Engine Checks [Archive] - PPRuNe Forums

Big Pistons Forever

6th Aug 2012, 01:49

Before answering 500 mans question I think I need to put a bit of context to my answer. What I am talking about is what I teach for the PPL student or low time PPL pilot. Since this group by definition does not have the benefit of a lot of experience a framework of procedures IMO is of significant practical value in helping them deal with abnormal situations.

So first we have to talk about the most likely scenario that a PPL will experience. It is not a sudden total engine failure with no warning, it will most likely be engine roughness and/or a reduction in engine power. The engine will still be running and producing enough power for the aircraft to maintain altitude, but the pilot feels that there is something definitely wrong.

The school I teach part time at flies C 172P's and for this scenario I expect them to go to the emergency checklist where I have added a checklist for engine roughness/Reduction in engine power. I want the student to methodically work through the checklist so that they don't forget anything.

It goes like this

Engine Roughness/Reduction in Engine Power

-Carb heat.........................................Full On for at least 30 sec
-Primer..............................................Full in and locked
-Engine gauges...................................Check
Note 1: if severe carb ice exists engine will initially run very rough until ice has cleared)

Note 2: If high oil temperature or low oil pressure is noted go to that checklist

If problem persists

-Carb heat........................................Cold
-Mixture ...........................................Full rich then lean to max RPM

If problem persists

- Mags............................................Select right and left mag individually
(Note if engine roughness is more pronounced on one mag select the other mag or both, whichever gives smoothest operation)

----------------Land at nearest suitable airport------------------------

If problem persists

- Fuel selector.................................Left for 2 mins

If problem persists............................Right for 2 mins

---------------Land at nearest suitable airport-------------------------

In addition to to this I have emphasized the importance monitoring the engine instruments in flight. Instructors now periodically and without warning cover the oil temp/press gauges and make sure the students know where the needle is actually pointing. (In the green is not a good enough answer ).

With respect to abnormal oil press/temp indications, these can indicate an developing mechanical internal engine failure potentially resulting in a total engine failure. This is the least likely cause of an engine failure but they do happen. The good news is there will almost always be some warning. Any internal misalignment or failure will almost always result in metal rubbing. This will cause a rapid rise in oil temperature with the oil temp gauge pegging at its maximum value. A dramatic drop in oil pressure will quickly follow. Any engine showing these signs should be presumed to be in danger of imminent total failure and appropriate actions to land ASAP should be taken. The only caveat is an open circuit in the oil temp wiring will cause the oil temp needle to peg at the highest temp. However in this case the oil pressure will be normal so it is likely just the gauge. However a landing at the nearest suitable airport would be prudent.

The next level of checks (Again for a C 172P) is a memory "cause check" intended to restore power when the engine fails or is producing so little power that the aircraft will not maintain altitude and with the aircraft more than 1000 feet AGL. If the aircraft is below 1000 feet then no cause check is done and the pilot concentrates on flying the aircraft to a survivable touch down point.

After establishing the gliding attitude and pointing the aircraft at the nearest survivable forced landing area.

Carb heat.......Full on
fuel ..............Both tanks
Mixture .........Full Rich
Mags.............Both/left/right/both

This check can be done in about 5 seconds if practiced. By that I mean every couple of flights you make a point of going through the sequence touching each control to build muscle memory.

If the reason the engine failed was caused by a mistake you made ( eg missing a build up of carb ice, running a tank dry, forgetting to enrichen the mixture and then adding a bunch of throttle) then these simple actions will restore power and instead of potentially wrecking a perfectly serviceable airplane after you smashed it into a field when the engine stopped, you will restore power, and fly away vowing never to do that again. :O

Don't forget that the accident statistic show that up to 80 % of the engine failures are caused by the actions or in actions of the pilot. The Cause check won't save you if you have run out of gas but it will save you from some other mistakes that are not all that hard to make.

Finally I also discuss the high altitude engine failure. This is one where you are cruising along more then 5000 feet above ground and you suffer a failure or gross loss of engine power. After doing the cause check and all the other appropriate actions preparing for the forced landing, assuming you are well placed for the field it may be possible to do some more advanced troubleshooting. A variety of carburetor/fuel injection failures can result in the engine only running at certain throttle or mixture settings. So consider going to mid range throttle setting and starting from full rich and then slowly leaning towards ICO. If that doesn't work go back to full rich and starting from full throttle slowly retard the throttle. Is that doesn't work try giving the engine a shot of prime. If the engine starts and then dies you can get some power back by setting a low throttle setting and continually pumping the primer. The little bit of power you can get may provide a useful stretch to the glide. However I must emphasize that these techniques must not get in the way of flying the aircraft and should be instantly abandoned if you start feeling pressured by trying to trouble shoot and manage the forced approach.

Finally I have presented the checks meant for a C 172P. They apply to most light GA aircraft except for C 172R or S models or other aircraft with fuel injected engines so for these aircraft where the check says carb heat insert "alternate air" and for low wing aircraft like Pipers and Grummans where the check says fuel to both, insert fuel.... change tank and boost pump on.

So 500 man, I Hope that answers your question.

The500man

7th Aug 2012, 12:47

Thanks for all the contributions!

'Balls to the wall, crossfeed on, boost pumps on'

That's an easy one to remember! I like it.

Switching tanks can be tricky, because there will be a delay before the engine restarts, which has caused some people to switch back to the original (empty) tank, after which the bit of fuel from the non-empty tank comes through, "confirming" your belief that you are on the right tank now

Good point. Waiting 2 mins on a tank would probably feel like forever so I can quite believe some pilots might not stick to that. It also makes me wonder about flight attitude. If you have unusable fuel presumably there are attitudes where you can still pick up the last bit of usable fuel?

So 500 man, I Hope that answers your question.

Thanks for that BPF.

Looking at potential engine related problems, I've scraped together the following list which are all problems listed in various POHs and the Lycoming engine operations manual. These are all things which a pilot can get some indication of in flight and possibly do something about. It's not a complete list by any means so feel free to add to it, but if we are thinking about a check list for engine related issues we should consider what problems can occur and what indications there may be. The fixes are only suggestions so don't take them as absolute gospel!

Idle roughness - Sometimes accompanied by a loss of power which can lead to stoppage in slow flight. Caused by an excessively rich idle fuel flow.

Fix - Leaning the mixture may improve roughness or be required to restart.

Engine driven fuel pump failure - Sudden reduction in fuel flow immediately followed by a total loss of power.

Fix - Switch on the boost pump.

Insufficient fuel - Oops!

Fix - Change tanks if you can!

Excessive fuel vapour - On injected engines may cause fuel flow variations and power surges which may lead to power loss. More likely to occur while taxiing.

Fix - Boost pump on, adjust mixture for smooth operation and if the problem continues try changing tanks.

Contamination - Most likely water which may cause fluctuating RPM, power loss or even stoppage. Other than noticing it I don't think there is much that can be done about it in flight.

Fix - Better preflight?

Lycoming:
Experience indicates that draining should be accomplished before refuelling, because fuel servicing mixes the water and fuel, and the water may not have settled to the bottom of the tank until the airplane is airborne.

Spark plug fouling - Caused by carbon or lead deposits forming mainly due to excessively rich mixtures. Identified by an obvious power loss running on an individual magneto.

Fix - Appropriate leaning should resolve this in flight.

Magneto malfunction - Sudden engine roughness or misfiring.

Fix - Select each magneto individually to identify the culprit and select the good magneto only. Different power or mixture settings may enable continued operation on both magnetos.

Intake ice/ carburettor ice - impact or refrigeration ice leading to rough running, power loss or stoppage.

Fix - With an injected engine use alternate air to bypass the blockage and carburettor heat on a carburetted engine (30s - 2min).

Q. If you had intake icing and had switched to alternate air, at what point would you consider switching back? Or would you at all?

Broken or deformed baffles/ seals/ cowl flaps - Reduction in cooling air around the engine. Higher than normal CHT or oil temperature. Possibly leading to pre-ignition (over heating spark plug barrels).

Fix - Reduce temperature by either en-richening the mixture, reducing power, or opening cowl flaps, or a combination of all three.

Oil loss - High oil temperature accompanied by low pressure likely means a failure is imminent. Likewise high oil pressure caused by a blocked breather tube may lead to a crankshaft nose seal rupturing and a spectacular loss of oil.

Fix - None

Interesting side note about preventing freezing in breather tubes which extend into the airflow (from Lycoming):
It is normal practice for the airframe manufacturer to provide some means of preventing freeze-up of the crankcase breather tube. The breather tube may be insulated, it may be designed so the end is located in a hot area, it may be equipped with an electric heater, or it may incorporate a hole, notch or slot which is often called a “whistle slot.”

Detonation - May be caused by leaning at high power settings and is unlikely to be noticeable unless severe.

Pre-ignition - Usually indicated by roughness, backfiring and a sudden increase in CHT.

Fix - (from Lycoming Engine Operations Manual)
The best temporary in-flight methods for correcting preignition and detonation are to reduce the cylinder temperature by retarding the throttle, enriching the mixture, opening cowl flaps if avail*able, or a combination of all of these.

That's all I've got time for, but one last note of interest from Lycoming:
Interpreting Your Engine Instruments

The present-day piston engine instruments used in the typical general aviation airplane are not precision laboratory instru*ments. We exclude the turbine and jet-powered aircraft from this discussion and will consider only piston engines, recognizing that the more expensive pressurized twin-engine models may also be exceptions. If one was to observe an irregular reading of one engine instrument, it calls for a cross-check on all other instruments, and not relying on one instrument as a basis for a decision affecting flight.

englishal

7th Aug 2012, 13:49

One other note...An engine monitor, like the EDM830 we have fitted is also very valuable. If the Oil P went zero yet the EDM showed normal, then I'd consider it an indication problem.

Likewise if (for example) one cylinder starts to get hot or oil temp exceeds the pre-defined red-line limits we entered (or any other paramater being monitored exceeds a max or min limit) then we have a big red light which starts flashing on the panel. We can then cross check the EDM with primary instruments and if both agree then it is very quick to realise that there is an actual problem rather than a gauge problem. I highly recommend a decent engine monitor.

(plus you can download the data after a flight and keep a historical trend of each parameter. Useful for examining you engine's health over time).

Big Pistons Forever

7th Aug 2012, 14:52

500 Man

To your list you can add

Abnormally high Oil Temperature/Cylinder Head Temperature: If the temperature is high but stable, open cowl flaps (if fitted), mixture full rich, increase airspeed (if climbing). If the oil temperature is steadily increasing and past the redline with a major drop in oil pressure then as I mentioned above you should consider the engine likely to fail and land ASAP.

The500man

8th Aug 2012, 11:23

I suppose that also highlights the use of maximum continuous power rather than full power in high speed cruise or extended climbs.

I discovered that an aircraft with an injected engine may not actually require the manual selection of alternate air when intake icing occurs as this can be automatic. Varying amounts of alternate air can be automatically selected depending on the severity of the blockage.

We can then cross check the EDM with primary instruments and if both agree then it is very quick to realise that there is an actual problem rather than a gauge problem.

Sounds like a useful bit of kit but presumably it must have duplicate probes to do this?

englishal

8th Aug 2012, 11:48

Yea, you fill up the CHT holes in the heads with probes, you put EGT probes in each cylinder exhaust, new oil pressure and temp sensors (Lycomings have space for second oil temp sensor), RPM sensor, Manifold Pressure sensor, Carb temp probe, TIT probe, fuel flow sensor and OAT probe.

goldeneaglepilot

8th Aug 2012, 12:35

With all those extra goodies, when does it get to be too heavy to take off? Does anyone run courses into how to understand the data stream being thrown back!!!

Easy answer to all the problems - PT6, Difficult to fit on the Kit Fox though.

Joking aside - keep it simple will get you out of most problems

Big Pistons Forever

8th Aug 2012, 14:39

keep it simple will get you out of most problems

Not a particularly useful statement.

So Joe/Jane PPL is flying along and the engine starts to run rough, what would you expect him/her to do under the guise of "keeping it simple" ?

Jabawocky

12th Aug 2012, 11:22

The solution to most of this is good education (lacking at ALL flight schools) and good instrumentation.

With good education and practises, you are less likely to suffer serious problems, as they usually start as minor ones. These you fix long before they are major.

Detonation - May be caused by leaning at high power settings and is unlikely to be noticeable unless severe.

Pre-ignition - Usually indicated by roughness, backfiring and a sudden increase in CHT.

Detonation is hard to create in a normal environment with a conforming engine on conforming fuel. However, short of having an all cylinder EMS and alarms set wisely you will never detect it in mild to medium to severe forms.

Pre-ignition is not likely to show you any signs either, until it is all too late, and this may be as soon as a few minutes from when it started. In a car perhaps, but not in a plane. Unless you see a CHT rising at a rapid rate, you will not know. Without an EMS and wisely set alarms, you will not know. You will not hear any backfiring! Folk who have had preignition failures and had engine monitors to capture the data, did not know anything apart from a weird CHT reading.

So in short, the engine monitor AND education in what it is really telling you (not from the local aero club or flight school who know nothing) are the best things you can invest your money in.

There are several good EMS products around to suit either certified or experimental aircraft and the only good source of education on the planet that I know of is at Advanced Pilot (http://www.advancedpilot.com)

Anyone who argues otherwise, is simply wrong, they are entitled to be wrong, but just don't follow their blind ignorance, your family will appreciate your vigilance.

peterh337

12th Aug 2012, 16:58

Time for another LOP thread? :E

Big Pistons Forever

12th Aug 2012, 18:53

jabowocky

Your absolute statement that "everyone else is wrong" is correct for the 2 % of the GA fleet where the aircraft is fully instrumented and you always fly the same aircraft. The second point is important because all engines run a bit differently and the true value of engine organizers is seeing the subtle deviations from normal that are indicators of a potential problem that you will only get to know from hours and hours of watching that engine.

For the other 98 % of the GA community and other than Peter 337, what I am guessing is everybody else reading this thread, your advice is completely and utterly useless.

The vast majority of GA pilots will be flying aircraft with only the basic engine gauges of RPM, oil pressure, oil temperature and ammeter. "Advanced" engine instruments likely not found in most aircraft, will only consist of a basically useless single probe EGT, and or CHT and maybe a carb temp gauge.

Therefore IMHO the knowledge delta isn't about a pilots not knowing how to run LOP, it is how to properly lean a carburated engine with no good EGT information.

Similarly the lack of knowledge and skill for recognizing and dealing with carb ice at the PPL level is truly frightening.

Finally while crude and insensitive the oil press and oil temp gauge will usually give you warning of an impending internal engine mechanical failure if you pay attention to what they are saying.

One pet peeve of mine is how few instructor insist on checking that the engine is making full static RPM at the beginning of the takeoff run.

A while ago I was asked to help out at a flying school. On the first lesson, flying a C 150, I thought the engine was a bit rough on runup. Sure enough on the takeoff as soon as the student had applied full throttle I checked the RPM and it was 150 RPM below the POH minimum static RPM range. We rejected the takeoff and maintenance confirmed a dead cylinder and metal in the filter which resulted in an engine change. The sad part of this story was that when the news of the engine condition became known the dispatcher said " You know the instructors have been complaining for 2 weeks that that airplane was a dog " :ugh:

Ok you and Peter can now get on with obsessing about LOP operation in privately owned high performance aircraft ;)

And goldeneagle pilot still waiting for your thoughts on "keeping it simple" :confused:

Jabawocky

12th Aug 2012, 23:50

BPF

Forgive me if I have this wrong, but this forum section is private flying, not ab-initio training, and I would think even there a greater need for education exists. So I do not subscribe to your 2% theory. We should not be catering for the lowest common denominator, we should be trying to raise the bar. Always!

As you say, all engines run a bit different, but you know, the subtle differences are not that significant. I can get out of one and into another and if something is amiss it is not found by absolute numbers (except where is rather obvious) it is from trends. Believe me, if you have a preignition event, it will not be hidden in the subtle differences you mention.

For the other 98% of people, I think the rest of my post is even more relevant as it requires even greater understanding to operate with a high degree of efficiency sans the instruments. Sure you can run around full rich all day long, but for the most part people use aeroplanes to go places, not just do circuits. Well at least here they do anyway! :O

will only consist of a basically useless single probe EGT, and or CHT and maybe a carb temp gauge.
Indeed! :ok: However with some really good knowledge, you can get by with this operationally, running LOP even, however it is sub optimal in fault diagnosis. In fact the carby temp sensor is a very useful tool for running a Carby engine LOP ;)

As this thread is about engine checks, having an EMS really helps in knowing things are right or wrong Vs only thinking they are right or wrong. The point here being, if the readers of this thread have any influence at all on the machine they operate, they should be thinking harder about this. For example, you have a slightly rough engine doing a runup/mag check, done LOP or at peak you can detect the fault and most likely diagnose exactly what it is. Done ROP and no instruments, you might not even detect the problem that is developing over time. This in itself can save thousands of dollars in mechanics bills. Being able to taxi to the workshop and say, No5 cylinder bottom plug needs replacing sure beats the hours and hours of hit and miss diagnosis and maintenance.

Not having this stuff and dismissing its promotion to those who do not is kind of like saying, hey, back 40 years ago we did not have seat belts, ABS, radial tyres, disc brakes, coil springs and airbags. So why buy that BMW, or better still buy it but rip out all that complicated and heavy stuff. Those who still drive around in less capable cars today do so with greater safety than years ago, why? Because they do not know how many accidents they have avoided because everyone else is driving better equipment and not hitting them. Same goes for aviation technology.

Therefore IMHO the knowledge delta isn't about a pilots not knowing how to run LOP, it is how to properly lean a carburated engine with no good EGT information.

Indeed, however I wonder how many can actually do this, and to do it really well you do need another instrument not even mentioned thus far. But I digress.

A while ago I was asked to help out at a flying school. On the first lesson, flying a C 150, I thought the engine was a bit rough on runup. Sure enough on the takeoff as soon as the student had applied full throttle I checked the RPM and it was 150 RPM below the POH minimum static RPM range. We rejected the takeoff and maintenance confirmed a dead cylinder and metal in the filter which resulted in an engine change. The sad part of this story was that when the news of the engine condition became known the dispatcher said " You know the instructors have been complaining for 2 weeks that that airplane was a dog "

Education in flying schools, dummed down, full of Old Wives Tales, resistant to change to data based facts, and taught by 200 hour pilots who know nothing about flying more than to pass an exam, which are often full of the above problems as well. :rolleyes: So am I surprised at your story.....not one bit!

Jabawocky

12th Aug 2012, 23:52

Time for another LOP thread?

Peter, start one if you want, but make sure it is full of really good questions and not some bunch of bozo's sprouting all the same crap I hear from usually old and respected but not very wise men. ;)

Big Pistons Forever

13th Aug 2012, 00:16

Jabawocky

I guess we will have to agree to disagree on your theme as the proportion of the GA fleet equipped with a full boat engine analyzer, at least in Canada, is so small that operating techniques based on its use are like the SOP's for flying a jet, interesting but ultimately irrelevant to the average private aircraft pilot; like the person who started this thread.

Indeed! :ok: However with some really good knowledge, you can get by with this operationally, running LOP even, however it is sub optimal in fault diagnosis. In fact the carby temp sensor is a very useful tool for running a Carby engine LOP ;)

I do have a question about the above comment. Personally I have operated the following GA carburated engines:

Continental, C65/C85, O200, O300, O470, O520,

Lycoming O235, O 320, O360, O435, O540, and

165 hp Franklin

I have never been able to lean any of these engines to true LOP because they all will start to run rough due to the inherent poor mixture distribution. SO I am quite interested in what engine(s) you are talking about and what technique you use to achieve smooth operation at LOP.

Rod1

13th Aug 2012, 02:57

Why do people think the probes etc are too heavy? A Rotax 912 comes with most of the probes as standard and adding coolant temp and EGT’s adds very little weight. Most of the Rotax powered machines I know are very well monitored with 2 X EGT, 2 X CGT, Oil Temp, Oil Pressure, Water temp, volts, and in some cases fuel flow. It is the old stuff which is reliant on out of date tec. It is true that most instructors find all this info confusing but adequate engine monitoring is a huge help in preventing a small issue growing into a failure.

Rod1

Pilot DAR

13th Aug 2012, 03:19

Anyone who argues otherwise, is simply wrong, they are entitled to be wrong, but just don't follow their blind ignorance, your family will appreciate your vigilance.

Huh?

I argue otherwise. Engine monitoring systems are a nice to have, and very handy for diagnosing some engine problems in very rare occasions. Diagnosing engine problems is great, if you get it early, and if you're in time to fix early. For that, I support their use - if the pilot knows what they are looking at. But if that problem has already shown symptoms in flight, you're also having to deal with it and fly the plane, perhaps as an inflight emergency. I have certainly flown with pilots of abnormally well instrumented aircraft, who were paying so much attention to the indications, that they forgot to fly the plane - and what they were seeing was really of little benefit to them anyway by that point.

All certified aircraft have engine operating instructions - just follow them! Keep the engine properly maintained, and serviced with the proper liquids, operate it as instructed by the manual, and it will run. The few pennys you might save by extreme leaning and other tactics are lost on a carburetted engine, because as Big Pistons correctly points out, no carburetted engine has fuel flow even enough to each cylinder to run "properly" leaned - that's just the way it is, and you the pilot cannot change that, so just pay for the fuel, and fly the plane. The only way a scanner can help with leaning is to assure that you are leaning to the leanest cylinder when reading the indication, and allowing you to find a power setting which has a more equal fuel distribution than other power settings, so your leaning is more meaningful. In reality, however, the generic "lean 'till first rough, then enrichen to smooth again" instruction works about as well as watching a scanner for 10 minutes while fooling with the mixture.

I have installed scanners for certification flight testing, where data collection well beyond the scope of any GA pilot was required. Two were for detonation testing - that's a whole other discussion, other than to say that if you operate as instructed, you will not detonate the engine. Incorrect leaning of an otherwise properly operated engine can cause damage, but not because detonation is a factor in that damage.

Both my planes do have multi cylinder scanners (left over from testing), and both are carburetted. All the scanners tell me is that I don't really need them 99.95% of the time! I do not peak, or lean of peak lean, as both engines prohibit it (same logic as not over speeding or over stressing it). Their only real benefit is that you can log a changing trend - if you notice in time, and you can identify which cylinder is sticking an exhaust valve or fouling a plug, in real time, and that's informative on the very rare occasion it happens. Though if you stick a valve, and have only that cylinder repaired, you're fooling yourself (and your family may thing you not vigilant!). Other than that, the operating instructions for the engine describe what you need to know to operate it the way it was approved. What else were you thinking to do?

My guidance is not blind in saying the forgoing, as I am delegated to certify the designs of these engines, including detonation testing. I write operating and maintenance manual supplements. The first thing we look for are safe operating margins, and instructions, which if followed, keep the engine well within those margins. People choose a certified aircraft [and engine] for the security of knowing it has been thoroughly tested. It has, so operate it the way is supposed to be. I am unaware that any aircraft has been certified as requiring an engine scanner as a part of it's type design - because they are not really needed!

If someone wants to install one, by all means. Don't let it distract you from the safe operation of the aircraft. Use it to follow (not circumvent) the engine manufacturer's operating instructions. And learn to use it properly. Most flying schools probably struggle to employ instructors who are conversant with the different scanner types, their relevance, and their correct operation. And students hardly want to spend an extra 5 hours of flight training costs to learn what it is telling them, and the relevance.

My family appreciates that I keep myself current and recent, and that I operate the aircraft legally, safely, and in accordance with it's instructions. More than that, they do not ask of me....

Jabawocky

13th Aug 2012, 03:21

I do have a question about the above comment. Personally I have operated the following GA carburated engines:

Continental, C65/C85, O200, O300, O470, O520,

Lycoming O235, O 320, O360, O435, O540, and

165 hp Franklin

I have never been able to lean any of these engines to true LOP because they all will start to run rough due to the inherent poor mixture distribution. SO I am quite interested in what engine(s) you are talking about and what technique you use to achieve smooth operation at LOP.

:)

In my experience, some of those but not all. All the lycomings, the bigger CMI's and no idea on a franklin or a piper cub, but there is a half chance they will too.

Of course you would need to have some instrumentation and education to do it. Refer to my first post.

And I should say, Radials are better, and you must have a well maintained "conforming" engine. Otherwise you are chasing your tail, but it soon helps fix induction leaks and plug/ignition deficiencies when you do try!

I hope you are not thinking of leaving the dark side now are you? ;) :}

PS: this stuff is not something that can be taught on a internet forum so I am not about to try here. As Walter Atkinson will tell you, we can't just give you a cook book with a recipe, you need to learn to cook before you become a master chef!

Big Pistons Forever

13th Aug 2012, 03:40

:)

In my experience, some of those but not all. All the lycomings, the bigger CMI's and no idea on a franklin or a piper cub, but there is a half chance they will too.

PS: this stuff is not something that can be taught on a internet forum so I am not about to try here.

Can't be taught on an internet forum eh :hmm:

That must be the new internet code for "I don't really know what I am talking about" :rolleyes:

Jabawocky

13th Aug 2012, 04:13

I am not going to debate point by point here, if I did I would spend hours and hours and still not get the message across. So here is something to prompt your interest further, or just ignore it. But do not take all the others down with you when I say they should be educating themselves further. That is like telling your kids, don't worry about high school, all you ever need you get in Primary school.

It is funny that the ones who always argue against this stuff are always those who do not have it. Both instruments and education. It never ceases to amaze me how many people do not know what they do not know. (myself included)

I argue otherwise. Engine monitoring systems are a nice to have, and very handy for diagnosing some engine problems in very rare occasions. Most problems most of the timeDiagnosing engine problems is great, if you get it early, and if you're in time to fix early.Yep, and you get a chance at early rather than at the worst possible time without For that, I support their use - if the pilot knows what they are looking at.Ahh yes we do agree, time for an APS class for all of them! But if that problem has already shown symptoms in flight, you're also having to deal with it and fly the plane, perhaps as an inflight emergency.And knowing exactly what the likely problem is will help you make the right call I have certainly flown with pilots of abnormally well instrumented aircraft, who were paying so much attention to the indications, that they forgot to fly the plane - and what they were seeing was really of little benefit to them anyway by that point. Because they believe the instrument will do it all for them, they need EDUCATION. The rest of your observation is 100% correct

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 Keep the engine properly maintained,YEP and serviced with the proper liquids,YEP operate it as instructed by the manual, and it will run.And some will run a lot longer if you do not follow that manual, the secret is knowing which is full of BS The few pennys you might save by extreme leaningExtreme?? engines stop and other tactics are lost on a carburetted engine, because as Big Pistons correctly points out,Incorrectly points out no carburetted engine has fuel flow even enough to each cylinder to run "properly" leaned - that's just the way it is,Not True and you the pilot cannot change that Yes you can, some more so than others, so just pay for the fuel, and fly the plane. The only way a scannera what? can help with leaning is to assure that you are leaning to the leanest cylinder when reading the indication bad advice, and allowing you to find a power setting which has a more equal fuel distribution than other power settings,you are now going from stone cold to luke warm... so your leaning is more meaningful. In reality, however, the generic "lean 'till first rough, then enrichen to smooth again" instruction works about as well as watching a scanner for 10 minutes while fooling with the mixture. It might in some but how would you know? And 10 minutes....geez you just proved my point. If it takes that long to lean an engine how long does it take for a pre-flight? You can do two complete GAMI Lean tets for injector tuning in that time. I lean and set up in under a minute, maybe 30 seconds at any level from 1000' up into the FL's

I have installed scanners for certification flight testing, where data collection well beyond the scope of any GA pilot was required. Two were for detonation testing - that's a whole other discussion, other than to say that if you operate as instructed, you will not detonate the engine. Never read a Piper Chieftan manual then huh? Incorrect leaning of an otherwise properly operated engine can cause damage, but not because detonation is a factor in that damage. 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 am genuinely interested. Incorrect leaning does cause longevity issues over a long period of time, not just in a 2 minute abuse period. Temperature and cylinder pressures are the things. And these are a result of incorrect leaning. The truth is if you are on the Lean side of Peak EGT you are less likely to do damage by getting wrong, than you are on the Rich side. So the point here is if you operate ROP which is a perfectly valid method for some ops, make sure you do it right. On the lean side there is far more margin for error, except at very high powers such as 1000' WOT and full bore RPM. If you are smart with numbers you can still do this just with fuel flow alone on a conforming engine.

Both my planes do have multi cylinder scanners (left over from testing), and both are carburetted. All the scanners tell me is that I don't really need them 99.95% of the time! 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, where do all the you beaut modern diesels run? ;) Their only real benefit is that you can log a changing trend - if you notice in time, and you can identify which cylinder is sticking an exhaust valve or fouling a plug, in real time, and that's informative on the very rare occasion it happens. Though if you stick a valve, and have only that cylinder repaired, you're fooling yourself Not true at all(and your family may thing you not vigilant!). Other than that, the operating instructions for the engine describe what you need to know to operate it the way it was approved. What else were you thinking to do?

My guidance is not blind in saying the forgoing, as I am delegated to certify the designs of these engines, including detonation testing. I write operating and maintenance manual supplements. The first thing we look for are safe operating margins, and instructions, which if followed, keep the engine well within those margins. People choose a certified aircraft [and engine] for the security of knowing it has been thoroughly tested. It has, so operate it the way is supposed to be. I am unaware that any aircraft has been certified as requiring an engine scanner as a part of it's type design - because they are not really needed!

If someone wants to install one, by all means. Don't let it distract you from the safe operation of the aircraft. Use it to follow (not circumvent) the engine manufacturer's operating instructions. And learn to use it properly. Most flying schools probably struggle to employ instructors who are conversant with the different scanner types, their relevance, and their correct operation. And students hardly want to spend an extra 5 hours of flight training costs to learn what it is telling them, and the relevance.

My family appreciates that I keep myself current and recent,Excellent!! As we all should and that I operate the aircraft legally, safely, and in accordance with it's instructions. More than that, they do not ask of me....

Enough for today.....

Jabawocky

13th Aug 2012, 04:27

Can't be taught on an internet forum eh

That must be the new internet code for "I don't really know what I am talking about"

No it is code for, to educate properly a few minutes here and there with banter on an internet forum, with all the distractions from morons on the sidelines, would take something like 10 years.... or it would feel like it.

The APS guys are continualy teaching free of charge on some internet forums, however they have found the bulk of the information does not sink in. When placed in a class room for several days with lots of good materials, real dyno runs and explaining the science of combustion properly, eventually folk start to understand things rather than just know a few things.

I have a friend who is a former NASA space shuttle astronaught, if I asked hime to get on here and explain a certain aspect of space shuttle missions, he would laugh at the prospect, but get you in a briefing room surrounded with the right stuff for a few days, and you too would learn what they know.

This is the wrong form of media for such things.

If I started now, all it would do is cause a squabbling mess and have a thread closed, and you would be none the wiser for it.

So it is code for read my previous post and seek the education from those who provide it very well indeed.

That must be the new internet code for "I don't really know what I am talking about"
:}:}:}:} That reminds me of Burt Reynolds in Smokey and the Bandit.....
Little Enos: I think you're just a little bit scared.
Bandit: That's real good psychology. Why don't you say something bad about my mother?
Little Enos: Your momma is so ugly...

At 1min 3 seconds
Smokey and the Bandit (1/10) Movie CLIP - A Real Challenge (1977) HD - YouTube

peterh337

13th Aug 2012, 07:08

One pet peeve of mine is how few instructor insist on checking that the engine is making full static RPM at the beginning of the takeoff run.

I agree 100%

For a non instrumented engine, flown by various people at various times, and "maintained as usual", it is likely to be the only warning of a proportion of e.g. the camshaft getting gradually relocated to the oil filter :)

Example (http://www.aaib.gov.uk/cms_resources.cfm?file=/Piper%20PA-28-140%20Cherokee,%20G-AVRP%2010-08.pdf)

I sent that report to a couple of respected US engine shops and both said the oil filter would have been full of metal - chromium specifically.

Re weight, it is not significant. I would think my EDM700 installation weighs about 2-3kg, with all the probes.

However I think accurate fuel flow, in the form of a GPS-linked totaliser (http://www.peter2000.co.uk/aviation/misc/fuel.pdf), is equally important if one is to go places with confidence.

The APS guys are continualy teaching free of charge on some internet forums, however they have found the bulk of the information does not sink in. When placed in a class room for several days with lots of good materials, real dyno runs and explaining the science of combustion properly, eventually folk start to understand things rather than just know a few things.

That's true but do you need to know the internals of combustion, to configure an engine correctly for each phase of flight? No.

This (http://www.peter2000.co.uk/aviation/engine-management/index.html) is an attempt of mine at condensing what one needs to know and I think it is short enough.

Internet presents the greatest learning medium by far, for the 99% of pilots whose initial training was prob99 p1ss poor. I suppose its value is going down for various reasons (forums filling up with banal ex-Iphone one-liners is my favourite ;) ) but if you ask a decent question (worded like you actually care for a useful reply, which is itself a skill) in the right place you will eventually get a decent reply. I learnt far more from the internet than I learnt from JAA & FAA PPL, FAA CPL, FAA & JAA IR theory.

Maoraigh1

13th Aug 2012, 21:53

Nobody has said listen to the engine. I mainly fly with an O200, just RPM and electrical oil temp and press - whose readings have on two occasions been affected by a bad connection. In the last year, we've spotted two potential problems early by responding to a slight changes in engine sound.

Jabawocky

14th Aug 2012, 00:20

Peter

That's true but do you need to know the internals of combustion, to configure an engine correctly for each phase of flight? No.

I would counter that claim with a Yes! I like your simplified article link, however there are a few things in there that need editing and refining. The biggest problem I have with it though is it is a "cookbook" approach, and not a thorough understanding approach. Herein lies the problem. It talks about "deep LOP" whatever that is? 80LOP is not deep LOP, it would be at low powers say 65% but at 80% or more it is the exact place you need to be. So here a cookbook approach does not work for all people in all missions.

This is why I say there is a difference between knowing stuff and understanding stuff. There is a big difference. Have you done an APS course? If not you should, you will enjoy it. Worth every penny.

You are quite correct in your assessment of flight training schools.

To finish up, I can believe you when you say you learned far more from the internet than any of the FAA/JAR etc training books. Problem is, they are full of little gems, that are all wrong!! :ugh:

The truth of the matter is, and APS survey their students going in and out and analise how well they perform as teachers every time, and it has proven that the internet in random forms of information is not the best teacher. What is a better teacher is a well structured, "building block" approach to educating. You must understand some critical things to move onto the next phase. (Anyone remember missing some critical maths classes :ouch:) So their course is structured that way. The APS ONLINE course is cleverly constructed so that you can't progress until you understand via small quizz sessions at milestone points.

I have searched, there is nothing better.

Big Pistons Forever

14th Aug 2012, 02:58

To finish up, I can believe you when you say you learned far more from the internet than any of the FAA/JAR etc training books. Problem is, they are full of little gems, that are all wrong!! :ugh:

.

The only thing I think that is "all wrong" is your assertion that you alone represent the sole provider of correct information. I post on things I think are of value to the pprune community but I would be the last guy to say "this is the only way to do XXX". I make a big effort at presenting not only the "what" but also the "why" for everything I post on. That way readers can see where I am coming from and decide if my information or advice has any value to them.

IMO your posts are just a waste of internet bandwidth and so I will not use up ppruners time with any further responses to your comments.

Jabawocky

14th Aug 2012, 05:08

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.:ok:

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

14th Aug 2012, 12:38

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

14th Aug 2012, 16:49

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

14th Aug 2012, 18:30

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

14th Aug 2012, 18:54

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 :ugh:. 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

15th Aug 2012, 09:19

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! :D

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. :ugh:

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 :hmm:

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. :rolleyes:

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 :ugh::rolleyes: And why would I want an STC for a manual? :ugh:

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

15th Aug 2012, 09:24

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

15th Aug 2012, 11:15

:rolleyes: And why would I want an STC for a manual? :ugh:

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. :rolleyes:

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

15th Aug 2012, 12:41

Derrrrrr :ugh::ugh: 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

15th Aug 2012, 14:14

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 (http://www.peter2000.co.uk/aviation/granada/index.html)) 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

16th Aug 2012, 01:14

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

16th Aug 2012, 02:20

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! :ok:

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

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! :uhoh: It just does not make sense.

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

Jabawocky

16th Aug 2012, 02:22

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

16th Aug 2012, 03:04

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

16th Aug 2012, 06:57

DAR,
agreed:ok:

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! :E

Pilot DAR

16th Aug 2012, 12:27

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

16th Aug 2012, 13:15

http://www.freesmileys.org/smileys/smiley-fc/popcorn.gif (http://www.freesmileys.org/smileys.php)

Pace

16th Aug 2012, 13:41

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

16th Aug 2012, 16:15

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

16th Aug 2012, 21:10

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.

Jabawocky

16th Aug 2012, 21:17

To the youngsters reading this thread and easily impressionable think about this for a minute

It is not what you don't know that will hurt you, it is what you know that isn't so!

Still waiting for a couple of questions to be answered.

Big Pistons Forever

17th Aug 2012, 04:45

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!

Seems to me that you are talking out of both sides of your mouth.

When professional highly experienced jet pilots have a rough running engine they go straight to the emergency check list starting with the memory items and then consulting the checklist. Sure sounds like "a by the numbers instruction sheet" designed to deal with a problem to me

So does that mean when a 100 hr PPL has a rough running engine and goes to a checklist that will ensures he methodically runs through the potential causes in a logical order without missing anything, which is exactly my response to the question posed by 500 Man in the first post, you "have to question the pilot not the problem" ?

Sorry I just don't follow your logic. :confused:

Big Pistons Forever

17th Aug 2012, 04:52

It is not what you don't know that will hurt you, it is what you know that isn't so!

Still waiting for a couple of questions to be answered.

You know of all the posters who have contributed to this thread it would seem to me that the quote best applies to you....

As for answers I am still waiting for an explanation on how you seem to be the only person I have ever heard of who could get a simple horizontally opposed carburated engine to run smoothly at a true lean of peak mixture. I have personally never been able to do that, not have any of my very experienced pilot friends had any success with LOP operation on these engines.

So what is the secret ?

Pace

17th Aug 2012, 08:42

BPF

I am not talking out of both sides of my mouth;) We are talking about engine problems which could or could not lead to a forced landing in a single engine piston.
Obviously in a single engine piston an engine problem is more critical than in a jet as the jet will not be contemplating a forced landing into a field.
The Jet and its systems are more complex and the emergency checklist covers many other areas other than engine problems.
The fact that an engine problem in a piston single opens up the prospect of a forced landing means that the forced landing part becomes more critical.
As I posted if you have time then yes go through check lists, experiment with different settings etc but not at the expense of jeopordising the outcome of the forced landing which could be fatal if you get it wrong.
The last scenario I would want is for some pilot to be fiddling around head in books and in the aircraft with an aircraft gliding down to lower levels when he should be selecting a suitable landing area and adjusting the profile estimating winds etc as priority number one.
You cannot compare the two as other than complete fuel starvation the jet is unlikely to ever be force landed the piston single is.
Even so I see nothing wrong with a mini emergency checklist for the single piston as it could be very useful especially if it is readily at hand and actually speeds up the thought process allowing more time to carry out a successful forced landing.
Aiding decision making not hindering it is the key to the use of a checklist in such a situation.
But the best decision making is the pilot who knows every beat of his aircraft and through experience knows where the problem lies and whether it is fixable or not.

Pace

Jabawocky

17th Aug 2012, 11:02

You know of all the posters who have contributed to this thread it would seem to me that the quote best applies to you....

This applies to EVERYONE you included and now I think the punters might be making the judgement call for themselves. Your attempt at insults really does your argument no good at all.

I have told you repeatedly, there is not enough space to sit here and debate how it works with a bunch of flat earthers, holocaust deniers and whatever other descriptions for non believing folk there are.

Plenty of people do it around the world. I am more stunned you have never heard of it and can't accept I am telling the truth. You lot are so bigoted that you believe that everyone else should take your word as gospel and others do not deserve that privilege also.

I promise you, it works on many engines. Most can achieve a level of effective LOP operations in the most economical range 10F LOP +/- a bit if they have a "Conforming engine" strategic use of the throttle position and a scientific application of carby heat. An EMS of some sort with digital fuel flow carb temp etc is damned handy to have also. Not essential but really good to have.

Perhaps if you sucked your pride in for a bit, and realised a weekend in Ada in October was a good idea, you could learn a whole heap more. Maybe you could teach George and Walter a thing or two!

Now how about a quick answer to my questions. If you ever fly a twin and could not answer that question in the first 3 seconds of reading it.... I will not let anyone I know fly with you. I would, because I would know what we saw.

Pilot DAR

17th Aug 2012, 12:54

take your word as gospel and others do not deserve that privilege also

For a certified aircraft, the "gospel" is what the regulatory authority has approved. Other than simple good airmanship, there is not other gospel.

Any "others" who wish the privilege of their word also being gospel, should go through the process to create, and have approved, a modification and/or supplemental instructions. That way, pilots will know what they have as authoritative instructions with which to operate the aircraft.

For those older large radial engined aircraft which I am aware were operated LOP, 'cause I had a friend who used to do it, I'm certain that there was an approved document describing that procedure - why not so for GA aircraft?

Jabawocky

17th Aug 2012, 13:18

Well some were even 25 years ago. If you really knew your stuff, you would know the exact model I refer. I am not saying you do not know stuff, but clearly there you are talking out your.. :mad: again.

As for several others, in the POH's some say do then a page later contradict. You tell me why? Its baffling to me.

As for the rest of the manuals, the manufacturers are either too lazy, too incompetent or just do not want to admit they got it wrong. Mind you I have seen an email from one prominent employee of a major manufacturer openly admit the manual writing was in fact.....very poorly written. He should know, he approved it!

It is about time you came out of the dark ages, circa mid 80's and stopped being so hard of learning.

And what is your answer to my questions?:ok:

englishal

17th Aug 2012, 13:42

I can't run LOP with our carb engine, and we have an EMS. Runs rough as hell.

Big Pistons Forever

17th Aug 2012, 15:19

But the best decision making is the pilot who knows every beat of his aircraft and through experience knows where the problem lies and whether it is fixable or not.

Absolutely no argument there, but my posts on this thread are aimed at a low time pilot that is flying a rental aircraft for possibly the first time in that particular airframe. So what do advise for them ?

Jabawocky

21st Aug 2012, 06:24

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.

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?

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.

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.

Not one attempt at answering a few simple questions. Very disappointing indeed. I would have thought with such a strong technical base on this forum there would have been several pages of replies.

Anyone wanna have a guess? :zzz:

BackPacker

21st Aug 2012, 06:34

Well, the only question that needs answering, as far as I'm concerned, is this one:

As for answers I am still waiting for an explanation on how you seem to be the only person I have ever heard of who could get a simple horizontally opposed carburated engine to run smoothly at a true lean of peak mixture. I have personally never been able to do that, not have any of my very experienced pilot friends had any success with LOP operation on these engines.

So what is the secret ?

So by all means go ahead, Jabawocky, and answer that one, instead of pretending to be the wiseguy without actually delivering.

(The aircraft I fly most often has an induction system that's so unbalanced that the POH doesn't even have instructions for setting the "best economy" mixture. All it does is "best power" (max RPM), and all the performance tables, including cruise, are based on that. So getting that one to run LOP properly would be a major breakthrough.)

Pilot DAR

21st Aug 2012, 11:09

Very disappointing indeed.

Disappointment happens Jab.

My participation on Proone is voluntary, as is my choice to not be further drawn into nonsense. I find many questions I believe to originate from the desire of a pilot to broaden their knowledge, and improve their skills. Where I can, I help. In other cases, I charge for the same service to the aviation industry, and I then often sign an STC for the modification.

Some questions on Proone I suspect are not "true", and asked in an honest spirit. I generally ignore them. Some statements on Proone I judge to be more unhelpful to new pilots than helpful to anyone, and perhaps leading the unwary pilot into troubled aircraft operation. Where I have experience, I will challenge those (as several other extremely skilled Prooners have here). The challenge not so much toward the poster, but more so everyone else sees the challenge, and takes the offending statement with a grain of salt. It is each reader's responsibility to judge the credibility of answers in their personal flying context. But, a few credible challenges could be the "red flag popping up" for those pilots who are impressionable.

For me personally, lean of peak operations pop up a lot of red flags. But, that is now well evident to readers here.

Does that answer your question about your being disappointed?

Two STC's were issued, based in part on my ground and flight detonation testing, which was done by my real time observation of cylinder pressures, measured by a piezoelectric sensor. This was my third detonation measurement system design (and the first which worked well). These tests were ultimately supervised by a national powerplant expert, and witnessed by a Transport Canada powerplant engineer, to his satisfaction. With their concurrence, and two STC's, I'm satisfied with my work. If others are not satisfied, I'm not worried.......

Jabawocky

21st Aug 2012, 11:34

DAR

I am genuinely interested in your detonation data aquisistion, mainly because very few people ever go to the length to measure that properly.

Just because I challenge the comments of other matters does not mean I am taking the same challenge to this topic.

So were your pressures recorded in a digital logger at a high frequency? There is some interesting work being done considering the detonation event and the pressure waves bouncing around after the peak event. Your experience might make for good reading.

Now as for the questions I posed, which were challenging the comments about pilot education.....I am disappointed nobody bothered.

As they say, you can lead a horse to water, you cant make it enjoy the view.

For me personally, lean of peak operations pop up a lot of red flags.
Another matter altogether, but that just means a greater degree of understanding is required. Especially with students and owners.

More red flags should show up with ROP ops, as it is well known and your ICP traces would also prove this, that engine longevity reduction through mixture mismanagement is far more a problem in Rich Mixtures, than in Lean Mixtures.

And before you choke on your lunch there, remember this. Rich Mixtures are ALL settings on the rich side of peak. To a scientist and engineer, they are all rich mitres. Lean Mixtures only exist on the leaner side of peak. This is a concept most people fail to understand.

A mixture that at high temps, high ICP that can cause detonation is most likely a rich mixture., Sure at very high MP's and say 10LOP you are still in the zone, but it takes very little extra leaning to get out of the zone.

These are concepts that scientists and engineers since Lindbergh have understood, pilots have not.

Anyway back to the questions, for the educational benefit of new pilots. :ok:

Jabawocky

21st Aug 2012, 12:10

So by all means go ahead, Jabawocky, and answer that one, instead of pretending to be the wiseguy without actually delivering.

(The aircraft I fly most often has an induction system that's so unbalanced that the POH doesn't even have instructions for setting the "best economy" mixture. All it does is "best power" (max RPM), and all the performance tables, including cruise, are based on that. So getting that one to run LOP properly would be a major breakthrough.)

Backpacker

Which engine and aircraft is it you fly? There are some combinations that will be very hard indeed.

So how far once you get to peak RPM, can you get before severe roughness sets in?

I would happily help folk who perhaps do not construct their posts with comments like "So by all means go ahead, Jabawocky, and answer that one, instead of pretending to be the wiseguy without actually delivering." And take a far more healthy and polite method of questioning.

I do not have time in my life for coming on here making false claims in the attempt to educate folk, and then having stupid debates forever and a day. You can actively engage me and learn, or stay in denial. Your choice.

To respond to your last post, I have already given you as much as a post on pprune can convey. The process of teaching is not achieved by one or two posts on pprune. Do you think you could successfully teach a student to fly to solo by a few posts on pprune? No, surely not. So the same applies here. To understand the answer for some folk requires considerably more. And when some bozo goes off half educated, and gets it all wrong, who do you want to blame.

Sorry, not going to happen.

If you are suitably equipped with knowledge and understanding, plus your aircraft equipped (makes it easier), I have already given enough info. Just for your benefit, I will give you a clue, read posts #28, #33, #46 and #65. The answers are there. Let me ask you to contemplate, Lindbergh crossing the Atlantic and the Doolittle raiders. Two famous pieces of history. Neither possible without carby engines running LOP. Your very freedom today depended upon LOP Carby engines.

Now will I give you a cookbook approach to running an engine LOP that could potentially have you do it wrong? 10F LOP at a high HP is not the same as 10LOP at 8500', so a cookbook approach will never be good. You need to understand this stuff, and I can not be sure you or any other reader understands it on a thread that is ambushed by flat earth society folk all the time.

I have given you enough to go and learn properly yourself. The rest is in front of you if you wish to embark upon the journey.

Now my questions were not that complex. What would you do in that C421 with a change in MP?

Clearly this demonstrates my point. Flying schools, hangar talk, and pprune have not educated even the very well experienced and qualified folk. I do make the assumption a few of the posters here have lots of qualification and experience. That I have no doubt. But I do have doubts about a system that has allowed a great number of people get through with poor understanding of the very thing that gets them airborne in the first place.

So just for fun, have a go at the questions, you can only gain something, never lose.:ok:

BackPacker

21st Aug 2012, 13:56

Big Pistons Forever

21st Aug 2012, 15:35

It's the Robin/Alpha R2160, with a Lycoming O-320-D2A engine. I can get it probably 25-50 RPM on the lean side of best power (max RPM), before it starts running rough. But between max RPM and 25-50 RPM lean of best power the mixture knob movement is less than two mm and there is a bit of "give" in the mixture control system, so it's pretty tough to find the "best power" mixture in the first place.

As for the rest of your comments: I visit this place to learn something, or to teach others about the areas I think I know enough about to answer their questions. Not to engage in a pop quiz where the person asking the questions already knows the answer. And not to answer rhetorical questions either.

Best power will be in the EGT range of 100 to 125 deg F rich of peak. Your 25 to 50 RPM drop will still very likely leave you on the rich side of peak although probably pretty close to peak on at least one cylinder, just exactly the place you do not want to be as operating at peak generates the highest CHT's and will stress the exhaust valves and could even result in detonation developing.

Theoretically heating the induction air should improve the vaporization of the fuel and therefore make the distribution of the fuel to air mixture to each cylinder more even, as it that unevenness which causes the engine roughness preventing LOP operation in carburated engines.

In practice I have never personally had much luck trying a bit of carb heat as I leaned. When the dust settled I did not think I was able to go appreciably leaner with the carb heat then without and still have smooth engine operation. Also I found that the Micky Mouse Cessna carb heat control made it hard to accurately set stable partial carb heat settings.

Interestingly though pilots who operate Cessna 180's with Continental O 470 engines in the Canadian North, an engine notorious for poor fuel/air distribution, find that in extreme cold weather the engine quite likes a bit of carb heat at all power settings.

The bottom line from my POV is that for the ubiquitous carburated engines found in small Cessna's/Pipers/Grummans/Robins, it is pretty hard to hurt the engine with the mixture knob. If it is running smoothly its OK. The only caveat would be low altitude, slow full power climbs with the mixture leaned.

As a general rule, all of the common simple carburated engines can and should be leaned in cruise at or below 75% power at any altitude. The flight school urban myth that it is dangerous to lean below some arbitrary altitude is wrong. In addition the engine should be leaned in a full power climb at and above the altitude specified in the aircraft POH. If no data is available then leaning above 5000 feet is a conservative practice.

A much more common problem for these engines is cylinder overheating by prolonged climbs on hot days at low speeds ( ie Vy). Even at full rich mixture damagingly high CHT's can be developed due to the lack of airflow over the engine at low speeds.

Jabowacky

Just for grins I will answer you question. One day flying a 421C I did in fact notice the MP of one engine drop an inch or so. Pulling the alternate air handle fixed the problem........but I am guessing that is not the answer you wanted to hear :E

If I was really bored I would add up the word count for all of your numerous and lengthy "it is all too hard to explain on the internet" posts. Since the concepts are not exactly rocket science, I bet that the same number of words could indeed be used to craft a post with a pretty useful description of the factors involved in leaning aircraft engines........but of course to do that you would actually have to know what you are talking about, something which you have yet to provide much evidence of.

For those interested in learning more about all aspects of aircraft engine operation I highly recommend the book by Kas Thomas "Fly the Engine"

Finally as the topic of this thread is "engine checks" and the original poster was interested in the actions to be take in the event of a loss of power/rough engine, then to get back on topic and away from feeding antipodian egos's, a poorly adjusted mixture can cause a rough running engine. The most likely cause is the mixture had been leaned for cruise and then the throttle advanced, but forgetting to enrichen the mixture first. Another scenario is that at high altitudes full rich could be so rich that the engine is choking on the excess fuel and so in this case leaning the engine is required for its smooth operation.

Jabawocky

22nd Aug 2012, 01:08

BPF/Back Packer

The good little O-320D2A, The exact same engine (D1A) as I use LOP and it runs smooth. We are talking about at cruise altitudes of typically above 5000' or if lower, start at a MP/RPM that is around 75% and by the time you achieve LOP you are then around 65%. Fuel flow instruments are a big help. around 27LPH is the number and it sits there all day sipping away and performing book numbers doing so.

Back to science though, BPF, we are splitting hairs here a little but best power is actually at 75-80 ROP, and the power starts dropping away at 30-40 and anything noticeable probably around 30 or less, so the fact is Back Packer is probably LOP on some and peak on some doing what he says. At 65% or there about there is no problem there at all. You are quite right about not doing this at high HP down low, but that is not what we are trying to achieve.

Your comment about operating at peak EGT and the worst place because of high CHT is false. Let me tabulate this for you for future reference and for the benefit of others. The order of peaks from Rich to Lean
1. HP peaks first 75-80F ROP
2. ICP peaks about 35-40 ROP
3. CHT peaks about 35-40 ROP and it responds directly to ICP, nothing else.
4. EGT peaks at........ 0F ROP/LOP (where else :O)
5. 1/BSFC peaks last and depends on the power setting, from 20LOP at low powers to 75-90LOP at high power.

Assuming we are at cruise powers, detonation on an O320 can not exist, and even at full power on that engine the chances of doing it are pretty hard. With Conforming fuel and a conforming engine. However, running high ICP and hence high CHT for long periods and with poor cooling gives the valves a hard time not so much from direct heat, at the valve but for stress on the cylinder head itself.

The exhaust valve is at ts hottest at 25F ROP, and it is at the same temperature when at 125ROP or 50LOP so even peak EGT the valve is cooler if you are worried about that.

Theoretically heating the induction air should improve the vaporization of the fuel and therefore make the distribution of the fuel to air mixture to each cylinder more even, as it that unevenness which causes the engine roughness preventing LOP operation in carburated engines.

Now we are onto it, ;):D the process is now working. plenty more to be discovered. It is determining the right amount of heat and the throttle plate cocking that is the key.

Back Packer, in short your engine will most likely do it, you just need to do a bunch of things right. Plugs, ignition system and chase all the induction leaks out. Again an EMS and knowing what to do helps this process big time. Maybe yours will be one that is forever a pig and not able to, but in general, most can. I have better things to do than make this stuff up.

The flight school urban myth that it is dangerous to lean below some arbitrary altitude is wrong. ABSOLUTELY :ok:

Any N/A engine in a Full power climb, should be leaned every couple of thousand feet, as has been described elsewhere. A Turbo or TN engine is full rich to match full MP and leaned only when appropriate, or when doing LOP climbs, but these are not that common as the time/distance/climb is only a bit of a saving and pilots like to be lazy.

Just for grins I will answer you question. One day flying a 421C I did in fact notice the MP of one engine drop an inch or so. Pulling the alternate air handle fixed the problem........but I am guessing that is not the answer you wanted to hear

Nope, that was not the answer i was looking for. Your actions were a lucky one, although I assume you had an icing problem perhaps, and nowhere in my question did I mention anything about icing or any other influential factor. Simply with no 100% certain good reason for the MP drop, what should you do? This is not a time to mess around and plenty of people have died from this, and I personally know of two cases where the pilots did the right thing, through good engine training and survived.

SHUT THE ENGINE DOWN & DIVERT

Chances are you had some minor problem, however unless you are 100% guaranteed you know exactly what the problem is you can not be sure you have not had a exhaust leak from a failed tube/joint. This will soon and it does, start burning through all manner of things until you have a fuel fed fire that you can't stop and a wing burns off. Sounds nasty hey! From the folk I know, they thought it was too and the photos prove it.

Lastly BPF..... I am not here to prove anything knowledge wise, least of all to you. When you get your fundemental facts straight, as I have corrected above for you on just what happens with EGT/CHT and the transition from Rich to Lean, then maybe you can start the "mines bigger than yours" willy wagging.

Clearly I have stumbled into your turf on this forum, where your supposed knowledge, and I am sure the majority of it is very sound and in some areas superior to mine for sure, but now that I upset the status quo you have been biting back with cheap shots like that.

Go ahead, I am happy to bug off again to my corner of the world and let the Old Wives Tales spread around some more. But for the sake of new students and private pilots/owners how about we aim to educate them sans the OWT's. :ok:

Big Pistons Forever

22nd Aug 2012, 01:21

Sorry guys I could not resist feeding the jabowacky. I think it is time to put a fork into this thread, it is definitely well done.

Pilot DAR

22nd Aug 2012, 02:07

Well, yes, it is well done Big Pistons, but it's like a horror movie, I can't look away...

The good little O-320D2A

If you've ever had to lift one out of the back of a truck, they're not all that little...

However, for an engine like most carb'd opposed engines, in which getting even two, much less four (or six) cylinders within 100F EGT of each other is near impossible, how could you ever manage to lean so as to be within 20 to 70 LOP?!? Which cylinder are you measuring?, what are the other's temps while you're doing that. That even precision is not possible on your average carb'd engine.

a exhaust leak from a failed tube/joint. This will soon and it does, start burning through all manner of things until you have a fuel fed fire that you can't stop and a wing burns off.

Well, maybe this has happened, though in 35 years of flying anf maintaining light aircraft, including 8 years working in an engine overhaul shop, I have never heard of anything other than exhaust gasket, flange, or baffle damage resulting from an exahust leak. That area within the cowling, by design, does not have vulnerable fuel lines close to the exhaust, and has lots of cooling air rushing around there. I'm not saying you can't have an engine fire, but I bet an exahust leak did not cause it. Perhaps Jab has had experience with these failures, and will warn off the impressionable with stories.

My O-360 powered aircraft has cowlings which make an visual inspection of the exhaust to cylinder connection difficult during a standard preflight. The first clue I had that I had an exhaust leak, (because of the nuts falling off, and that side's exhaust dropping down 3/8") was my wife telling me that when I took off it sounded different the past few times. I investigated more deeply, and sure enough saw exhaust soot where I should not. It must have been that way for some time - no fire or other damage. I just inspected it, and did it all back up again.

Like anything leaking or falling off a plane, exahust leaks are bad, and should be repaired without delay. But, I doubt that they are a cause for an inflight diversion, if suspected during a flight, with no other abnormalities in the engine. Oh, and if I'm wrong, and you do have a fire in the engine compartment, because somehow the fuel line was burned through, pull the firewall fuel shutoff, and it will self extinguish for lack of fuel.

There are many things I would be worrying about long before I worried that an exhaust leak might cause a fire.

Big Pistons Forever

22nd Aug 2012, 03:47

Pilot DAR

Exhaust failures in turbocharged engines which have resulted in catastrophic in flight fires has been an issue in the past and resulted in a AD mandating continuing exhaust system inspections for all Cessna turbocharged twins.

Failure of the tail pipe is particularly bad as it points aft towards the firewall before making a 90 degree turn down right next to the firewall. Failure at the flange out of the turbo or at the bend will result in the exhaust jet impinging directly on the firewall. The Turbocharged Lances had the same system for their turbocharged Lycoming and the same vulnerability.

The Navajo has a much superior layout of the exhaust IMO. But the bottom line is these kind of failures are invariably associated with poor, or probably non existent, maintenance of the exhaust system. Exhaust leaks at the joints will also result in tell tail soot trails on the cowling or in bad cases discoloured paint on the surface of the cowling. Any discolouration or paint blistering on the cowling is a grounding snag. Still abnormal operation of any turbocharged engine should make the pilot alert for the potential for fire.

However for your average carburated non-turbocharged engine the good news is fire risk from exhaust leaks is much much less and as you pointed out there are a lot of other more likely problems you might encounter then an exhaust leak induced fire.

The even better news is I have yet to find a case of an inflight fire where the fire did not immediately go out if the engine was shut down at the first positive indication it was on fire. All the tragic accidents I have seen reported involved the pilot keep the engine running even though it was on fire

All that being said I have a fair bit of time on twin Cessna's, including C 421's and there is no way I am going to mindlessly shut down an engine just because it shows a loss of 1 inch of MP. Do a fault check, sure but immediately shut down, probably not, well that is the difference between actual operating experience and deciding that you are the expert because you took a course....

Jabawocky

22nd Aug 2012, 05:12

Here you go again......... you dont read very well. These failures are from people I know. Not just from a course. But of course you wouldn't know....you have never been.

DAR
You are quite correct, they are not that little in terms of single human engine cranes :eek: But on the scale of engines they are a great little/Big engine. I don't own one, but fly a few of them from time to time and I must say what a great little powerplant they are. And the IO320 is even better! :ok: Although a bit rare.

BPF
Seems the name calling has started, and that about does it for me. Science and fact never trumps some things.:=

I think I have worked it out, this is the ab initio max 160HP No need to make it any more complex forum. No wonder the specialised forums thrive so well.

Cee Yaa, Jaba going No Coms :ok: No need to waste a reply.

BackPacker

22nd Aug 2012, 07:42

Seems the name calling has started, and that about does it for me.

I don't know whether to laugh or cry at that remark. If anyone started the name calling and the condescending remarks, it was you, Jabawocky.

the local aero club or flight school who know nothing
Anyone who argues otherwise, is simply wrong, they are entitled to be wrong, but just don't follow their blind ignorance, your family will appreciate your vigilance.
Education in flying schools, dummed down, full of Old Wives Tales, resistant to change to data based facts, and taught by 200 hour pilots who know nothing about flying more than to pass an exam, which are often full of the above problems as well.
I am not going to debate point by point here, if I did I would spend hours and hours and still not get the message across.
What drugs are you on man?
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"
debate how it works with a bunch of flat earthers, holocaust deniers and whatever other descriptions for non believing folk there are
(To be honest, I expected you to be banned by the mods after that holocaust remark.)
You lot are so bigoted that you believe that everyone else should take your word as gospel and others do not deserve that privilege also.
If you really knew your stuff, you would know the exact model I refer. I am not saying you do not know stuff, but clearly there you are talking out your.. again.
As for the rest of the manuals, the manufacturers are either too lazy, too incompetent or just do not want to admit they got it wrong.
It is about time you came out of the dark ages, circa mid 80's and stopped being so hard of learning.
Flying schools, hangar talk, and PPRuNe have not educated even the very well experienced and qualified folk.

...need I go on?

peterh337

22nd Aug 2012, 08:56

Don't feed them (http://en.wikipedia.org/wiki/Troll_%28Internet%29)

This one is actually clever but his manner is difficult to deal with.

Pace

22nd Aug 2012, 10:04

Hmmm?

If I could wave a magic wand which miraculously transported everyone writing on these forums into one large room sitting behind their laptops facing each other I have no doubts there would be some very red faces.

It is the nature of anonymous internet forums that people will act differently to one another than they would do face to face.

Text itself can be misunderstood or taken the wrong way.

With something like aviation which is often ego based real world put it into an anonymous forum and there is bound to be sniping, willy waving and hurt egos.

I have met quite a lot of posters off these forums and most have become good friends real world.
Networking is so important for getting opportunities not just in commercial flying but also private flying and if used correctly the forum gives golden opportunities of meeting up with some of the posters who are anonymous but who then can become good real world friends.

As for banning? We all loose our rag sometimes or take things the wrong way and make defensive comments even if they are sometimes attacking comments.

The genuine troll for me is someone who hunts through the internet taking delight and excitement from others hurt and posts to encourage that.
It is a form of bullying akin to the classroom bullying and that should not be tolerated.

Pace

Pilot DAR

22nd Aug 2012, 12:06

Exhaust failures in turbocharged engines which have resulted in catastrophic in flight fires has been an issue in the past and resulted in a AD mandating continuing exhaust system inspections for all Cessna turbocharged twins.

Thanks Big Pistons, Thinking back, it's been 28 years since I've flown a Cessna twin, so I'm out of touch.... (okay, now I feel old!)

Big Pistons Forever

22nd Aug 2012, 15:06

Pace

You are right about the internet perhaps allowing people to say things that they would never say face to face. As for what it takes to be a troll, well I think Jabowacky met the test, not because he questioned my competency ( my wife does that all the time;) ), but rather he made several posts along the lines of

"Here is a question, I won't tell you what I think is the answer, you post what you think and then I will pronounce on it worthiness"

When posters do this it is clearly to bait the audience into a reply whereby they can publicly humiliate them by rubbishing the poster. These posts only purpose is to attack and disrupt the thread narrative so that the originator gets an ego boost. That IMO is trolling and jabawocky was doing it.

I think Peter337 is right, unlike many trolls, I think jabowacky probably does have the knowledge and experience to provide real value to this forum but as long as his attitude is "I am right, you are wrong, I don't have to explain myself and no discussion is necessary or desired" then him going NORDO is a good thing

Pace

22nd Aug 2012, 15:56

BPF

I am not taking sides so its just an observation! I was very heavily involved in flight simulator addon companies a few years ago.

We had one poster on a FS forum who professed to be a 747 Captain. He posted with absolute authority in detail which left me floundering in the water :( Until he made a couple of major mistakes which had us all questioning the authenticity of this so called 747 Captain.
He turned out to be a 12 year old kid with excellent googling abilities.

There are people who post here for all manner of reasons some genuine some blown up their abilities , some not!
Some are known to others here as genuine.

But in any anonymous forum you do not really know who you are talking to.
There are people I have met and some I would love to meet (you included) as the depth of their knowledge and experience would mean I would find them interesting to talk with and I too learn a lot from some of the members here.

But it is part of the nature of the animal to treat internet forums with caution and the posters with extra caution.

We had one poster called Guppy who was amazing in his detail and authority! You dare not cross him for fear of public castigation.
He always won an argument.
He was banned and the forum lost his detail of knowledge wherever that came from!
I often wondered how real he was!
Genuine Trolls yes ban them but others give them slack.

Jabawoky??? he has more posts than me here and my instincts give him some slack ;)

Pace