Engine Analyzer Question/Lean vs Rich of Peak/Engine Longevity

[SkyKing]

One other thing... Read the TCM engine manual for your TSIO360C & CB's. Why would you go "against the grain" of the sage advice in that manual or your POH from the people who built the engines and the plane be chancing total destruction of your engine with this LOP nonsense? READ AND HEED THE MANUALS!!

Go read the NTSB accident report on the T210 that recently lost an engine at altitude... GAMI's and the whole gambit of monitoring gear... burned a hole on one jug and the engine came apart with oil over the windscreen... he IFR'ed it through the overcast from near FL200, broke out, crashed, burned and DEAD as a do-do bird. Got GAMI? Want to take this kind of a chance?

Follow the TCM and POH manuals... they know best.

SkyKing

[gwbraly]

SkyKing,

Could you be a little bit more specific about the T210 crash to which you refer.

I researched the NTSB accident database for the last five years and did not find the accident to which you are referring.

Regards, George

[SkyKing]

You were looking TOO far back... this happened in November of last year. And I see that I goofed too... the accident airplane was a P210 and not a T210.

NTSB Identification: IAD05FA012
14 CFR Part 91: General Aviation
Accident occurred Friday, November 12, 2004 in Paint Lick, KY
Aircraft: Cessna P210, registration: N6539P
Injuries: 1 Fatal.

SkyKing

[KyleTownsend]

LOP vs. ROP really isn't an emotional issue for me.

It appears to me that it works, and that the LOP advocates have done a better job of making their case with actual data than their opponents.

Nonetheless, at my level of usage (100 to 200 hrs per year) in this type of airplane, the economics don't make sense to me. If if was just a matter of buying GAMIs, the payback period would be a couple of years, and this would make sense. But with the cost of the JPI added in, the payback period is out in the 8 to 10 year range. That seems beyond reasonable to me.

Of course, there is the argument that LOP operations aside, having an engine monitor is good because of it's value as a diagnostic tool and early warning device. I think this is a valid argument, but it is very hard to quantify what value to place on this. I certainly agree with Skyking that the value of digital fuel flow is a lot easier to see.

[SkyKing]

Ears have worked good for years. So have the eyes. Then there are trends with the smell of things, and how things feel to the touch and sensing vibration. Mother nature has done an incredible job of equipping each one of us with the right tools... if but we will only exercise them.

Like I said before, if Cessna in their infinite knowledge of their own product and the many thousands of hours of testing before the P337 ever came to the market place... if they felt you really needed all these little gadgets to fly and maintain their airplane, they would have equipped them with all that junk. That they didn't speaks loads about the simplicity of the product ... IF... you go by the book. And the best book besides the TCM Operators Manual and the Cessna POH would be the Cessna Service Manual.

BTW, I'm not 'emotional' about LOP either. I go by what the manufacturer states in their recommended procedures. It's not about 'making a case'... it's about safety and longevity of the engines. Cessna and TCM obviously KNOW the score... and then some.

So save your money Kyle. Maybe look around for a serviceable Hoskins 2000A or maybe even a Shadin system which can be coupled to Loran or GPS. Surprisingly, the Cessna fuel flow indicator is pretty darn close to what the Hoskins gage indicates, but with a few additional features. But understand, I bought the bird equipped this way... and my sense is that unless you plan on keeping the bird for a LONG time, you'll never recoup the investment cost of adding NEW gear. Sometimes the old way is the better way.

SkyKing

[kevin]

I am not a LOP fan, I always ran my engines 100 degrees rich of peak. There is some evidence from these recent discussions that that might not be the right thing, but I want to ignore that for the moment.

For me, the purchase of an engine analyzer was never tied to running LOP. I wanted an analyzer to allow me to monitor and troubleshoot the engine. I had the inexpensive EI guage that provides the EGT for each cylinder on both engines, the CHT on one cylinder on each engine, and the TIT on each engine, all in one 2 1/2 inch hole.

I wanted this guage primarily to help me avoid inadvertantly harming the engine, without knowing it. This could happen with a clogged injector for example, which could raise the EGT in the cylinder to peak, and running it there for hour after hour would very likely be harmful. With the analyzer, I would know immediately if it happened, because the gauge would alarm. I didn't have to watch the gauge much, just set the alarms and let it watch the engine for me, alerting me to out of range values.

Even when it would not have harmed the engine, if I got a fouled plug or something, it was nice to be able to know what cylinder the problem was in, before I even shut down. Yes, there are other ways to troubleshoot, but they take a little more time.

So, my only point is that I think there is a lot of value to analyzers, especially the less expensive ones, just for doing a good job of monitoring your engine, easing maintenance, and sometimes preventing signifcant damage.

I think it is important to note that when our airplanes were manufactured, the monitoring technology was FAR more expensive than it is now. I believe Cessna does offer engine analyzers as an option on new piston 206's built today, just as they used to offer the single needle EGT gauges as an option when our birds were built, because back then the single needle indicator was the only reasonably affordable and practical option.

Last, and probably most importantly on a center line thrust airplane, the EI gauge would give me an immediate indication (via a red light on the gauge) which engine has failed if I lose one. Even if it was only a partial power loss, one operating parameter or another would be off, and would cause the alarm light for that engine to illuminate.

For the same reason, I used to have oil pressure sensors connected to an annunciator to warn me when oil pressure dropped in an engine. This would immediately alert me if I lost oil pressure (hopefully in cruise) so that I could shut the engine down and maybe save it. I know, we should all be scanning gauges fast enough to catch it, but the sensor would be an instant indication, and would alert me even if I got busy. But that is kind of off topic, sorry.

Kevin

[gwbraly]

>>Go read the NTSB accident report on the T210 that recently lost an engine at altitude... GAMI's and the whole gambit of monitoring gear... burned a hole on one jug and the engine came apart with oil over the windscreen... he IFR'ed it through the overcast from near FL200, broke out, crashed, burned and DEAD as a do-do bird. Got GAMI? Want to take this kind of a chance?<<

So... did you actually read the report before you posted that message???

Unless I am reading a different report for the same N number aircraft, there is no mention of GAMI's, Lean of peak, engine monitor, or anything at all about engine operation in the entire report.

Do have some secret source of information ?


Regards,

[Dave Underwood]

I have a EDM760 in my FT337GP. It's great and I now would not fly without it.

It would be nice to have some of the 800 series features, but you can't always have everything. I can always look at the power charts to get % power and I would expect the charts to be more acurate as they account for temp. etc.

My setup has FF, OAT, cyl, EGT. I did not get oil temp as all the other gauges are working.

What do I like about it. I have set the alarm levels lower than red line and I get good alerts when the cyl temps are starting to rise on a long ground hold. I then just turn into the wind a bit and they go down and you can see it.

When on decent, it helps you manage keeping the heat up and avoiding shock cooling.

I liked the fuel flows, but I think I need to rework the hoses as the runs on both sides of the sensor are a little shorter than they should be and I think line turbulence is causing irregularities. In fact I get zero FF most of the time.

I have it interfaced with the Garmin 530, but have yet to actually use that ablility. It would make long distance fuel management better. I will be working on that as yet another a new project.

It recently helped pin point the need for baffle rework.

Lean find makes leaning very easy. I only run 100 ROP and always use 55% to 65% power setting and it makes getting there fast and easy.

I like the data logging a lot. It is great to be able to look at all the data after a flight. I have all the flights on my PC and the look back ability is very nice. I use the SAVE utility that comes with it, and bought EGview. That is a great piece of software, much better than the spreadsheets I was using. If you are interested go to www.egtrends.com and take a look. BTW, that software supports a number of units.

When on the first flights with a new rear engine it was great to go back and look at the flights and look at all the temps. One comment I have heard is that with the logging, warranty issues become difficult for TCM to dispute.

What don't I like. I wish it had an alarm for OAT so the need to watching for ice could be alarmed.

Pay back - long for sure as the units are not cheap. Try negotiating for a discount. Mind you if you take the 5 year view and don't tell your wife, the cost sort of disappear (unless you are raiding her food budget).

Final word. I like it and I think it has improved my engine management and makes me feel more comfortable that I know what is going on in the engine.

My 14 cents worth.

Regards - Dave

[kevin]

In my opinion, the exchange between Skyking and gwbraly is degenerating into a flame war. The most recent message from each has been deleted. Messages on this board should be an attempt to move forward a civil discussion of Skymaster or O-2 related subjects or they will be removed.

Kevin
webmaster@337skymaster.com

[Ernie Martin]

I'm generally in agreement with Skyking that LOP isn't cost effective given the equipment required, that the extra work (as opposed to enjoying the scenery and spending more time scanning for traffic) isnt worth it, and that the manufacturer's opposition speaks volumes. However, as others have already noted above, I could not find evidence that the Nov. 12 Cessna P210 accident had anything to do with LOP or GAMIs (and even if it did, one incident isn't statistically significant) and I don't find the argument that Cessna didn't put engine analyzers compelling since they were not reasonably priced when these airplanes were designed.

Ernie

[gwbraly]

Ernie,

IF you do a careful Failure Effects Modes Analysis, one of the FAA's favorite activities, one normally comes to the conclusion that the person operating an engine on the rich side of peak EGT needs an engine monitor to protect against a more serious and potentially fatal set of engine failure modes - - than does the person operating with the mixture set lean of peak.

Regards, George

[gwbraly]

No dispute with your removing the messages.

However, I would suggest that at some point, when factually erroneous statements are posted, that are subject to clarification by reference to official public documents, that there needs to be some ability to deal with the truth of the matter.

I don't envy your position in having to deal with that sort of issue.

But surpressing references to public records and crticism pointing out erroneous reports of those records calls for the exercise of some extraordinary wisdom.

My regards, George

[Ernie Martin]

George, you may be right. I have heard your presentation and find all the data very compelling, including the point that at ROP the exhaust valve runs hotter than at LOP. Your engineering expertise also seems very impressive. But like you say, it's analysis. On paper, numbers and equations. In the real world, no one can deny the robustness of these engines when they are operated per Continental's recommendations.

And Lycoming's current response to LOP also speaks volumes: yep, we use to recommend it years ago but it led to many failures, so ROP is the bulletproof way to run these engines. So, the numbers might say one thing -- and in a laboratory environment you may even be able to show these advantages for LOP -- but up in the air, with busy and often tired pilots, some of whom are not technically inclined, do what the manufacturer tells you: stick with ROP.

Ernie

[KyleTownsend]

As Kevin mentioned, there is evidence that running at 100 ROP may be the "wrong" thing to do.

Here is my take on that. In the articles I have read by the LOP proponents, they say that the power setting in the 50 to 100 ROP area are where (1) the effective timing of the combustion event is most retarded, leading to the highest cylinder pressures and (2) this causes correspondingly high cylinder temperatures (note that cylinder temps peak before EGT peaks). Therefore, they conclude that this is the "worst" place to run the engine.

On the other hand, this setting is typically very close to "best power" as published in the POH's, and most performance charts show running the engines at this setting for best power. Also, because the power curve is fairly flat in this area, individual cylinder's will likely be generating closer to the same power, leading to smoother running and less vibration. The POH's usually recommend a maximum sustained cruise setting of 75% power.

On the face of it, the LOP guys appear to have their facts straight. They have proven the data on the test stand, and I have not seen any data which contradicts their published data.

On the other hand, I don't think you can make the across the board statement that this is the "worst" place to run the engines. As I think most everyone now agrees, as long as your CHT's are under 400 or so, it doesn't matter what you do to any great degree. If the engines were designed to run at this power and mixture setting, then it should be OK to run at this setting. I think this is where the 75% limitation comes in. I would imagine that the engines are designed to run at this power and mixture setting to simplify engine management and protect the engines, because any change richer or leaner from this "design point" would actually lead to lower temperatures and pressures.

On the other hand, if you go to all the trouble of getting instrumented, educated, and do run lean of peak, then you should be able to run at sustained power settings greater than 75% while maintaining equivilant temperatures and pressures. Doing this should be fine as well. However, there would be more room for pilot error, as enrichening the mixture from this point could lead to operation at temperatures and pressures beyond the "design point" and possibly induce detonation.

PS:
Returning to the subject of the engine monitors, I emailed JPI for a little info. They said they had no plans at this time to incorporate MP and RPM into the 760, or come out with a twin version of the 800. Too bad. On the bright side, they said they would be offering a $300 discount on units purchased at sun-n-fun. But, it's still a lot of money <sigh>.

[Kevin McDonnell]

Kyle,

In reply to a question you asked several postings back ... No, I no longer have the JPI-760. From your last posting it looks like you can see one of the benefits of using a pair of singles (RPM).

Referring back to a question previously in this thread (hard to believe there's even a debate on this):

The fact Cessna did or did not install a piece of equipment in their aircraft is hardly the basis for determining whether a device is useful or not. The fact the EGT gage was optional should illustrate this point. The single alternator & vacuum configurations are not evidence that redundant systems aren’t needed.

Engine monitors give you a much better view of what's happening in an engine. The digital read-outs let you see trends that are too small to notice on the analog gages. Shock cooling (as a rate of degrees per minute) can be displayed. And, there are alarms that can be programmed when numbers get out of range.

Regarding leaning, let’s say your target is 125 Degrees ROP. By observing the one cylinder that has the Cessna EGT (assuming you have that option installed), you have no clue as to whether the remaining cylinders are closer or further away from peak. It has been clearly demonstrated that the fuel flows at which each cylinder peaks can vary by a couple of gals/hour. You might think you’re running 125 dROP when in reality one of your cylinders could be at peak. Further compound this by having a blocked injector and you’ll unknowingly be running a cylinder LOP (pretty scared for the “non-believers” <grin>). It’s simply not possible to know how you’re leaning these engines without the proper instrumentation.

The Advanced Pilot Seminars shows some very interesting pictures of JPIs that help you interpret some of the monitor numbers. For instance, how can you tell a blocked injector from the beginnings of preignition (which is how you're going to burn a hole in a cylinder). What fluctuating numbers indicate which cylinders have exhaust valve wear?

I personally saw a situation, in which the plane felt fine, but the CHTs were hotter than normal - yet the EGTs were cooler. In my case the shop had set the ignition timing incorrectly. I would not have been able to see this without the monitor (and have prior use to recognize "normal" readings for this installation).