carb Ice

[Maoraigh1]

Frequent carb ice on the O200 in our Jodel, using mogas. It often ices on start up. I'm wondering if Konsin on the runway increases the carb ice risk at temperatures that seem too low from the diagram.
Transport Canada say that the usual carb ice diagram does not hold for mogas, and that it can occur 20C higher.

[RTN11]

had no problem with it despite flying through the winter.

The greatest risk of carb ice is realitively warm OAT and high humidity - i.e. summer.

During winter months I would only expect Carb Icing in cloud, or when taxiing on wet grass.

[Genghis the Engineer]

Originally Posted by mrmum

Genghis,
Not so sure that the majority of mainstream GA like flying around in aircraft which are particularly susceptible to carb. icing. While there's certainly an element of appreciation of the geriatric, I'd certainly buy a simple cure for carb. icing if it was available to retrofit. But it's not is it, and the reason for that isn't a lack of demand, or love of the black art of appropriate application of carb. heat, it's the onerous and outrageously expensive certification requirements for a solution.

Hmm, not sure you are right.

Look at the decision made by Cessna to switch from a 912 to a Continental in the C162. Not the only reason, but the preference amongst the market for "known technology" was a major factor.

There have been many disparaging comments here and in most flying club bars about aeroplanes that used newer technology (and far less carb ice prone) engines rather than the old reliable Lycontinentals.

At the same time - are the certification costs that bad? I recently certified an unapproved oil cooler with no paperwork on a CofA vintage aeroplane. It took a couple of days of my time, and a £62 CAA fee. The big issue isn't the cost - it's that virtually nobody understands the mod approval system. I'm lucky in having a professional education that means I can do this, which is the real issue: very few people do. You could argue that CAA and EASA should explain the process better, and they probably should - but it's lack of professional skills in mod application writing that is the real issue: doubtless if you don't know what you're doing, CAA will start charging a fortune to explain your failings.

G

[peterh337]

At the same time - are the certification costs that bad? I recently certified an unapproved oil cooler with no paperwork on a CofA vintage aeroplane. It took a couple of days of my time, and a £62 CAA fee. The big issue isn't the cost - it's that virtually nobody understands the mod approval system. I'm lucky in having a professional education that means I can do this, which is the real issue: very few people do.

That is a very valid comment.

FAA approvals are free - subsidised by the US taxpayer. This is equally true for both a Major Alteration (337 + Approved Data) and for an STC application.

EASA major mod approvals are not expensive either. I have never sumbitted one but recall reading about one instance where somebody did one as a DIY job and it cost him of the order of £200.

The real costs come from one or both of two areas

1 - the cost of generating the data to support the application

2 - the cost of in-house staff generating the paperwork and liasing with the certification authority

Normally, with most aircraft mods, 1. is trivial, but it would not be trivial with say an engine which needs to be demonstrated as capable of restarting at 18,000ft which means screwing it to some plane and actually going up there and doing the tests. With a new airframe this is an even bigger cost because of the flight testing required.

Item 2. is the main cost with most "small" mods e.g. avionics. The agency approval fees are usually insignificant or nonexistent.

But in all cases IF you have the personnel in house that is familiar with the process (and all the big names will have that in copious quantities) none of the stuff is hard. It's a process you go through, ticking all the right boxes.

Small outfits will farm out stuff to outside people (e.g. a DER in the FAA system, to generate Approved Data) and these can be very expensive, e.g. charging $10k for a paperwork pack for the installation of a single instrument. But Lycoming won't be doing that.

but it's lack of professional skills in mod application writing that is the real issue:

It's not a professional education you need; it is being able to read and write A rare skill these days, among the smartphone generation which cannot write more than a line or two of pidgin english...

I think the wider issue in the USA is that if you have a company like Lyco which has not introduced a new product in many years, there won't be anybody left in there with any intelligence. Smart people move on to more interesting jobs. I see this with Honeywell (GA avionics) where nothing has happened in over a decade, and there is nobody there who knows anything. Currently they are fumbling and bumbling trying to fix the major design defects in the KFC225 autopilot of which they sold a few thousand 1999-2002 and which are packing up all over the place.

You would think Lyco could screw an RSA5 fuel servo onto the bottom of an O-200 engine and get that certified, and do away with carb ice. But it would increase the cost of the engine by maybe $1000, which will be a major issue with Cessna. And pilot forums would fill up with questions on how to do a warm start on an IO-200

There is another big factor here: the market is declining and blaming certification costs or product liability for a rationalisation of the business is an easy way to do it without losing face. For example Cessna's recent dropping of piston production, citing product liability, was a dead handy excuse for dropping stuff which nobody was buying anyway.

[Rod1]

The two engines which suffered in my experience are the C85 and the VW Ardem conversion. Most Rotax 912 installations do not have carb heat as the under cowl temp of a water cooled engine is much higher than an air cooled installation.

Rod1

[Crash one]

Looking forwards to someone saying they are extra careful on frosty mornings....

I bet you are & I'll bet there are a few others waiting for that too.
I've only got about 120hrs on my Cont C90 off a grass strip, but the only time I had any apreciable ice was in high summer on the ground.
As a result I usually taxi with carb heat on, just for fun!!! regardless of the time of year.
No doubt I should select cold in the winter cos it doesn't need it.

[englishal]

Of course taxying with carb heat on can lead to its own dangers

[Crash one]

For short distances over wet grass I'd prefer it to walking out of the barley.
Tarmac/concrete/gravel/dirt, no.

[mikehallam]

FWIW. The Rotax 912 has AIR Cooled cylinders. [Only heads are w/c].

mike hallam.

[rotorfossil]

I think the most useful mod in absence of an easily certifiable anti ice system is a carb temperature guage. It is surprising how much carb heat is required, particularly at low power, to prevent the temperature at the back of the butterfly from getting below freezing.

[fs27]

As a result I usually taxi with carb heat on, just for fun!!! regardless of the time of year.

That's a pretty bad idea. The air you select with carb heat goes in unfiltered, so any bit of crud lying around will get sucked into the intake. It also effectively enriches the mixture, increasing the risk of plug fouling.

[mrmum]

GtE
Interesting point, I'd never noticed that the Skycatcher comes with a carb. heat knob. Why on earth have they not designed out, when they had a clean sheet of paper to start with?

As to modification/certification costs, I'll take your word for it as I've never tried it myself. Just been warned off a few times, even for seemingly straightforward stuff like changing avionics.

[fwjc]

You'll note that while summer is a gotcha since people think it's warm and therefore ice won't form, winter isn't necessarily safe. As I write this my local METAR is giving +9/+7, which puts us bang in the serious icing regime at any power setting. Similarly, at 0 degrees, there is plenty of opportunity for serious icing with various power settings.

[Crash one]

Quote:
As a result I usually taxi with carb heat on, just for fun!!! regardless of the time of year.
That's a pretty bad idea. The air you select with carb heat goes in unfiltered, so any bit of crud lying around will get sucked into the intake. It also effectively enriches the mixture, increasing the risk of plug fouling.

I suppose there is little point in mentioning that I also said:

For short distances over wet grass I'd prefer it to walking out of the barley.
Tarmac/concrete/gravel/dirt, no.

[Pitts2112]

I've only had 2 experiences with carb ice.

The Continental C65 has a reputation for attracting the stuff, and I got it one cool, wet day on a protracted taxy out to the runway. Started to lose power nearing the hold and couldn't figure out why. Thought I'd try the carb heat and, wouldn't you know? That cleared it up.

The other recurring problem was on my Harley 1200 Sportster. In the cool, wet days of autumn, it would ice up and stall the engine but would restart again after a few minutes. After a few times of this I asked the dealer and they suggested carb ice. It had totally slipped my mind that it was a possibility, but on the V-twin, the carb is on the side of the engine and enjoys no heat from the cylinders at all. Harley sell a fuel additive that, when added to the tank, did the trick. No problems after that.

[dont overfil]

I am amazed at the number of folks in the UK say they have never/seldom experienced carb icing. Must be the global warming.

The worst I have experienced was in a Cherokee 6 250 (on one particular day). In VMC I had to leave the carb heat on.

You are almost guaranteed to get it in a Warrior after start on wet grass.

I am sure a lot of people get carb ice and don't know. Probably the same ones who don't know the difference between a carb hot air check and a check for carb ice.

D.O.

[Peter Gristwood]

Quote:
As a result I usually taxi with carb heat on, just for fun!!! regardless of the time of year.
That's a pretty bad idea. The air you select with carb heat goes in unfiltered, so any bit of crud lying around will get sucked into the intake. It also effectively enriches the mixture, increasing the risk of plug fouling.

Our Robin with an 0-200 is an 'ice-maker' so we are very careful, especially when we've been parked on wet grass. But the one to beat them all was the VW engine we had on the Turbulent. We seemed to spend most of the time with carb heat on, esp on the ground.

Since then I have been paranoid about ensuring we check for ice regularly, having had the engine stopped in flight a few times through icing.

What I find really interesting is when I fly with other pilots with little experience of icing. They occasionally think of using carb heat and even then for no more than 5-10 seconds. Doing that in my Robin, they would have a nasty shock!!!!

[Loose rivets]

In the days when one could lob into LHR for 10s/6d, I spent a day in a sim, and then climbed into my little taxi to get back to my field in Essex.

It was night, and a drizzly base at 300'. I soon realized even the carb heater was not going to get me any reasonable climb rate, so told London tower. They simply said, "continue on track, not above 500 feet. " The last time they'd said that to me it was a wonderful clear morning, but now every sphincter muscle I owned was at full torque.

I can't tell you how much I wanted to put that heater off for a while, and get some space under me, but I sat it out and soon found the clear air promised.

Commuted night and day to work at Luton in this little beastie.

[dont overfil]

There was an aftermarket ice warning device available for PA28s. All the AST Warriors had them fitted. There was a red warning light, which was adjusted in the same way radio squelch is adusted. The light was just turned off. If it came on ice was building.
Most of these aircraft were sold to Oxford Air Training in the mid '90s. I see that G-BTRY is still in their adverts..
I have never seen this device since. I suppose it is not worth the bother or cost as it should be within the ability of the conciencious pilot to use carb from time to time.

D.O.