OAT Sensor location M20J

[autopatch]

My temperature sensor for the Garmin GTX 330 is installed in the co-pilot airscoop. I wish he had asked me before he put it there. I'll have to double check tomorrow where it is for the JPI.

[Bennett]

Mine is in the pilot's side cowl vent. LoPresti cowl, and I didn't chose the location, but it seems to work well at that location.

[bradp]

Zombie thread.  Plane came back from paint and the OAT is inop.  I used to recall a button looking thing in the center of an inspection panel under the right wing but now I can't find it.  I have a 1977 J  24-0138.  Not much in the parts catalog or service manual as to the location of the thermocouple.  

I'm pulling inspection panels for the annual (starting Tuesday), so something tells me I'm going to find it in the wig somewhere.  

Thanks -B

[KSMooniac]

Right wing, outboard of the gear in one of the panels. I wonder if your shop removed it for paint and forgot to reinstall... I think I still have my original probe somewhere if you need another, but I don't know if it is still good.

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[dcastor]

Old thread I know, but I'd like to add a data point.  I have a davtron OAT guage connected to a sensor in the right wing (factory location).  Recently an avionics shop installed an EDM-730 for me and I expected they would remove the DAVTRON and put the sensor for OAT in the same spot...no, they drilled a hole in the co-pilot scoop.  On sunny days, the OAT guage reads about 4 deg C warmer than the one under the wing.  So, to those reading this thread, I highly recommend mounting under wing to get a reliable temperature...it could be the difference between icing and no icing.

Dave C

[KSMooniac]

Piss poor behavior by the shop. I would let them know about the difference and ask them to put it in the proper location.

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[cnoe]

The JPI Installation Manual states "Install the OAT probe, P/N 400510 in the airframe manufactures recommended location. If this is not possible, it is recommended that the OAT probe be placed in clean airflow such as in a cabin air scoop or below the underside of the wing away from engine heat or exhaust."

On my J the original (I'd suggest recommended) location is under the right wing outboard of the main gear. I too believe the cabin-scoop mounting location skews the temp measurement.

The problem is that it's considerably more work and time installing the probe in the wing. If the installation cost was quoted it's unlikely they'll place it in the wing unless it's specified beforehand or you pay extra.

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[Andy95W]

On August 10, 2016 at 4:15 PM, dcastor said:

...no, they drilled a hole in the co-pilot scoop.  On sunny days, the OAT guage reads about 4 deg C warmer than the one under the wing.  So, to those reading this thread, I highly recommend mounting under wing to get a reliable temperature...it could be the difference between icing and no icing.

I put mine in the air scoop and it reads very accurately while flying, though I'll admit I haven't really noticed it while just sitting on the ground with the engine only at idle.

But when have you ever gotten ice when flying on sunny days?