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Thread: Cold Start Engine Procedures?

  1. #1
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    Default Cold Start Engine Procedures?

    Was recently renting a C-172SP from a local flight school and had a bit of an odd incident.
    Arrived early for my 8am flight time, plan was to go for a short hop and a 100$ breakfast with a buddy. It was a nice and cold -27 and this school has a history of forgetting to plug in aircraft overnight. Anyways, we arrived to see the plane already sitting out on the line rather than in the hangar. After a normal walk around and preflight, we went out and I got my buddy seated while I went to the front to pull the prop through a few times. The idea, so I've been told, is too loosen up some of the oil while checking to see how loose it actually is. Hopped back in the cockpit and began the pre-start, right as I go to turn the starter I see the CFI of the school running down the steps waving his arms...He runs over and begins to get in a big huff about hand turning an engine over, how dangerous it is etc...with slightly too many profanities for that early in the morning haha. After appeasing him and swearing I'd never do it again, everything continued as normal. The eggs were still worth it IMO!

    Brings me to my question, was I wrong in hand-turning the prop (mags and master were confirmed off)? I dont have the POH with me right now, but im certain this is in there somewhere.
    What kind of cold-weather procedures do you guys have?

    Regards, Mack

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    Well lets see,,,, minus 27 Celsius is the same as minus 16.6 Fahrenheit.
    Was the plane actually left out cold all night or was is semi-warmed up before you tried to start it ?
    If it was really a cold engine, that flight school has bigger problems than you pulling the prop through....

    The CFI probably thought you were attempting a hand-start and many businesses have insurance policies which strictly prohibit hand-propping.

    I must ALWAYS hand-prop my plane because I have no starter. BUT...Even my insurance policy makes a big deal about it......

    Most folks are not properly trained to hand-prop a plane these days because everyone is afraid of being the victim of an ambulance chasing lawyer.
    If you are going to pull the prop through, you need to act as if the mags are hot and take the same precautions you would while hand-propping.... BECAUSE every now and then the mag switch fails and you could get a face full of prop.


    There are some additional risks when hand starting a cold engine in very cold temps. Over the past 30 years I have started two carburetor fires while attempting to hand start a cold engine when it was below zero. The engine started without firing on all the cylinders and then kick backwards a few times and back-fire into the carb. The flooded carb then burst into flames..... Not much fun...

    With a functioning starter you are always pulling the prop through and it sucks any carb fire up into the engine.
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    With an engine that's adequately per-heated and with electric start there's no reason to pull the prop through. I suspect the instructor saw a pilot that was in position to get hurt if a P lead was bad and a mag was hot. You should get somebody to instruct you to hand prop. You'll probably be shocked at how easy it is and how slowly you can turn the prop and have it fire. You won't take moving the prop as casually the next time.

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    When I looked it over, engine was bone cold. No preheating seemed to have been done. Either way the whole idea of an accidental firing does still seem like risky business.

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    Any time one moves the prop by hand, a serious situation exists. The potential for disaster is real. Just ask the ghost of Max Shellabarger, one of the truly fine old pilots. His feet slipped on the lake ice, the engine started, and that was the end of his flying.

    Many of us learned to fly before generators, batteries, and starters were available to us. Hand propping was a regular chore. But we had been carefully schooled in the technique, which reduced the risk factor considerably. Nothing, however, removes it completely, so be very aware of what you're doing when you reach out and grap that prop !!!

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    When I looked it over, engine was bone cold. No preheating seemed to have been done
    WOW...at negative 27C, .... that engine is on its way to an early rebuild...... or worse...
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    REALLY, minus 27????? Or 27?

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    I used a Red Dragon propane heater ducted up into my supercub exhaust. You can watch your gauges reach proper temp. But at -27 not sure I would head out just for a morning meal. May end up being a very expensive meal.

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    Yep, -27C...or -16F. Daytime was supposed to get back up to -15C or 5F with some warmer weather moving in. Either way I'm feeling kinda silly for pulling that prop through. Always learning.
    Picture from a bit later that morning

  10. #10

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    People are trying to point out that pulling the prop through was not the only bad idea. The other really bad idea was starting an engine that had not been preheated when the temperatures were that low. People have different rules...mine is no start without preheat when the temperature is below freezing.
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    Cold temperature starting requires lots of fuel and a good battery. While Lycoming says the deciding preheat temp is 10*F the reality is I've never had a plane that will start reliably at that temp without some preheat. TCM says 20* is the trigger temp for preheat. My engine starts fine down to that so I don't hesitate to start at that. There's no way in hell my plane would start in below zero temps without heating it first but there's no way in hell I'd try.

    http://www.lycoming.textron.com/supp...dfs/SI1505.pdf

    http://www.tcmlink.com/pdf2/SIL03-1.pdf

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    Yes, I also shouldn't have attempted a start. Thats a fault on my part again. There must have been some preheating in the morning as it turned over fine. Still should have preheated more before starting. Especially if the engine seemed cold to me. Dumb move on my part.

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    I would chalk it up to "You don't know what you don't know" Until someone points it out to you. Hopefully you have a good instructor to teach you the basics. It's not until you purchase your first aircraft that the next level protecting yourself and your aircaft comes into play. (It shouldn't happen that way, your instructor should be educating you on how to be safe and how to care for the aircraft) Most aircraft owners can flush a $100.00 bill down the toilet without blinking an eye. However, we try to spend more of our hard earned money on fuel for flying instead of engine repairs.

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    Well the only thing I can see that you didn't ask about pre heating before you started your pre flight- I don't have a problem with what you did, gee's I done the same thing more than once in my sorted career with out any ill effect. Now I have a problem with that instructor pilot, If he was working for me- he be gone. You don't throw profanities at customers or worst students period. What I like to do when its that cold out and I know the airplane is going to be flown. Keeping in a warm hanger is preference number one. Having something along a tanis heaters installed and the airplane plugged in with some electric space heaters in the cockpit so the radios and gages stay warm is what I really like, last I will drain the oil out on the last flight while warm and put that oil on the stove and heat it up then put it back in the airplane put the prop thru a couple of times and well starting should not be a problem. I am aware that there is more wear and tear on engines in winter, and metal tends to get brittle with cold. I look at it as more of the price you pay for operating in winter. It might be a little more work than you might want to do for a 20 min fly out breakfast run, under those conditions, I would sooner go by snow machine- nobody ever said airplanes or flying is a cheap pursuit. Its not and it never has been. As for that Instructor, I would not take lessons from him, he just told you what an abusive zero he really is.
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    This is embarrassing to say but I am glad to have read this topic, as I do the same thing regularly! And I just discovered that one of my mags is not turning off. I know how to hand prop and have done so many times but after a pre-heat I have been known to stand in front of the prop and turn it to move the oil!

    This topic may have saved my life as I will never do this again! It's just one of those things I have been doing on my own for over 150 hrs now and no one has said different!

    Thank you

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    If you need to turn the prop.... Stand behind it and treat it like a hot prop.
    Also turn off your mags occasionally when the engine is down at a very low idle , just before the fuel starves... If is dies right away your mags are working correctly... If the engine continues to bang away on one mag,,,, you have problems.
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    If everything is just right an engine will start if you just move the prop, or wheel on a motorcycle. I once was holding a plane at the dock by the nose cone, found it is not the thing to do. Also once I was sitting on a motor cycle, trying to shift it out of gear so I could start it, I rocked the rear wheel just as I was pulling in the clutch, it started much to my surprise.

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