I had an interesting experience Monday afternoon. My friend and I got the plane out about 5:00 pm for a couple practice T & L's. We had not flown for eight weeks because of the weather and the runway conditions. After start up we let it run at about 1400 rpm for a few minutes to warm up and then did a taxi down the turf runway and back checking for soft spots. We then did a run up and everything checked out normal so off we went. The plane accelerated a bit slowly and we took maybe half the runway to get off the ground as opposed to a few hundred feet. I noticed that it was not climbing with the speed it normally does. So I stuck close to the airport and landed. Once again I did a runup and everything checked out. I then held the brakes and did nearly a full power runup to check where the RPM's were. Again, it appeared normal. So off we went again. Same result.

This time however, I was paying such close attention to the instruments that I was a bit high and fast on final so rather than force it, I went around. When I shoved the power in, it responded like it always does and really climbed! So I went around and landed and put her away till I had more time to make checks.

It occurred to me today that I had pulled carb heat on the downwind leg rather than on base/final because I was trying to be more cautious. Maybe there was carb ice that melted and that resulted in the normal power when I went around?

Anybody had any experience with carb ice while waiting for the plane to warm up? Could that be it?

It is possible to get carb ice during taxi. That is the reason you test the carb heat during run-up , checking to see there is a normal RPM drop not more not less. Often if I am in high humidity and suspect a possibity of carb ice I taxi with the heat on.

2 years ago at Johnson Creek, I got a ride out to Caldwell with N6EA. It was early in the morning with a lot of dew and condensation. We taxied quickly to the takeoff end of the strip, at which point he started a runup, and pulled the carb heat on, and we got an rpm increase! He left it on while waiting for the other guys to depart, until we powered up for takeoff.

Being a greenhorn, that kind of stuck with me.

Yeah, when I pulled carb heat on during the run up I got a reasonable decrease. But, to tell the truth, I was not real concious of how much of a decrease.

Skystrider wrote:Anybody had any experience with carb ice while waiting for the plane to warm up? Could that be it?

Yes, I think so. A couple of times, during the runup, I've pulled carb heat and had it drop then increase. I read somewhere a suggestion to pull carb heat and count to 10 to clear any carb ice that might be there.

One time, coming in for a landing on a fairly humid day, I hit the runway (not hard). The engine died during rollout. I rolled it to the taxi way then realized I hadn't pulled the carb heat. I cursed myself and praised my luck and am now extra diligent about making sure that knob is pulled. It started back up and ran fine.

There are some types that have carb icing on ground ops more than others.

The Stinson is one example that is known to ice during ground ops now and then.

It can take considerably longer than counting to 10 depending on the amount of ice, dew point and temp.

The only times I've had carb ice, it ran rough as well as a noticable power loss, but that was a C-85 and a 1340. The 1340 ran OK until I tried to increase power. The manifold pressure would increase, but no more power and the farther I pushed the throttle, the rougher it ran.

I always pull carb heat when landing because the O470 engine in my 182 was bad for making ice on landing I had heard. I have never had that trouble while warmup or taxiing That I know of.  Bob

Actually, I was just telling my students today what a sneaky little bastard carburetor icing can be.

Yep, taxi can do it.

MTV

mtv wrote:Actually, I was just telling my students today what a sneaky little bastard carburetor icing can be.

Yep, taxi can do it.

MTV

Ditto what Mike said.

Our C180 is an incredible carb ice maker. It happens frequently during warm - up and taxi. Even had it happen with climb power coming out of Whitehorse one day. I had my initial training in the desert, where it rarely surfaced. I had a lot of learning to do when I moved to the coast. Still do, in fact.

gb

We had a emergency landing due to carb ice just a few hours after my hubby got his PPL. We were flying a C172 and were going to look at a C182 were thinking about buying. 45minutes into a beautiful flight the engine went from cruise to idle and started racing up and down erroneously. During training he was taught that there would be a gradual reduction in rpm if carb ice was present and this is not what happened. Long story short, we landed at an airport close by and after much discussion determined it was carb ice. Needless to say, things don't always go as planned and expect the unexpected.

As a footnote. We purchased a 182 (not the one we looked at) and had a carb temp guage installed. After a year and half of flying we have never encountered carb ice again and boy do I love to look over and check that gauge.

Those of us who fly behind small continentals, the C series and O-200 are very familar with carb ice during taxi and takeoff. The carb is mounted below the engine and doesn't get much heat from it. I had three flights last spring where I started to loose power dramatically right after take off. Pulling carb heat nearly killed the engine for a few seconds (seemed like several minutes at the time). I've gotten in the habit of pulling carb heat as soon as I'm 1,000agl on each flight now. I also check for carb ice right before takeoff if I've been delayed since my runup.

On the Lycombings and larger continentals the carb is bolted to the oil sump and recieves some heat from that once it's warmed up. Seems to make them much less prone to carb ice.

Phil

I only get carb ice when I'm flying at night, over water, or in mountain canyons.

Just wondering why more folks don't run a carb ice dtector. I have used one for many years and have be very happy to have it.Not that expensive and let's me know before the ice becomes a problem.

I would like to hear why more people don't use them.

Gary

Gary...what kind do you have? How about anyone else?

As a student pilot, I've been in a good habit of always pulling the carb heat on at run up and on final. I will ocasionally pull the carb heat on while in cruise to check for rpm drop and rise, too. Now, I've been trying to get into a habit of turning the carb heat off just before touch down as you would at non-pavement runways.

donknee

It is made by Lamar Industries. I bought it from A/c Spruce.

Gary

I am not aware of a "carb ice detector" available. Most of the engine monitor manufacturers offer a "Carburetor Inlet Temperature" option, though. Many Cessna 180/182 came from the factory with such an instrument, largely cause those engine/carbs are somewhat susceptible to carb ice.

Check JPI, EI, or... My EDM 700 Gives carb inlet temps.

MTV

mtv wrote:I am not aware of a "carb ice detector" available. Most of the engine monitor manufacturers offer a "Carburetor Inlet Temperature" option, though. Many Cessna 180/182 came from the factory with such an instrument, largely cause those engine/carbs are somewhat susceptible to carb ice.

Check JPI, EI, or... My EDM 700 Gives carb inlet temps.

MTV

ARP has built one for years that uses a optical probe instead of actual temperature. I had one on the 182 it worked great. The one we had on the 150 had some issues but the company took care of it.

I have never had any ice with the Scout but still continue to give a blast of carb heat before I pull the power back on downwind. And always give a blast just before takeoff, making sure everything is reacting the way it should.

The "Iceman" carb ice detector by ARP, I've looked at these before:
http://www.aircraftspruce.com/catalog/i ... etect2.php
Optical probe with a light, when ice forms and reduces the light intensity a warning device sounds.

There are other factors than temperature to create ice...so this seems to make sense and most of the reports I've heard from pilots who have them concur favorably.

I was being a little humorous about "over water, in a canyon or at night" because I'm sitting in the comfort of my home. Of the recent carb ice incidents though, those were the situations. So, don't do that and you won't have carb ice? My airplane tends to make ice if theres moisture around.