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Is a primary EGT required?


jaylw314

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I was thinking of upgrading my EDM 711 (essentially a primary version of the 700) to an EDM 730 or 830, but I have a potential problem--the factory EGT gauge was removed and the EDM 711 was installed in its place.  The EDM-711 is supposed to function as primary for CHT (I still have the factory sensor and gauge as well), but I can't tell if it is primary for EGT, or if a primary EGT gauge is even required.

So I'm hoping to be able to upgrade to an EDM 730 or 830, which are non-primary.  Since I still have the factory CHT, oil pressure/temp, I presume this is okay.  My only worry is that I need a primary EGT gauge, in which case my only options would be the EDM 900, or to reinstall a primary EGT gauge (which sounds stupid).

Does anyone know if a primary EGT is required (and if the EDM-711 fulfills that function)?

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Your POH will list all of the required instruments for flight...

Expect one CHT is required...

Expect that there is no requirement for EGT... as most of the early Mooneys didn’t need one, but got an uncalibrated one anyway...

The POH is the reliable resource...  look for day/night/VFR/IFR.... better and more specific than tomato flames...

PP thoughts only, not a CFI...

Best regards,

-a-

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I don't believe there is an aircraft manufactured with a required primary EGT gauge.  TIT, sure.  Some manufactures have mistakenly labeled a TIT probe EGT, but it's not monitoring a single cylinder's temp, it's monitoring the temp at the collector, just before the turbo.  There are far too many factors that can affect absolute EGT temperatures.  Type of probe, thickness of the material used and the installed distance from the cylinder to name a few.  As such, absolute temperature is not nearly as important as the temp relative to peak.  

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Some NA G1000 equipped planes have a 7th  EGT TC (mis?)labeled TIT... It is resident after the confluence of three exhaust streams...

Similar planes with the same 7th TC have an analog gauge marked EGT... It is calibrated with temperature ranges clearly marked.  The location is set by the engine/plane builder....

This TC has a higher reading than an ordinary single cylinder EGT... solely because it is an average of three exhaust pulses in the same period of time as the single cylinder EGT...

PP thoughts only... not an instrument guy...

Best regards,

-a-

 

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I've certainly got all I need without an EGT gauge according to required equipment for VFR/IFR, there's no MEL for an M20J, and there's certainly no safety issue not having a factory EGT gauge.  I just wanted to double-check there wasn't some little gotcha buried in the service manual or something...

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Big gotchas everywhere...

Are you sure there isn’t an MEL for an M20J?

That doesn’t sound right.  The MEL is in the Mooney POHs back in the 70s...

 

Want to see an example of somebody that could have used some non-required instruments..?

Often we find engine monitors to be very valuable when engine problems arise... they do without warning, and last until fixed...

Problem solving itself is a similar price as the engine monitor... pay for the problem solving, and not have the monitor when you are done...

 

FF instruments are pretty good, a fuel totalizer makes it more valuable...

Digital fuel level instruments aren’t required either, but make really good sense when flying long distances...

 

We have a few MSers that have engine incidences that are diagnosable in flight using an engine monitor...

We have a few MSers that have run out of fuel in flight... and more Mooney pilots that aren’t MSers...

 

The really cool thing about an engine monitor... you can download the data, and have somebody else read it with you... no requirement to be an engineer or a mechanic...

 

I’m not looking for the government to require anything before I act on some things...

EGT gauges, are required to get reliable fuel usage data... without FF instruments... 50°F ROP?  

The mixture knob without an EGT gauge is impossible to know the FF with any accuracy...

EGT gauges, are required to get decent protection from operating in the red box...

Engine monitor is required to find a blocked FI...

Engine monitor is required to identify a sticky valve before it becomes a stuck valve.

Nothing like having a stuck valve in flight...  having an engine monitor will help with the diagnosis, and planning the landing, straight ahead, or circle to a runway... (experience helps)

 

A single EGT is dirt cheap and probably pays for itself in one flight by better controlling FF...

What is the logic of not having one? :)

Best regards,

-a-

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Anthony, the OP's plane had EGT replaced by an early JPI engine monitor that was certified for EGT. He now wants to upgrade to a more modern JPI, but is concerned about the legality if flight without a certified EGT. Neither 730 nor 830 are approved for primary gage replacement. 

Sounds like he may be good to go, but I'm the wrong person to ask. My original EGT works fine, no monitor yet . . . .

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15 minutes ago, carusoam said:

Big gotchas everywhere...

Are you sure there isn’t an MEL for an M20J?

That doesn’t sound right.  The MEL is in the Mooney POHs back in the 70s...

...

A single EGT is dirt cheap and probably pays for itself in one flight by better controlling FF...

What is the logic of not having one? :)

Best regards,

-a-

Well, for me the EDM 730 or 830 would be relatively easy upgrade in terms of ergonomics.  I already get the same info on the 711, but the presentation leaves something to be desired--having to press the step button a few times to get to OAT, then a few more times to get back to temps just seems like a distraction I could do without when I'm work saturated.

There was an MEL in the earlier POH's?  Mine doesn't have one, and I assumed the vast majority of single-engine piston aircraft don't?

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Just grabbed my M20C POH off the shelf...

Section 4, Limitations...

Required equipment

It has a page or so of ‘required equipment’, including landing gear position indicator.... :)

Is that the light, or the big chrome handle in the block marked down and locked?

CHT is there, no EGT listed...

 

Having one makes sense... even if not primary, or required...

 

Check your POH, Mine is the October 1977 version for the M20C...

Best regards,

-a-

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1 hour ago, gsxrpilot said:

Give yourself a Christmas present and step up to the EDM-900. Primary for everything and as the most used instrument in my panel, at around $4K, the hands down best value per dollar of anything in my panel.

I thought about that, but I just don't feeling like bothering with taking out the old primary instruments and redoing the panel.  My panel already looks like Frankenstein, but I don't want the cost of making a new panel.  So I couldn't see the advantage of the 900 if I'm just going to leave the old instruments in place...

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7 minutes ago, orionflt said:

the CGR-30 will allow you to use the existing holes for the tach and MP gauges and give you all the primary instruments. you can put a blank off plate where the old gauges were.

Brian

If you are at all interested in upgrading from the EDM-711 to our CGR-30P, we have an upgrade path available that will save quite a bit of money and labor as the upgrade utilizes the existing CHT/EGT probes and cables.  If you are not interested in replacing existing gauges, I would suggest our CGR-30P Basic with includes RPM, EGT, CHT (can be primary), fuel flow, OAT and volts.  Please PM me for details or send me an e-mail at support@buy-ei.com.  We may be able to offer additional discounts as we are looking for willing aircraft owners to assist in the launch of these new upgrade packages.  

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13 minutes ago, oregon87 said:

If you are at all interested in upgrading from the EDM-711 to our CGR-30P, we have an upgrade path available that will save quite a bit of money and labor as the upgrade utilizes the existing CHT/EGT probes and cables.  If you are not interested in replacing existing gauges, I would suggest our CGR-30P Basic with includes RPM, EGT, CHT (can be primary), fuel flow, OAT and volts.  Please PM me for details or send me an e-mail at support@buy-ei.com.  We may be able to offer additional discounts as we are looking for willing aircraft owners to assist in the launch of these new upgrade packages.  

I'll keep that as an option, my thinking was more along the lines of making a simple swap out of the 711 for the 730, and then connecting the RPM and MAP a later date.  Does the CGR-30P use the same wiring harness as the JPI instruments?

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Part of the upgrade package is to build conversion harnesses from the existing monitor's cabling, whether it be E.I, JPI, Insight, etc, to interface with our system.  Worth noting, the Basic version of the CGR-30P does not typically include manifold pressure, however, I'd be happy to go to bat for you and see if there is something custom we could do for you.

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2 minutes ago, oregon87 said:

Part of the upgrade package is to build conversion harnesses from the existing monitor's cabling, whether it be E.I, JPI, Insight, etc, to interface with our system.  Worth noting, the Basic version of the CGR-30P does not typically include manifold pressure, however, I'd be happy to go to bat for you and see if there is something custom we could do for you.

Hmm, the idea of included conversion harnesses intrigues me.  I will be thinking more about the CGR-30P if and when I do this, then.  I'll have to swing by Pacific Coast Avionics, I remember they had a running demo model of it on display...  Thanks!

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7 minutes ago, jaylw314 said:

Hmm, the idea of included conversion harnesses intrigues me.  I will be thinking more about the CGR-30P if and when I do this, then.  I'll have to swing by Pacific Coast Avionics, I remember they had a running demo model of it on display...  Thanks!

You are most welcome!  Dewey, Randy and the crew know our stuff well and can certainly help you out.

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I've done engine monitors in two Mooneys. My thought was always to be as economical as possible without spending money that would be completely wasted if I needed to take a step further.

The factory gauges don't last forever and eventually will have to be replaced. The CGR-30P allows you to take a "smaller economical" step forward. And when the factory gauges start failing, you can take another step of adding the 30C to complete the Primary replacement.

Any of the JPI units short of the 900, will be completely wasted $$ and work, if/when the factory gauges start failing and you have to go to a Primary unit.

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42 minutes ago, gsxrpilot said:

I've done engine monitors in two Mooneys. My thought was always to be as economical as possible without spending money that would be completely wasted if I needed to take a step further.

The factory gauges don't last forever and eventually will have to be replaced. The CGR-30P allows you to take a "smaller economical" step forward. And when the factory gauges start failing, you can take another step of adding the 30C to complete the Primary replacement.

Any of the JPI units short of the 900, will be completely wasted $$ and work, if/when the factory gauges start failing and you have to go to a Primary unit.

That may be, but how often do they fail?  I mean, most of my primary factory gauges are still working after 30 years, I just can't see the idea of PLANNING for them to fail.  If they do fail, how costly is it to replace them?  The previous owner replaced the tach with an EI-R1, and that's "only" about $500.  I'd much rather deal with the rare small expense than foot a significant up front expense. 

My main priority is having available information displayed in a more useful fashion rather than eliminating the old gauges.  The fact that this may not be my forever plane also weighs into that decision.

I see where you're coming from, and it does make sense with other priorities, but YMMV

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1 hour ago, jaylw314 said:

That may be, but how often do they fail?  I mean, most of my primary factory gauges are still working after 30 years, I just can't see the idea of PLANNING for them to fail.  If they do fail, how costly is it to replace them?  The previous owner replaced the tach with an EI-R1, and that's "only" about $500.  I'd much rather deal with the rare small expense than foot a significant up front expense. 

My main priority is having available information displayed in a more useful fashion rather than eliminating the old gauges.  The fact that this may not be my forever plane also weighs into that decision.

I see where you're coming from, and it does make sense with other priorities, but YMMV

I see your point. And since the Tach has already been replaced, you're ahead. That's often one of the main ones that fail.

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Has anybody with a vintage Mooney installed a JPI EDM 900 in the position where the cluster gauge pack is?   It appears to be a fit but may be close. Also does it make sense to keep the multi pin cannon plug on the back of the cluster gauge and have a harness made using a male cannon plug connector for the JPI.  It might allow a simple replacement back to original if the JPI needs long term repair?

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It appears to be a fit but may be close. Also does it make sense to keep the multi pin cannon plug on the back of the cluster gauge and have a harness made using a male cannon plug connector for the JPI.  It might allow a simple replacement back to original if the JPI needs long term repair?

No, it requires special wiring, reusing old wiring is sure to cause problems. The sensors cannot be connected with copper wires.
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My EGT only has marks with no numbers.  There is an astrick on one of the tick marks.   By everyone else's digital numbers, bar graphing standards, my plane should not even be able to make it off the ground.  Per the POH the tick marks are important as in go here, then reduce 2 tick marks.

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