First brush with carb ice

[N659HB]

Happened this morning while maneuvering for downwind. I'd been puttering around for an hour or so at normal power levels/speeds. It wasn't a severe power loss, maybe 100 RPM, but I wasn't sure what was happening until power increased when I added carb heat for landing.

Be careful out there.

 

[Omalley1537]

Happened this morning while maneuvering for downwind. I'd been puttering around for an hour or so at normal power levels/speeds. It wasn't a severe power loss, maybe 100 RPM, but I wasn't sure what was happening until power increased when I added carb heat for landing.

Be careful out there.

Had mine a few years back. I was crossing the mountains in WA from East to west. As I was flying along minding my own business, MP started dropping and the engine started running rough. After a couple seconds that seemed like hours, I realized what was happening and pulled carb heat. Sure enough, brief roughness followed by a recovery of the lost MP.
I fly high enough over the Cascades to glide to safety in any normal wind situation after a loss of power, but it still definitely got my attention.

 

[William Pete Hodges]

It happen to me once on a fly to Sky Bryce. It was very subtle, just barely a change in the engine sound. No real power loss, but I expect that was coming next. I called my AI when I landed and he picked up on it right away. I had owned the airplane over 12 years and never had it happen before.

 

[NealRomeoGolf]

Fixed that problem by moving to fuel injected.

 

[flyingron]

Bryce isn't a fun place to have decreased engine performance.

I had carb ice a couple of times in the 170, but you expect that.
We got carb ice once in the Navion (PS-5C carb at the time). It was a relatively warm day and the pressure carbs are supposedly relatively immune to it, but it happened. Margy was flying and we'd were manouvering to the pattern at VKX. I told her just head for the numbers and she landed uneventfully. After rolling out, it occured to me and I pulled the carb heat and told her to give a little throttle, and sure enough it cleared.

 

[midlifeflyer]

Had mine while in the clouds over the Rockies. A good time was had by all.

 

[Dan Thomas]

There are many more carb ice incidents that go unobserved. Carb ice isn't a yes-or-no thing. It can be occurring in minor amounts when the conditions are right and the pilot just thinks the throttle has slipped so he opens it some more, and the increased airflow often sublimates it out. This is especially true at lower throttle settings such as on approach.

 

[Huckster79]

Flying a known ice maker I have a habit of hitting heat now n again in cruise... I’ve experienced it undoubtably twice in Cessna 150s... once almost took us down... I was training and it was running rough... we headed back to the airport... I asked my instructor after minutes of rough tuning “doesn’t the book say to try carb heat?” He said he didn’t think it was that but try anyway... pulled it and omg it was!

So it’s always on my mind and so I hit it now n again as a preventative measure...

 

[Dan Thomas]

I asked my instructor after minutes of rough tuning “doesn’t the book say to try carb heat?” He said he didn’t think it was that but try anyway... pulled it and omg it was!

Too often, that's the level of instruction these days. There have been many perfectly avoidable crashes due simply to ignorance of the physics of carb ice. An AOPA study found that carb ice was the single biggest cause or suspected cause of power failure. Now I can't find that link. Lost it.

 

[midlifeflyer]

Flying a known ice maker I have a habit of hitting heat now n again in cruise... I’ve experienced it undoubtably twice in Cessna 150s... once almost took us down... I was training and it was running rough... we headed back to the airport... I asked my instructor after minutes of rough tuning “doesn’t the book say to try carb heat?” He said he didn’t think it was that but try anyway... pulled it and omg it was!

So it’s always on my mind and so I hit it now n again as a preventative measure...

Application of carb heat for an unexplained loss of power should be pretty much automatic.

 

[Dan Thomas]

https://www.aopa.org/news-and-media...ing-magazine/the-case-of-the-mysterious-lever

This is a pretty good article on carb ice. One thing he gets a little wrong about carb ice being more likely at low power settings is his assertion that less heat is available at that time. The real cause is the throttle plate, being mostly closed, represents a major restriction to the airflow and acts like a venturi that makes a much bigger pressure drop than the main venturi does, causing a large temperature drop that will cause ice to form on the plate and walls adjacent to it.

 

[midlifeflyer]

https://www.aopa.org/news-and-media...ing-magazine/the-case-of-the-mysterious-lever

This is a pretty good article on carb ice. One thing he gets a little wrong about carb ice being more likely at low power settings is his assertion that less heat is available at that time. The real cause is the throttle plate, being mostly closed, represents a major restriction to the airflow and acts like a venturi that makes a much bigger pressure drop than the main venturi does, causing a large temperature drop that will cause ice to form on the plate and walls adjacent to it.

My carb ice "event" included a completely frozen throttle.

 

[N659HB]

Well, what's really interesting is I had only a minute or so before turned off the carb heat following a brief descent to pattern altitude. Thinking back on the flight, there were a couple of times I advanced the throttle for more power, thinking it had slipped. I now think it was subtle carb ice. Next time I'll add carb heat to see what happens to the power.

Thanks for all the responses.