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Carb Ice anyone?


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norman2"]Has anyone ever experienced it whilst PPGing? ---------------NO

If you did what were the symptoms you experienced. ----------------- Loss of power (engine running lean)

What did you do about it? --------------------------- Let the throttle off to low revs and allow the ice to melt

How long did it take to clear?---------------------------- 5-30 seconds

Did it return?------------------------------------------ Only happens if you keep a constant throttle setting

Ta! ---------------------------------------------------------No Probs :D

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Had it with the microlight (and its got a carb heater) flying on a misty low cloud day a classic carb icing day ... :? ......it caused a forced landing on a beach...it cleared within 5 mins started up and away we went...the only problem was that I aged 5yrs .....in the time of engine stopping to the landing....

also I wouldnt say I was flying at a constant throttle setting.....

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Granted carburettor icing is not such a common phenomena with Paramotors but it still exists and I have had plenty of annoying experience of it.

To understand why you need to be aware of the course.

Inside the card is a venturi a restriction that creates a low pressure which in turn sucks the fuel as the pressure tries to equalize. The problem with low pressure areas is that it reduces in temperature thus lowering the temperature of the carburettor body in some cases to below freezing, not a problem with dry air but if the air has moisture then this can stick to the carb parts as it passes over.

Our machines tend to be one cylinder one carb but if you have a twin cylinder sharing the same carb then you have twice the volume of air being drawn through creating a greater low pressure so the carb body can freeze sooner in higher ambient temperatures.

Now you know moisture is also a key part, think about areas where moisture will be at its greatest or air at its most saturated, under cloud base, coastal flying, and the list goes on.

Carb icing is more of a problem at lower rpms and even tick-over as the partially closed butterfly creates an even further restriction and greater low pressure and thus a further drop in temperature. So if you experience carb icing and have no physical way of increasing the carburettor body temperature then keep the throttle fully open and reduce height to increase the ambient temperature and prepare for landing as the engine may not recover.

Clive

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Single barrel carbs ice too but agreed more problematic on multi-barrel single carb as already discussed.

The carb design will dictate the effect of the icing, its not true to say that the engine will go lean unless your carb has an extended outlet to the centre of the venturi like the Walbro 37 as this tends to ice over and restrict the fuel flow but still allowing airflow so mixture becomes lean, must carbs ice up around the butterfly and venturi restricting airflow only so restricting the combustion capabilities but maintaining correct mixture.

When ever I have encountered icing, if I reduced the power the engine would normally stop, so found the cure to maintain throttle setting which was normally the one I was at and reduce height until ice broke off and engine coughed as it digested it and then could resume to normal flight.

Clive

BHPA Instructor

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interesting one this

I was told when learning to fly microlights the time most likely to experience carb icing is when descending at a low throttle setting.....which is why when coming in to land with a GA aircraft you turn on the carb heat to try and avoid it happening...when my microlight experienced icing as said before it was a classic day for it to happen ... :? but that said while I was descending I was blipping the throttle every now and then to try and avoid it.... (it still got me) the aircraft was my old mainair blade with a rotax 582 two stroke 2 cylinder twin carb heated by a carb flange which contained the warm water from the engine.......

ps I use the blipp the throttle while descending with my paramotor as well

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I used the word normally because this is what typically happened, the first I know I had carb icing was the power would reduced by itself and I couldn’t maintain level flight until it cleared. Reducing the power further is was not really an option unlike GA where you can retrim to a slower airspeed and throttle back (and introduce carb heat).

I did experience card icing a lot when I owned a JPX twin and got feed up of being forced virtually to the ground.

Unless you start to descend through the reduction in power, carb icing is hard to recognise, sometimes rough running is an indication or an unwillingness to respond to the call of power, either way it’s a pain.

Clive

BHPA Instructor

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Has anyone ever experienced it whilst PPGing? ---------------YES

If you did what were the symptoms you experienced. ----------------- gradually increasing loss of power, followed by spluttering engine

What did you do about it? --------------------------- went to higher throttle to keep the engine running, started spiraling lower to increase air temp, simultaneously choosing my safe landing field

How long did it take to clear?---------------------------- made it low level back to my home field - just; after landing the carbs outside was 1cm thick covered in ice, there were ice remains in the fuel chamber (Walbro carb)

Did it return?------------------------------------------ only twice, try to avoid the combination of low temps and small spread (see meteorology)

CU, Gunnar

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Carb icing is carb icing whether it’s a 2 stroke or flat four as they are all normally aspirated engines, what is constant is the conditions it happens in, what is different is how a particular engine copes with it.

Carb icing happens and yes this can be somewhat negated by analysing the conditions before each and every flight but how many Paramotor pilots really do that? Maybe we should discuss Density Altitude and the effects on performance next?

Don’t understand your question about throttle position?

Clive

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  • 2 weeks later...

Only once in 9 years, after 3 touch & go's I lost power at 10' and landed without incident. The GA pilot on the scene explained that my circuits at low revs were the culprit. I was flying a slide carb (bing) which is more susceptible to icing than a cv??

Dew point is the concern http://www.weatherquestions.com/What_is ... rature.htm and possibly more frequent in summer than mine which was slightly below freezing weather.

"Dew point " in below freezing temps is also called "frost point" http://amsglossary.allenpress.com/gloss ... =dewpoint1

dew the dew, Ciao

Marko D

p.s. http://www.newton.dep.anl.gov/askasci/w ... a00140.htm

p.p.s.

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