Is there a second engine hour meter?

Discussion in 'Flight Following' started by Chesterspal, May 14, 2019.

  1. Sundancer

    Sundancer En-Route

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    Our engine has several hundred hours more than is shown on the tach, 'cause the tach was replaced. We have the "offset" noted in the logs.

    I don't think most tach times match the actual engine times, not once an engine has been replaced/rebuilt.
     
  2. Ravioli

    Ravioli Final Approach

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    you've lost me.

    Tach x 1.2 is generally recognized as being the same has hobbs.

    I don't know what your editing has to do with the fact that your assertion that a Tach will always exceed a Hobbs ON A SQUAT SWITCH is illogical.
     
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  3. SToL

    SToL Line Up and Wait

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    Ok, maybe we should start over. Maybe it's me who's confused. I 'thought' you said a hobbs that is running at 1.2x.

    What I was trying to assert, was a hobbs runs on TIME... an hour of time, is an hour on the hobbs meter. A hobbs that is running at 1.2x is not correct.

    A tach does not care or know about time. It simply counts the revolutions of the propeller.

    I think the confusion was, you meant tach, but you were speaking of hobbs? I'm not sure why a hobbs meter would run at 1.2hrs?

    PJ
     
  4. Eric Stoltz

    Eric Stoltz Line Up and Wait

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    Now let's count cycles......
     
  5. cowman

    cowman En-Route PoA Supporter

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    Tach hours are for maintenance, hobbs hours are for billing and flight time. Tach hours are relative to engine RPM, hobbs is not.
     
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  6. Ravioli

    Ravioli Final Approach

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    This isn't difficult.

    The Hobbs meter is generally accepted to be 1.2 x the tach time. Right?
    Then the assumption that the hobbs is on a squat switch means it doesn't run at all while on the ground, but then runs faster than the tach.

    So. how long must you spend in low power regimes and/or on the ground to support your idea that tach will always, or even ever, exceed the hobbs?

    We'll ignore that many hobbs are on oil pressure and/or master switch to start clocking.
     
  7. 3393RP

    3393RP Pattern Altitude

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    Why is he scaring you? He's asking about things he has no knowledge of or experience with. Everyone replying to his question knows that, but it hasn't prevented multiple snarky replies.

    To those that responded in this manner, congratulations on being so helpful to a newbie.
     
  8. dmspilot

    dmspilot En-Route

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    It's not the questions being asked it's the unwillingness to listen to the answers.
     
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  9. Ryanb

    Ryanb Final Approach PoA Supporter

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    Asking questions is what this community is about.

    My point, is that one needs to educate themselves on aircraft ownership prior to any purchasing agreement and make sure they realize what all it will involve.

    As @dmspilot stated, it also comes across as not willing to listen to the answers being provided and thinking they have it figured out...that’s what’s concerning to me.
     
  10. MauleSkinner

    MauleSkinner Final Approach

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    Not that I’m aware of. Tach time is tach time, it doesn’t match flight time, Hobbs time, or anything else. You may use whatever formula to decide something, but I’ve never heard of a “generally accepted” ratio.
     
  11. Skip Miller

    Skip Miller En-Route

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    Why not ask your mechanic? How does he explain the difference? -Skip
     
  12. Chesterspal

    Chesterspal Pre-Flight

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    Spoke with my mechanic this morning and here is what he told me.

    The rectangular hour meter on the right side of the console, the DATCON just above the right side yoke, is the Hobbs meter. It reads around 1690.

    The round RPM guage just above the Hobbs meter is the tachometer. That now reads 5785.

    The tachometer read 3904.5 (taken from log book) when the new "rebuilt" engine was installed in 1994. That's how he came up with the engine time of 1880 engine hours.

    He assumes the Hobbs meter was replaced at some point and that's why the lower hours.

    Mystery solved... I hope.
     
  13. Rgbeard

    Rgbeard Line Up and Wait

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    This makes sense. I'm glad you cleared this up with your mechanic.

    Why a C150 vs. a Cherokee 140?
     
  14. Chesterspal

    Chesterspal Pre-Flight

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    I took my 1986 classes in a C152 and am accustomed to that high-wing style in a way.

    I did not like the fact that the lower wing 140 blocked your view of the ground. Kind of the point to be flying I felt... to be able to see the ground.

    The C150 uses only 5.5 gallons of fuel so easier on my budget. It will run on MOGAS, which is a plus.

    I like that the C150 windows open to let air in and since I will be taking my little dog with me on flights after getting my license, I can leave him in the plane on mild days. Much as I can do now in my pickup truck.

    I like the fact that you can get shade from the wings on hot days and cover from the rain, too.

    I was able to find a plane close by that I could go and see and found a great mechanic to do the pre-buy and now the annual.
     
  15. Ryanb

    Ryanb Final Approach PoA Supporter

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    Which is exactly what everyone here told you.

    Best of luck!
     
  16. luvflyin

    luvflyin Final Approach

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    That rule of thumb can come in handy when your comparing rental rates between a Tach time joint and a Hobbs joint
     
  17. MauleSkinner

    MauleSkinner Final Approach

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    Sure...or you could use the .5 tach to 1.7 clock time that I used to get doing stop & goes in a Champ.

    Or it could be 1.1 tach to 1 Hobbs for cross country flying.

    Depends entirely on how you’re flying the airplane and what RPM the tach is calibrated for...there is no “generally accepted” ratio.
     
  18. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser! PoA Supporter

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    Building time or going somewhere?
    Going some where: Rent by Hobbs and run full rental power until short final.Log tach time.
    Building time: Rent by tach and pull back to about 50% power as soon as you are a few hundred feet off the ground. Log Hobbs time.