Carb Ice

[N1478D]

This subject has been touched on in different threads. Here is a link to an interesting article on the subject of carb ice by FAA Aviation Safety Councilor Pete Humphrey.

http://www1.faa.gov/fsdo/btr/carbice2.htm

[rudymantel]

Thanks, Joe- it's always good to be reminded of carb ice, especially this time of year !
Rudy

[blueldr]

Joe,
In reference to your recommendation to read the article on carb ice by the friendly helper from the Fuzz:
It sounds to me like Mr. Humphrey of the FAA is trying to make brownie points by publishing. He is really not at all well versed in the mechanics of where carburetor heat comes from. He repeatedly refers to heated air from the engine compartment for carburetor heat. Warm or hot air from the engine compartment is the source of alternate air on a fuel injected engine, but in sixty years of flying I've never seen anything other than a "stove" on the exhaust system of a carburated engine used to supply carburetor heat. Engine compartment heat alone would never in hell provide any de-icing capability without exhaust heat.

[N1478D]

Joe,
In reference to your recommendation to read the article on carb ice by the friendly helper from the Fuzz:
It sounds to me like Mr. Humphrey of the FAA is trying to make brownie points by publishing. He is really not at all well versed in the mechanics of where carburetor heat comes from. He repeatedly refers to heated air from the engine compartment for carburetor heat. Warm or hot air from the engine compartment is the source of alternate air on a fuel injected engine, but in sixty years of flying I've never seen anything other than a "stove" on the exhaust system of a carburated engine used to supply carburetor heat. Engine compartment heat alone would never in hell provide any de-icing capability without exhaust heat.

Congrads on 60 years of flying, that is fantastic! Obviously, you have smarts and skills to be able to fly for 60 years. Some of us, like me, only have 5 years of flying. I read everything I can get my hands on to improve my knowledge base, and am always appreciative when someone informs me of some worthwhile aviation reading. I enjoyed reading his article and wanted to share it's location in case anybody else might enjoy it. At my knowledge level, nit-picking someone's writing just isn't how I approach it. I look for valuable information and don't even pay attention to how perfect it is, or isn't. His article was referenced in another great article from the Southwest Group of FAA people talking about the throttle controlling the volume of fuel to air ratio and was great reading and very informative too. All of us are at different places in our aviation life, for me, it is a great article. For you, apparently, it is not.

[GAHorn]

All the good words and stories of aviators who've "gone before us" are what make up our own experiences and are what can keep up alive when things start happening. It is unfortunate that many (not all by any means) FAA and other "experts" are not all that experienced themselves. Many of the FAA's "experts" have only been in this business a few short years and many of those even have little or no experience with light planes or reciprocating engines. Some regions have adopted a "publish or perish" policy promoted by certain district managers, and that is unfortunate because some of the writings (that are taken as gospel by an unwary public) are truly shallow and without the background operational experience that should be a prerequisite of such self-appointed "expert"-authors.
Only recently did I overhear an FAA inspector (recently discharged from a 10-year service career) advise a new CFI that he should teach students to "militantly" maintain altitude if caught in a TRW in order to avoid wild altitude excursions that might put him into the assigned altitude of IFR traffic above/below him. Such techniques were discarded in the late '50's/early '60's by experienced pilots because it was proven to be a chief cause of airframe failures (chasing altitude in turbulence.) Sometimes things come full circle, purely out of ignorance and lack of experience.
So, ...just because someone has a gov't name-tag on doesn't mean they know what they're talking about. My 2 cents.

[Bruce Fenstermacher]

Joe, I appreciate your mentioning the article. I have not read it. I think what BL was trying to say was better said by George. It is to bad we can't trust the FAA to put out accurate information. I haven't heard or meet an FAA guy yet that seems to know much about small GA aircraft. I'm sure there are some but not enough.

I recently heard one of my FSDO guys tell an EAA crowd that experimental aircraft could only be given their annual condition inspection by the builder of the aircraft. Experimental aircraft could almost never be flown over densely populated areas and certainly never IFR. WRONG.

A friend was recently denied a ferry permit for a six-minute flight for his aircraft after his IA wired his mixture control full rich cause the mixture control broke. The FAA said this was extremely dangerous after all "how would the engine be shut down on arrival with out a mixture control".

Recently a local IA was scolded for finding an aircraft airworthy when only one side of a pair of seat belts had a TSO tag. He only got off cause he pointed out that there was no log book entry for seat belt replacement therefore the seat belts had to have come from the factory since the FARs would require an entry had they been replaced.

Unfortunately the list goes on. I'm sure you have heard more.

[N1478D]

Hi Bruce, and thanks for your reply.

Sometimes there is a learning experience in even reading something from a self proclaimed expert who is not one. I don't know if that is the case or not here about the author's expertise level. And, George did point out what BL was probably trying to point out. Reading about carb ice is interesting to me. All of us have to be able to determine if what we read or hear is worthy of sticking in our minds as fact. It would have been smarter of me to have used the word interesting instead of the word excellent in my post.

I've gone back and edited the post to make that change.

[rudymantel]

Joe, I think it was a good article, timely for this time of year when I for one can use a little refresher on carb ice. In S. Florida I rarely use carb heat most of the year. FWIW-
Rudy

[N1478D]

THANKS Rudy,

I don't use carb heat in the 100 degree days of summer here either. Some winters it has been easier than others to get back in the habit of applying carb heat.

[GAHorn]

Carb ice actually is less common in winter. (Freezing temperatures means that any moisture is already frozen, so there's none in the air to freeze inside your carburetor throat. Remember that carb ice is formed by the freezing of airborne moisture when it contacts the chilled carburetor body/throat. The reason the carb was chilled was because the evaporation of gasoline carried away the latent heat of the carb, ...not because of cold ambient temperature.
Carb heat can develop throughout the year as long as there is available moisture in the atmosphere.

[Dave Clark]

Hey fellows the answer is to fly Arizona where the humidity is usually too low to produce ice.

[mit]

Hey fellows the answer is to fly Arizona where the humidity is usually too low to produce ice.

Or Alaska at -40 and the airplane performs so much better too!

[David Laseter]

Hey mit,
So far this winter in Arkansas my plane is performing great ( when running ) just like a nice summer day in Alaska.
Sure get's a lot of attention down there!
They think the 8.50's are huge!

[mbeare]

For many years I was privileged to fly in the Reno, NV high desert & dry California. Great country, wide open spaces with 100 mile visibility. I had never experienced carb ice symptoms. Used carb heat any time the rpm dropped below the green ~2000 rpm. Then I flew the family (wife & two kids) up to Washington in the summer (July) to attend the EAA Arlington fly-in.
As we came across the Columbia river from Oregon & were happily bumping along the underside of a scattered cumulus layer at about 4500 ft, the engine started dropping a few RPM. Only about 100 or so at first - but.. the first words out of my mouth were: "Oh, Shi..."
My delightful wife freaked out completely. I promptly assumed carb-ice & added full heat & started to look for a place to land. The carb-heat took away an extra 100 RPM or so - we are now down to about 2200 (I usually cruise at 2450 rpm). I did not instantly add full throttle (not sure what the recommended technique is here... experts?).
I did find a small airfield almost directly below us & as I circled, added full throttle & tried to calm down my wife. After flying in circles for about 10 minutes, the plane seemed to be flying fine & the rpm were now back up to around 2450 (with the carb heat on). I asked my wife if she was ok to go on & we did.
When we landed, she burst out of the airplane crying & grabbed & hugged the kids!
Unfortunately, that was the last time we all flew as a family (over 1 1/2 years ago). She returned with one of the kids by commercial airline.
Just thought I'd share this little story & it's hidden lessons (watch what you blurt out when that first drop of rpms hit if you have sensitive passengers on-board & carb heat can bite - in more ways than one!).
Blue skys.

[wa4jr]

I hate to hear stories like yours...glad everything turned out OK...with the exception that now you only need a C-140! I am very fortunate to have a wonderful wife that had everything in perspective even before I purchased our 170B in order to ESCAPE the airline mess. She was a bit apprehensive about what would happen after a complete engine failure, so I showed her. Nothing to worry about. Just spiral down to a landing in somebody's field. Now she is looking forward to really getting into her flying lessons with me this spring. May not change anything, but show your wife the statistics for highway deaths. Now THAT is something to cry about! Imagine that guy coming at you on a two lane road. Closure rate in excess of 110 mph. Does he have a license? How is his medical condition? Has he been drinking at the bar down the road? Not a good situation. Most folks know that the most dangerous part of any journey to most any point on the globe is that part taken in an automobile. Don't know about up there, but around here and down in Texas it has become somewhat of a "custom" for families who have lost loved ones in car crashes to erect small crosses or memorials at the site of the crash. I see them all along the roadways now. Really brings home the point what a chance we take by getting into a car these days. Point these out to your wife as you drive along. Maybe she will come around in due time. Best of luck and hope you fill those seats up with happy family members once again soon. I know I sure love it when the family is along with me on a trip.