What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Garmin GEA 24 location in RV-8 ?

humptybump

Well Known Member
I am interested in where builders / shops install the Garmin GEA24 engine instrument module in an RV-8 ?

I'd also like to know if the EGT/CHT wires in the sensor kit can reach this location without needed extensions.
 
Glen,
There are no wires in the sensor kit for the EGT/ CHT probes.
You will need to get some 22 gauge type K thermocouple wire for that.
In the past, I've found the 6 foot harness that is usually standard to be a little short. I now order 64 ft of thermocouple wire and make the harness 8 ft long.
I never wind up short that way, and can mount the module anywhere convenient.
 
Thanks Jon, I didn't realize the EGT & CHT probes would come without wire. My prior setup came with the wires attached to those probes and they were a little short (as you noted).

I'm still looking for recommendations on where others installed their GEA 24.
 
It seems to me that the goal should be to keep the GEA 24 close to the engine instead of close to the instrument panel. There are many wires to the engine and two wires to the rest of the G3X system (is that a correct statement?).)

For instance, on a pusher aircraft with the engine in the back, I'd mount the GEA 24 on the cool side of the firewall (perhaps 6 to 8 ft from the IP). On a twin, I'd mount each GEA 24 out on the wings near the engines.

Am I looking at this correctly?
 
In an RV-8, the cool side of the firewall is either the pilot footwell or the baggage compartment. I feel both are a compromise and hope some RV-8 builders/installers can comment on their choices.
 
I am also looking for a suitable location. I am thinking I might put it on the underside of the floor of the forward baggage compartment. That keeps it out of the way of rudder pedals, but close to the firewall.
 
It seems to me that the goal should be to keep the GEA 24 close to the engine instead of close to the instrument panel. There are many wires to the engine and two wires to the rest of the G3X system (is that a correct statement?).)

For instance, on a pusher aircraft with the engine in the back, I'd mount the GEA 24 on the cool side of the firewall (perhaps 6 to 8 ft from the IP). On a twin, I'd mount each GEA 24 out on the wings near the engines.

Am I looking at this correctly?

Nope!

The module gets a quite a few other inputs besides engine. Mount it on the aft side of the fwd baggage wall or on a shelf between the gear tower cross braces.
There is no need to keep it close to the engine other than the cost of shielded and thermocouple wire.
 
Mount it on the aft side of the fwd baggage wall or on a shelf between the gear tower cross braces.

OK, I'll plan to install it on a shelf behind the instrument panel and plan for an appropriate route for the wire bundle that will come from the engine compartment.
 
Yep.

We looked at this for a little while and put the EIS at the back of the instrument bay on the right side as we ran our wiring out to the engine just under the lip of the baggage door through the fire wall there. This seemed to be a good place so that all the wiring would reach as needed. Just where we put ours. Yours, R.E.A. III #80888
 
Mine is mounted on the left side of the fwd baggage compartment aft bulkhead, inside the volume between the panel and the bulkhead. The GEA24 has four DB connectors, hence a LOT of interfacing, so I found it convenient to keep it close to most of my other avionics. I have two firewall penetrations for cable bundles, the left side for "data" connections, and the right side for "power" wiring.
 
I made a shelf between the Z-bracket between the gear Towers and the Z-bracket behind the baggage compartment. On this shelf I mounted on top the GSU-25 and the GAD-27 and below the GEA-24 and the FLARM (anti collision device mostly used in Europe). Here are some Pictures (not yet finished with the cabling thus it looks not organized).
2whh8jr.jpg


2u9tsmx.jpg


14u86sz.jpg



27yai54.jpg


I hope this helps. I cant yet say if my shelf is stable enough as the Manual calls out a very stable shelf for the GSU-25. But I am confident otherwise I will replace it by a much stronger one.
On the shelf everything is done with anchor nuts to be able to unmount a device more easily. I can reach all the connectors from below the instrument panel or by removing the big GDU-460. So I do not have to deal with nuts and washers once everything is installed. This installation also allows me to remove the baggage floor without having to unscrew something which is mounted to it. Thus it should be easy to check any cable from the panel towards the engine / firewall.
 
Last edited:
Just fine.

I made a shelf between the Z-bracket between the gear Towers and the Z-bracket behind the baggage compartment. On this shelf I mounted on top the GSU-25 and the GAD-27 and below the GEA-24 and the FLARM (anti collision device mostly used in Europe). Here are some Pictures (not yet finished with the cabling thus it looks not organized).
2whh8jr.jpg


2u9tsmx.jpg


14u86sz.jpg



27yai54.jpg


I hope this helps. I cant yet say if my shelf is stable enough as the Manual calls out a very stable shelf for the GSU-25. But I am confident otherwise I will replace it by a much stronger one.
On the shelf everything is done with anchor nuts to be able to unmount a device more easily. I can reach all the connectors from below the instrument panel or by removing the big GDU-460. So I do not have to deal with nuts and washers once everything is installed. This installation also allows me to remove the baggage floor without having to unscrew something which is mounted to it. Thus it should be easy to check any cable from the panel towards the engine / firewall.

You should be just fine with this shelf. We made one that goes all the way from the lower lip of the instrument panel to the Z bracket. it is made from 3/16" plate and runs from about 3" from the right side to a little over half way across to the other side. This lets us mount the TX under the shelf, crosswise and most of the other boxes on top. This also stiffens the panel and the AHDAR can be put on the back of the GDU. All we have to do to service or inspect inside is unscrew the 10.6" GDU and pull it out of the way, with the quick little Safe Air fittings on the back of the AHDAR, the unit can be taken out in less than two minutes and put on the wing or bench out of the way. Good work, keep it up. Yours, R.E.A. III #80888
 
Last edited:
I have an existing shelf between the two Z braces. It has the remote transponder. I will replace it will a larger one to accommodate the GeA24.

Of course, this work would be an order of magnitude easier "during a build" then as a redux since nearly everything needs to be accomplished from within the cockpit and through the panel. :eek:
 
Little things.

I have an existing shelf between the two Z braces. It has the remote transponder. I will replace it will a larger one to accommodate the GeA24.

Of course, this work would be an order of magnitude easier "during a build" then as a redux since nearly everything needs to be accomplished from within the cockpit and through the panel. :eek:

If you cut out the upper panel between the instrument and baggage and also make the hinge pin removable for the front baggage door, you can come in from both sides if you like. Just an extra idea that worked for us. Yours, R.E.A. III #80888

P.S. we did this all after the airframe was all together. Its not that bad.
 
Last edited:
If you cut out the upper panel between the instrument and baggage and also make the hinge pin removable for the front baggage door, you can come in from both sides if you like.

I can't imagine how you cut that area, added all the necessary nut plates and riveted the hinge..

Any change you got some photos?
 
No need.

I can't imagine how you cut that area, added all the necessary nut plates and riveted the hinge..

Any change you got some photos?

Drimal cut-off disk, throw the cut-out into the spares box, make a cover plate and put 8-32 screws about every two inches or so. You squeeze the nut plates to the bulked from the inside, with the instrument panel out of the way.
After you prime everything first that is. Hope this helps, just what we did.
Yours, R.E.A. III #80888
 
20 or 22 Gauge thermocouple wire will work

I wanted to add to an earlier comment about thermocouple wire being 22 gauge. With the GEA 24, either 20 or 22 gauge thermocouple wire will work. The GEA 24 uses standard density DSUB pins which can handle the 20 gauge wire. From my experience, the 20 gauge wire is cheaper and more readily available.
 
Thanks Levi. That is good data to know.

Glen,
There are no wires in the sensor kit for the EGT/ CHT probes.
You will need to get some 22 gauge type K thermocouple wire for that.

I asked G3Xpert the question regarding probe wires. Here is the message I received:

The length of the EGT and CHT wires are not critical. The extension wire for the EGT and CHT does have to match the wire that the probes have. This is usually Alumel/Chromel wiring and it red and yellow in color. This is for the Type K thermocouple EGT and CHT probes that come with the 4 cylinder engine kit.

This suggests there is wire attached to the probes. I am a bit confused. It looks like there is wire but it's not clear if it's a pigtail or a few feet.
 
Hello Glen,

There is about 12" of wire on the CHT probe and 10" on the EGT probe.

86253-new.jpg


4536-300x210.jpg


There is a large section in the G3X Installation Manual dealing with EGT/CHT probe installation. Page 23-15 of the Rev. AB manual explains that you will need to obtain the appropriate amount of 22 AWG type K thermocouple extension wire and even provides a supplier and part number for this wire.

Many of the common aviation electrical parts suppliers also stock type K extension wire. As Levi reported, you should also be able to use 20 AWG type K extension wire which is more readily available.

Thanks,
Steve
 
The probes have about 1 foot of wire and a #4 red ring terminal attached.
You will need some # 4 ring terminals to mate up to the probe terminals.
#4 screws, nuts, and lock washers are supplied with the probes.

Yes, 20 or 22 gauge wire will work. A friend ordered 24 gauge from Spruce and although it will work, it looks like it might be a pain to strip.
 
Of course I reply at 7 am eastern time, and can't beat G3Xpert Steve, who replied at 5:59 CST!!!!!!
 
There is about 12" of wire on the CHT probe and 10" on the EGT probe.

Thanks Steve,

Neither my inquire to g3xpert nor the documentation clued my in on "how much wire" was on the CHT probes.

Your answer and photos were what I had been looking for.

BTW: given the short length of leads, the following documentation is a bit silly - "If the supplied sensor wires are not long enough to connect directly to the GEA 24/GSU 73, then Type K TC extension wire must be used."

Garmin's short pigtails and placement guidelines make it impossible to not use extension wire.
 
Last edited:
Of course I reply at 7 am eastern time, and can't beat G3Xpert Steve, who replied at 5:59 CST!!!!!!

Sometimes I think Steve is an advanced artificial intelligence with thousands of pages of documentation in memory, the ability to type complete sentences in milliseconds, and is able to stay online 24 hours a day, sevens days a week. :rolleyes:
 
Last edited:
Garmin TC wiring

I was planning to use MGL avionics BECAUSE the engine monitor can be mounted on the engine side of the firewall. I have had numerous issues on my -3 and replacement of long TC wires through the firewall potted with firebarrier 2000 is a PITA. I was told at OSH in the Garmin tent that the GEA24 can tolerate 400F, but the Xteam on the phone says the manual insists cabin side of the firewall.

I have started ordering G3x components and had decided to live with the PERCEIVED shortcoming of troubleshooting TC's terminated aft of the firewall. Thank you G3expert for the pics of of short ( easily replaced) sensors. This is one of many examples of Garmins mastery of their purpose.
 
Hello Glen,

There is about 12" of wire on the CHT probe and 10" on the EGT probe.

86253-new.jpg


4536-300x210.jpg


There is a large section in the G3X Installation Manual dealing with EGT/CHT probe installation. Page 23-15 of the Rev. AB manual explains that you will need to obtain the appropriate amount of 22 AWG type K thermocouple extension wire and even provides a supplier and part number for this wire.

Many of the common aviation electrical parts suppliers also stock type K extension wire. As Levi reported, you should also be able to use 20 AWG type K extension wire which is more readily available.

Thanks,
Steve

Re-opening this old thread to ask maybe a dumb question: When extending these probes with type K thermocouple wire, I assume you need to crimp a similar #4 ring terminal on the extension cable in order to mate with the ring terminal on the wire from the probe. Question is: Do you need a special ring terminal just for thermocouple wire? My understanding of this wire (from reading multiple threads) is that using a connector of any sort made out of the wrong metal will introduce errors in the sensor reading.
 
According to the installation Manual (Rev. AL / Page 24-19) it only says to place the connectors / splices close together to assure that they have the same ambient temperature.
I have used the Omega Connectors but I assume that a normal ring connector will do the job as well.

Yves
 
Ryan, I did how you described above by just using the #4 ring terminals and have not had any issues that I know of. I just used the aircraft quality terminals that you buy from places like ACS or Stein and not the junk they sell at the auto part store.

Maybe my readings are off by a few degrees because of this? :confused::rolleyes: Naaah:D
 
As long as the connections are in the same location (temperature) and made from the same materials, the junction effects cancel each other. i.e. use the same ring terminals on both wires.
 
Back
Top