mtv wrote:Well, to go back to Ted’s certification point: If this information is so essential, why hasnt any aircraft manufacturer either installed it as standard equipment or reqiured equipment?

Cessna did offer the carb temp gauge as an option in the O-470 aircraft they built (180/182) which are arguably the most prone to carb ice of any engine around, yet it was never required equipment.

With people crashing weekly from this scourge, you’d think the liability alone would cause manufacturers to install as required equipment.

But, as Ted noted, it’s prolly a good thing I don’t design or manufacture aircraft......on a whole bunch of different levels.

I can tell you this, though: I’ve never even come close to having an issue with carb ice. I’ve had a number of instances of carburetor icing, especially in Kodiak, but none even suggested it was close to an emergency.

It’s what that little black knob is for.

Just lucky I guess.

MTV

It seems that more and more we have more things in our plane that were not required for certification. I find it odd that your a huge proponent of shoulder harnesses as they were not required for certification. I know the GPS and phone or tablet / ipad that you use in the plane are not on the TC either.

I know that for damn sure the engine analyzer in my plane is not on the TC, but it has damn sure helped me figure out what was up with the engine and has led me down the rabbit hole of new baffles, rear mount cooler etc.

Just because something is not ABSOLUTELY required for flight does not mean that it does not enhance safety on a huge magnitude. Wig Wag lights are not on the TC.. they probably do more to enhance safety and see and avoid than any other single item out there. Just because the technology was not available when the plane was TCed does not by any means mean that we should not update our planes and give ourselves the best chance we can at getting back home alive.

Yea... my bird was built in 1946, barely had a compass back then.

Good thread...

I’m a rotor head, which does require a carburetor temp gauge simply because the ship is partially throttled 99.99% of the time. Here’s a thought on contemporary aircraft (built today):

Helicopters are required to have a “low fuel” warning light system, which is required to be thoroughly inspected every 100 hours/annual. The damper and warning light are tested every preflight. Yes, tested every preflight per pilot operating handbook.

It is calibrated and dampen for about 10 minutes. Which means “Hey folks we are making an unscheduled landing”

A yellow low fuel warning light was installed in my Porsche 40 years ago. In Japan a nice female voice would tell you “Low fuel des ka.” that was 45 years ago.

Side Note: The equipment list for a recently manufactured IFR certified helicopter is literally insane and so expensive it’s mind boggling.

The human mind is not perfect. Let’s help us all fly safer, eh? I adore autopilots!

I test that light below every preflight, POH & Rotorcraft Flight Manual:

I think the Mighty Birddog has had a few versions of the trusty 0-470 under its hood. These clips are from the Canadian Air Cadet L-19 POH

Aryana wrote:

mtv wrote:Cessna did offer the carb temp gauge as an option in the O-470 aircraft they built (180/182) which are arguably the most prone to carb ice of any engine around, yet it was never required equipment.

I'd argue the O-300 in the 170/172 is more prone to carb ice than the O-470 180/182

I live on the wet coast and it’s really not a problem with my 0-300. I guess it does make ice occasionally, but I pull the carb heat all the time, as I was taught. It’s second nature. I have a carb temp gauge but only use it on startup to check that the heat is working. I just pull heat all the time, every time.

Maybe it’s more dangerous if it’s not expected.

mtv wrote:Which doesn’t change the point that these airplanes did not come equipped with a carb temp gauge as required equipment.

MTV

I can agree with you there. Many have flown more than 60 years without a carb temp gauge just fine. The post quoted below is a good example of how they survived all those decades without that instrumentation.

daedaluscan wrote:I live on the wet coast and it’s really not a problem with my 0-300. I guess it does make ice occasionally, but I pull the carb heat all the time, as I was taught. It’s second nature. I have a carb temp gauge but only use it on startup to check that the heat is working. I just pull heat all the time, every time.

Maybe it’s more dangerous if it’s not expected.

I have a wet, foggy coast here too. I was based in Half Moon Bay for many years.

Your discipline of regularly using carb heat during all the at risk phases of flight means you are not likely to get caught out.

There's usually only a small penalty to having carb heat on when you don't actually have ice (less engine power, unfiltered air), but the consequences can be huge if you don't have the carb heat on when you should.

All things equal, an O-300 usually ices up easier than an O-470. Use carb heat sparingly in the O-300 in the right conditions and you will get tested before you ever have a chance to study!

The O-300 is capable of icing up while idling on the ramp. I always leave my heat on after my run up and turn it off just before take off.

But if you instead err on the side of caution and use carb heat regularly, you won't ever experience the terror of listening to one of these engines choke on water and quit running.

But if you instead err on the side of caution and use carb heat regularly, you won't ever experience the terror of listening to one of these engines choke on water and quit running.

Wise words to live by Aryana, if all follow this "operational" disipline everyone will live long & prosper.

Carburetor heat adds about 1500-2000’ DA to engine performance at standard temperature. But, is not linear. Heat reduces power much greater above 80F (which is not a standard atmospheric temperature). Hot days are dangerous anyway.

R44 Cadet, POH / Rotorcraft Flight Manual, Safety Notice 25:

I hope I get to fly a helicopter with a governor someday. I never thought about the potential pitfalls regarding icing/carb heat that come from giving up control of the throttle.

Aryana wrote:I hope I get to fly a helicopter with a governor someday. I never thought about the potential pitfalls regarding icing/carb heat that come from giving up control of the throttle.

Hence, the full (nearly full) throttle light.

You can turn off governor. Not recommended.

Note: the 24.9” redline, derated:

It seems that more and more we have more things in our plane that were not required for certification. I find it odd that your a huge proponent of shoulder harnesses as they were not required for certification. I know the GPS and phone or tablet / ipad that you use in the plane are not on the TC either.

I know that for damn sure the engine analyzer in my plane is not on the TC, but it has damn sure helped me figure out what was up with the engine and has led me down the rabbit hole of new baffles, rear mount cooler etc.

Just because something is not ABSOLUTELY required for flight does not mean that it does not enhance safety on a huge magnitude.

In fact, every NEW (as in current production) airplane I know of IS required to be equipped with shoulder harnesses. Many are also equipped with engine monitors in the form of the common glass cockpits.

Now, GPS? I’m Absolutely a big fan. But is GPS really required to fly safely? I for years and thousands of hours without it.......

Which brings me back to my point: if a carb temp gauge is such a safety item, one would think it would be required equipment on SOME airplane today. Maybe it is.and I missed it, but I don’t thinks.

I expressed my opinion, which is that a carb temperature gauge in fixed wing aircraft, is basically a gadget. Is it a HUGE safety item? Hardly, or it’d be required equipment in every current production airplane with a carburetor. That opinion obviously isn’t widely shared here. So be it.

Rather than learn something from the initial post on this thread.......as in what that little black knob is for, the apparent “solution” you folks would choose is installing another gadget. The OP could have had a really bad day had his icing encounter been a bit worse. But a quick pull on that black knob could have fixed it.

Whatever.

MTV

Mike, my point is I run carb heat (it’s filtered on the Robbie) at lower humid altitudes 100% of the time per POH. But, I love seeing an indirect confirmation on the gauge too. That way I know it has sufficient hot air to work correctly. I’m not against the periodic physical application but, secondary information is not bad is it?

MTV your total commitment to being a Luddite is admirable! I'm not being facetious...it's so easy to rationalize cool doo hickeys in this day and age of GA instrumentation, and I see your point.

I find I enjoy flying much more when I just have a throttle, carb heat, fuel valve, stick, and rudder. No GPS, only a paper sectional & wet compass. Looking at the airspeed is optional because the whistle of the airframe is more accurate. Engine instruments are rpm, oil pressure, oil temp. Simple.

You might be happy to know that I largely ignore the carb temp instrument in my 170B. I won't remove it because I don't have anything to fill the weird hole it occupies!

Hey and look at that...lumbering along at 2270/18" with the carb temp at the bottom of the yellow/top of the red, 0C/32F...and carb heat off. [emoji16]




Better view of the useless scoundrel [emoji1787]

I'll give an example of carb temp gauges being only one tool. I fly an O-520 Pponk in a 180 with a digital EI carb temp gauge. I run a particular cruise MP setting most of the time so I can tell quickly if it starts to fall. Twice in the last couple weeks I noticed it start to fall, checked carb temp and applied heat - once was 37 degrees, next 34 (before heat). I assume that's probably the yellow range for the color code gauges. Not sure how accurate the probe is, but just because the gauge is above freezing doesn't mean there won't be ice.

When it comes to anti-ice equipment installed on IFR platforms, the operators manual typically require the equipment to be turned on when the outside air temperature is 4-5 degrees C ( about 41 degrees F). At 34-37 degrees, other parts of your carb were probably at freezing. It can happen quick in the right condition.

During IMC flight (RW/FW) I’ve seen “gotta blow the boots” ice build up happen in only a minute or two. In the airplanes it was dropping into a cloud on the descent and with the air above in the 40-50 degree range. The helicopter was on climb out. In three specific cases, temps were hovering around freezing to a little above. Staying ahead of icing is the game. Over years of hard won experience we get a feel for the conditions that are right, we understand what the beginnings of carb icing sound/act like. But for new pilots, low time pilots, it’s a good tool for awareness. As a life long turbine driver turned piston engine owner, it’s a good tool on my dash. I don’t trust it blindly, but it’s way better than nothing.


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Why is it widely believed that carb ice happens primarily with reduction in power? The temperature reduction happens as a result of the pressure drop across the Venturi. The faster the air flow, the greater the pressure drop and, consequently, the temperature drop. That would seem to suggest that carb ice is most common with a wide open throttle. Reading John Deakin, as well as my own experience, is consistent with this, though just suggesting it has caused people on other forums to say that my parents were illegally closely related.

StuBob wrote:Why is it widely believed that carb ice happens primarily with reduction in power? The temperature reduction happens as a result of the pressure drop across the Venturi. The faster the air flow, the greater the pressure drop and, consequently, the temperature drop. That would seem to suggest that carb ice is most common with a wide open throttle. Reading John Deakin, as well as my own experience, is consistent with this, though just suggesting it has caused people on other forums to say that my parents were illegally closely related.

I agree, but understand that when you close the throttle in damp cool conditions, you do two things

1. You have set up a situation that is somewhat conducive to icing.....not severe, but.....

2. At reduced throttle in a glide, the engine isn’t making much heat, there is still a lot of cool air flowing through tthe muffler shroud, thus dumping any heat over the side, so that IF you did create some carb ice, you MAY not have sufficient residual heat in the system to melt it if you were to select carb heat to hot.

By running carb heat to hot during low power descents, you may retain enough heat in the system and in the intake to prevent ice accumulation.

That’s the theory, in any case.

Next time your exhaust is apart for inspection, take a look at how the system is designed to work.

Finally, Lycoming engines tend to be more resistant to carb icing than Continentals. That’s because the induction tubes come right from the carb into the oil sump, so there’s constant heating of the carb and induction tubes.

MTV

mtv wrote:
Finally, Lycoming engines tend to be more resistant to carb icing than Continentals. That’s because the induction tubes come right from the carb into the oil sump, so there’s constant heating of the carb and induction tubes.

MTV

No, there's more to how susceptible an engine is to carb icing than that.

The Continental O-300 (which is more prone to icing than any Lycoming I've ever flown) has the induction going directly from the carb right into the oil sump as you describe above.

I got a good lesson on leaving the carb heat on during hot weather AND a high altitude takeoff. My T-Craft's A-65, with my limber girlfriend on board (and yes there is enough room in a T-Craft), one time was all it took for me never to do that again, an otherwise good performer, that day it was a real dog until I wised up.