ship Design and Ship Production. His books have been translated into six foreign languages. Over 100,000 copies of his books are in print. He has published over fifty technical papers and reports.

He is a member of the American Institute of Aeronautics and Astronautics and ACM SIGGRAPH as well as a past member of the Society of Naval Architects and Engineers.

Recently, one of his former students; Kevin Sharer, CEO and president of Amgen, endowed the David F. Rogers Chair in Aerospace Engineering at the United States Naval Academy in his honor.

Dr. Rogers is the founder and former Director of the Computer Aided Design Interactive Graphics Group at the United States Naval Academy. He is series editor for the Springer-Verlag Series Monographs in Visualization and the founding editor of the journal Computers & Education. He also is a member of the editorial board of The Visual Computer and of Computer Aided Design. He is a former member of the AIAA Thermophysics TC and is currently a member of the AIAA Interactive Computer Graphics TC. He habitually serves on the technical program or organizing committees of both national and international conferences.

Dr. Rogers was the Fujitsu Scholar at the Royal Melbourne Institute of Technology in Melbourne, Australia during 1987 and Visiting Professor at the University of New South Wales, Sydney, Australia in 1982. He was an Honorary Research Fellow at University College London in England during 1977-78 where he studied Naval Architecture with the British Royal Corp of Naval Constructors.

He wrote an article (the link was provided by megan) of why the step exists. I am more inclined to accept his theory as to why the step exists against your opinion of why it doesn't. I would be more than happy to read similar articles to back up your claim that provides:

actual data, measured by some reputable and verifiable entity, together with some coherent explanation in aerodynamic terms of the nature of the phenomenon. So far that has been lacking here.

but there doesn't appear to be any that supports your opinion, other than your opinion.

[Bend alot]

Aircraft that operate at sea level.

As you have no experience as a pilot, you’d not be aware that it’s possible to be operating at sea level so far as the engine is concerned, even though it’s higher than sea level. Indeed, it’s possible to be operating below sea level so far as an engine is concerned, and that’s where it’s particularly important to keep within the parameters in the engine limitations section of the flight manual/POH.


No experience of any legal type, correct!


So you now say "engine" !!


Aircraft do not operate at sea level.


On occasions the take off or fly in sea level conditions - but not at sea level, ground effect is close but not sea level.


** So your above and the corrected statement is correct.

[Connedrod]

That is what the flight manual is being quoted as saying.

At 70000ft feet there is 24.5 times less px than at sea level. That means roughly you may only use 24.5 less fuel. This means the engine will not work. Clearly you have never done bgt.
Whislt as you decrease fuel as you increase alt the compressor has to work hard to give you enough air to continue the cumbustion. Basic gas.
Every gas turbine work on the same principles. The u2 is nothing special.
The n1 at 70000 feet would be at or near max n1 and not at sl n1 speed.
The engine will not work at sl n1 at 70000feet. My i suggest you go do basic gas

N1 is the dead give away for engine profromance. It is one of the very first t hings that is looked at when a drop in power is detected.
The higher the alt the faster for a give power setting the n1 must work, in other words whist at sl the n1 will give 1 to get to X whislt at 70000 it will have to work 24.5 times as hard to give X
Idle will be a few % above self substaining that % is the same at alt but the compressor must work harder to maintain it ie an increase in n1

[A Squared]

He wrote an article (the link was provided by megan) of why the step exists.

Well, no, he did not. he wrote an article about a contrived situation where someone climbs at a speed less than the best rate of climb airspeed and through this exercise of poor airmanship gets stuck on the back side of the power curve. this has nothing to to with the "on the step" theory.

[Lookleft]

So when are you going to provide the contrary evidence?

[Connedrod]

Tbm to get over this same problem use a engine that is rated near doulble the hp they require. Then derate that engine in half. Ie 1400 hp derated to 700 hp. This is so when it gets to its cruise alt it has sl profromance ie 700hp if it continues to climb the rated hp now decreases from 700 minus till it achives it selected alt. But as it increases its alt the n1 will increase wf will decrease as will itt. BGT .

[oggers]

LB

“Full Rich” isn’t “pure fuel”, is it? Full Rich is just the point on the lean curve that has been chosen as the mixture you get when the control is set there.

By definition all mixtures rich of stoichiometric are rich and vice versa. So I have no idea what you think you add to this subject by insisting that all mixtures are lean.

[Lead Balloon]

Hi again oggers

When convenient:

You want to run an engine at 74% power. What mixture do you set, by reference to peak EGT?

Real world numbers please.

At what mixture do you maximise the risk of detonation, all other variables like RPM, timing and manifold pressure being equal?

A straight answer please.

You’re the one flying all the precious passengers around each day. You must be setting the mixture somewhere, and doing so to avoid detonation?

[Connedrod]

Hi again oggers

When convenient:

You want to run an engine at 74% power. What mixture do you set, by reference to peak EGT?

Real world numbers please.

At what mixture do you maximise the risk of detonation, all other variables like RPM, timing and manifold pressure being equal?

A straight answer please.

You’re the one flying all the precious passengers around each day. You must be setting the mixture somewhere, and doing so to avoid detonation?

Seaming your in the mood for asking some questions how about answering the questions i ask yourself which i may add you havent answered as yet.
So here is a few more for you i sure you can answer

When you run lop at what point do you pass through the detenation range and how long are you there

How many ga type aircraft run lop and how many run rop.

Would you agree that more run rop than lop

Please advise then we in the maintenance field arnt seeing damage to aircraft engines that run rop from detenation as you have discribed previously

Please advise the folk here about what causes a burnt exhaust valve.

Please advise what are the damage that is caused by detenation.

Please advise what damage is cause by extreme leaning .

What is the time limit for calibration of your edm instruments and conponents

What is the reson for uneven breathing in aircraft engine cylinders

What is the difference between gami fuel noz and old standard cont fuel nozzles

Pleade advise the difference between a opposed engine in ga and a lagre radials that were used in a time since past.

Please advise us of your maintenance experience and training and licence coverage.



Thanks that do it for now.
Lets see how you go.

[Connedrod]

Oh leadie also as your such an expect on magneto timing can you please explain how to find tdc.

That easy for you

Cheers

[Lead Balloon]

It couldn’t possibly be as easy as explained here: http://www.ritesystem.net/images/Instructions%20Brochure.pdf

If it were that easy, even a pilot could do it.

[Connedrod]

It couldn’t possibly be as easy as explained here: http://www.ritesystem.net/images/Instructions%20Brochure.pdf

If it were that easy, even a pilot could do it.


So as i thought a key board warrior able to quote a web site. So how do you do it if you dont have a timerite. Btw the timerite is not a prefect method and can give a degree of error. So how do you do it exact.
Then maybe you can answer the other questions now if they not to hard for you.

[Eddie Dean]

It couldn’t possibly be as easy as explained here: http://www.ritesystem.net/images/Instructions%20Brochure.pdf

If it were that easy, even a pilot could do it.Easier than that, just use a big screw driver.

[megan]

Idle is not referring to N1, but fuel flow. The throttle may be at idle as indicated by bolding.The minimum fuel flow is adjusted to approximately 750 lbs/hour. An altitude may be reached at which this minimum fuel flow equals that required for maximum exhaust gas temperature. In this case retarding the throttle to idle will not change the power condition. The flight may be continued at constant altitude. In the event that the maximum EGT is exceeded, it can be reduced by losing I altitude and increasing airspeed as outlined in SECTION II, "Altitude Control".

[Connedrod]

Idle is not referring to N1, but fuel flow. The throttle may be at idle as indicated by bolding.

Once again you need to read and understand what is going on.

The limiting factor is the egt. The power lever is reduced to maintain a maximum of 750lbs per hour. The compressor speed would be at its maximum hence the higher egt. In this state the engine is not in idle. Its no where near idle. Only the flow fuel is near idle. The fcu will maintain compressor speed to the set figque. The engine has no more fuel to give due to the air ratio to continue to climb or maintain operation above this flight level. Idle speed is a factor of compressor speed and not wf. Wf on the ground and prefromance runs is a factor of compressor speed and must be within it graph for compressor speed to wf.
The engine is not in an idle condition due to the speed of the compressor. The engine would not be consided as in idle.

[De_flieger]

Once again you need to read and understand what is going on.

The limiting factor is the egt. The power lever is reduced to maintain a maximum of 750lbs per hour. The compressor speed would be at its maximum hence the higher egt. In this state the engine is not in idle. Its no where near idle. Only the flow fuel is near idle. The fcu will maintain compressor speed to the set figque. The engine has no more fuel to give due to the air ratio to continue to climb or maintain operation above this flight level. Idle speed is a factor of compressor speed and not wf. Wf on the ground and prefromance runs is a factor of compressor speed and must be within it graph for compressor speed to wf.
The engine is not in an idle condition due to the speed of the compressor. The engine would not be consided as in idle.

Connedrod, it seems like people keep trying to explain it to you, and you keep trying not to understand. N1 is back at idle rpm, not at its maximum, at that point, which is what the flight manual says. In flight, at high altitude, the maximum allowable N1 reduces, not increases, for those engines. Again, from the manual, at 50,000ft, max allowable N1 is 90%. At 60,000ft, max allowable N1 is 88%. Above those altitudes other limits are more restrictive so maximum N1 figures aren't published, but the N1 achieved will be reducing.

The n1 at 70000 feet would be at or near max n1 and not at sl n1 speed.
The engine will not work at sl n1 at 70000feet. My i suggest you go do basic gas No, no it won't, the flight manual states this clearly. At the maximum cruising levels N1 is at idle RPM, fuel flow and power produced are all at their lowest levels, and the power lever is on or near the idle stop. I don't know how else this can be described as other than at idle power.

Have a look through the manual if you like, here's the link I found to it: https://www.scribd.com/document/119476487/Utility-Flight-Hb-1-Mar-1959 the engine limitations are on around page 244. Takeoff is done at around 94-96% N1, idle N1 is 55-57% N1, which will be close to the N1 achieved at maximum cruising altitudes; all this is in the flight manual which is freely available to read.

[A Squared]

So how do you do it if you dont have a timerite. Btw the timerite is not a prefect method and can give a degree of error.

That's not a Time-Rite. It's a Mag-Rite. Different device. Essentially it's an electronic version of the protractor you put on the spinner. I have one. Procedure is the same as with a mechanical protractor but the electronic protractor is more accurate, easier to read and not subject to friction like the mechanical ones. I would venture to say that this is what he was referring to earlier about the "timing fairy" telling him one of his mags was set at 25 Deg. BTDC.

[Lead Balloon]

Good guess, A2.

Fortunately the timing fairy has a CAR 42ZC(6) maintenance authority. :ok:

Rod: I have no clue what I’m talking about and nobody should take seriously anything I say.

[NFK4X4]

What aircraft operate at sea level?


Hmmm
I flew from Coffs to Syd at FL160 today with my Turbo IO-550 engine at sea level. Yep one of the high compression ones.
Had I ran my engine at 84% ROP I am sure I would be on the evening news.
I will not let an engineer touch my plane unless I am part of the process. Get it..My Plane!
AWOL in the FL's

[Lead Balloon]

You dangerous out-of-control fool.

How could FL160 possibly be sea level for your engine?

Don’t you know your aircraft is the plaything of the regulator and engineers, so that you remain “safe”?

[oggers]

Hi again oggers

When convenient:

You want to run an engine at 74% power. What mixture do you set, by reference to peak EGT?

Real world numbers please.

At what mixture do you maximise the risk of detonation, all other variables like RPM, timing and manifold pressure being equal?

A straight answer please.

You’re the one flying all the precious passengers around each day. You must be setting the mixture somewhere, and doing so to avoid detonation?

I set 100ROP because it gives me best power. Not all our aircraft have EDMs and as commercial operation we have to obey the SOP in the ops manual that is based on a single analogue instrument whose probe is mounted on the collector. Our SOP is min 75ROP. We do not have discretion to operate LOP and we are not equipped to anyway.

The mixture with the smallest detonation margin at any given power setting is peak EGT.

[Lead Balloon]

So for the aircraft that don’t have EDMs, how do you know where on the lean curve each cylinder happens to be when leaning is by reference to a single probe? If we assume that LOP operations are not only “not approved” but “unsafe”, how do you know that each cylinder is peak or rich of peak far enough? Do the laws of physics and safety only apply to the cylinder with the probe?

You say that the mixture with the smallest detonation margins at any given power setting is peak EGT. Are you sure about that?

[rutan around]

Where is Andrewr? He has gone missing since post 95 where I suggested he find out a bit more about how the 520s work so he can understand the problem and why gami injectors are an affordable solution because they don't involve rebuilding the induction system. Perhaps he has been busy with work or just possibly he took me seriously and found there is much to learn from sources other than rev heads in car engine shops.

Post 95 still stands.

Andrew

Quote:
If the injectors don't flow the same amount of fuel then maybe they need to be matched - but by fuel flow, not EGT.


Before I or anyone else take the time and effort to explain the induction and fuel injection system used in IO 520 aircraft engines please let us know whether or not you know roughly how it works. If you do know give us a brief rundown of how the fuel and air end up in the cylinders ready for compression. It is very important you understand this because not understanding makes you say silly things which later will embarrass you.

[andrewr]

https://imgs.xkcd.com/comics/duty_calls.png

I was trying to resist getting sucked back in.

I did read up on the Continental fuel injection but I didn't figure out what you are trying to say. One thing I learnt is that the nozzles seem to be matched to cylinders in the factory (see the proviso in my post you were referring to) which seems to suggest that if the fuel flows or mixtures are uneven it is by design.

Can you be a bit less cryptic?

(Haven't been talking to rev heads in car engine shops.)

[andrewr]

By definition all mixtures rich of stoichiometric are rich and vice versa. So I have no idea what you think you add to this subject by insisting that all mixtures are lean.

Rich and lean are relative concepts, not absolute. You can pick your reference point. It could be:
rich/lean of stoich
rich/lean of best power
rich/lean of peak egt
or simply rich/lean of the intended mixture.

[andrewr]

Setting the mixture to around 25C ROP is the worst setting for a piston aero-engine whatever the power setting. It will produce the highest CHT possible for that power.
Given the choice of a 74% power setting with a CHT of X and a 74% power setting with CHT less than X, I choose the latter.
Detonation is not the only thing that is detrimental to engine longevity. So is heat. The manufacturers say so. :ok:

The logic here doesn't make sense. Sure, keeping temperatures under control is essential for an engine.

However, to avoid engine overheating, should you:
a) adjust the mixture to settings that are not recommended by the manufacturer?
or
b) ensure that you have adequate cooling?

Thanks for finding that Lycoming doc. I was only able to find the quotes from it by John Deakin.

Key phrases in that document:

Lycoming is in complete agreement that it is possible to operate an engine on the lean side of peak

we can attest to the fact that things that work well in the test laboratory have not always proven successful in service

the technique of operating lean of peak and power recovery was discontinued due to the resulting increase in service issues

For optimum service life, Lycoming suggests operating 50 degrees rich of peak EGT or TIT

Lycoming are in the best position to gather data about service issues. That information is direct enough and specific enough that I am prepared to assume they are not lying, and follow their recommendations.

[Connedrod]

That's not a Time-Rite. It's a Mag-Rite. Different device. Essentially it's an electronic version of the protractor you put on the spinner. I have one. Procedure is the same as with a mechanical protractor but the electronic protractor is more accurate, easier to read and not subject to friction like the mechanical ones. I would venture to say that this is what he was referring to earlier about the "timing fairy" telling him one of his mags was set at 25 Deg. BTDC.


Oh sorry my mistake however same still applies. Dont matter if its a digital or a normal protractor unless it set on tdc for intital calibration it will be out.
So leadie please explain how you get tdc.
A timerite is gets tdc but as i said it still has a degree of error.

[Connedrod]

Good guess, A2.

Fortunately the timing fairy has a CAR 42ZC(6) maintenance authority. :ok:

Rod: I have no clue what I’m talking about and nobody should take seriously anything I say.

No clearly you dont know wtf is going on out side your aps course. This is not your fault you had no formal training so why do you continue to promote yourself as some sort of expert.

[Connedrod]

You dangerous out-of-control fool.

How could FL160 possibly be sea level for your engine?

Don’t you know your aircraft is the plaything of the regulator and engineers, so that you remain “safe”?

Yep that sums it up ! Once again its turbo engine !

[Connedrod]

Where is Andrewr? He has gone missing since post 95 where I suggested he find out a bit more about how the 520s work so he can understand the problem and why gami injectors are an affordable solution because they don't involve rebuilding the induction system. Perhaps he has been busy with work or just possibly he took me seriously and found there is much to learn from sources other than rev heads in car engine shops.

Post 95 still stands.


While there is a problem with the inlet maniflolds thats not were the problem starts. The cylinder breathing is a problem foremost of crank angle.
May i sugest that some people that propagate their views dont even understand basic engine construction and operation. The flow of air into a n/a engine is crontroled by many variables starting at crank angle mainifold flows valve angles. By varying the flow of fuel is masking the problem the difference between a gami and normal old is extremely small. But just enough to make a difference.
These engines are low reving high tq engines.

[Sunfish]

Translation of lycoming: "Yes it works in theory and in the laboratory, but its not profitable for us to make it work in the field and anyway, pilots are ham fisted idiots who wouldnt operate it correctly."

[Eddie Dean]

The IO550 referenced above does not "think" it is at seevel. It "knows " exactly where it is. The clue is in the density controller maintaining power output to the sea level power.

[Lead Balloon]

Translation of lycoming: "Yes it works in theory and in the laboratory, but its not profitable for us to make it work in the field and anyway, pilots are ham fisted idiots who wouldnt operate it correctly."Precisely.

[Connedrod]

Translation of lycoming: "Yes it works in theory and in the laboratory, but its not profitable for us to make it work in the field and anyway, pilots are ham fisted idiots who wouldnt operate it correctly."

And what is tbe end result of damage to the engine ?

[Lead Balloon]

Let’s see if I can guess this one.

My guess is that the end result of damage to the engine is: damage to the engine.

I think the strongest argument against LOP operations is that no engine operating ROP has ever failed or suffered damage during those operations.

[Lookleft]

Translation of lycoming: "Yes it works in theory and in the laboratory, but its not profitable for us to make it work in the field and anyway, pilots are ham fisted idiots who wouldnt operate it correctly."

Sorry to burst yours and LB's bubble but all engine and aircraft manufacturers have field service teams that will recommend changes from the theoretical to the actual based on in service results.

[Lead Balloon]

That’s right. No engine operating ROP has ever failed or suffered damage during those operations.

[Eddie Dean]

This conversation is like a 18 year old girl and a sixty year old man having sex. Virgin on the ridiculous.

[A Squared]

Aircraft do not operate at sea level.



There are plenty of airports adjacent the ocean whose runway surface, in the context of engine performance, is not meaningfully higher than sea level.

Would you say that an airplane in the middle of it's take-off run at such an airport is operating or not operating?

That said, do you seriously not realize that sea-level ISA standard day is a common reference for aircraft performance, and more specifically engine power output? Take a look the Type Certificate Data Sheet for almost any piston engine. The Rated power is referenced to sea level.

Besides, what on earth is your point? The point LB was making with his rhetorical question is the same whether he'd used sea level, 1,000 ft, or 10,000 ft.