When I bought my airplane, it did not have an OAT. I assume it was not replaced the last time a new windscreen was installed.
Anyway, I would like to get an OAT. Are there any recommendations? I don't need anything fancy. Is the original style that looks like a glorified meat thermometer the best way to go for cost and reliability?
If you have a Garmin 330 transponder (and maybe a 327?), there is an option to attach an OAT. I have that on mine. The nice part is that it transfer the data to the 430W for calculations. The only bad part is that I now have 2 electronic OATs and one in the windsheld. And the Xerion I have ordered will have another.
Tony Thigpen
Commercial-SEL + IFR
KSFB - Sanford FL
PA32R-300
Edited 1 time(s). Last edit at 03/15/2008 07:53PM by thito01.
I also have the digital OAT sensor interfaced with my Garmin 330 and then on to the 430. It cost $75 plus installation (maybe an hour). I found out how inaccurate my "meat thermometer" OAT gauge really is. It reads about 10 degrees cold. Having the digital temp is really nice for monitoring cold clouds for icing potential.
Tony - with all those dueling temperature readings, I hope they converge to about the same value!
To clarify, the core of my avionics package are two KX-170Bs and a KT-76A xponder. At this stage, anything I get will be stand alone, so I am looking for something simple and functional. I am considering an engine analyzer and I know some of those have a port for an OAT probe, but that's the only compatible accessory I see purchasing in the near future.
Are the old style "stick through the Plexi" OATs generally accurate or is Gary's experience more the norm?
Chris, The thru the window style thermometer can be accurate for a while, you need to check it often. All you need to do is put it in ice water for 5 minutes or so to check it. It should read 0 deg C. Digital in my opinion is the way to go, however, and if you do get an eng analyzer, you can tie it in there for cheap money. Although, you have to be careful where you put the probe for the digital, or else it will be farther off than the stab style. I work in the refrigeration industry, and I had the same style temp probes that our Pipers used, with the exception I could calibrate it, when digital came out, the stab style went by way of the dinosaur, just for the fact that they rarely stay accurate for long.
my digital (connected to EI clock) reads higher than the windshield in flight. It is mounted the same place several others I have seen are, on the side of the fusselage forward of the door.
Since they tend to agree on the ground, I suspect my problem is warm air flow off the cowling.
Radar Wrote:
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> Garmin's website confirms that the 330 transponder
> is capable of displaying the outside air
> temperature. The 327 is not.
Although Chris isn't going that route, the 328 is also capable of displaying OAT.
I installed a Davtron model 330.The probe is mounted on the right side slightly forward of the door. I still have the 30 year old thermometer installed in the windshield and have found the readings appear nearly identical when the engine is running. In the air or on the ground doesn't seem to make a difference. With aircraft just sitting, a difference may be seen depending on where the sun is in relation to the Davtron probe, meaning that if the sun is on that side of the plane, the temperature indication may be higher.
The Davtron 330 also provides a buss voltage monitor. There is a small push button switch on the unit so you can switch between voltage or temp anytime you choose. Easy to install, requires a 337. I like the unit.
I am replacing all of the windows in my 73 PA-28-180 and want to eliminate the Pilot window OAT probe as the original one keeps catching on the cockpit cover and cracks the plexi. I have a JPI engine analyzer, GNS 430W and a Garmin 330 transponder to all of which can be added a digital OAT. My avionics shop is telling me that none of these digital options are certified to replace the original meat thermometer as the Primary OAT for IFR certification.
