Engine Analyzer Question
 

Hello 337 Devotees,

Can anyone help with the following?

I would like to install two Electronics International UBG-16 engine analyzers in my 73 T337G (pressurized.)

Owing to a paperwork error at the time Electronics International secured STCs for the UBG-16 in a host of airplanes, the STC for the C337 approves installation only in the C337 but not for the various models: C337B, C337G, etc., etc.

My mechanic, therefore, takes the position that the UBG-16 is not STC-ed for the T337G.

I found a 2003 thread on SOAP in which one contributor made the point, that the C337 and its various models were
Type Certificated without a EGT gauge (there was an "economizer" gauge available as an option) and, therefore, any EGT may be installed. These seems logical. Does anyone know whether this reasoning will hold water with the FAA?

However, the C337 was Type Certificated with a cyllinder head gauge. But the installation of an engine analyzer that incorporates a feature displaying cyllinder head temperatures does not replace the required cyllinder head gauge, rather it supplements that guage. Would this argument hold water with the FAA?

Bottom line: can I have the UBG-16 installed in conformance with FAA regs?

Lastly, has anyone had a UBG-16 or any other engine anlayzer installation approved under the Form 337 process?

Best regards,

Gordon

Gordon:

Why two UBG-16's. You can get analyzers that will monitor both engines in one instrument. JPI makes them, and so does Insight. I have an Insight GEMS1200 which shows bar graphs for 12 EGTs, 12 CHTs, and digital readouts for all CHT's, EGTs, two TITs, plus OAT. I think some of the JPI units also incorporate other information such as fuel flow. I believe the Insight unit was STC'd for my aircraft, which is the same model as yours.

Mark

Thanks for replying, Mark.

Yes, you're right about needing only one Electronics International UBG-16. I misstated the case.

The UBG-16 can display all EGTs and all CHTs for both engines. It can also display oil temperatures and pressures. And it has an option for a warning played through the headset whenever any temperature or pressure limit is violated.

The Insight Gemini 1200 or the JPI Twin will do the job nicely, but they don't have the oil pressure and oil temperature feature or the aural warning option.

I'm still hoping a 337 owner has discovered a way to use the UBG-16.

Best,

Gordon

Gordon,

I had an EI US-8A (previous, not bar graph model) in my P337.

I don't see what your mechanic's big obstacle is. The EGT guage is not required on the type certificate, so why is adding an EGT gauge any different from adding an ammeter or such? It just requires a 337, and should be very easy to get approved.

I think your mechanic is right that there may be an issue with the STC. Have you, or he, talked to EI about getting the STC paperwork fixed (by EI)? They are good folks, they might be able to help.

Failing that, I would think getting a field approval on a 337 would not be hard, even in today's environment. EI is well known, aircraft quality stuff that should not create any safety worries in an inspector's mind, and it IS STC'd for the Skymaster.

My two cents, I am sure others will have opinions.

BTW, if you do get the US-16 and buy the voice annunciator, I would strongly suggest you get oil pressure sensors on each engine wired to the annunciator as well. It is cheap to do, and will give you an instant audio warning if you lose oil pressure in either engine, perhaps helping you to shut the engine down in time to save it, or at least reduce the damage.

Kevin

I had one in my NA model. 1967 337B. I guess it all depends on the disposition of the person signing the paperwork. Silly.

Thanks for replying, Richard.

Yes, I think you're right. It depends on which mechanic you speak with and which FAA person he speaks with. You can have one set of facts and two opposing opinions.

I'm hoping that you or another SOAP reader still has the FAA Form 337 approving the installation of the Electronics International UBG-16 in any model of C337. That would help a lot.

Best,

Gordon

I must be missing something here:

The UBG-16 has a graph that shows 7 bars (6 for the cylinders and one for the TIT). How do you use one of these on a twin? Do they have a mode that switches the bar graphs between the two engines?

Furthermore, aren't you going to run out of inputs on that device? The UBG-16 has 16 inputs. You have 12 cylinders in your aircraft. That means you have 12 CHTs, 12 EGTs, 2 TITs (using 26 inputs so far), and you said you want Oil Temp and Pressure. By my count, that puts you at 30 inputs.

I don't understand how you're going to make that work with just one device.

Regarding the earlier comments about using 2 single engine monitors vs. a multi-engine monitor, I greatly prefer having to singles. In my case, I actually removed my JPI-760 and replaced it by a pair of JPI-800's.

Here are my reasons: on each engine you are likely to have a critical temp that you are monitoring. For instance, you might be watching CHT 3 on the front and CHT 5 on the rear. A twin monitor requires you to display the same parameter on each engine at the same time. For instance, both CHT 3's must be displayed if one of them is to be displayed.

Also, the JPI 760 lacked in available inputs, meaning things like RPM weren't available. When you use a digital RPM indicator, you'll see just how poor the Cessna stock gages are. In my case, one of mine was 100 RPM in error. And manually sync’ing the engines with digital RPM is trivial.

Engine Analyzer
 

I was wrong -- again. Electronics International does not make a bar graph gauge that displays both engines in one gauge. One needs two UBG-16s, one for each engine.

I'm now trying to solve the issue of wheter the STC covers the 337G. My mechanic is doubtful, but I've been in touch with the FAA office in Seattle that issued the STC, so I hope to have a definitive answer, which I will post.

Kevin:

I'm not familiar with the JPI product line. I have a GEMS 1200. It is designed for twin engine applications. It has two sets of bar graphs (one for each engine) and two digital readouts (one for each engine). The bar graphs show the EGT's for each cylinder, and use a missing element of the graph to show the CHTs for each cylinder. The digital displays are switch selectable and are independant of each other. So it is possible to have all of you CHTs, EGTs, and independant temps displayed in a single 3 1/8" insturment.

Unfortunately the GEMS does not have inputs for oil temp, voltage, fuel flow, and some of the other things that the JPI apparently has. I already have those things in other instruments, so maybe ultimately we are both using the same number of instruments anyway!

Mark

Mark,

You're correct. The Gemini 1200 does not suffer form the problem I was describing (and I should have remembered that since I have one in my 414A <grin>). The JPI 760 was specifically the unit I was complaining about. It does not let you view different probes for each engine simultaneously .

Form 337
 

I put a JPI Twin with Fuel Flow, OAT and TIT's in my FT337GP (a 1977 Reim's Turbo P model) under a Form 337 with local FAA approval. The FAA was OK, but of note, we left the existing EGT's in place.

Drop me an e-mail and I can scan the form 337 for you.

BTW, it is great to fly with. I run slightly lower alarm limits and it is great to see the alarm when the CHT's start to creep up even though the standard instrumentation is not showing increasing temps. It also helped point out the need for rework of some baffling in two areas that would not otherwise have been seen (two cyls running hotter than the rest).

I had hoped there was an alarm setting on the OAT for icing level temps, but that is not to be.

The Lean Find feature is also great and allows you to lean both quickly and accurately.

Regards - Dave

Note: Please reply to engine analyzer questions in this thread, and use this thread

http://www.337skymaster.com/messages...&threadid=1208

to reply to the rich of peak/lean of peak question.

Thank you.

Webmaster

The more I read about the benefits of these engine monitors, the more I would like to have one. I have tried to stop reading about it, but so far, that hasn't worked.

Looking at the available options, it appears that the EDM-760 is the most powerful and flexible, if you don't already have fuel flow, etc. and want these things. Of course, it is also the most expensive <sigh>.

On the other hand, like Kevin M., I find it dissapointing that JPI hasn't updated the unit to the 800 series so that it will do MP, RPM, and % horsepower.

I suppose Keven has the best of both worlds by using dual 800's. Unfortunately, I don't have the panel space for that.

At first glance, it appears that I am looking at $6,000+ for a JPI with fuel flow. I am curious to know if those of you that have these things feel like the expense was worth it?

Would you consider running LOP without an engine monitor (but with GAMI's) or is this out of the question?

What has been your payback period for all of this technology in fuel savings (assuming you are running LOP)?

PS: Kevin. Do you still have that 760 you took out? I'm in the market, I guess.

My answers to the last two questions:

No.

Long.

Ernie

Dim bulbs ... or bright bulbs?
 

Kyle,

This matter with the addition of the big expensive monitoring system seems to be an exercise in futility. We fly a '77 P337 with AA intercoolers and the only instrumentation we have in addition to the stock items the plane came with is the EGT, which provides a good indication of what's happening with TIT, and a Hoskins 2000A fuel flow instrument. Above all, it seems to me that knowing the amount of fuel flow and quantity used on a trip between fill-ups is FAR more useful info than the 'gidgets' to measure the amount of heat on the end of a Mosquito's leg!! My God man, look at how much fuel $6,000 will purchase! Besides, looking at gadgets with small little dials is taxing... when you're out there for a fun flight. And even more importantly, better to have your eyes looking out the windscreen. Far too much time, energy and resources is spent on unnecessary gadgetry, in my estimation. Look at it this way, if Cessna in its infinite wisdom thought you needed all that junk to fly the plane -- they would have installed it!!!

My Dollar's worth.

SkyKing

Oh no... not another 'LOP' question!
 

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

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

P210... sorry~
 

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

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.

Diagnostic tools... "EWD's" (Early Warning Devices!)
 

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

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

Re: Oh no... not another 'LOP' question!
 

>>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,

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

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

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

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

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

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

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>.

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).

Kyle:

For the most part I agree with your post. A couple of very minor nits in the interest of accuracy:

1) The mixture where the highest CHT's and highest ICPs are noted is between 25 and 75dF ROP.

2) We have tried to induce detonation at any LOP setting without success as long as the timing is set correctly and the fuel is correct.

3) The most detonation-prone mixture setting is 40-50dF ROP. That is a fact of the physics.

Walter Atkinson
Advanced Pilot Seminars

Called TCM
 

I just got off the phone with TCM. They told me that anything that is traceable to the GAMI's that causes a problem will void their warranty. When I pressed, and asked what "anything" meant, the lady told me I would need to call back in the morning and speak directly with the tech department.
I also asked if TCM had ever voided a claim because of GAMI's, call back and ask the Tech guy.
I should say, that I called at 500pm Mobile time and the department closes at 430.

>> do what the manufacturer tells you: stick with ROP.

Ernie<<

Ernie, cut me a bit of slack, please, because my response is going to be a little bit "hard". It is not directed at you, but it is designed to illustrate the problem.

So your statement is "true" - - but only if one excludes each of the following manufactures from the scope of the statement:

Teledyne Continental Motors;
Piper;
Mooney;
Cirrus;
Lancair;
Lycoming;
Cessna;
Beech;

Each one of which specifically approves or endorses operation lean of peak for their most difficult high powered engines.

Regards, George

Re: Called TCM
 

>> They told me that anything that is traceable to the GAMI's that causes a problem will void their warranty. <<

Rick, that is and always has been their warranty position with respect to any STC'd anything that one puts on one of their engines.

You don't have to call, we have a letter that says the same thing.

We have about 10,000 sets of GAMIjectors flying around on TCM engines. We have about 350 Bonanzas and Cessnas, with not only GAMIjector(r) fuel injectors, but also with turbo systems added on to their engines. Naturally, we keep pretty close tabs on these issues. So far, to the best of our knoweldge, after nearly 10 years, TCM has never declined a warranty claim because of either the fuel injectors or the turbo normalizing systems.

Regards, George

It would be great if somebody did a scientific survey of engine longevity in the "control group" (manufacturer recommended settings) versus the "experimental group" (gami's / LOP).

Unfortunately, this kind of thing is pretty hard to do in GA because of the small sample size, fairly long engine life, and number of extraneous variables.

It sure would make it a lot easier to let go of $8,000 or so if I was reasonably certain that I would get it back in extended engine life.

Of course, the fuel savings alone are compelling, but $8K is a lot of gas at my burn rate.

If anybody is aware of any studies like this, I would be very interested.

>In the real world, no one can deny the robustness of these engines when they are operated per Continental's recommendations.

I'm afraid I am going to have to take issue with this statement. I think the robustness of the engines is questionable. I was looking at some back issues of Aviation Consumer a while back, and they listed the TSIO360 engines in their "worst engines" category. Their basis was an informal survey of overhaul shops. Apparently, these engines are quite a bit less likely to make TBO than the average engine (especially not without some top-end work).

It would be easy to blame the pilots and just say that there are too many "ham handed" pilots flying around in Skymasters. However, I doubt, as a group, that we are any worse than Barron owners, for example.

Looking back at our log books, neither of the engines even came close to making TBO. While I suppose that the previous owner may have been "ham handed," he sure didn't strike me as that kind of guy. Quite the contrary, he seemed to be a very precice and conservative "engineer type" who really took care of the plane (he was the only owner since new, and was trading up to a King Air).


PS: I am not trying to make the argument that running LOP would solve this problem. I think the jury is still out on that. It's just an observation.

Kyle,

That's a great point about a controlled study of engine longevity. It's strange that the manufacturers haven't done this, but I suspect it would only further illustrate their poor QC.

What would you expect to see if you tested two identical engines in exactly the same conditions, power settings, fuel flows, leaning techniques, temps, etc.?

This is exactly the environment in which twins operate. You might argue that a Skymaster front vs. rear engine is not an identical installation, so let's leave that out of this example. A conventional twin with a right and left engine are operated this way.

Just look at Trade-a-Plane and see how many twins have very different times on their left & right engines. Continental & Lycoming can blame pilot operation all they want, but this example clearly shows that the problem with these engines is in the manufacturing.

Kevin,

The twin argument might well be correct, but it might not.

For example, how many of those twins had the fuel flow set up "differently" for the left and right engine, so that they experienced very different internal cylinder pressures on each takeoff and climb?

Clearly TCM is having problems with valve fit and geometry.
We saw one 78 hour TTAFE Bonanza that had a prop strike. On engine tear down, the #6 exhaust valve was wobbly in the valve guide - - at 78 hours of run time.

Regards, George

I strongly suspect (but can't prove) that the #1 factor in engine longevity for the piston fleet has more to do with usage patterns. Or, more accurately, lack of usage. I doubt that there are many airplanes out there that don't experience an occasional period every few years where they sit for 30 days or more without being flown.

I read an article some time ago that supports this theory on an anecdotal basis. I was about one of the commercial piston operators (cape air or island air, I think). Their operating policy only allowed their pilots to use 4 distinct power settings for simplicity. They didn't have engine monitoring or anything fancy. And yet, they routinely made extended TBO's in their 400 series Cessnas (I believe the extended TBO was in the 3,000 hr range).

I am guessing that quality control at the factory would be the #2 factor, and that engine mismanagement would be #3.

I think that it is telling that we don't have anything like "Power by the Hour" in the piston fleet (to my knowledge). The turbine boys have had these kind of programs available for years. I can't believe that entrepenuers (or even the factories) haven't looked at offering this for piston engines, and have run scared because of the variability in piston engine life.

Kyle:

I'm going to combine a few comments into one post. Some of these things are not in answer to you, but to others.

The scientific study you would like to have done has already been done... long ago. The results were very compelling and support the statements George, Tom and I have made in this thread and in others. The study was over a sample size of 400 MILLION flight hours of data. No one I know (who has read it) thinks there is any reason to duplicate it. It would be very expensive to do so, and to what end? TCM and Lycoming DATA agrees with that study.

More recently, the FAA conducted a study which proved beyond any doubt that lead is not a lubricant for valves, but that OWT won't go away either.

The concern over the cost of an engine monitor to save gas is misplaced in my opinion. Engine monitors tend to pay for themselves all at once and in spades. The cost savings is not over fuel, it is over a serious engine problem which threatens your wallet and/or your life. My best calculations figure that my engine monitors pay for themselves at least once every two years in maintenance savings alone. I have a growing list of pilots who have saved their engines and their LIVES becasue they had an engine monitor. That's not at all an exaggeration. Do not buy an engine monitor to help you lean the engine. It will do that, but buy and engine monitor to save you maintenance costs, save your engine, and maybe yourself. I don't know a single pilot who understands how to interpret an engine monitor who is now comfortable flying without one. It was an unexpected effect of having the information so radily available.