Cold Weather Operations

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  • #83602

    Had my first taste of winter in my 421C with a trip to Duluth this week. The airplane sat outside all night and it was in the high 30’s when I went to start the next morning.

    I got her started, but the right engine took a lot of “coaxing”. Other than “put her in a hangar or get a pre-heat dummy”, any advice for cold weather starts? I’ve heard that the GTSIOs require “lots of fuel” for cold starts, but I’m not really sure what that means operationally.

    Any other cold weather thoughts? The heater seemed to work great on the ground, and de-icing worked as expected.

    Robert

    #95142
    bthomason
    Participant

      Robert,

      421’s are harder to start in cold weather than other Twin Cessna’s. Tony will talk about this in the seminar but there is no magic solution. If it’s below about 20 degrees, a preheat is about your only option. My 421 (now Tim Johnson’s who will also be at the Mobile seminar) had Reiff engine preheaters. I carried a 100 foot extension cord with me when I traveled and used it fairly often. It’s a lot cheaper than a hanger overnight. I’m a huge believer in engine preheaters.

      #95145

      Robert,

      Just had the same experience this morning with my 421C. The left engine, almost new, started quickly, but the higher time right engine took the same coaxing. I did not want to over prime and after about four tries with a rest for the starter in between and a purging as per ops. handbook just to be sure we didn’t overprime the engine started. Interested in hearing of others techniques. This is my third twin Cessna and first experience with the GTSIOs.

      Tim Shields

      #95146

      My hangar is an un-heated T. When the OAT gets down to 40F and below, I always pre-heat. EZ Heaters are plugged in to a heavy duty outdoor timer. A second timer runs a small ceramic heater in the cabin. Several hours gets things nicely warm.

      Like Bob, I carry cords with me when traveling and I always ask for hangar space overnight, un-heated preferred. It’s saved me aggravation on early morning departures when airplanes outside on the ramp are frost and/or snow covered. Works for me, YMMV πŸ™‚

      ps: I don’t leave the heaters plugged in continuously. If I heat, I fly…

      #108936

      I’m a bit frustrated this morning. Beautiful weather outside, calm winds, sunshine, but 29-31F temps… I tried to start my 421C with no success. I primed, started, just like before, but can’t get the engines fire at all. Tried a couple times, now I gave up.

      I had no problems before at all starting the engines cold (sometimes when hot, wasn’t easy, but got a good routine and now I nailed those starts), but now I need to nail these cold morning starts…

      Any advise? (I’m new to the 421C, only a bit over 100 hours in the plane, mostly late summer/fall time flying).

      Thanks!!!!

      #108941

      ZPulai,

      I never start my engines w/o pre-heating them in the morning if the temps were below 32F overnight. That is my procedure but I never have any issues starting when the engines are heated.

      When it gets nasty cold I sometimes use my engine heaters inside the heated hanger and cover on if I am going to pull it out on the ramp and not start up immediately. (when I need to fuel it up). Sitting out on in the wind when it is around zero F it will cool the engines off so fast that they will fail to or struggle to start.

      But, 29-31 is not all that cold out, but GTSO engines need warmth. My opinion though is they should be pre heated before starting up at that temp. Good luck.

      Jim

      #108943

      I pre-heat and it makes a huge difference. If you cannot pre-heat then you need to prime until fuel is splashing on the ground via the drains, crack the throttle slightly, and prime while cranking. Having a ground power unit attached helps too. In that case starting the right engine first is easier on the person who put the ground power in (vs 30deg hurricane blast)

      Bottom line is a preheater is an excellent investment and will also reduce accelerated engine wear at low temps. I have not had the occasion to use it (as I like flying from my hanger to warm places) but I have tested the honda 1000i 16lb, 1kW generator and it will power my two 500 watt engine heaters. My cold weather plan was to arrive earlier and let the honda generator run. It will run for 3+ hrs under full load.

      Eric

      #108946

      Plug your Tanis heaters in the night before if it’s going to be below 40F. Your engines will thank you in the long run, and start much easier. πŸ™‚

      #108949

      What I was taught flying 135 in Alaska, but it wasn’t a 421, is that you really can’t over prime when it is cold. The problem is that the fuel does not vaporize very well so you prime more than normal then wait 30 seconds before starting so that the fuel has some time to evaporate into the air in the intake tubes. Probably should keep the throttle completely closed until the engine fires and prime while starting.

      A cold engine that cranks but will not fire is caused by two things:

      1) Despite all your priming efforts the mixture is still to lean.

      2) The gap in the spark plugs is iced over. This is rare but happens when the engine attempts to start, fires a few times, and then fails. Enough heat is released in the cylinders that the air holds more moisture but then condenses on the cold plug electrode bridging the gap and quickly freezing. Once this happens you can’t start until you pre-heat enough to get the plugs above freezing, which normally requires a warm hangar.

      I agree with everyone suggesting pre-heat. You can damage cylinders when the aluminum piston warms up and expands faster than the cold soaked steel barrel.

      Also carry some old wool blankets in the wing lockers, like the kind you get at an Amy surplus or farm supply store. When you shutdown a warm engine and plan to restart it that day you cover the engine with a blanket and stuff it into the cowl inlets.

      #108951

      Funny – I typed a response to this and didn’t realize it was my post that started the thread originally!

      I ended up tutting a Rieff system in my plane and it’s worked very well – highly recommend. I haven’t been in a situation where I coukldnt plug in yet, but a small generator isn’t a bad idea. I carry a fair amount of extension cords when flying in the winter and it seems to work. Every once in a while I’ve had to go to the airport early, plug her in then go to breakfast.

      I don’t know why the GTSIOs are harder to start than a TSIO though… Never had a good explanation about that.

      Robert

      #108965

      Once again thanks for the replies, ideas and suggestions.

      Today it was the same weather, around 32-34F outside. I wanted to give it an other try.

      This is what I did:
      1.) Fuel pump low, throttle fully open, mixture fully rich
      2.) Prime engine for 4-6 seconds until I see fuel coming out on the bottom
      3.) Fuel pump off, throttle back to idle, mixture left fully rich
      4.) Waited for 30-45 seconds
      5.) Starter engage, while cranking, I added some prime and the engine turned on perfectly on both sides.

      Success!!! πŸ™‚

      BTW, I have engine heaters installed on both engines, but I didn’t have them plugged in. Can they be plugged in right after engine shutdown? Does anybody know how much power they need (namely, can I run them on a small Honda 500W portable AC generator when I park elsewhere?) Thanks!

      #108974
      quote ZPulai1:

      Once again thanks for the replies, ideas and suggestions.

      Today it was the same weather, around 32-34F outside. I wanted to give it an other try.

      BTW, I have engine heaters installed on both engines, but I didn’t have them plugged in. Can they be plugged in right after engine shutdown? Does anybody know how much power they need (namely, can I run them on a small Honda 500W portable AC generator when I park elsewhere?) Thanks!

      Can they be plugged in right after engine shutdown? Yes

      And engine heaters require the engines be wrapped up with covers.

      #108975
      quote JODAY:

      And engine heaters require the engines be wrapped up with covers.

      One correction – they don’t require it, but they sure do work better with blankets. I never had the engines on the Aztec wrapped up, and on the 310 sometimes it doesn’t happen. With blankets they’re hot enough that I have to use hot start technique rather than cold.

      Obviously some variables. In a hangar, you shouldn’t have a breeze so it won’t cool off things so fast. On your ramp at Fargo (thinking to this time last year when I stopped in and how frigid and breezy it was), without blankets they wouldn’t work at all.

      #108976

      Well, you are correct, they will operate w/o blankets.

      It has been my experience that w/o the engines covered, they will not really get the engine warm, even in a hanger.

      And Ted, you were here on a windy night, but it really was not that cold out. πŸ˜‰

      #108980
      quote JODAY:

      And Ted, you were here on a windy night, but it really was not that cold out. πŸ˜‰

      I think this is why our experiences are different regarding blankets. Remember, my body is French – it was built to surrender. πŸ˜‰

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