Sure didn't know carb heat could stir up so much typing. Here's my 2 cents....
As a student pilot of the early fifties, I learned to ALWAYS pull full carb heat on downwind ALWAYS FROM CRUISE POWER... and push it off if/when going around. You would bust a check ride if the above was not followed. Here I am 47 years later doing the same thing religiously and it hasn't killed me yet. I've had ice over the years occur at cruise even on 80 degree days. I rarely ever got carb ice in winter unless there was visible moisture in the air like snow, rain, sleet, etc. If you're going to wait for a "rough engine" you might be too late for carb heat. If not, pulling it out ABRUPTLY can allow a slug of ice in the carb to break loose and block the carb throat. Pull heat on ever so cautiously with a rough engine full of ice... if it ever does get rough at all. At cruise, the only indication of ice with a fixed pitch prop is a GRADUAL loss of RPM. So, if you have to keep bumping your rpm up and it keeps dropping off, best to suspect carb ice and use heat. If the engine revs right back up, it WAS ice. With all that said, the above technique was required of Continental engines. Lycomings are a different animal..... because they run the INTAKE AIR THROUGH THE HOT OIL PAN. I didn't find this out until two years ago. There are Lycoming drivers that claim to have never, ever used carb heat. Good for them. Maybe they will still be flying in 47 years... and again, maybe they won't. Be well, Bob Steve Dold wrote: > > At 02:21 PM 9/8/99 -0400, you wrote: > > > > > >1. should heat be checked randomly and often or only if the engine becomes > >rough ? > > > > It might not run rough, it might just reduce the rpm. > The times I've had ice in cruise flight, it was choking off > the venturi just like reducing the throttle, so there wasn't > any real indication of ice except that it took more throttle than > usual to get the same rpm , and I had to periodically add > throttle to maintain the same rpm. > ------------------------------------------------- > Steve Dold [EMAIL PROTECTED] > Say NO to useless over-quoting > -------------------------------------------------
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