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

[GJ Humphrey]

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

[Mark Hislop]

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

[GJ Humphrey]

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

[kevin]

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

[Richard]

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

[GJ Humphrey]

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

[Kevin McDonnell]

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.

[GJ Humphrey]

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.

[Mark Hislop]

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

[Kevin McDonnell]

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 .

[Dave Underwood]

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

[kevin]

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

[KyleTownsend]

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.

[Ernie Martin]

My answers to the last two questions:

No.

Long.

Ernie

[SkyKing]

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