LownSlow, Doh!!
you are absolutely correct, shows how often I fly a C150!
What's nice about the R22 though, is that it has a prominent carb temperature gauge and the ability to use partial carb heat to maintain at least 15 deg.C. I've only ever had carb ice on start up in an R22.
People should use the carb heat more judicsiously, especially on the ground. Low power settings, high humidity (dew on the ground) and mediumish abient temps. Sounds like a recipe for carb ice if ever I heard of one. I have only had carb ice form once in flight, but at least 50 times on the ground, usually in the morning, but not always. As Jez has mentioned, when do you actually need full power most? At T/O, so having a restriction in the carb and a potential stoppage just because the carb ice check was only to see if it worked, not if you have any. Madness!!
Check lists should be written so as there is no doubt that you must check both function AND for ice. Instructors themselves need to make sure students understand this. Alot of people do seem to think of the carb heat as a distraction and for some reason are loath to use it. I still cannot really understand why, but it is something I point out and make sure is understood with everybody I fly with.
You don't however need to use 30 seconds of carb heat every time. A good ten seconds should allow you to see whether any has formed. If you get rough running and the RPM picks up, then leave it on until the engine runs clear. One way of noticing if you have carb ice on a fixed pitch aircraft is if the RPM reduces slightly for no reason, often this is due to the throttle slipping against the friction or a change of speed, but why take the chance, apply carb heat just to be sure.
Whirly, I hope when you say you use carb heat "little and often" that you don't mean you use partial carb heat in a fixed wing. I'm sure it isn't, but I don't want there to be any misunderstanding by anyone.