How Cold Is Too Cold

Discussion in 'Maintenance Bay' started by Huckster79, Jan 20, 2019.

  1. Huckster79

    Huckster79 Pattern Altitude

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    So I know planes do fly in very frigid temps, but how cold is too cold for flights that don't need to be made for the sake of not being too hard on the equipment? I'm not asking about pre-heat, but at what temp do many folks consider just too cold for the sake of the plane in frigid temps? Mine is a Cessna 140 so I have fabric, Stitts, and have heard cold flying can be hard on fabric, I forget in what way or why I was told it was, so some insight there would be great too.

    Today it was -8F in the morning but beautiful out CAVU with no wind, but for the sake of my bird should she stay in the hanger at that temp or not?

    What are your thoughts?
     
  2. Clip4

    Clip4 Final Approach

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    -8 in drafty old C140 is to cold for me. If preheated properly, the engines don’t care.
     
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  3. Huckster79

    Huckster79 Pattern Altitude

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    She does have a draft here or there :) I call them my "Anti-CO" system. But with the 150 Muffler conversion and the larger of the skat tubing options from the 150 used, she has cabin heat to spare! She will cook you out...

    So is it not harder on non engine parts being so cold? That was my concern, the fabric on wings, the brittleness of non-engine parts, etc...
     
  4. Tom-D

    Tom-D Taxi to Parking

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    Oh yes they do,, that's why we have winterization kits. plug up those holes, to get it warm enough.
     
  5. Gary Austin

    Gary Austin Pre-takeoff checklist

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    What did those pilots of long, long ago in Alaska and Northern Canada do when all they had were fabric covered aircraft?, just thinking
     
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  6. Tom-D

    Tom-D Taxi to Parking

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    The carb's on most engines are made to flow enough fuel to run at -40f
     
  7. Tom-D

    Tom-D Taxi to Parking

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    mostly old alaskan aircraft were dope over cotton, now it is ura-somptin over ceconite.

    how cold can you operate ceconite, not a clew?
     
  8. Tom-D

    Tom-D Taxi to Parking

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    when is it too cold? when I decide :) 70 seems nice.
     
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  9. Huckster79

    Huckster79 Pattern Altitude

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    So I'm not being especially hard on anything flying that cold if I so choose and pre-heat right?

    A follow up too:

    I have the blast tube opening inside the engine taped off, the lower cowl vents taped shut and the main cowl openings up top taped off for about 3" ,on the inboard side of course, and I cant get it over 150, if my temp probe is accurate. I am going to test that at first oil change this week hopefully. I used foil tape for all of it and will get a nice winterization kit before next year.

    I know they had a wool "bag" for the oil sump, but that isn't going to work as the old philips preheater I have on mine isn't a pad like the newer units, its like a heating element that runs in a butterfly shape around the sump. So even if I find a wool bag for it, I can't use it. Being she's pretty much stock I don't have CHT guage and just concerned about taping off anymore of the main opening being I'm "Flying Blind" on CHT. But I hate knowing I'm running 35 degrees cooler than I should be for babying the old girl... Any Suggestions?

    One thing I thought of was using the foil tape to bridge the gap around the Carb Filter intake and the cowl, probably 1/4" or so, and that air would be going right back towards the sump, but wanted to ask more knowledgable folks before I just start sticking more foil tape everywhere...
     
  10. Stewartb

    Stewartb Final Approach

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    Carbs set to-40??? Not in the past few decades. Carbs too lean to handle the cold is a real problem that most of us have to address. Does a 140 have an oil cooler? If so, cover the majority of it. CHTs will be pretty normal. My low temp limit for fun flying is zero. For flights I need to make it's -30. Things break in the cold so don't manhandle anything. The DA will be really low so horsepower and lift are increased. MAKE SURE your fuel flow is adequate for the temps. Cold air requires lots of fuel. You need to be able to lean at least 100* from full rich in a well warmed engine. If you can't? Adjust the jet size.

    Dress like you'll have to walk home. Sub-zero temps aren't forgiving.
     
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  11. Huckster79

    Huckster79 Pattern Altitude

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    No Oil Cooler, Limited leaning capabilities, and no EGT to know I can lean it 100*. It has a leaning knob but full out won't cut the engine, and that isn't an oops, the factory shut down procedure is "mags off" to kill it...

    That effect of cold of making things easier to be broken is what I was concerned about and wondered where people consider that more likely to start happening... I don't need to go for the heck of it and break something I wouldn't have on a more reasonably temperatured day...
     
  12. nrpetersen

    nrpetersen Line Up and Wait

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    I had a harrowing experience with a club 172H takeoff about 40 years ago with 80 octane fuel (probably the same properties as 100LL) at KFCM on a bitterly cold (-20 degF) day. Someone else had flown it for ~1 hr & I took it with fresh fuel, did a normal run up and takeoff. It got 200 ft in the air when the engine suddenly faded away. I did a desperate 180, and landed downwind on the parallel runway, having never left the boundaries of the airport. Definitely not a recommended procedure but it somehow all worked out. Major fuel tank sumping from the 172 showed light snowflakes in a large sample. But the carb was not getting any fuel until a small amount HEET deicer was added to clear snow from the gascolator.

    The FBO sumped their tanks, otherwise the FAA had no explanation of what had happened. Later I contacted Amoco Chicago office & found data that supported gasoline will dissolve a certain amount of water, and that the amount decreases as the temperature drops.

    The FBO fuel was from an underground tank and probably as cold as it had ever been since being refined and has to be assumed saturated with water from their distribution system. At say 40 degF that fuel had been added to the 172, then severely chilled, precipitating out the water as snow, a small amount of which can plug a gascolator.

    I wrote about in in the Dec 1986 EAA's "Sport Aviation". I consider the information in that article still pretty much correct, even though this problem has not been addressed much otherwise.

    In Summary - BEWARE of fuel that has been severely chilled since it was last filtered.

    See post 48 below for the original data.
     
    Last edited: Jan 31, 2019
  13. iflyvfr

    iflyvfr Pattern Altitude

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    Anecdotal evidence for OP: last year I flew one day when it was 18* F on the ground. On landing at a small airport, my nose strut seal gave out. I aired up the strut and it was OK when the weather warmed but I replaced it at annual anyway. However, I see from your pic you can't have that problem at least.
     
  14. Huckster79

    Huckster79 Pattern Altitude

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    No I can't at least specifically that one but doesn't mean I couldn't have others... I just wondered if there was general consensus or how varied the opinions were at what point on the mercury does it just become hard on our girls to be used...
     
  15. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    I've flown at temps in the negative teens F... I probably wouldn't go past -20F, and even at less than 0F I'd like to have a better reason than just "I wanna" or a $100 burger.

    Close to -20, I've had the air filter be frozen solid and have to run the engine on the ground for 20 minutes to thaw it enough that the engine would run without carb heat.

    I've also had an engine just be really unhappy at the super-cold temps and decide to turn around and try again on another day.

    You definitely want to have whatever winter kits are available for your aircraft installed, and a "real" preheat system (Tanis or Reiff), and have it on for a good 8 hours prior to engine start. I also recommend that you put a space heater in the cabin, preferably on the floor in front of the front seats, and let that run for an hour or two so that your gyros warm up. LCD screens won't be damaged by the cold, but they can be difficult or impossible to read and very slow to update until they warm up to freezing or so as well.

    I know nothing about how the cold affects fabric.
     
  16. tawood

    tawood En-Route

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    I flew on Monday and it was -20F at 2000 feet. Engine ran very lean, 75 degrees from peak EGT full rich (its normally around 200 degrees from peak EGT at full rich), and I didn't dare lean it.

    And to the OP/at least as far as a Cherokee is concerned, I know mine does fine down to -40, as I've flown at that temp before. Heater worked well thankfully. And if you're wondering whether that was -40 F or C, the answer is yes (its the same at that temp).
     
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  17. Huckster79

    Huckster79 Pattern Altitude

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    I think low single digits will be about as low as I go. Yea I think I’m going to need to buy the sump “bag” for my lil continental as I can’t quite get to 150... going to change oil soon and will test gauge accuracy then decide. My preheater is an old Phillips brand unit, 275w I think- like an oven element that goes around the sump... with cowl and prop all wrapped up cylinders are warm to touch... though long term I think I’ll replace with a reif...

    No LCD screens in the ‘ol 47, but I should do the space heater for the T&B I guess...

    I flew Monday in low teens, she climbed like a raped ape! Not the norm for the ol 140!
     
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  18. Dan Thomas

    Dan Thomas Final Approach

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    We used to fly the flight school airplanes down to -25C (-13F) with no trouble. Even the fabric-covered Citabrias. Just use some power on descent to keep the engine warmed up or it might not respond after a long power-off glide.

    Bigger problem is oil not getting hot enough to boil off moisture that gets into the case as combustion gases blow past the rings when the engine is cold. Water in the case is a bad deal and causes corrosion.
     
  19. Huckster79

    Huckster79 Pattern Altitude

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    I have been concerned about this, even in the 30's I can't hit 150 with the proper spots taped shut and such. These lil continentals have a reputation for running cold. I am going to test my temp gauge accuracy at oil change this week, and if accurate going to get a sump insulation bag made for small continentals to get it up. So to try to mitigate it for now I built and engine dehydrator and it seems to be helping. I hook it up open loop after shutdown and can watch the steam "blow" out the vent tube, and then close the loop in the next day or so. The hygrometer sealed in the system currently reads 16% RH so its keeping it pretty dry in the crank I would say... I will know more this week once the temp gauge is tested for accuracy of my next step.
     
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  20. KayDeeW

    KayDeeW Pre-Flight

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    Thought you said your battery was dead?
     
  21. Stewartb

    Stewartb Final Approach

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    When you live at sea level and it’s -35 or colder the DA is minus 7000’ or greater. That’s hard on a piston engine. Limit power by reducing revs. The added lift and prop bite more than makes up for the reduced power settings. Or.... lay the whip to it and a long prop spinning at 2850 can make noise like you’ve never experienced before. ;)
     
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  22. Tom-D

    Tom-D Taxi to Parking

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    actually, with -7000 Atmospheric pressure the prop will get a bigger bite which will require more power to maintain the same RPM. but, the engine will also feel the Atmospheric pressure, MAP and make more power, the two should equal each other out.
     
  23. Tom-D

    Tom-D Taxi to Parking

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    apply winterization kit, pre-heat, and go fly.
     
  24. Stewartb

    Stewartb Final Approach

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    I live in a cold climate. I don’t know anyone who owns a “winterization” kit. Unless that’s what you call a roll of duct tape.
     
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  25. KayDeeW

    KayDeeW Pre-Flight

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    that was your car battery you were talking about @tawood my mistake.
     
  26. NavAir

    NavAir Pre-takeoff checklist

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    My airplane (a Diamond DA40) has an operating limitation of -40 degrees. I was told by the factory that it had to do with the functioning of the avionics displays. Of course, living in TX, it is not an issue...
     
  27. Dan Thomas

    Dan Thomas Final Approach

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    Speed of sound goes down with lower temperatures, so those prop tips are closer to the sound barrier when it's cold. More noise.
     
  28. Dan Thomas

    Dan Thomas Final Approach

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    I wouldn't trust a dehydrator. I've taken apart engines that were just run in the cold and needed repair, and found water between the piston and cylinder wall. Dehydrators would have trouble removing that.
     
    Last edited: Jan 23, 2019
  29. Stewartb

    Stewartb Final Approach

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    I think the current Continental service letter says that oil temps at or over 135* are good. Lycoming says 180*.
     
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  30. Huckster79

    Huckster79 Pattern Altitude

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    I'm still working towards running at proper temp... This is a mitigating step until I figure it out...
     
  31. Huckster79

    Huckster79 Pattern Altitude

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    Oooohhh, maybe I'm okay then??
     
  32. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    One other point I forgot to bring up before. If you live in a cold climate and fly in the winter, be religious about your 500-hour mag inspection/overhauls, and be sure that they ALWAYS replace the gears. The gears are nylon, and when you heat it up (while running the engine) and cool it way back down, they get really brittle after a while. I've had a mag fail because a brittle gear came from together.
     
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  33. Stewartb

    Stewartb Final Approach

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    I can block100% of my oil cooler in winter and be lucky to get140* oil temps on the really cold days.

    I'll try to find the Continental service letter tonight.
     
  34. edo2000

    edo2000 Pre-takeoff checklist

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    I learned to fly in Alaska and flew there for 40 years. Flying up there goes on routinely at -30F temps (and colder). I'm sure the cold has some negative effects, but I would never ground myself to avoid them. The Iditarod will be starting soon and thousands of hours of single engine flying will be done to support the race. Plenty of very low temps. Many of the aircraft doing the flying will have Stits or Ceconite covering. I flew a Scout on skis for decades, never noticed that the cold was degrading the fabric. I did have one possibly cold-related failure when the oil cooler on a C185 cracked while flying, saw oil on the windshield, reduced power and landed ASAP, lost 2.5 quarts. it was -25 on the ground that day, I didn't notice what the temp was at my cruise alt of 4500.
     
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  35. midwestpa24

    midwestpa24 En-Route

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    Our rule of thumb around here is usually 0F. Sure you could fly colder, but for the few days a year where it stays below that, it usually isn't worth it. It's been a topic of discussion around here because our temps are forecasted to get below -30F with windchills of -60F.
     
  36. Stewartb

    Stewartb Final Approach

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    Cold won't affect fabric that was applied correctly. My last Cub lived outside. Never an issue. My new one is spoiled! ;)
     
  37. KaiGywer

    KaiGywer Line Up and Wait

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    I did my commercial 2 hour night XC in a 172 at -35. It was really cold when the nose wheel blew as I was about to begin my takeoff roll. A very long cold walk back to the midfield FBO after pulling the plane off to the side at the runup pad. Not sure what the wind chill was, but it was cold.
     
  38. Mooney Fan

    Mooney Fan Line Up and Wait

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    I flew the other morning and it was 17 degrees. Everything was stiff as a buckboard. The primer was hard to pump, throttle stiff as heck.... including the mixture
     
  39. Mooney Fan

    Mooney Fan Line Up and Wait

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    Was that XC a dual requirement?
     
  40. KaiGywer

    KaiGywer Line Up and Wait

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    Yeah, the dual 2hr night XC