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Robinson Safety Notice SN-25 (carb ice) - additional 1.5 in. HG MAP?

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Robinson Safety Notice SN-25 (carb ice) - additional 1.5 in. HG MAP?

Old 13th Dec 2023, 15:18
  #61 (permalink)  
 
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Originally Posted by Robbiee
Interesting, I've always been under the impression that slow flight took more power, and that those Cattle Mustering pilots busted MAP limits all the time (at least that's what they mentioned a few times at the Safety Course),..but anyway, are a lot of R22 Cattle Mustering pilots crashing due to carb ice?
About 98% of the time chasing cows is spent somewhere around 30-40 knots or so, and solo, which is near the bottom of the power curve. Contrary to what certain (idiotic) YouTube clips may portrait, mustering is not very spectacular or exciting almost all of the time, nor is it particularly hard on the aircraft. In fact, cylinder glazing due to the long time spent at low power is a common problem. Reliable statistics don't exist because there is not much reporting let alone investigating going on as long as nobody dies (some may say, as long as no commercial airliners are involved), but I do personally know of engine failures due to carb icing while mustering. It was always something that needed to be stressed to new pilots, because the desert environment is really deceptive when it comes to perceived RH, and ice is not exactly the first thing you think of in that part of the world.
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Plus, its not just humidity, there's also the outside temp and visible moisture,...but I'm sorry there's no humidity guage in the R22. There's no fog guage either, and I could have used one of those plenty of times, lol.

,...and it was a brand new 2000 Saturn, lol.
You say the solution is not to use the heat when it's not required. To know when it's not required, one needs to know both the OAT and the humidity, because they haven't managed in 40 years to put the probe for the CAT in the right spot. The humidity range in which carb icing is likely to occur is quite large, and can definitely not be determined by looking out the window







Oh,...and if the throttle is wide open at just 18" at high altitude, you should know that its not going to create that venturi like effect on that side of the butterfly valve, so carb ice shouldn't be a problem. Its probably why they tell you to lower the carb heat on short final at high altitude, but not at sea level.
I understand the concept, thanks, that's why I brought up altitude. Now there are in fact altitudes in between 0 and 10,000ft. How far open is the throttle at 18" and 2500ft? 4500? 6500? When do I no longer have to worry about it?
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Anyway, everyone knows Robbies are budget helicopters. So, either accept them for their flaws, or go fly something else. Plenty of other choices out there you know.
"Budget" is the excuse for this? I am not asking why they don't have SCAS or radalt or even a better crash structure. A temperature in the correct spot costs exactly the same amount of money as one in the wrong spot. I am completely dumbfounded how someone could find the energy to defend this idiotic issue. I have the option to fly something else which I've been exercising for some time now, but many of us do not especially at the start of our careers. "Instead of fixing this easy problem, why doesn't everyone just fly something else".
lelebebbel is offline  
Old 13th Dec 2023, 15:40
  #62 (permalink)  
 
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R44 Cadet has carb heat, but you can set it at the start of the flight and pretty much forget it. There is no need to apply full carb heat below 18". I think the temp probe is in a different place.
hargreaves99 is offline  
Old 13th Dec 2023, 16:07
  #63 (permalink)  
 
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Originally Posted by lelebebbel
About 98% of the time chasing cows is spent somewhere around 30-40 knots or so, and solo, which is near the bottom of the power curve. Contrary to what certain (idiotic) YouTube clips may portrait, mustering is not very spectacular or exciting almost all of the time, nor is it particularly hard on the aircraft. In fact, cylinder glazing due to the long time spent at low power is a common problem. Reliable statistics don't exist because there is not much reporting let alone investigating going on as long as nobody dies (some may say, as long as no commercial airliners are involved), but I do personally know of engine failures due to carb icing while mustering. It was always something that needed to be stressed to new pilots, because the desert environment is really deceptive when it comes to perceived RH, and ice is not exactly the first thing you think of in that part of the world.
​​


You say the solution is not to use the heat when it's not required. To know when it's not required, one needs to know both the OAT and the humidity, because they haven't managed in 40 years to put the probe for the CAT in the right spot. The humidity range in which carb icing is likely to occur is quite large, and can definitely not be determined by looking out the window









I understand the concept, thanks, that's why I brought up altitude. Now there are in fact altitudes in between 0 and 10,000ft. How far open is the throttle at 18" and 2500ft? 4500? 6500? When do I no longer have to worry about it?
​​​
"Budget" is the excuse for this? I am not asking why they don't have SCAS or radalt or even a better crash structure. A temperature in the correct spot costs exactly the same amount of money as one in the wrong spot. I am completely dumbfounded how someone could find the energy to defend this idiotic issue. I have the option to fly something else which I've been exercising for some time now, but many of us do not especially at the start of our careers. "Instead of fixing this easy problem, why doesn't everyone just fly something else".
I defend the R22 because I love flying it, and because I understand (and accept) that when you buy a Saturn, you don't complain that it doesn't have the power going up hill to pass a semi, and that the fuel guage isn't very accurate.

Until now I've never heard anyone make such a big stink over the carb ice guage in the 22,...but hey, if its such a big issue for you, all I can say is; write a letter to the complaint department at Robinson. They're a huge corporation so I'm sure they'll get right on it, lol.

,...and I did my training in the Arizona desert in a Beta II.
Robbiee is offline  

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