OAT Probe Location

[ttflyer]

Hello everyone,

We are getting the GAD13  + GTP59 added to our M20J which apparently is needed for the already installed GTN750xi + G5 + G500 to do "SmartGlide."  Any suggestions on the best location for the temp probe?  The installer is talking about the left side just forward of the wing (easy access to panel).  Is that the best choice?

Thanks!

Ian

 

[ArtVandelay]

I’d remove original OAT probe on the right side and stick it there, I think the roll servo goes on the right side, so you’d have that open anyway.

[PT20J]

23 minutes ago, ArtVandelay said:

I’d remove original OAT probe on the right side and stick it there, I think the roll servo goes on the right side, so you’d have that open anyway.

That's what I did. And I put the GMU 11 magnetometer in the left wing where the old Bendix-King flux gate was originally. I wouldn't put the temp probe on the fuselage because the Garmin probe is pretty big  it will not look great and may be in the way when you clean the airplane.

[KSMooniac]

Put it in an inspection panel under the wing, where it belongs. It doesn't take much more effort.

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[David M20J]

i know a few guys around the airport here who say the access panel just outboard of the main gear

[Yetti]

replaced the original one on the Starboard side wing.   On the Dynon it plugs into the magnometer so I installed that there to on an access panel

[Ragsf15e]

You’ve got the idea at this point… out under the wing on an inspection plate.  It shouldn’t be in the sun.  It should be outside the prop wash.  It shouldn’t be too hard to wire.  If you already have one, that’s a good place to start - remove/replace.  Fwiw, my older airplane didn’t have one under the wing, so mine was installed under the left wing on an inspection panel (not fuel tank obviously) between the fuselage and gear near leading edge of the wing.

[mhrivnak]

My understanding is that the Garmin STC does not allow a G5 (or g3x touch) with GAD13 to replace the original certified OAT, and so you'll need to have two temp probes. Your installer can confirm.

You want the probe under a wing, where it won't be in the path of heat coming off the cowling, nor will it be in direct sunlight. It's more work to run the wire into and through the wing, but worth it. If the installer pushes back, ask to look together at what the installation manual says about placement, and you'll find similar guidance.

[Ragsf15e]

2 minutes ago, mhrivnak said:

My understanding is that the Garmin STC does not allow a G5 (or g3x touch) with GAD13 to replace the original certified OAT, and so you'll need to have two temp probes. Your installer can confirm.

You want the probe under a wing, where it won't be in the path of heat coming off the cowling, nor will it be in direct sunlight. It's more work to run the wire into and through the wing, but worth it. If the installer pushes back, ask to look together at what the installation manual says about placement, and you'll find similar guidance.

Possibly, but if you’re using a g3x and eis, etc, wouldn’t the garmin temp be the primary?  I bet @PT20J knows!

[ttflyer]

Thanks everyone!  That's why was asking.  I wasn't thrilled with the side of the fuse idea!

[PT20J]

30 minutes ago, mhrivnak said:

My understanding is that the Garmin STC does not allow a G5 (or g3x touch) with GAD13 to replace the original certified OAT, and so you'll need to have two temp probes. Your installer can confirm.

 

27 minutes ago, Ragsf15e said:

Possibly, but if you’re using a g3x and eis, etc, wouldn’t the garmin temp be the primary?  I bet @PT20J knows!

I’m not aware of any such limitation. If your installer tells you that, politely ask to see the Garmin document that states that limitation. There is a ton of Garmin documentation and Garmin issues frequent revisions. 

Skip

[mhrivnak]

If you have Garmin EIS, that may be a different story and is worth asking about. My JPI EDM 900 is an approved replacement for the original OAT. The same may apply for Garmin's or another primary engine monitor that displays OAT.

[Wildhorsetrail]

On 5/21/2022 at 9:14 AM, Ragsf15e said:

You’ve got the idea at this point… out under the wing on an inspection plate.  It shouldn’t be in the sun.  It should be outside the prop wash.  It shouldn’t be too hard to wire.  If you already have one, that’s a good place to start - remove/replace.  Fwiw, my older airplane didn’t have one under the wing, so mine was installed under the left wing on an inspection panel (not fuel tank obviously) between the fuselage and gear near leading edge of the wing.

When you say it was installed on an inspection panel, was a hole drilled in the inspection panel to expose the probe to the outside air?

[kortopates]

When you say it was installed on an inspection panel, was a hole drilled in the inspection panel to expose the probe to the outside air?

that’s the idea, i personally wouldn’t actually install it on an inspection panel but just nearby one. i wouldn’t want anything attached to the inspection panels removed at every annual unless it was too hard to avoid - but it’s not.


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[Ragsf15e]

1 hour ago, Wildhorsetrail said:

When you say it was installed on an inspection panel, was a hole drilled in the inspection panel to expose the probe to the outside air?

Exactly what @kortopates said.  I’ll try to get you a picture tomorrow.

[PT20J]

On my M20J, the factory probe was installed on an inspection panel, but it’s in one not regularly removed. In fact, it is one of several attached with pop rivets.

Edited May 24, 2022 by PT20J
Clarified that the panel is NOT regularly removed.

[ttflyer]

Like PT said, our original one is in an inspection panel that is pop riveted on.  They are installing the new probe in the same panel next to the old one.  They didn't want to remove anything.  I'm happy with this location and plan. 

[NicoN]

We have the factory OAT-probe mounted under the right wing.

And also have a second OAT-probe connected to our EDM 830. This on is located in the NACA AIR inlet on the left side/fuselage.

Inside the hangar bot probes show exactly the same temperature, but in the air there is a difference of at least 5-8° Celsius!

The EDM probe is always "hotter", Maybe it is the engine affecting the probe.

 

[ArtVandelay]

We have the factory OAT-probe mounted under the right wing.
And also have a second OAT-probe connected to our EDM 830. This on is located in the NACA AIR inlet on the left side/fuselage.
Inside the hangar bot probes show exactly the same temperature, but in the air there is a difference of at least 5-8° Celsius!
The EDM probe is always "hotter", Maybe it is the engine affecting the probe.
 

You can adjust it in the settings with the 900…don’t know about the 830.

[jetdriven]

Is the original certified oat gauge required? 

[NicoN]

@ArtVandelay: Yes, I know. But the funny fact is: In the hangar they are identical!

[ArtVandelay]

[mention=11849]ArtVandelay[/mention]: Yes, I know. But the funny fact is: In the hangar they are identical!

It is the engine heat….in my case it was 3-4° difference.

[carusoam]

Interesting….

Many Mooneys put the OAT sensor…

• Under the wing
• away from the engine and exhaust heat and sun
• in an inspection panel…

+1 for installing permanently not in a removable panel….  

Things haven’t changed in decades for the OAT sensor…

Best regards,

-a-

 

[Ragsf15e]

7 hours ago, NicoN said:

@ArtVandelay: Yes, I know. But the funny fact is: In the hangar they are identical!

Engine heat and any sun on it will definitely make that one hotter.  The location in the duct is popular with avionics guys installing new equipment who don’t want to take the time to run wires out the wing and install it in a better location.

[FJC]

On 6/8/2022 at 12:40 PM, Ragsf15e said:

Engine heat and any sun on it will definitely make that one hotter.  The location in the duct is popular with avionics guys installing new equipment who don’t want to take the time to run wires out the wing and install it in a better location.

Yup...avionics guy wants to install mine in the NACA duct on right side. Makes sense to place under wing away from heat sources. My 830 probe (I think) is in the NACA duct left side.