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r22 in extreme cold flying??????


mattcob
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hello all!!

 

been a while since i posted but got a pretty important question to ask!! im now flying r22 in northern minnisota, its a bit jolly cold up here!!! anyway, on an average day the temps here can be anything from between -10c - -25c and humidity 75 -97% we are having days when we are out flying, pulling full carb heat, for the whole flight with it still in the yellow, but if we push it in its still in the yellow!!! both situations are making me uneasy and its getting colder here!!

 

i have called robinson and they did not get back to me and would really appreciate some technical advice asap!!! my gut feeling tells me im pushing things and should not fly, would like to hear from someone who knows what they are talking about!!!!!

 

all the best

 

blue skies

 

mattcob

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If you never pull the carb heat at all it's still in the yellow? I would not be comfortable with that.

 

Cheer up though -- I'm sure it will get colder and you can fly below the yellow!

 

HVG

 

(P.S. Thanks for the reality check. I used to live in MSP but have been so long in the mild NW now that I was whining about today's 15 degrees...)

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Seems like if you're flying in temps that are that cold, -10 - -25 then the needle shouldn't be in the yellow. The air gets colder in the carburetor and the bottom of the yellow is -15. Plus any moisture in the air should already be frozen. If your carb temp is in the yellow with heat on or off then it's probably not the wisest to fly. I'd probably wait until it got colder or warmer. You might want to check to see if the carb heat is working as well as it should. There could be a leak in the air duct or something. Now some one with more experience operating in temps that cold may have a better answer for ya.

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According to my notes (and the ASA R-22 Pilot's Guide, written by John Swan) pulling carb heat when the OAT is below -10 C is not recommended, since doing so can actually raise the temp in the carb to the area most condusive to carb ice. It actually can melt the ice crystals in the air coming into the carb (which would normally just pass through and into the engine with no problem) and cause them to then re-form as ice on the butterfly valve.

Can't find anything that really says you can't fly below certain temps, other than maybe the manifold pressure limit placard which doesn't go below -20 C. But if your gut's telling you something, I've always found it's usually good advice. Let us know if you hear back from the factory!

Edited by raptor
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I asked Frank last March if there was a minimum operating temperature and he said that there wasn't one. He also mentioned that a lot of operators in Canada are flying in the -30F temps. He also talked about metal fatigue in the course and I would think the colder temperatures would affect the stress point of the metals, bonding materials (blades), and other materials but he didn't mention that.

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I think Raptor has the most comprehensive and accurate response. While you might be tempted to pull carb heat in the cold temps, remember that the extra heat can actually melt the ice crystals suspended in the air and then re-freeze on the butterfly valve. Follow the Carb heat temperature guidelines.

Edited by jaskins
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its a bit jolly cold up here!!! anyway, on an average day the temps here can be anything from between -10c - -25c

 

 

Matt- excuse me?

 

We have a huge coldfront moving thru L.A. tonight, its currently 49 F, damn near freezing. I'm thinking of buying my first windshield scraper for the car. I don't need one, I just thought it would look neat in the glovebox.

 

I have to ask....what the heck are you thinking?? It's fricking -25C up there??? Do density altitude charts even go that low?

 

Ok, so you do what you think is right, you die. You do what we recommend and you're still dead. I do remember the same line of questions asked in Robbie school. And the same answers about not pulling heat for fear of generating an icing condition.

 

However, with temps that cold, I would definitely want to ignore all of our responses and talk to Pat Cox at the factory.

 

Some contact info below:

 

Technical Support: Pat @ Ext 212

Daniel @ Ext 214 (se habla Español) email ts2@robinsonheli.com

Chris @ Ext 208 email ts3@robinsonheli.com

Mail: 2901 Airport Drive, Torrance, California 90505 USA

Telephone: (310) 539-0508

Fax: (310) 539-5198

 

 

BTW- wear a jacket.

 

Goldy

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However, with temps that cold, I would definitely want to ignore all of our responses and talk to Pat Cox at the factory.

 

Some contact info below:

 

Technical Support: Pat @ Ext 212

Daniel @ Ext 214 (se habla Español) email ts2@robinsonheli.com

Chris @ Ext 208 email ts3@robinsonheli.com

 

 

I did just that two days ago, asking about what i should have done on a flight with an OAT of -6 to -8C (DP -13C), resulting in a CAT of barely +5C with the carb heat on, but in the middle of the yellow arc with carb heat off.

 

Here is the answer:

Customer Service <customerservice@robinsonheli.com>

 

Hello Dirk,

 

Your readings seem to be normal. As stated in the R22 POH carb heat should be applied between 27C and -4C. Colder than -4C carb heat not required.

Your CHT and OAT with a cold engine should be approx. the same.

Please refer to the R22 POH.

 

Best Reagrds,

Chris Sennett

RHC Tech Support

 

Guess I'm going to take his word for it, although the way I interpret the POH, it only talks about not having to use ("unlatch") the Carb Heat Assist in a Beta 2, IF the OAT is below -4C (like he says) AND the dewpoint spread more than 11C.

 

I would also like to know what happens if I take off at an OAT of, say, +2C, then climb to a higher altitude where the temperature is -5C. Can I push the carb heat down and let the CAT decrease through the yellow arc in flight? Does the dewpoint spread matter in this situation? What if I'm descending at the same time?

 

There seems to be a outside air temperature range somewhere between about -7C and maybe -11C where the CAT will be in the yellow arc, no matter what you do with the carb heat knob.

Edited by lelebebbel
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Here is this mornings metars, still a little chilly

 

KHIB 181353Z AUTO 00000KT 10SM CLR M31/M35 A3011 RMK AO2 SLP251 T13111350

 

Hey, at least its not windy !!

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Hate to revive a dead thread, but I was reading once again one of the books I use to help study for the one day I can actually afford to pursue my flight career (kinda like reading how to ride a unicycle - if you never get on one it is hard to put it into practice, but it will pay off in the long run). And I remembered this thread...

Anyway here is what the Canadians think about Carb Ice.

http://www.tc.gc.ca/publications/EN/TP9982.../HR/TP9982E.pdf

Starting on page 22, and more to the point page 24 - Note 6, Point A and B

 

Thanks,

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