IMC with a carbureted C Model

[oisiaa]

Any tips, tricks, or things to watch out for when flying IMC with a carbureted O-360? I don't have a carb temp gauge so it's all or nothing with the carb heat. Should I be running carb heat at anything other than wide open throttle? Can I expect carb ice even at WOT regardless of OAT (100% RH afterall in cloud)? Avoid IMC all together until I get a carb temp gauge?

I understand the O-360 to be somewhat less susceptible to carb ice than other engines, but that isn't something I want to count on.

Just looking for inputs on realistically what to expect from experienced carb owners.

[Jackk]

Tons of people fly IMC without a temp gauge, and just because the instrument says you’re fine doesn’t mean you are.

 

Obviously run it on decent, but keep in mind you do need a little bit of power (EGT) to keep that heat hot

 

In cruise occasionally turn it on to check for ice.

 

Dont play around in IMC is the temps are close to freezing, unless its like -20c where it doesn’t stick

 

For the best answer just follow the POH, and even better also download the engine operators manual.  I don’t recall reading much about using partial carb heat in many planes

Edited Sunday at 05:16 PM by Jackk

[midlifeflyer]

Not a Mooney but I had a serious carb ice event in the clouds in a Comanche years ago.

Here's the tip:

An unexplained loss of power (especially partial) should be met by an immediate application of full carb heat. Any delay could mean that there ain't no heat when you finally get around to it. We are taught this  very early on. If you are one of those who uses carb heat all the time as a preventive when reducing power for landing, your brain is keyed to correlate any power reduction with applying carb heat. But if you are not one of those, it is highly likely you will forget to use it when you need it. The NTSB did a study of that years ago based on ASRS reports. It even came out with a recommendation (ignored by the FAA and manufacturers) that carb heat always be used at low power settings just so it's not forgotten. 

So the key isn't flying around with carb heat when icing conditions exist. That's just unnecessarily wasteful of power. Rather find a way to ensure it is what you do when an issue occurs. Best is to always pull out that checklist. Perhaps even placing "Carb Heat ... As Needed" in that otherwise mostly empty Cruise checklist that many pilots ignore altogether. But find something to act as a reminder.

[midlifeflyer]

9 minutes ago, Jackk said:

Dont play around in IMC is the temps are close to freezing, unless its like -20c where it doesn’t stick

Problem is the carb ice doesn't require airframe icing conditions. They books talk about it but my big carb ice event actually took place when the temp was 70°F and I was in cruise flight.

[DXB]

33 minutes ago, oisiaa said:

Any tips, tricks, or things to watch out for when flying IMC with a carbureted O-360? I don't have a carb temp gauge so it's all or nothing with the carb heat. Should I be running carb heat at anything other than wide open throttle? Can I expect carb ice even at WOT regardless of OAT (100% RH afterall in cloud)? Avoid IMC all together until I get a carb temp gauge?

I understand the O-360 to be somewhat less susceptible to carb ice than other engines, but that isn't something I want to count on.

Just looking for inputs on realistically what to expect from experienced carb owners.

Carb temp gauge is a pretty simple install and is nice to have. The O-360 configuration in our Cs is resistant to ice, but I still adhere to keeping carb temp above 40F in any visible moisture including clouds (except at full power when climbing down low). Having the temp gauge simply lets you keep some of the power you would lose by using full carb heat.  Upon reducing power for descent, I usually use full carb heat simply because I'm usually thinking about landing and don't want to distract myself by futzing with partial carb heat. The gauge also show you that carb temps are typically quite high at low power in the pattern.  For that reason, I turn carb heat off when turning final and performing my last GUMPS- one less thing to worry about if one needs a go-around.  Doing so also limits dust ingestion close to the ground.  

Lastly note the hinges, seals, cable etc. that actuate the carb heat door and bypass valve in the C's airbox are a bit fragile and often need maintenance.  Having a carb temp gauge can tip you off when something isn't right (this has happened for me).  

[Jackk]

17 minutes ago, midlifeflyer said:

Problem is the carb ice doesn't require airframe icing conditions. They books talk about it but my big carb ice event actually took place when the temp was 70°F and I was in cruise flight.

correct, two different topics and do intertwine if operating close to places you shouldn’t be operating non FIKI (impact ice)

 

 

 Per the gauge, to me one of the issues I see in some non working planes is owners installing too much junk, aileron trim systems, CD players, 4 attitude indicators, carb ice detectors, panel mounting tons of portable electronics despite having a certified moving map navigator, etc etc 

 

 Money that would be better spent on training in the plane or sim, weight and electrical draw, complexity and more stuff to break, and complicating a panel which is 100% what you want to not do for a plane, especially one flying IMC

Edited Sunday at 05:43 PM by Jackk

[oisiaa]

1 minute ago, Jackk said:

correct, two different topics and do intertwine if operating close to places you shouldn’t be operating non FIKI (impact ice)

 

The problem I have with these carb icing charts is that they are so broad that it makes it seem like you're going to fall out of the sky without full carb heat unless you're flying mid-day in the desert. 

[Jackk]

1 minute ago, oisiaa said:

The problem I have with these carb icing charts is that they are so broad that it makes it seem like you're going to fall out of the sky without full carb heat unless you're flying mid-day in the desert. 

 It’ll take a good bit to do that lol

 

 Just know your power settings and speeds (I have a cruise chart for my common altitudes on the back of my single half page checklist)

When you’re not preforming right try carb heat, and every once in a  while even if you are preforming well try carb heat

Also good to keep a eye on your trim and know where it likes to live, just like your engine instruments and “in the green” being not good enough.

 

 Don’t overthink it 

[Jackk]

I would say this would be a wise investment to consolidate engine instruments and fuel 

 

It also can show carb temp and you could probably set up a warning on it

 

https://www.garmin.com/en-US/p/897577/#additional

[Rwsavory]

When flying in clouds or rain in my C I would put the carb heat on and re-lean the mixture. Set it and forget it until in the clear. 

[Hank]

The carb temp gage really simplifies IMC, i check ot periodically and pull enough carb heat when needed to stay out of the orange stripe (at the edge of the photo just left of the yoke). I do turn on pitot heat before entering clouds.

I rarely use carb heat in the pattern, and never reduce power to descend, so no carb heat there, either--just push for 500 fpm and trim away yoke forces, then every couple of thousand feet, pull back the throttle and advance the mixture to what your cruise settings were for MP and EGT. Save power reduction for slowing to flap speed at pattern entry, and for descent to land.

[cliffy]

Old school trick- keep an eye on your manifold pressure gage in cruise.  If it starts to go down (and you haven't moved it)

the carb throat is being closed by ice.

[47U]

1 hour ago, cliffy said:

If it starts to go down (and you haven't moved it)

the carb throat is being closed by ice.

The previous owner of my ‘63 C told me of this… the one time he had carb ice in his 35 years of ownership, he saw the manifold pressure was dropping.  I added a carb air temp probe when I installed the FP-5 and have a warning light set at 35 degrees.