On Jan 7, 2021, at 6:49 AM, One Sky Dog via groups.io <Oneskydog@...> wrote:

Bill good data,

Summed up three numbers -4C, 25F to 30C, 86 F temperatures with dew point delta less than 15C, 27 F Is in the danger zone.

Basically the temperatures we fly in most of the time. So that leaves the dew point delta as the best clue on carb ice conditions.

Referring to my only certificated data My PA-22 / Lycoming O-320 POH states make sure carb heat works on warm up and to clear out any ice that may have formed. It states carb ice can happen between 20 F and 70F and use carb heat intermittently to check for carb ice if RPM sags. For landing full rich carb heat off unless carb icing conditions prevail. The POH does not mention how to determine when carb icing conditions prevail.

I now have a quick way to check by looking at the OAT to Dew Point spread.

Checking local conditions: KFHU 10:58 Z 5C Dew Point -16C     41F - 3.2F = 37.8F indicates a slim chance to none for carb ice this morning.

KLVK is 6C with Dew Point 4C a spread of 2C ! Looks like carb heat is in order besides looking out for IFR conditions.

KDEH -6C Dew Point -6! Looks like Kevin B will not be flying today. 😢 

Great info,

One Sky Dog

My you tube channel

https://www.youtube.com/channel/UCr3x6bkHUw1UUQ96ATcRFfg

On Jan 7, 2021, at 4:03 AM, Bill Allen <billallensworld@...> wrote:



Here’s some more data on carb ice from the Robinson R22 POH.  A heli is different from a fixed wing in that normal takeoffs are at part throttle (ie; not WOT) so making them more susceptible, and they run some heat to get the carb temp gage in the green all the time.  

Bill Allen

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On Sat, 2 Jan 2021 at 16:54, Keith Welsh <klw544@...> wrote:

Hello everyone,

I hope y'all had a great bringing in of the new year. 

 

I've attached an article I read about once every five years or so regarding carb icing. 

We all know about carb ice and the danger it poses.  I experienced it years ago in my then Aeronca Chief when, in the summer, the engine stopped producing power on final.  At least it would not throttle up when flaring to land and stopped on touchdown.  After setting a bit she started just fine...by hand propping of course. 

 

The highlighted area toward the end of the article gets my curiosity up and is what I would like your opinions on since many of you are much smarter than I.

The reason for asking is that somewhere in the 90's I had the throttle shaft, throttle plate and intake manifold teflon coated on my Quickie and this article is where it all started.

 

One hot humid day back then while looking down the carburetor with the engine running I was surprised at the amount of water that was forming on the throttle plate, the size of the droplets and the time it took for them to run off.  Onan carbs are on the top of the engine as most know.

I found a company in Indy that did industrial teflon coating, Keco Coatings, and they are still there and this is their website https://www.kecocoatings.com/coatings/teflon/

After the Teflon coating was done the water still formed but with a notable difference.  The droplets were miniature sized and it was like a contest to see who could run off the throttle plate first.  Very impressive.

 

I've never sought the opinion of others regarding this article but knowing the breath of knowledge among you Q guys I thought I'd reach out and see.

 

Thanks for taking the time.

Keith

N494K

 

 

 

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