Carby Icing

[Admin]

This graph was taken from the US CT Forums and is a good "watch out" indicator for carby icing.

 

 

 

[pudestcon]

Very useful

 

Thanks Ian,

 

I have often thought about carby icing and this graph sets out the information very well. I have saved a copy for reference.

 

Thanks Ian,

 

Ian Jones

 

 

[Paul Willett]

Something to consider in the sub-tropical and tropical climes of QLD - more often than not we are flying in Carb Icing conditions.

 

 

[Guest Fred Bear]

Full carb heat on final in high humidity in Jab is always good!

 

 

[Ben Longden]

Last week at Shepp with the high humidity and stinking temps was perfect Carby Ice conditions...

 

Ben

 

 

[Guest Fred Bear]

Golden rules chaps :)

 

 

[Guest Teenie2]

Install a carb temp gauge ?

 

 

[Admin]

The last day I went flying in the Gazelle up at Port Macquarie at 06:30 the temp was 15 deg and humidity was 99% - danger time!!!

 

 

[Yenn]

Carby ice seems to happen to some aircrft all the time and to others never. I used to fly a C150 which developed ice if there was a cloud within sight, which in the tropics means always. The corby starlet has never had carbie ice, even under stratus clouds with high humidity. I once put my Thruster with a Rotax 503 down in a paddock next to home when it ran rough and it must have been carbie ice, although there was no evidence. On a later flight the carbie was externally coated with ice after landing but there was no roughness. Basically there are no rules except apply heat if you suspect ice and give it time to work, before removing heat, when you should se an increase in rpm.

 

Ian Borg

 

 

[Guest Teenie2]

Are you running a vw in the corby? If you are what type of carby is it?

 

 

[Guest Juliette Lima]

Hi All,

 

I'm not sure if I'm telling you something you don't already know, but for those that don't.....there is a carby heating add-on device, like a fitted ring suited to Rotax 912 engines that directs heated water from the engine cooling system around the carby, thus eliminating the carby ice problem altogether....and without any loss in performance.

 

Naturally it is on the entire time.

 

I've had them fitted to my engine and have enjoyed 105 hrs trouble flying in this particular aircraft, sometimes in conditions mentioned in earlier posts.

 

Hope this helps

 

JL

 

 

[Guest bateo]

I have been told there is no need for carby heat in a P92 Tecnam.. Apparently they are not prone to it.. I have not experienced anything since owning the aircraft.. Should I be looking at one of those attachments for a 912??

 

 

[PaulN]

Sam,

 

As a CT owner I spend a fair bit of time on a US forum for CTs and on that there has been quite a bit of discussion about carb ice and the Rotax 912s. In summary, it seems from other's experience, some quite considerable in hours, the Rotax is not prone to icing. From my own experience I too find this to be so, at least in the CT.

 

Hope this helps,

 

Paul

 

 

[Guest Juliette Lima]

Hi Paul,

 

Hmmmm....wonder why Airbourne Aviation fit the collant carb heater to all their R912 trikes ???

 

JL

 

 

[Guest bateo]

Thanks Paul,

 

Well I have done over 50 hours since owning the 912 and have not had a carby ice problem yet.. I rang Bruce Stark the Tecnam Distributor and he stated that they were not prone to ice, and there hadnt been one reported to date...

 

 

[Guest bateo]

JL,

 

I would think that the Trikes have Carby heat because of the open engine.. they are more exposed to the climate and dont hold as much heat around the engine..??

 

 

[Guest Juliette Lima]

Hi Sam,

 

Thank you....you are probably right as I have found a couple of posts on the net re. carby icing, and the engines are mounted on pushers mainly exposed.

 

Thanks again

 

JL

 

 

[Guest ozzie]

Just a few comments on carby ice. having looked 912's in several different types of aircraft, i'd say that the position of the carbs behind and above would have them sitting in warmer surrounds the air inlet hosing would be in warmer surrounds as well. so the difference in air temps may help as well as efficient aircleaners. different for uncowled pushers tho.

 

i noticed on a storch being re-engined with a 912 that it had a very neat air inlet manifold with two seperate hot air inlets operated by butterfly valves. don't know if this was made by the owner. i think i would prefer this over the water jacket method unless i was flying a drifter type

 

The C150. From experiences from working on C types long time ago.. the inlet ducting must be perfectly sealed and taking air only thru the inlet. Air sucking in thru cracks in the metal work induce visible moisture into the inlet ducting. Also the use of the right type of scat hose is a must. Most have the wrong type fitted and it can and does collapse under the negative pressure. The venturi affect thru a partially collapsed hose will also induce visible moisture. The positioning of the carb. on lycomings and continentals on the bottom of the engine recieves less heat soak and makes it prone to ice building on the outside of the carb body, has been known to freeze linkages tight.

 

makes for a long float down the runway and a very dodgy go around.

 

story.

 

Sitting around after a day of jumping at Shute Harbour the topic of carby ice came up and we talked about it for some time. Then some of the jumpers hopped into their C182 with their (low time) pilot (who was the one to bring up the subject) and headed home to Hamilton Island. The jumpers jumped onto the island and the pilot ditched the aircraft short of the runway when it never responded to opening the throttle. After the conversation about icing in the tropics and being briefed by our experienced long time jump pilot on engine management on decent, it seems he never used carby heat or cleared the engine during the entire decent. So makes for good rule. if you have carby heat use it as per manual.

 

thanks, some time to burn waiting for tea.

 

ozzie

 

 

[Yenn]

Most of the icing problems in tropical areas are due to evaporative cooling. When the throttle is closed the pressure in the induction can drop very low giving a coling effect plus the evaporation of fuel lowers it further still. Clearing the engine on long descents prevents the icing getting serious enough to stop the engine, but if the engine does stop there is very little heat available rom the exhaust manifold and therefore little chance of a restart.

 

I don't have trouble with my engine but will always apply carby heat with an unknown engine. Better safe than sorry and it doesn't cost anything, even if it is left in right up to the start of a go around.

 

Ian.

 

 

[Guest Teenie2]

Folks ,Ill say it again, fit a carby temp gauge.You will then know exactly what is happening .THE ENGINE MISSES ,IS IT ICE? look at the temp gauge. Is it approaching zero? YES, put heat ON(and watch the temp rise). Believe me ,I wish I had fitted one before I crashed due carby ice .

 

 

[ZULU1]

HKS carb icing

 

Hi All on the KZN north coast, sub tropical very high humidity and typical Feb weather, every flight I guarantee the HKS will try to ice up..they have a very neat cartridge electric heaters which fits in the throttle body. Same carbs as 912. The inlet manifolds actually get frost on them after landing.

 

The elements came with the motor. The 912 they have little oil heater rings around them and I think not as effective as what came with the HKS. I had two engine "not outs" but serious misfires with my old 582 "they that now said I had too weak a mixture" as i flew it in higher altitudes and didnt re jet.

 

Paul

 

 

[Guest CptKelly]

Carburetor Ice...

 

I went through the Army Flight training program. Throughout this training carburetor ice was stressed, and the key indicator was VISIBLE moisture. If you can see any water of any kind, look out for carburetor icing. That being said, I have had several types of continentals that either would ice at the drop of a hat, or never ice at all. Go figure. Too many variables.

 

My XP360 never ices. Our Cessna 182 will develop ice, but it gives you lots of warning. I don't believe any chart is particular to your plane, but in general, might have merit.

 

Mike