Flying High

[7JD]

Edit

[Ed Cesnalis]

Descending from 9,500 to 800' is one I do often. I retard my throttle until I have a 500'/min descent. The throttle is only partially closed, far from 'a touch open' That seems to match the descent profile that I get from my 496 ( perhaps 500 fpm is a setting somewhere? )

 

Using carb heat makes sense on descents and landing approaches with traditional aircraft engines, the jury seems to be still out with a 912. If you don't use it routinely then you should have in your mind that you will use it if carb icing symptoms develop. I think its safest to just use it, if you are not in the habit carb heat may not occur to you when you do need it.

[Jim Meade]

Does anyone know of anyone who has a carb temp gauge on the 912, and if so, what kind of readings does it yield?

[Flying Bozo]

What are the symptoms of carb ice in the CT... The carb is self adjusting for altitude so I don't know how the carb ice would look any different to the carb than a change in altitude. I don't think I have ever had carb ice in the CT but can't say that I would know it or not. Comments on this would be helpful.

Larry

[josjonkers]

What are the symptoms of carb ice in the CT... The carb is self adjusting for altitude so I don't know how the carb ice would look any different to the carb than a change in altitude. I don't think I have ever had carb ice in the CT but can't say that I would know it or not. Comments on this would be helpful.

Larry

I "think" I have only experienced this once going into Helena, Mt. In descent I noticed an engine sputter/hickup. Just a burb with a noticeable drop in rpm for maybe 0.5 seconds. And then it was smooth again . Did pull the carb heat just in case.

[Ed Cesnalis]

Pressure differential acts on the diaphragm / needle jet to provide leaning at altitude when throttle is not wide open. The carbs wouldn't be fooled by icing.

 

Icing will richen the mixture and cause rough running and if allowed to develop eventually stop the engine. If one carb iced before the other it could cause violent shaking?

[C ICEY]

flying in BC, seasonally we get lots of icing conditions that appear to turn the Cessna pilots white. Cool to cold temps and high humidity. I have never experienced icing with the CT. When temps dip, I cover the rad with strips of aluminum tape and that keeps the oil and cht temps the same as summer.

[Rich]

Good afternoon,

 

If I was descending from any altitude from cruise RPM I'd use carb heat every time.

I don't think there's anything to gain by not using it in a descent but a lot to loose if you get carb ice without enough time or altitude to clear it.

 

Also, if I was in cruise and noticed my RPM's dropping, (the first sign of carb ice) I'd apply carb heat. The RPM's may drop a little more when applied while the melted ice goes through the induction system but will clear rapidly.

 

I don't know if the water jackets around the carbs in my 912ULS is an option that the dealer installed or if it's standard on the 2012 + models. The water jackets that allow warm coolant to flow around the carbs will help prevent carb ice with no reduction in RPM, as there's no warm air ingested in the induction system.

 

I've had carb ice develop in cruise while flying a C-172 over the Catskill Mts. in NY.

So far, with 106 hours on the 912 ULS I haven't had a problem.

 

Rich

 

 

[WmInce]

Carburetor Icing

by FLIGHT LEARNINGS

in AIRCRAFT SYSTEMS

 

Thanks for posting that Roger.

Clear as mud now.

[Ed Cesnalis]

Symptoms of carb icing are running rough and losing power. Both attributes of disruption in atomized fuel flow to the intake manifold that feeds the pistons. I have heard the CT is better than other planes regarding carb ice. But you can recognize the symptoms mainly by loss of power, and that is a bad thing obviously on takeoff.

 

You need a venturi effect to encourage carb ice, that means a closed or partially closed throttle, it is a concern on descents and landing approaches but not on takeoffs. In fact takeoffs should be done with carb heat off to maximize power.

[Dan Kent]

I believe another response to carb icing is to go to full throttle while applying carb heat. A wide open throttle reduces pressure drop in the carb which will raise temp (or reduce temp reduction).

[Doug G.]

If I understand correctly carb heat on an SW simply means the air is not going through the filter. On the CTLS heated air comes from the muffler shroud. Is this understanding correct?

[Doug G.]

Yes, I mis-stated the air filter comment. I know they both take the filter out of the intake circuit. So the SW depends on the warmth inside the cowling to provide heat. I wonder how much difference that would be on a cold day up north? It seems to have worked though.

Was the change just to be in line with the common carb heat practice, or was there a problem that caused them to change it on the LS?