Carb Ice and 912 Rotax's

[BrendAn]

9 hours ago, danny_galaga said:

Sorry for the Necro. Has anything changed with the 912 since the last post here? My kit (tractor) comes with carb heaters, but if it really doesn't need it then id rather reduce the complexity a bit, and the weight, and gain an  xtra horse or two

The tecnam I have been training  in has no carb heat. He has had the plane for years and is on his second engine now. He has never had icing except cold idle 1st start on a cold morning. He just bumps the throttle up a bit for a few seconds and then its fine. The club tecnam is the same. The horsepower loss is negligible. I know it's not my plane but it's real world experience. I would not bother with carb heat if you don't need it. Kiss principal.

[RFguy]

somewhere around there is a nice FAA chart of likelihood of icing versus temperature and humidity

 

it is worth a look .

here is a study on it

http://www.tc.faa.gov/its/worldpac/techrpt/ct82110.pdf

 

 

[Blueadventures]

14 minutes ago, BrendAn said:

The tecnam I have been training  in has no carb heat. He has had the plane for years and is on his second engine now. He has never had icing except cold idle 1st start on a cold morning. He just bumps the throttle up a bit for a few seconds and then its fine. The club tecnam is the same. The horsepower loss is negligible. I know it's not my plane but it's real world experience. I would not bother with carb heat if you don't need it. Kiss principal.

Have a check of the Tecnam maintenance schedule or speak with the maintainer of the aircraft; you may discover that it has carb heat to the intake manifold constant from the muffler shroud.  I would not leave a carb heat out of a build.  Re carb ice been there, experienced that in a Skyfox Ca21 with Rotax 912 80 hp.

[Blueadventures]

10 hours ago, danny_galaga said:

Sorry for the Necro. Has anything changed with the 912 since the last post here? My kit (tractor) comes with carb heaters, but if it really doesn't need it then id rather reduce the complexity a bit, and the weight, and gain an  xtra horse or two

I would fit a carb heat.  I fitted the electric type purchased from Xair in Ireland.  Re carb ice been there, experienced that in a Skyfox Ca21 with Rotax 912 80 hp and would never fly with out it on a Rotax 912.

[BrendAn]

1 hour ago, Blueadventures said:

Have a check of the Tecnam maintenance schedule or speak with the maintainer of the aircraft; you may discover that it has carb heat to the intake manifold constant from the muffler shroud.  I would not leave a carb heat out of a build.  Re carb ice been there, experienced that in a Skyfox Ca21 with Rotax 912 80 hp.

It has nothing that I can see and there is no carb heat knob on the panel. If it used a shroud wouldn't it have to have a means of stopping the heat on a hot day. The CFI is a lame with years of rotax 912 experience.  He told me there is no carb heat and I didn't see any shroud on the manifold. Just an air filter on each carb. Same as my Jabiru.

[Blueadventures]

2 minutes ago, BrendAn said:

It has nothing that I can see and there is no carb heat knob on the panel. If it used a shroud wouldn't it have to have a means of stopping the heat on a hot day. The CFI is a lame with years of rotax 912 experience.  He told me there is no carb heat and I didn't see any shroud on the manifold. Just an air filter on each carb. Same as my Jabiru.

Sounds good, what model Tecnam is it as the current P92's have carb heat.  The P92 in my hangar is now up north so can't ask him.  If unsure of model post rego and I'll look it up as just curious.  Either post details here or message.  Cheers.

[RFguy]

Like everything Italian. cheap.

[BrendAn]

2 minutes ago, Blueadventures said:

Sounds good, what model Tecnam is it as the current P92's have carb heat.  The P92 in my hangar is now up north so can't ask him.  If unsure of model post rego and I'll look it up as just curious.  Either post details here or message.  Cheers.

I don't know. It's on its second engine now so it's not a new model. And I would not bring my instructor into an internet argument without his permission.  If you are implying that I am telling lies just say it. As far as putting cautions on my post. Well anyone that reads stuff on here should take it with a grain of Salt anyway. 

[facthunter]

Where you have carburettors you'll get carb ice. People are STILL getting caught with it. Both ways. Leaving it on and not putting it on. You'll get icing at quite high ambients at times. Put it on before you pull the power back and make long descents with power ON.  In humid conditions   Nev

[danny_galaga]

I misspoke I realised afterwards. The Rotax carb heat I have actually only warms the inlet (water jacket). It's on all the time so I was imagining you would lose power. But since it is only really warming the inlet, and not the air there is virtually no power difference. I guess I'm trying to avoid all the extra plumbing and weight.

[BrendAn]

17 minutes ago, Blueadventures said:

Sounds good, what model Tecnam is it as the current P92's have carb heat.  The P92 in my hangar is now up north so can't ask him.  If unsure of model post rego and I'll look it up as just curious.  Either post details here or message.  Cheers.

Does the current model use a cold air intake or filters on the carbs.

[Blueadventures]

7 minutes ago, BrendAn said:

I don't know. It's on its second engine now so it's not a new model. And I would not bring my instructor into an internet argument without his permission.  If you are implying that I am telling lies just say it. As far as putting cautions on my post. Well anyone that reads stuff on here should take it with a grain of Salt anyway. 

There is no intent about lies.  These posts are to assist people especially pilots.  I learn from them and share info.  The post is mainly about pros and cons of carb heat to assist a member.  My request was about the model Technam and would appreciate the model info.  You can look up with a rego check to RAAus and it will give that.  

[BrendAn]

9 minutes ago, facthunter said:

Where you have carburettors you'll get carb ice. People are STILL getting caught with it. Both ways. Leaving it on and not putting it on. You'll get icing at quite high ambients at times. Put it on before you pull the power back and make long descents with power ON.  In humid conditions   Nev

If fuel injection was standard on every motor icing would not even be talked about.

 

[BrendAn]

1 minute ago, Blueadventures said:

There is no intent about lies.  These posts are to assist people especially pilots.  I learn from them and share info.  The post is mainly about pros and cons of carb heat to assist a member.  My request was about the model Technam and would appreciate the model info.  You can look up with a rego check to RAAus and it will give that.  

It's hard to tell sometimes on the net. I step on a lot of toes without intending to. I have experienced carb ice training in a j230.

I will look up the tecnam reg in my logbook.

[facthunter]

Injection will practically eliminate the possibility of ice. You can still get "impact ice " on the intakes. but that's rare in the planes we fly. Nev

[RFguy]

6 minutes ago, facthunter said:

Injection will practically eliminate the possibility of ice. You can still get "impact ice " on the intakes. but that's rare in the planes we fly. Nev

Indeed, because a mechanical method is used to produce a fine spray with a fuel injector. whereas a traditional carb there is  an evaporation/vapourization process at work. 
Lycoming users will know the carb is attached to the oil sump, acting as an supplimental  oil cooler and carb warmer.


 

[IBob]

2 hours ago, BrendAn said:

The tecnam I have been training  in has no carb heat. He has had the plane for years and is on his second engine now. He has never had icing except cold idle 1st start on a cold morning. He just bumps the throttle up a bit for a few seconds and then its fine. The club tecnam is the same. The horsepower loss is negligible. I know it's not my plane but it's real world experience. I would not bother with carb heat if you don't need it. Kiss principal.

Hi Brendan, we had a club Tecnam make a forced landing here some time ago. Very experienced pilot, long descent to finals, I think, started running horribly rough so he set it down. Started and ran no problems thereafter, no fault found and subsequently returned faultlessly to club use, so high likelihood it was icing.

The aircraft I mentioned on short finals was a Savannah, they take air from outside the cowl, the pilot described it as being like the engine wanted to leave the aircraft.
Selecting carb heat in my Savannah certainly results in reduced power, I wouldn't call it negligible.
As for the kiss principal, you are in no way complicating anything by having heating available, as most of the time you won't be using it. So I don't see the advantage of kiss here. What it is is an option that's very nice to have on the day that your engine starts to cough and run rough...

 

[BrendAn]

18 minutes ago, Blueadventures said:

There is no intent about lies.  These posts are to assist people especially pilots.  I learn from them and share info.  The post is mainly about pros and cons of carb heat to assist a member.  My request was about the model Technam and would appreciate the model info.  You can look up with a rego check to RAAus and it will give that.  

Rego search just says p92 super echo but it doesn't state year of manufacture, I will ask the CFI when I see him. I haven't done any lessons for a couple of months because of the weather.

[BrendAn]

23 minutes ago, facthunter said:

Injection will practically eliminate the possibility of ice. You can still get "impact ice " on the intakes. but that's rare in the planes we fly. Nev

A friend has a brilliant setup in his sonex. He builds his own EFI setups. He has his own EFI on his 912uls.

But he has left the carbs on as well. If the EFI stops for any reason he pulls a cable and sends fuel to the carbs. Redundant fuel system and ignition. 

Edited December 18, 2022 by BrendAn

[Blueadventures]

4 minutes ago, BrendAn said:

Rego search just says p92 super echo but it doesn't state year of manufacture, I will ask the CFI when I see him. I haven't done any lessons for a couple of months because of the weather.

Thanks,  all good.  My experience with carby ice was my first flight in the Ca21.  Mate took me up he had forgotten about the carb ice pull for on.  On downwind engine spluttering and full throttle even could not maintain height, let alone climb.  Made it back onto strip.   In those days there was a gate across the strip for when drag meeting on.  Lucky it was open as would have left undercarriage on it if closed.  Very good lesson learnt for me and him.  Cheers.

[BrendAn]

So after reading the comments I concede that the carb heat is good idea if the option is there.

[BrendAn]

22 minutes ago, IBob said:

Hi Brendan, we had a club Tecnam make a forced landing here some time ago. Very experienced pilot, long descent to finals, I think, started running horribly rough so he set it down. Started and ran no problems thereafter, no fault found and subsequently returned faultlessly to club use, so high likelihood it was icing.

The aircraft I mentioned on short finals was a Savannah, they take air from outside the cowl, the pilot described it as being like the engine wanted to leave the aircraft.
Selecting carb heat in my Savannah certainly results in reduced power, I wouldn't call it negligible.
As for the kiss principal, you are in no way complicating anything by having heating available, as most of the time you won't be using it. So I don't see the advantage of kiss here. What it is is an option that's very nice to have on the day that your engine starts to cough and run rough...

 

In regards to power. When your engine takes air from inside all the time you wouldn't know any difference.

[facthunter]

You're playing Russian Roulette if you don't have it and it should work in no 1/2 measures.  Nev

[sfGnome]

My Tecnam Sierra had no carb heat either. Lovely plane, and I can’t imagine that it was omitted to save $$. It’s not like icing would not be a problem in Italy, so I can only assume that they had a design solution. 

[danny_galaga]

39 minutes ago, IBob said:

Hi Brendan, we had a club Tecnam make a forced landing here some time ago. Very experienced pilot, long descent to finals, I think, started running horribly rough so he set it down. Started and ran no problems thereafter, no fault found and subsequently returned faultlessly to club use, so high likelihood it was icing.

The aircraft I mentioned on short finals was a Savannah, they take air from outside the cowl, the pilot described it as being like the engine wanted to leave the aircraft.
Selecting carb heat in my Savannah certainly results in reduced power, I wouldn't call it negligible.
As for the kiss principal, you are in no way complicating anything by having heating available, as most of the time you won't be using it. So I don't see the advantage of kiss here. What it is is an option that's very nice to have on the day that your engine starts to cough and run rough...

 

Oh, KISS applies here. See attached. the thin black hoses are the extra needed for the carb heat. Which have to splice into the main hoses. Plus I have to press fit the heating manifolds to the carbies. I am actually almost certainly going to put them on now, because despite the extra weight and complexity, they dont at least seem to rob any power. Just waiting on the kit manufacturer nowto elaborate on the loctites used. One of them in the manual is not even on loctites website. Could be a typo, but its repeated maybe 4 times. I dont wanna guess with this sort of stuff...