Engine Checks

[Jabawocky]

The only thing I think that is "all wrong" is your assertion that you alone represent the sole provider of correct information.

What drugs are you on man? I never said I was the font of all knowledge, but I do similarly agree that the texts and flight school training is full of incorrect myths...Old Wives Tails if you will.

The source of the best training package is in Ada OK, USA, some 15-16 hours of B747 direct travel distance away. If you must find the one guy who has done more research than anyone in the modern era, he lives right there! Take your flat earth theories down there and try them out, let us all know how you go. I can't wait.

I think you tried to be a smart a$$ with your previous "waste of bandwidth" comments on "code for not knowing what I was talking about" and when subsequently found short of the mark you have decided to go to ground.

Funny how you claim you can't run carby engines LOP, I say you can, in fact I do and several different types, and when I explain how it is not something I am prepared to do via a pprune post, you acuse me of not knowing what I am talking about.

I asked some serious questions, did I not answer yours? And no I cant give a 2-3 day seminar of pprune, not even the APS guys could pull that off.

Have you ever made the effort to travel to Ada for a training seminar? I believe not but willing to be corrected.

When the student is ready, the teacher appears. Perhaps those who seek the knowledge will gain something anyway.

I am sorry I added anything to this thread, wasted a lot of my time it seems. Strangely enough from the PM's I get wanting one on one tuition and help with concepts of this topic, I usually discover these folk don't post their questions for good reason. Those who want some guidance and pointing in the right direction feel free to PM me at any time

Ciao!

[Pilot DAR]

I do not peak, or lean of peak lean, as both engines prohibit it (same logic as not over speeding or over stressing it).You are kidding me...which engines are these? You do realise the big radials of Connie and DC6 days had a TBO some 4-5 times longer when run LOP FACT not folk lore! LOP has lower stress on EVERY engine,

[Pilot DAR in black, other poster's response in red]

'Not kidding, these are Lycoming engines - just about all of them.

I do not peak or LOP operate Lycoming engines, because I have read Lycoming's Service Instruction No. 1094D, which is applicable to: "All Textron Lycoming Opposed Series Engines" (which I am certain would cover a Piper Navajo Chieftain - Though I have only flown "regular" Navajos). It states on Page 6 of 6: "TEXTRON LYCOMING DOES NOT RECOMMEND OPERATING ON THE LEAN SIDE OF PEAK EGT". So I just operate the engines in accordance with the manufacturer's recommended procedures - it's simple!

I have never operated "big" radials, as I have never encounterd any on aircraft associated with Private Flying. When I operated little radials, I did so in accordance with the deHavilland instructions!

Ohhh, how so? I do want to hear about this? How exactly did you do detonation testing in flight, with which engine and what data collection probes?

I have detonation tested a carburettor modified Continental IO-520D and IO-470F engine. As a result of my detonation (and a lot of other) testing, both these engines were STC approved in C-180 series aircraft to be operated on Mogas. The bulk of my testing was on the ground (where I did purposefully detonate, and observe it), but I did some verification in flight. This modification reduced fuel economy over the injection systems, but the other benefits balanced this out well. Anyone who would like to know how I did it is welcomed to inquire about my DAR (= DER) services for this work.

All certified aircraft have engine operating instructions - just follow them!No, not always and I can show you some that are very poor or bad

Poor or bad? - Well they are FAA approved, perhaps you should apply for an STC to change them if you know better....

Have you ever made the effort to travel to Ada for a training seminar?

No. There a lot of very informative and valuable training courses "out there" and I have taken some. However, those which are associated with a design change, or operating change, which are authoritative, are also likely associated with an STC approval for the associated change (if it's applicable to a certified aircraft).

For those pilots who do not have the time or resources to travel to Oklahoma, just read the instructions which come with your engine and aircraft, and do it that way. Yes, you might waste a bit of gasoline - it's just the cost of flying - live with it! You can do a lot of flying with a waste of $10 an hour in fuel, for the cost of a "15 hour" flight to Oklahoma and several day seminar!

[The500man]

Has anyone completed that APS online course? The overview suggests it will make you comfortable using an engine monitor to diagnose a wide variety of engine problems, but for most GA aircraft that isn't exactly applicable. Would it be a useful course for pilots with more typical instrumentation?

With regards education, the JAA/ EASA CPL/ ATPL syllabus adds very little about engine management over the PPL and next to nothing of practical use. It seems very much like a pilot is expected to only ever operate the engine as detailed by the POH and to not think anything else about it: keeping an engine in good condition is something the engineers do!

It sounds from reading my Lycoming manual like they would rather provide a one-size fits all solution with regards leaning to keep things relatively simple. They don't recommend operating at LOP and they don't recommend leaning above 75% power, although they make some exceptions along the lines of if the POH says so! I can quite believe there are more efficient ways to operate an engine in the various conditions that may be encountered in flight than the fairly hard line of the POH, but for most private pilots in single pilot aircraft, ultra-fine engine management is probably a little too much to ask. It's good to aspire to fly as well as possible though, so for anyone that wants to learn how to improve on the manufacturers operational recommendations it's probably definitely worth spending money on extra education even if you aren't going to recover the cost through fuel savings. There probably should be a disclaimer here about not ignoring your POH because you THINK you know better. Make sure you KNOW what you are ignoring and more importantly why.

Anyway this thread was about engine checks and someone mentionecd a static RPM check.

Lycoming:

If static RPM is below the minimum speci*fied, the engine could be low in power. However, experience has shown that this is not always true. Faulty induction air systems and/or faulty exhaust systems have been shown to contribute to indications of low power. A propeller which is ever so slightly less than perfect may cause the static RPM to be outside the des*ignated full throttle static RPM zone. In addition to these other factors, it is not unusual to find a tachometer which is inaccurate.

Something else: Sticking valves - almost always indicated by rough-running on start up which may then smooth out as the engine warms up. There may also be considerable oil leakage. Can be caused by overheating, frequent long periods of inactivity and oil deposits like lead sludge from incomplete combustion.

Fix/ avoidance: preventative maintenance (oil/ air filter). Operate within specified temperature range and check/ top up oil as required. Lean mixture for more complete combustion.

[24Carrot]

Faulty induction air systems and/or faulty exhaust systems have been shown to contribute to indications of low power

(my bold).

This seems to imply that these are both fixed when the airspeed rises, i.e. that there is no reduction in airborne power, just a reduction during the static test.

Does anybody know how this works?

Surely, truly blocked induction and/or exhaust systems must actually reduce power. Is there no way to tell on the ground whether it is real or apparent?

Genuinely curious - I know zilch about engines apart from my "Aircraft Technical".

[Big Pistons Forever]

Originally Posted by The500man

It sounds from reading my Lycoming manual like they would rather provide a one-size fits all solution with regards leaning to keep things relatively simple. They don't recommend operating at LOP and they don't recommend leaning above 75% power, although they make some exceptions along the lines of if the POH says so! I can quite believe there are more efficient ways to operate an engine in the various conditions that may be encountered in flight than the fairly hard line of the POH, but for most private pilots in single pilot aircraft, ultra-fine engine management is probably a little too much to ask. It's good to aspire to fly as well as possible though, so for anyone that wants to learn how to improve on the manufacturers operational recommendations it's probably definitely worth spending money on extra education even if you aren't going to recover the cost through fuel savings. There probably should be a disclaimer here about not ignoring your POH because you THINK you know better. Make sure you KNOW what you are ignoring and more importantly why.

Anyway this thread was about engine checks and someone mentionecd a static RPM check.

I think there is a subset of pilots who are LOP nerds and I mean that in the nicest possible way. That is they have spent the big bucks to buy and install an engine analyzer and learned how to understand what it is saying so that they can achieve measurably more efficient flying with respect to the only metric that really matters, Miles of flight per Pound of fuel.

However for the average PPL flying a trainer/tourer with a simple carburated engine IMO 80% of the maximum possible fuel efficiency can achieved by simply leaning to engine roughness and then pushing the mixture knob up to smooth operation plus a little bit. But most people just seem to fly around with the mixture full rich all thr time . The engine should be leaned anytime the aircraft is in cruise. I don't think it is well understood that excessively rich mixtures can be just as bad for the engine as too lean a mixture.

With respect to the static RPM check I will abort any takeoff where I do not see the initial RPM within the POH range. Yes it could be a out of tolerance RPM gauge but it could be something more serious and if it is the gauge the unit should be fixed as it will be impossible to accurately set any power.

[Jabawocky]

BPF

The engine should be leaned anytime the aircraft is in cruise. I don't think it is well understood that excessively rich mixtures can be just as bad for the engine as too lean a mixture.

Well said!

The500man

Has anyone completed that APS online course?

Absolutely, and it has been my recommendation they make it a requirement to complete that prior to attending the live course. The online one fills the bucket of knowledge with rocks, the live course ours in a heap more sand, then adds a little water. When the masters course comes out this should almost fill the bucket with water!

I usually find that the only folk who ever knock the course, have never actually attended.

500 man and DAR
Some history and it is brief, so dont go getting carried away due lack of details.
Lycoming and TCM (CMI now) have written many manuals, then the aircraft manufacturers incorporated them and modified them to suit specific agenda's at the time. Why did we get the 75% power performance comparisons? To sell aeroplanes! Magazine test articles. So how do you get the best from your plane at 75% or more power? Run at 75-80 ROP of course.

Engineers say hang on a minute, we don't want that, we want more like 150-00 ROP, but that does not satisfy the economy and speed comparisons. So a tug of war begins.

In the old days, operating on the Lean side of Peak was well known and widely practised. The problem TCM and Lycoming had was their carby engines and later the injected engines were so poor in F/A ratio that running LOP was not easy, nor was the instrumentation good either. In one Lycoming publication they basically said pilots were not smart enough to do it!

So.....Factory can't produce a good reliable LOP performer without rough (scary) running engines, so lets just remove the whole LOP side of the graph...Don't Go There! Next problem is without accurate gauges and pilot training the Rich side of Peak is far more dangerous to engine health if mishandled, so lets go full rich until TOC even though we know its full of deposit causing excess fuel, it is just easier. So hence we got the manuals we did.

Next problem is so many manuals contradict each other. I do not have time nore space in this thread to post them all, but believe me, I have them, and its weird

As for LOP operations, well they are coming around full circle....and DAR's quote about Lycoming does not recommend....... well that just depends on which publication you read.

Poor or bad? - Well they are FAA approved, perhaps you should apply for an STC to change them if you know better....

Poor or bad? On second thoughts BOTH!! Yes they may be FAA approved, but check out the FAA A&P exams And why would I want an STC for a manual?

I am interested in the sensors you used for detonation testing, were they precise pressure sensors with a data capture rate well over 20kHz or even up to 1mHz buried in the heads or were you using a Delta T method on CHT? Accoustics can work of course but in an aero engine not so well. Just curious, as I like to learn anything I can, and this is certainly interesting.

[peterh337]

I think there is a subset of pilots who are LOP nerds and I mean that in the nicest possible way. That is they have spent the big bucks to buy and install an engine analyzer and learned how to understand what it is saying so that they can achieve measurably more efficient flying with respect to the only metric that really matters, Miles of flight per Pound of fuel.

I will let you into a secret

LOP does not give you more MPG

Once you are stochiometric (peak EGT, or close) you are getting all there is to be had out of the fuel.

People who fly LOP and claim great MPG are simply getting more MPG because they are flying slower.

I don't fly LOP.

[Pilot DAR]

And why would I want an STC for a manual?

The "manual" for an aircraft (and there will be several) is an extension of the aircraft's Type Certificate (TC). The TC usually says something like "The aircraft must be operated in accordance with applicable placards and manuals", which removes the pilot's choice about whether to fly it the way the manufacturer specifies. So if you want to operate beyond the TC - by doing something which the manual says don't, you'll need to supplement the TC with that additional information. An STC, which could be nothing more that a supplemental manual.

It's quite common for STC's to be obtained to approve the operation of an aircraft beyond what the manufacturer approved or recommends, yet without mechanically changing the aircraft. Some gross weight increase, or Mogas STC's are two of many examples of doing this, as well as three STC's I hold that cover hundreds of aircraft types. The aircraft you fly probably has many approved supplemental manuals.

and DAR's quote about Lycoming does not recommend....... well that just depends on which publication you read.

From a Lycoming Type Certificate Data Sheet (with my bold)

"Engines of models described herein conforming with this data sheet (which is a part of type certificate No. 1E12) and other approved data on file with the Federal Aviation Administration, meet the minimum standards for use in certificated aircraft in accordance with pertinent aircraft data sheets and applicable portions of the Civil Air Regulations/Federal Aviation Regulations provided they are installed, operated and maintained as prescribed by the approved manufacturer’s manuals and other approved instructions."

Lycoming's Service Instruction 1094D is FAA Approved

[Jabawocky]

Derrrrrr now tell us something we don't know! Just because they are approved does not mean they are not dumb, full of contradictions or errors. Many are, despite their FAA acceptance. Get over it.

I repeat: lycomings and Tcm's publications often contradict each other,and more recently are endorsing LOP ops. Fact. If you are still in the early 90's, time you started researching again.

Now how about the interesting suff I asked about?

Quote:
I think there is a subset of pilots who are LOP nerds and I mean that in the nicest possible way. That is they have spent the big bucks to buy and install an engine analyzer and learned how to understand what it is saying so that they can achieve measurably more efficient flying with respect to the only metric that really matters, Miles of flight per Pound of fuel.
I will let you into a secret*

LOP does not give you more MPG*

Once you are stochiometric (peak EGT, or close) you are getting all there is to be had out of the fuel.

People who fly LOP and claim great MPG are simply getting more MPG because they are flying slower.

I don't fly LOP.

Peter, please show me a reliable data source that backs up that ridiculous statement.

If you want to look at a properly set up engine at say 1000 feet, And it is set up for 80% power with whatever MP & RPM you choose, that engine is say a Lycoming IO540D4A5 all 260 ponies. The airplane speed is say V80 because no matter how you twist it, 80% power will give you a constant result. So if speed is derived by power delivered, and we have the 80% power, what do you think the fuel flow will be for this engine when run properly ROP?*

I have the answers if you are unsure, and I am happy to help, but it is not hard to calculate.

*So then tell me what you think the LOP speed and fuel flow will be?

What do you think the CHT and Internal Cylinder Pressures will be like compared to each other?




Nitery nite

[peterh337]

I don't know who you are, Jabawocky, but I think you have been to too many seminars

I like John Deakin and he has done a huge amount to educate pilots and extract them from the Lyco-Lawyer dogma, but I think they go a little too far in commercialising their courses

To back up my statement (LOP does not produce more MPG than peak EGT) I have done extensive flight tests. I can measure fuel flow to 0.1USG/hr resolution, and similarly for the TAS (using the 3-leg GPS GS method).

There are possible second order savings to be had from burning a very lean mixture if running at a low RPM, say 2200, which given the fixed ignition timing we have can produce a better result. I have used this on long trips (example) where one is able to fly at low level (say FL100) where the engine is happy at such a low RPM. But the improvement is really very small and I don't bother anymore. Anyway I often have to go to FL140+ to stay above wx and one cannot fly below ~2400 up there anyway (no turbo).

[Tinstaafl]

The manual for the 1980 PA31-325 I fly approves LOP. It even details how to do it. Didn't do it with the stock single point EGT & CHT gauges except once to show the owner and recommend have an EDM fitted. Now I nearly always fly LOP with much cooler CHTs than ROP.

[Jabawocky]

Peter,

I don't know who you are, Jabawocky, but I think you have been to too many seminars

hehehheheh

It matters not who I am, it is data backed facts that matter. Play the ball and not the man they say!

Too many seminars Perhaps, but I think like always, you and many others have been to too few!

Answer my question please.

I measure my fuel flow down to 0.026GPH, that is irrelevant. The tradeoff for fuel flow Vs Lost Speed is not niminal and hardly worth the effort.

For example at high altitudes as you do, if I go from 37.0 to 40.5 LPH do I go 10% faster? No. I am lucky to see 4%. This is around peak or just ROP, been so long I dont recall the exact numbers. If I go to a high altitude ROP setting burning say 40% more fuel, I am lucky to go 10% faster.

If you do not find similar things, you must be doing it wrong! It just does not make sense.

Now back to my question please, and these numbers I do remember because I took photos.

[Jabawocky]

Back to engine monitors and education for a minute.

Private pilot in his ....say C421, boring along fat dumb and happy. He or she notices the MP on one engine dropped a bit, inch or so.

What should he/she do and when and why?

This is all the info you need. Simple one. By the way even without an EMS, this question applies.

[Pilot DAR]

Just because they are approved does not mean they are not dumb, full of contradictions or errors.

... perhaps a broader applicability that just aircraft publications....

No one is perfect.....

We who write and approve these documents do so in an industry agreed format, and with appropriate quality and conformity checks along the way. It is with the intent of providing properly trained pilots and maintainers the information they need to assure that they can operate and maintain the aircraft safely, and the way it was approved.

If pilots or maintainers do things a different way, it's theirs to justify to whomever should inquire.... I'm not inquiring - I'm not in enforcement or warranty!

[Jabawocky]

DAR,
agreed

So I gather you also concede thet they are often poor or bad in terms of scientific facts, data and recomended practises then?

So how about a crack at either of my questions? You blokes (blokettes) don't play fair!

[Pilot DAR]

So I gather you also concede thet they are often poor or bad in terms of scientific facts, data and recomended practises then?

Unfortunately I cannot concede to such a broad statement. I have found and reported a few errors in approved documents over the years.

Otherwise, the documents are the intellectual property of the Type Certificate/STC holder. They are required to be compliant with the design requirements, not perfect in the estimation of people at large. Indeed, and I certainly have done it, they may be written to be conservative and to provide the required margins of safety and durability. There's often more than the obvious that determines the wording. Let me give you a non engine example:

The Cessna Grand Caravan flight manual states the "normal climbout speed of 85-95 KIAS". You might say: "I can get airborne, and climbout, at a slower speed than that - the plane will do it!". Indeed it will, and I had to demonstrate this at 80 KIAS, instead of 85. It sounds trivial, and the plane handled it fine. However, when the authority then required that I demonstrate a "Vref-5", which meant flying the departure and approach at 75 KIAS, it was un-nerving. Then I was required to demonstrate a land back from an engine failure at 50 feet at the slower speed. That was downright scary (much worse that the 14 spins I'd had to demonstrate in it!).

The book does not say 85 KIAS 'cause that's the best the plane can do, Cessna has built in the Vref -5, and the land back ability margins to the "average" pilot skill, into the speeds. You will never know those margins were there, unless you suddenly find yourself in that situation, and you manage to get yourself out. You'll think it was your surerior skill, but in part it was built in margins of safety.

Eager aftermarket salesmen love to show you what the airplane/engine will really do, and often it will - but with greatly reduced margins. That means super pilot skill may be/is required to compensate. Aircraft are approved to "average" pilot skill, not super skill. If these eager salesmen went to certify (STC) these techniques, they might find that the required margins of safety or durability could not be demonstrated, and for that reason, certification is not available. There's a message there for users - why is it not STC'd?

[FullWings]

[Pace]

Going back to the original question I think we instinctively know when something is not quite right in an aircraft we know well!
It is about decision making and part of that decision maybe to do nothing but concentrate on flying the aircraft to a forced landing and not be pulling this or that while loosing the plot on what you should be doing.
If you know the aircraft so badly that you need a fly by numbers instruction sheet then you have to question the pilot not the problem!
I fly jets! We have memory items and we have an emergency checklist.
Any emergency item and its straight to the emergency checklist for that fault!
The main thing is to fly the aircraft! If the engine stops at 1000 feet chances are you will threaten your chances of a successful forced landing by opening checklists and wading through restart items when you should be concentrating on selecting a suitable landing site and flying the aircraft down to a successful landing.
Ok in the cruise and one engine runs rough or there is a vibration and you have plenty of time to experiment, check everything is where it should be and make decisions on whether to divert while keeping the engine going.
As in the jets there could be an argument for having an emergency checklist which is quickly and easely available for different scenarios.
I stress the word quick and easily available as priority is always flying the aircraft not being distracted by wading through books!

Pace

[The500man]

Pace, absolutely a pilot should fly the airplane first, but keeping the engine running or knowing when something is wrong and what that might be shouldn't be excluded altogether if there is time to do something about it. I agree any emergency checklist should be a memory one where possible, but for a rough running engine or if you notice some strange vibration or a power loss, a simple checklist could prove useful.

Pilot DAR, that's a good example. I don't think it's uncommon for pilots familiar with a particular aircraft to start flying it in their own way because they feel they know better than the flight manual. In some ways they may be right, but you can guarantee there is some knock on effect that they would never have even considered. It does make me wonder why all of the applied safety margins aren't detailed in the flight manual though?

[Jabawocky]

DAR, indeed. And that discussion is worthy of a thread of its own.

What concerns me here is, you are reluctant to accept my statement based on multiple manuals from various manufacturers, that are literally three feet away from me and I assure you they are contradicting each other, and known science. Science that pre dates the manuals themselves. Yet you speak and expect the punters here to believe your authorities words.

This has very little to do with the comparison you have just tried to make. Aerodynamic performance is a fairly steady state of knowledge, as best I know the manuals are accurate and the data as you explained is achieved through certification testing. A C208 pretty much behaves the same as all it's brothers assuming no serious mods are done to airframe.

The same cannot be said of engines. The manufacturers manuals vary, and vary a lot, and in some cases are so bad, it makes you wonder how they got published.