Dynon EGT Probes

[Derek]

My aircraft has been flying for a little over 18 months now, during that time Ive replaced all 4 EGT probes (faulty).

A few weeks ago I got this on my display and immediately thought "oh no here we go again".





Upon inspection I decided to pull on the wire crimps and guess what, one of the wires popped straight out.




Lesson: Before assuming the probe has gone belly up, check the crimps.

[Pmerems]

I too have had issues with the factory crimps on the CHT and EGT probes. After an intermittent EGT reading I replaced the factory connector and crimped new ones on. No issues since.

[dlloyd3]

I was surprised by the picture. All the bad crimp problems I experienced on the EGT probes were on the probe side of the connection. Recrimp and solder solved the problem for me.

[ArlingtonRV]

I just replaced #1 and #2 on mine. #1 failed first and I tried re-crimping (both sides of the connection), but it didn't help.

Does anyone know of another sensor that will work with a Skyview system?

[Derek]

in another aircraft, during previous EGT probe fault finding missions, I replaced the faulty Dynon probe with the GRT one, it worked fine (and still is).

The probes look slightly different, the GRT probe has thicker insulation on the wires. As for exact technical differences, I can't comment.

[RV7A Flyer]

Had one go bad at around 75 hours, now have another one giving up the ghost at 345. In between, have recrimped a couple of them, as well.

I've heard everything from "EGT probes are a consumable" to "mine have lasted for [some ridiculously long time]".

I don't know if Dynon's EGT probes are just cheaper, or if all of them are pretty seriously life-limited, but it does seem to me that after all these years of airplanes, there *must* be more reliable solution out there somewhere.

Grrrr....

[dynonsupport]

EGT probes are a compromise.

You want them to react as fast as possible, which means you want the metal around the probe to be as thin as possible to have the lowest thermal mass. However, making thin metal that survives at 1,600F in combustion gasses for thousands of hours is a challenge.

So, you can go with thick metal, and deal with the fact that it can take 20 seconds for the temperature to read right. Or you can go thin, and deal with the fact that after a long time, they will burn though.

The rate at which they burn through has everything to do with where they are and how you operate your engine. The closer to the valves they are the hotter they run and the quicker they wear. The more you run LOP the nastier the gasses are too.

Dynon has had two probe types over the years. The first were stainless, and were fine, but about 4 years ago we switched to an Inconel sheath which does better in the exhaust environment. All our probes are "fast acting" meaning they prioritize speed of reaction over long life. As most people appreciate with Dynon, they do also prioritize cost. Note that our probes are only $36 each, and you are getting an Inconel probe at that price.

Now, if you actually burned though one in 75 hours, that's not normal. In our experience, an engine running about 1,450F cruise should last around 1,000 hours. My plane has 800 hours in 3 years and runs LOP all the time and all the probes are still fine. Runs about 1,500F in cruise.

With your SkyView, you can run any K type thermocouple for your EGT. There are lots of vendors, and some may be more robust. Generally these will cost more per probe and will be slower reacting, but electrically they will work fine with SkyView (or any Dynon EMS)

--Ian @ Dynon

[ArlingtonRV]

Is it normal for the metal in the probe to deform? I had to replace 2 after 25 hours and they were a bear to get out of the hole in the exhaust pipe. The #2 probe was obviously bulbed at the end. The #1 was so deformed that it broke coming out through the hole. The new ones fit in perfectly.

Thanks

[s24789]

The metal crimp on connectors annoyed us so we purchased dual TC wire connectors from Omega. Make replacements much easier and th connection are not subject to vibration. Have them on 4 CHTs and 4 EGTs.

[RV7A Flyer]

Originally Posted by dynonsupport

EGT probes are a compromise.

You want them to react as fast as possible, which means you want the metal around the probe to be as thin as possible to have the lowest thermal mass. However, making thin metal that survives at 1,600F in combustion gasses for thousands of hours is a challenge.

So, you can go with thick metal, and deal with the fact that it can take 20 seconds for the temperature to read right. Or you can go thin, and deal with the fact that after a long time, they will burn though.

The rate at which they burn through has everything to do with where they are and how you operate your engine. The closer to the valves they are the hotter they run and the quicker they wear. The more you run LOP the nastier the gasses are too.

Dynon has had two probe types over the years. The first were stainless, and were fine, but about 4 years ago we switched to an Inconel sheath which does better in the exhaust environment. All our probes are "fast acting" meaning they prioritize speed of reaction over long life. As most people appreciate with Dynon, they do also prioritize cost. Note that our probes are only $36 each, and you are getting an Inconel probe at that price.

Now, if you actually burned though one in 75 hours, that's not normal. In our experience, an engine running about 1,450F cruise should last around 1,000 hours. My plane has 800 hours in 3 years and runs LOP all the time and all the probes are still fine. Runs about 1,500F in cruise.

With your SkyView, you can run any K type thermocouple for your EGT. There are lots of vendors, and some may be more robust. Generally these will cost more per probe and will be slower reacting, but electrically they will work fine with SkyView (or any Dynon EMS)

--Ian @ Dynon

I don't know that I've actually "burned through" any of the ones I've replaced; it seems the problem is more in the connectors, but I frankly gave up trying to recrimp them and/or put on new connectors and just replaced the ones that quit working. They *looked* fine when I pulled them out, but who knows?

I know that the solid wire-crimp has always been a problem...just wishing a better solution was out there for these connections.