Storing airplane with throttle wide open

Discussion in 'Pilot Training' started by Ryanb, May 4, 2019.

  1. Ryanb

    Ryanb Touchdown! Greaser! PoA Supporter

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    what’s the science behind this? I’ve seen several photos of folks who store their airplane with the throttle wide open. I probably should know this, but I admittedly don’t.

    :)
     
  2. overdrive148

    overdrive148 En-Route

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    You scare the line guy even more when he goes to move your plane :eek:
     
  3. MauleSkinner

    MauleSkinner Final Approach

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    It’s not so much storing it as shutting it down...in older airplanes without an idle cut off mixture, you’d shut the engine down by turning the mags off, and then wide open throttle would reduce the amount of fuel that got pulled into the cylinders until the prop stopped.

    Some people still do that, even though they don’t know why other than “That’s what my instructor taught me.”

    And there may be other reasons, but I can’t think of them. ;)
     
  4. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser! PoA Supporter

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    It is done as a public service and a warning to others about the dangers of hand propping. This way, if the mags are hot, and someone flips the prop for some reason or another, the throttle is wide open and they get chopped into little bits as the airplane runs them down.
     
  5. Ravioli

    Ravioli Final Approach

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    Hmmm... I leave throttle at 1000RPM and then mixture to idle cut-off. Engine shuts off.

    When starting, I use boost pump and prime, NOT touching the throttle, and it starts really close to 1000RPM.
     
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  6. hotprops

    hotprops Line Up and Wait

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    Maule ,with a aircraft that has no mixture control I am interested in how full throttle would actually result in lower full pull than idle. I am not disbelieving you but in 40 years of owning such aircraft this is news to me . was I just rickroled or onioned?;)
     
  7. MauleSkinner

    MauleSkinner Final Approach

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    There’s a separate idle jet in the carb, placed right at the butterfly valve when the butterfly valve is closed. Even at the low rate that the pistons pull air through the carb, it generates a significant venturi to pull fuel into the carb. Wide open throttle gets the butterfly valve away from the idle jet.
     
  8. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    I've always just gone full rich and then turn the mags off. If a cylinders are full of fuel than there's no room for water to condensate. Duh
     
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  9. GRG55

    GRG55 Final Approach

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    Thread title is asking about throttle position, not mixture position.
    Trying to deliberately hijack the thread are we?

    Reported :p
     
  10. Ryanb

    Ryanb Touchdown! Greaser! PoA Supporter

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    That’s what I do too, but the throttle remains closed once the prop stops. In fact, I was out at the airport just a few nights ago and a transient C150 was on the ramp and they left it with the throttle wide open. I’ve seen it more and more...
     
  11. asicer

    asicer En-Route

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    All the knobs fully in gives you more knee room. Also, less likely to catch on something when crawling across a one-door low wing.
     
  12. Dean V

    Dean V Pre-takeoff checklist

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    Maybe a poll is needed for this. I have never heard of it.
     
  13. Van Johnston

    Van Johnston Cleared for Takeoff

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    Actually, my manual does in fact say to go to full throttle and then shut down.

    My manual for my John Deere mower.
     
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  14. MooneyDriver78

    MooneyDriver78 Pattern Altitude

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    Full throttle and mixture dumps the fuel out of the lines on a Lycoming IO360. I sometimes do this in preparation for a hot start, allows fresh avgas to cool the lines enough not to start vaporizing.


    Tom
     
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  15. Ryanb

    Ryanb Touchdown! Greaser! PoA Supporter

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    There’s an answer!
     
  16. GRG55

    GRG55 Final Approach

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    Sounds like an obsessive-compulsive making sure all the knobs line up. :goofy:

    Me neither.

    I wonder if these people also put all the switches in the same position on shut-down. :idea:
     
  17. Tom-D

    Tom-D Taxi to Parking PoA Supporter

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    WOT at low RPM will not create any vacuum to pull fuel out of float bowl.
     
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  18. Eric Stoltz

    Eric Stoltz Line Up and Wait

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    Can you please explain this further? I have the same engine and hot start it the same way. I don't think I ever knew the reason why I should start it this way other than what my engine mechanic told me. I've forgotten, or just didn't listen to him on why.
     
  19. MooneyDriver78

    MooneyDriver78 Pattern Altitude

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    I’m not a mechanic so...I’m just regurgitating what my mechanic told me. It seems like if the stop is just 5 minutes, standard hot start procedure works, but if 10 minutes or more...then the avgas vaporizes in the lines, and it just coughs and sputters. So firewalling controls dumps all the vapors...you will see fuel pressure drop when you do this.


    Tom
     
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  20. JAWS

    JAWS Line Up and Wait

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    Old wives tale? Stupidity? Complacency? Wanting to make a nicer home for a mouse?

    If you want to open the throttle after mixture cut-off / mags off, as the engine is winding down, whatever. But don't leave it that way. That is a link in the chain of events of an incident down the road.
     
  21. Zeldman

    Zeldman Touchdown! Greaser!

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    This started out sounding so serious that I actually paid attention....:lol::lol:
     
  22. asicer

    asicer En-Route

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    You read me like a book. :D
     
  23. Skyrys62

    Skyrys62 En-Route PoA Supporter

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    Yes.... It's like having a few drinks before lunch.
    Because it's just not good to eat on an empty stomach.
     
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  24. PaulS

    PaulS Final Approach

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    Moving the throttle frightens me, I do it as little as possible.
     
  25. hotprops

    hotprops Line Up and Wait

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    so I always thought having cylinder's coated with oil rather than raw avfuel would be better for storage/sitting, whether it be short or long.
     
  26. Silvaire

    Silvaire En-Route

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    How about this: it is of no consequence one way or the other. The engine is not running therefore the position of the throttle is meaningless.
     
  27. Ryanb

    Ryanb Touchdown! Greaser! PoA Supporter

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    You must not understand how a carbureted engine works.

    If you move the throttle while the engine is not running (Ie., trying to pump the throttle to get the engine to start), fuel drips downward out of the "bottom" or inlet side of the carburetor. Too much (easy to do) will drip out, and load the inlet box, and can also drip to the ground. If the engine has even a small backfire, it may ignite the additional fuel there, which will rapidly heat up the carb which has an ample supply of more fuel, ultimately leading to an engine fire.

    So moving the throttle while the engine isn’t running is NOT meaningless.
     
  28. Kenny Phillips

    Kenny Phillips Pattern Altitude

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    Unless you also select alternate air source. Then the bugs have a pathway into your engine. Still, I always left my throttle where it was at idle, and yanked the mixture.