OAT Sensor location M20J

[mcpilot]

Hello everyone,

 

My AP is installing an JPI EDM 830 in my MSE.  He asked where I would like the OAT sensor placed.  Any suggestions from you folks that already have this installed would be appreciated.

 

Regards.

 

Mike

[Marauder]

Most people install it in the pilot or co-pilot air scoop (where the eyeball inlet is by your knee). My AP installed it on the wing itself. Don't like it there.

[mcpilot]

That's what I thought... I can't remember how it was in my 231, is it hiddden in the scoop or just coming off of the side 90 degrees to the airframe?

[Marauder]

That's what I thought... I can't remember how it was in my 231, is it hiddden in the scoop or just coming off of the side 90 degrees to the airframe?

 

The ones I have seen have it mounted right in the scoop. Except for mine, which is mounted behind the leading edge hanging straight down.

[fantom]

It's not sticking out, but horizontal, in the scoop. Rumor that readings are inaccurate in this location are incorrect in my experience. It agrees with the factory OAT.

[KSMooniac]

The factory put the OEM one in an inspection panel under the right wing, for a reason.  Putting it in the fresh air scoop subjects it to warm engine air as well as possible direct sunlight, both of which can make it read higher than actual.  When you're flying in cloud do you want to know if it is 30 degrees or 35 degrees?

 

I added a secondary probe on the left wing opposite the original factory location.  It isn't that much harder to do it right...

[bumper]

On the underside of the wing a couple of feet out from the root. The underside of the wing has some advantages for computing density altitude when on the ground (shaded, though will be affected by radiant heat from the tarmac - - not entirely a bad thing). Easy to wire in this location.

 

In flight I agree that a probe in the air inlet should not be much affected by engine heat.

 

bumper

[mcpilot]

Thanks very much for the helpful info guys...  Very much appreciated.

[Bob_Belville]

My OAT probe for the EDM 930 is on the port side below the rear window. The shop used the same hole that had been an OAT probe used with an old Davtron 5 function instrument that was mounted on the far left of the panel which might explain the location.

[FlyDave]

I have an Davtron unit with an OAT probe mounted in the co-pilot airscoop. I also added a JPI 830 last year and put that OAT probe under the right wing. The Davtron consistently reads 3-4 dF higher than the JPI.

I trust the JPI probe under the wing to be more accurate than the Davtron in the airscoop.

[Cris]

Has anyone considered mounting it in the nose wheel area? I have an insight G2 and find it redundant with the digital factory gauge. For the moment I am using it for the inside cabin temp. but I am considering moving it to the nose wheel area.

[mcpilot]

That might put it in conflict with engine and exhaust factors.  The OAT is used to calculate %HP in the EDM 830

[Cruiser]

what Scott said (KSMooniac)

it is not hard to run the thermocouple wire in from the right wing inspection plate to the instrument panel and you will get a clean stream of outside air there for an accurate reading.

[mcpilot]

How is that routed?  THe thermocouple wire that JPI provides is not very long....

 

 

 

what Scott said (KSMooniac)

it is not hard to run the thermocouple wire in from the right wing inspection plate to the instrument panel and you will get a clean stream of outside air there for an accurate reading.

[N201MKTurbo]

I replaced the factory probe and gage with a Davtron. I put the probe in the same place as the factory probe in an inspection panel under the wing. When it hits zero the ice starts to form and when it gets to +1 the ice melts. So it must be a good place. I won't fly IFR without a reliable OAT.

[N601RX]

How is that routed?  THe thermocouple wire that JPI provides is not very long....

Run it along the front edge of the wing.  There are a few other wires that run through the same area and you can follow them.  You will have a couple of ft extra wire.

[mcpilot]

I replaced the factory probe and gage with a Davtron. I put the probe in the same place as the factory probe in an inspection panel under the wing. When it hits zero the ice starts to form and when it gets to +1 the ice melts. So it must be a good place. I won't fly IFR without a reliable OAT.

You have to be careful with replacing the factory gauge with one that is not on the type certificate...

[KSMooniac]

It is an easy 337 to replace the factory gauge.  We got it done with no fuss when I swapped a Davtron M655 into the original location.

 

Routing the wires along the leading edge is not difficult, just a little bit tedious but can be done in less than an hour.  I went on the left side and had to remove the interior side panel to continue routing to the panel and that was the worst part.  If it is already out for annual inspection it is easier of course...  Going from the right side would be easier.

[mcpilot]

OK.. Next question... Has anyone installed the Oil Pressure sensor on their installation?  The factory gauge uses an oil line off of the accessory case.  Is there any other place to run a line off of the engine so as notto have to route through a hole in the cooling baffle?

[Cruiser]

get one of these

Earl's - 100188 -3AN Male with 1/8" NPT Female Port Pressure Gauge T-Fitting

and one of these

Earl's - 915103 AN Coupler Swivel Fitting

 

put your EDM830 O/P sensor on the same hose and the existing one.

 

disclaimer: verify your fittings are the same size and compatible with the above.

[mcpilot]

get one of these

Earl's - 100188 -3AN Male with 1/8" NPT Female Port Pressure Gauge T-Fitting

and one of these

Earl's - 915103 AN Coupler Swivel Fitting

put your EDM830 O/P sensor on the same hose and the existing one.

disclaimer: verify your fittings are the same size and compatible with the above.

Aren't those aluminum fittings? My AP says that only steel fittings are to be used on oil pressure and fuel lines in the engine compartment because the aluminum ones are prone to crack and failure

[Awful_Charlie]

Bit late on the OAT subject, if it's not too late, here's my .02

For my JPI OAT, I put it on the exit from the air filter - might sounds strange, but there is a reason:

The temperature for flight I get from the factory gauge (under the wing) and from the Aspen (sensor on the fuselage)

The engine performance depends on the induction air temperature, which is a function of the turbo and intercooler, but also if alternate air is selected (or automatically activated)

I use the JPI for engine monitoring, not flight conditions, so having the JPI record the air it was getting into the turbo was what I wanted.  Without the Aspen I would probably have wanted it for a backup, so another under-wing or NACA duct mounting would have been preferable

[wishboneash]

OAT sensor: Mine is under the left wing in an inspection panel. It sticks out a couple of inches. 

[Marauder]

The factory put the OEM one in an inspection panel under the right wing, for a reason. Putting it in the fresh air scoop subjects it to warm engine air as well as possible direct sunlight, both of which can make it read higher than actual. When you're flying in cloud do you want to know if it is 30 degrees or 35 degrees? I added a secondary probe on the left wing opposite the original factory location. It isn't that much harder to do it right...

I'm sure that is why mine is located there (same reason my mechanic used).

[Marauder]

OAT sensor: Mine is under the left wing in an inspection panel. It sticks out a couple of inches.

And that is what mine looks like too...