Carb Heat Cessna Vs Piper

[pall]

I read an article discussing the differing use of Carb Heat in Piper to Cessna singles on AV WEB about a year ago. Can't find it anymore.

The gist of it was that Pipers do not require use of Carb Heat on low RPM settings in every circumstance, while Cessnas do.

Did I really read this or was I dreaming?

I have always used Carb Heat routinely on descent when engine is throttled back in both types. I do note though that Pipers I have flown have no markings on the Tach like Cessnas do to indicate when Carb Heat should be used.

[Sunfish]

Markings on the tach to indicate where carb heat should be used????

At the risk of my already tattered reputation, Cessna's appear to have downdraft carbs, Piper use side draft.

The Piper inlet manifold passes through the sump and that provides a little heat to the carby. The Cessna ones seem to dangle down lower and hence get colder. So Piper (warriors) appear to be less susceptible than Cessna's. The C150 is especially sensitive.

However, since I don't want to ever test this theory, I use full carb heat on Cessna or Piper carburetted aircraft.

OK, go on, tear me to shreds.

[pall]

For Clarification.

"Markings on the tach to indicate where carb heat should be used????"

I refer to the Green Arc of normal operating range. Below the Green Arc markings Carb Heat is to be used.

[Sunfish]

Ummmm Pall mate, are you trying to suggest that you can't get carb icing in the green range?

[piston captain]

Just another thought to add, many Piper POH's suggest to only use Carb heat when carb icing conditions exist.
So to get around this many flying schools I knew of just taught to put the carb heat on at low power settings, that way there was no risk of the student not knowing when carb ice conditions existed!

[karrank]

From C150 POH:

Descent...(c) Watch for carburettor icing, and only use a carburettor heat as required

From P28A POH:

Cruise descent...Carby heat must be used should icing conditions exist or whenever in doubt.

Descent...carby air "HOT"

Are we all reading the same books, or have they changed with the models:confused: :confused: :confused:

[NAMPS]

Isn't it more accurate to say "continental vs lycoming"?

[piston captain]

perhaps NAMPS.

With regard to my earlier Piper comments, I was referring to the PA44 and PA38 specifically, Not too sure about the PA28 sorry.

[pall]

SUNFISH, No I do know Carby Ice can be experienced within the GREEN RANGE.

I have always been taught to use Carb Heat on descent in both types and do so.

I have noticed too that Piper types I have flown (PA28-140,160,180) seem not to like Carb Heat settings. They run uneven and seem to struggle with Carb Heat on when you increase RPM on approach.

[Sunfish]

Haven't noticed the Piper problem with carb heat.

Have noticed that at YMMB that a C150 will ice up if you look crosseyed at it.

Have noticed slight reduction in power on go around if muppet has forgotten to turn carb heat OFF on go around:}

[Aerodynamisist]

I have three criteria for the use of carby heat in any carby aircraft.

* Low air temperature < 18 degrees
* High humidity
* Visible moisture

any one or more of these is about I use carby heat on descent and in cruise for short periods every so often to check for the presence of ice.

If your getting a rough running engine with the carby heat on then your probably running to rich, c 182 (or should I say continental o470's ?) tend to run very rich with the carby heat on.

[Wheeler]

Carby heat is one of those very rediculously inexact guessing games. The diagram put out by CASA(?) shows which conditions of temperature and humidity are likely to cause a problem. Its a good idea to carry one with you. I suggest pay less attention to that green arc and take a look at that because it says you can get ice in a very wide range of conditions, in the green arc or not. True, some aircraft are more prone than others - I fly one of the rarer PA28 variants that seems to get carb ice at the drop of a hat - so I'd say dont generalise about PA28's being less prone. Fortunately, it has an excellent carb ice detector that takes a lot of the guess work out of it. If it comes on, give it a shot of hot air, the engine makes gobbling noises for a few seconds and then runs smoothly and the carb air temp either goes straight back into the icing range (so leave the hot air on) or stays a bit warmer. Either way, you know much better than guessing.

It always amazes me in this day and age of technology, we are stuck with this rediculously crude hot air device, which if not guessed correctly can stop your engine. Unyet almost if you look like sneezing, the medical dept will ground you. CASA call that risk managment!

[pall]

A special thank you to all who have taken the time to respond to my posting. Your collective insight and advice has been helpful. Far beyond the limited instruction we recieve from our flight school.

[the wizard of auz]

It always amazes me in this day and age of technology, we are stuck with this rediculously crude hot air device, which if not guessed correctly can stop your engine.
and maybe we should add "stop your 1930's technology, overpriced and under developed, engine.
but thats a whole new thread
I must be lucky. I have never encountered carby ice in a tad over 7000hrs of flying bug smashers and whirlymagigs, and cannot remember using carby heat unless in visible moisture.
had some induction icing once on decent through cloud in my three ten, but that was to be expected as the wings were picking some up as well.

[pall]

I had carby ice in flight on climb in a C152 at 2000ft. RPM changed, uneven running, falling RPM. After application of Carb Heat, initial spluttering then power restored.

Once in a C172 as a passenger with 2x commercial descending IFR in cloud. Forgot to engage Carb Heat on descent. Very cold and some airframe ice evident on descent through cloud.

I know of a C206 Skydive pilot who suffered a total enging failure necessitating a forced landing onto the airfield because he forgot to activate carb heat on his rapid descent fom 10,000ft.

[the wizard of auz]

I know we were all taught to use the carb heat during training, but in the part of the world I operate in its a knob on the dash we soon forget about, due to lack of use.
I understand the operating conditions on the east coast are far different than my patch of ground, and the use of that knob would be a far more important factor in everyday flying.
I managed to throw meatbombs for twelve months up to 15000 and never had to use any form of ice deterant at all.

Pall, it must of been a bloody old 206 to suffer carby ice........ or was it induction icing the fellow suffered?. lucky they operate just about overhead most of the time. some poor young chappy building hours and experiance no doubt. bet he got some experiance outta that. :}