Manually pulling prop though in cold weather

Discussion in 'Maintenance Bay' started by JOhnH, Dec 3, 2017.

  1. JOhnH

    JOhnH Touchdown! Greaser!

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    We flew in a day early to miss today’s weather. They do have a nice FBO here. They are hangaring our plane too.
     
  2. FastEddieB

    FastEddieB Final Approach

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    Snowing here in Mineral Bluff right now.

    Rare enough in the "Southeast" that we really look forward to it.
     
  3. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser!

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    I only burp my Rotax when I feel that I might need to add oil. If the level high enough on the stick, good enough.

    That. And, that's why you don't pull a Rotax backwards.

    Back in the olden days when cars had carburetors and I worked on emission systems for a living, the fuel guys would do things like make clear plastic manifolds to observe the flow of the fuel from the carb to the intake for cold starts. The engine would start when the liquid film on the wall finally made it to the intake valves - the relatively higher flow rates around the valve would strip fuel from the back of the valve and mix it in the air during the intake stroke.

    You do put a little heat in the cylinders from compression, but I doubt a couple pulls would make much difference.

    Now, I would assume that the POH is written a lot like the service manuals for automobiles and trucks. I used to work with some of the guys that wrote the manuals. That's all I'm going to say.
     
  4. Paulie

    Paulie Line Up and Wait

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    You must be in North Florida.
     
  5. JAWS

    JAWS Line Up and Wait

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    Heated hangar, best way to go!
     
  6. JOhnH

    JOhnH Touchdown! Greaser!

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    The hangar wasn't heated, but the temp reached 30 before we started the engine. I pulled the prop through a few times, in the opposite direction, and it started on about the 4th blade turn.
     
  7. Duster

    Duster Pre-Flight

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    If it's a 6-cyl Continental with a new style starter adaptor, do not rotate prop backwards, it will damage the adaptor spring. One compression stroke should not hurt anything, but pulling it backwards for multiple strokes is not permitted, per Continental's manual.

    If below freezing, pre-heat the engine. For winter ops, use Phillips 20W50, or some other multi-weight. I pre-heat below 55 degrees, oil pan heater, partly just to not have to ground run as long.

    Another note on 470/520 engines; many operators insulate the crossover tube for cold weather ops, helps keep the fuel distribution more even, carbureted versions. EGT spreads that will normally run 80-120 or so, will often be 200-250 in the 30's and below. Running partial carb heat, can help to even out the EGT spread as well.


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  8. JOhnH

    JOhnH Touchdown! Greaser!

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    Which manual would that be, and does it override the POH?
    Any idea where I can read that, because my POH does say to pull the prop in the opposite direction.
     
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  9. Duster

    Duster Pre-Flight

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    John,

    I'm away from airplane and documents now, so will have to verify where I read that at a later date. After receiving the engine from last overhaul, got an email from the engine builder, which warned CMI advises not turning the "new style" adapters backwards, and that this engine had a new style adapter. There is no limitation on the "old style" adapters concerning direction of engine rotation, in this regard.

    Certainly, this is not mentioned in my POH from 1959, as it was the old style adapter, on a different model engine. However, on this aftermarket STC'd engine, which came with its own users manual, it did supersede the POH upon installation. Can't speak for what the POH's say on newer aircraft with "new style" adapters, would be very interesting if they advised differently than Continental though.

    Quick search on the interwebs turned up the brief article linked below. Will try and verify the previous statement regarding the Continental manual when I get a chance, could be wrong. I did verify the old email from Custom Airmotive about this, and I'm not totally crazy yet haha

    https://www.aviationengines.com.au/technical-articles/important-information/


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  10. Dan Thomas

    Dan Thomas En-Route

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    More accurately: http://www.tcmlink.com/pdf2/M92-10.pdf

    Quote:
    NOTE...These new adapters will exhibit varying degrees of resistance to propeller rotation in the
    direction opposite of normal engine cranking rotation. This is caused by the light friction which is
    required to initiate clutch engagement in the cranking mode and is considered normal.
     
  11. JOhnH

    JOhnH Touchdown! Greaser!

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    Interesting. Thanks.
    From the article:
    My propeller doesn't exactly turn "freely" in either direction, although I am not exactly sure what that means either.
    But it does turn similarly and fairly easily in either direction, so I assume I have the old style. I guess I will have to ask my A&P.

    But there is no hurry. If it ever dips below 40 here, we shut down the city and my next trip is Key West and I don't expect any cold weather starts down there.
    But I am headed to Alaska in May, so I will verify before then. And I will switch to a cold-weather multigrade oil for the trip.