The Weedeater

[r601020]

Ahhh good old carb ice. Lol just keep an eye on rpm's if they start dropping and u didn't touch anything ie the throttle or mixture assuming you've leaned properly , give a little carb heat.

In this instance, I noticed altitude loss first, subtle, but enough, then glanced at RPM to confirm. Didn't need 100% carb heat to bring it back to par, and eventually flew out of the conditions causing it. That said, the home conditions I fly in are mountainous, humid, and now with autumn and winter, this constant checking and adjusting the carburetor heater will probably be a norm.

[r601020]

[AKar]

If not having strong reasons to do otherwise, I would suggest that you use the carburetor heat as if was an on/off control. In these GAs, the mixture temperature is an unknown value. Also is the heating effect from the heat control, for we don't have a carburetor inlet temperature indication either.

There are circumstances where the use of carburetor heat can render the particles of water already in the form of ice when reaching the surfaces where they could form some ice on if they were liquid, into liquid. Whereas the particles of ice would be sucked through the induction system, the particles that are converted into liquid can readily freeze up and form ice where they again meet temperatures and/or surfaces below freezing. Therefore, the carb heat can actually make things worse.

In most practical circumstances when using significant engine power, the full carburetor heat will most likely bring the induction heat up enough to keep the temperatures thorough the icing-critical segment of the induction system well-above freezing. I'd guess it would take some OATs under -15...-20 °C to perhaps defeat the full carburetor heat effect at any point. And those temps are way colder than commonly reasonable ranges of usage of carburetor heat in GAs at all, making this binary choice of none or all of it somewhat sensible, unless having a proper means of instrumentation to guess better.

-Esa

[r601020]

Credit where it's due, someone linked to this in another thread re: carburetor heater (I think Nick).

A good read . .
http://www.pilotfriend.com/training/fli ... b_heat.htm

What I've got out of all this, as it applies to this plane:

* check carburetor heater at run-up before takeoff.
* be ready during climb for using carburetor heater.
* during flight, monitor drops of altitude (via drops of RPM) for applying carburetor heater.
* I will add checking weather conditions to my routine.
* because of my general atmospheric conditions, mountainous, humid, and cold, apply carburetor heater during decent (before landing) - since I would've turned on fuel pump during decent, this is a good time to turn on the carburetor heater, and likewise, turned off fuel pump once landed, turned off carburetor heater.

Noted: 100%, as partial usage under certain conditions could make the problem worse, thanks.

[r601020]

Night flying (with dome or red), can't see anything below the dash, ie., tank selection, parking brake, rudder trim, cabin temperature.

Suggestions?