Solo student pilot in Cessna crash at Parafield walks away. 05/01/26

[BrendAn]

1 minute ago, skippydiesel said:

"Yes. 912 with carbs on top are. Pretty immune to ice unless they have a ducted carb inlet."

 

I would not go so far as to use the " immune" word - perhaps resistant.

 

My last 912ULS/Zephyr, with individual air filters, under cowl temp, ran a consistent 10C above ambient. In 10+ years of ownership and may 100's of hours, never a suggestion of catby ice.

 

My 912ILS/Sonex has an air box, with direct access to outside air. Under cowl also runs 10C above ambient. However the carby inlets are fitted with Cozycarb coolant heated rings, claimed to prevent carby ice.

 

😈

Are cozycarb rings coolant heated or electric. My jab 2200 had an electric carb heater but it didn't look like it would heat much.

 

[skippydiesel]

Coolant heated ie plumbed into the cooling system.😈

[Moneybox]

In my RAAus training in the Harmony with a Rotax 912 we only ever tested carby heat operation at run-up. Carby heat was never used in flight.

[Kiwi]

My father in law had a Tecnam P2008. Every time you pulled the carb heat knob your feet got hot.

 

It might have said carb heat on the knob, but it went to the cabin heat.

 

(Came that way from the factory)

 

[BrendAn]

1 hour ago, Moneybox said:

In my RAAus training in the Harmony with a Rotax 912 we only ever tested carby heat operation at run-up. Carby heat was never used in flight.

I trained with 4 different instructors and they all used carb heat on descent. As well as testing at runup

 

[kgwilson]

7 hours ago, BrendAn said:

I trained with 4 different instructors and they all used carb heat on descent. As well as testing at runup

 

That should be standard practice. If there is a carb heat device fitted, it is there for a reason and that is to help avoid carburetor icing. By just dismissing it as not necessary is poor judgement and passing this on to students is poor management. Carburetor icing can occur at ambient temperatures up to 35 degrees under the right conditions.

[BurnieM]

10 hours ago, Moneybox said:

In my RAAus training in the Harmony with a Rotax 912 we only ever tested carby heat operation at run-up. Carby heat was never used in flight.

I have a few hours in an Evektor Harmony wth a 912IS so no carb heat.

Occassionally when the Harmony was u/s we would use an Evektor Sportstar with 912ULS.

While I was taught to use carb heat when pulling power the instructor commented that on most 912ULS the carb heat did not make much difference. He is not the only experienced Rotax user that I have heard say this.

 

Edited 17 hours ago by BurnieM

[facthunter]

There  are Parameters that Carburetter heat should Meet. It seems to Me, the whole thing is getting a bit Lax. Engine failures due to Icing will continue to Happen. Injection reduces the Likelihood significantly. Evidence of Icing disappears often so the fault goes Undetermined. Proper technique is APLY FULL Heat BEFORE reducing Power for descent and don't have Prolonged Power OFF descents. It can Barrell face Piston rings too. Nev

Edited 17 hours ago by facthunter
expand

[skippydiesel]

"While I was taught to use carb heat when pulling power the instructor commented that on most 912ULS the carb heat did not make much difference. He is not the only experienced Rotax user that I have heard say this."

 

Its a widely held belief that Rotax engines do not get carby ice. For sure they are resistant to icing but to think they never get ice is one big mistake.

 

My advice;

If the engine is fitted with a manual carby heat system - use it for every reduction in power (landings,stalls or just going to loitering power). Its a good habit to  cultivate and will stand you in good stead should you transition to other engines more prone to carby icing.😈

 

[facthunter]

IF they DON'T NEED  de and anti icing, it would indicate the Airbox is hot enough to stop it. THAT would mean the Loss of potential Power in Normal Ops. Nev

[BrendAn]

2 hours ago, BurnieM said:

I have a few hours in an Evektor Harmony wth a 912IS so no carb heat.

Occassionally when the Harmony was u/s we would use an Evektor Sportstar with 912ULS.

While I was taught to use carb heat when pulling power the instructor commented that on most 912ULS the carb heat did not make much difference. He is not the only experienced Rotax user that I have heard say this.

 

very true but my instructors made me use carby heat anyway . 

[Moneybox]

Perhaps that big aluminium airbox absorbs enough engine bay heat to do the job?

 

[facthunter]

Perhaps is an unfortunate word in this situation?   Nev

[Moneybox]

12 minutes ago, facthunter said:

Perhaps is an unfortunate word in this situation?   Nev

I can't think of a better one. If you are going to draw air through an aluminium box mounted high in the rear of the hot engine bay then you are going to be feeding preheated air into the carburettors. I don't don't have the data to back that up but Skippy has stated previously his engine bay temperatures. The upper rear unventilated area is most likely as hot an area as you can find. Heat transfer is inevitable. 

[skippydiesel]

1 hour ago, Moneybox said:

I can't think of a better one. If you are going to draw air through an aluminium box mounted high in the rear of the hot engine bay then you are going to be feeding preheated air into the carburettors. I don't don't have the data to back that up but Skippy has stated previously his engine bay temperatures. The upper rear unventilated area is most likely as hot an area as you can find. Heat transfer is inevitable. 

The following is speculative;

 

Yes there will be heat transfer, how much this raises the air temp in the box, will depend on the air flow (speed) & volume.

The air temperature entering the carbys will also be effected by the ambient temperature ie if cruising along at 7500ft, OAT - 2C, the temperature rise may only be a degree or two. 

😈

 

[facthunter]

Perhaps there is enough fuel. Perhaps the axle nuts have  been adjusted right. Perhaps the gear is down. Perhaps that Plane is the ONE you want to be On. People don't say "Perhaps" around Planes where I'm Involved. 

 Also the thing about de icing IT MUST Be PROVEN to Be effective. Whether there's icing doesn't depend on the brand Name of the engine The entire Installation is part of the deal.. IF Normal is Hot enough to make it Impossible to occur. then you are Losing Power and economy engine getting Less Dense Fuel Mixture IS Less Power than you Might think/hope you Have. In some cases the engine May tend to Overheat or detonate as well. 2  things cause temp around the Carburettor to  reduce. The Lowering of the Pressure (Adiabatic expansion at the venturi. dashpot, throttle Butterfly) and evaporation/ vaporisation of the Liquid fuel . If it ends up below 0 C and there's some Moisture in the Air, you WILL get icing. Nev

[Moneybox]

19 minutes ago, facthunter said:

Perhaps there is enough fuel. Perhaps the axle nuts have  been adjusted right. Perhaps the gear is down. Perhaps that Plane is the ONE you want to be On. People don't say "Perhaps" around Planes where I'm Involved. 

 Also the thing about de icing IT MUST Be PROVEN to Be effective. Whether there's icing doesn't depend on the brand Name of the engine The entire Installation is part of the deal.. IF Normal is Hot enough to make it Impossible to occur. then you are Losing Power and economy engine getting Less Dense Fuel Mixture IS Less Power than you Might think/hope you Have. In some cases the engine May tend to Overheat or detonate as well. 2  things cause temp around the Carburettor to  reduce. The Lowering of the Pressure (Adiabatic expansion at the venturi. dashpot, throttle Butterfly) and evaporation/ vaporisation of the Liquid fuel . If it ends up below 0 C and there's some Moisture in the Air, you WILL get icing. Nev

 

 Perhaps Rotax did their homework on this one and thus prevented a known problem with carburettor icing by the induction of preheated air. 😉 

[facthunter]

Not funny. .IF you want to make a joke of things do it in the correct section and stop wasting MY time for ONE. It's NOT easy to write this stuff. and surely SOME one will benefit from this. Icing STILL Causes Crashes. Not ALL Rotax installations are the same. Unqualified People fiddle with Airboxes and under Cowl Temps vary considerably.  Floats sink In HOT Fuel and the Motor can flood as a result.  Don't make a Virtue out of Ignorance. Knowing what is going on can never be a burden. I fully covered your Comment in the explanation. Having hot air all the time is not without Problems.  It is NOT the answer. Nev

[turboplanner]

20 minutes ago, Moneybox said:

 

 Perhaps Rotax did their homework on this one and thus prevented a known problem with carburettor icing by the induction of preheated air. 😉 

.....and perhaps in doing this they lost some power output by pumping hot air into the cylinders. There is an overall balance with peripherals.

[Moneybox]

11 minutes ago, facthunter said:

Not funny. .IF you want to make a joke of things do it in the correct section and stop wasting MY time for ONE. It's NOT easy to write this stuff. and surely SOME one will benefit from this. Icing STILL Causes Crashes. Not ALL Rotax installations are the same. Unqualified People fiddle with Airboxes and under Cowl Temps vary considerably.  Floats sink In HOT Fuel and the Motor can flood as a result.  Don't make a Virtue out of Ignorance. Knowing what is going on can never be a burden. I fully covered your Comment in the explanation. Having hot air all the time is not without Problems.  It is NOT the answer. Nev

I think you're missing the point Nev. Having the air pass through a large aluminium chamber in a hot engine bay will be introducing heated air. If Rotax wanted to prevent this they could have easily reduced the surface area of the box or it could be insulated from the accumulated heat in the top rear of the engine bay. Perhaps they intend to raise the temperature of the incoming air to prevent carburettor icing particularly at lower engine revs where the air spends more time in that chamber.

[BrendAn]

2 minutes ago, Moneybox said:

I think you're missing the point Nev. Having the air pass through a large aluminium chamber in a hot engine bay will be introducing heated air. If Rotax wanted to prevent this they could have easily reduced the surface area of the box or it could be insulated from the accumulated heat in the top rear of the engine bay. Perhaps they intend to raise the temperature of the incoming air to prevent carburettor icing particularly at lower engine revs where the air spends more time in that chamber.

i doubt that aluminium airbox is a rotax product. i may be wrong but bolt ons like that are usually made to suit the installation by the installer of the engine.

[Moneybox]

3 minutes ago, BrendAn said:

i doubt that aluminium airbox is a rotax product. i may be wrong but bolt ons like that are usually made to suit the installation by the installer of the engine.

The photo above is a snip from the Rotax website so it appears to be an original Rotax component. 

[BrendAn]

1 minute ago, Moneybox said:

The photo above is a snip from the Rotax website so it appears to be an original Rotax component. 

i did say i might be wrong😁. 

[skippydiesel]

2 minutes ago, BrendAn said:

i doubt that aluminium airbox is a rotax product. i may be wrong but bolt ons like that are usually made to suit the installation by the installer of the engine.

The air box pictured looks to be a Rotax product. Mine, a home made,  is diffrent  in a number of ways - location of float bowl breather tubes spigots, length of carby tubes, presence of a hot air inlet, etc😈

[BrendAn]

1 minute ago, skippydiesel said:

The air box pictured looks to be a Rotax product. Mine, a home made,  is diffrent  in a number of ways - location of float bowl breather tubes spigots, length of carby tubes, presence of a hot air inlet, etc😈

i learn't today that rotax do make airboxs, i always thought that sort of stuff was made to suit .