Does anybody know what jpi uses to trigger Hobbs time?

Discussion in 'Maintenance Bay' started by Salty, Oct 13, 2018.

  1. Salty

    Salty En-Route

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    my google-fu isn’t coming up with an answer nor does any of the docs spill the beans. The number is trending a bit lower than my expectations, so I’m just curious what it’s using to start the clock.
     
  2. Bell206

    Bell206 Line Up and Wait

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    Don't know if this will help, but recall others refering to this:
    https://www.jpinstruments.com/FAQCategory/tach-time-and-hobbs/
     
  3. Salty

    Salty En-Route

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  4. Unit74

    Unit74 En-Route

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    Hobbes on power up....... Tach on RPM.
     
  5. ybitz

    ybitz Pre-Flight

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    The manual for 900/930 says the Hobbs meter turns on at 1000RPM by default.
     
  6. Salty

    Salty En-Route

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    Wonder why I didn’t find that. Thanks.

    I’ve double checked my data and I was just wrong about My feeling that it was lower than it should be.
     
  7. Salty

    Salty En-Route

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    Ok, I figured out the source of my confusion. I've been uploading my data to savvy analysis and reading it there. They are labeling the tach time as hobbs time, which tripped me up.
     
  8. Hawker800

    Hawker800 Line Up and Wait

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    Just remember the five C's.
    Confess
    Communicate
    Climb
    Comply
    Connect the Hobbs back up
     
  9. alfadog

    alfadog En-Route

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    Sound like something Machado would say.
     
  10. flyingron

    flyingron Touchdown! Greaser!

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    Correct. The Hobbs counter is configurable and the default is to start counting at 1000 RPM.
    The Tach time is configurable, but it behaves like a traditional tach with the "true time" being at 2400 RPM.

    The Hobbs settings set with HOBS ON (minimum RPM) and RPM FACTOR (number of blips per revolution on the sensor, typically the number of cylinders you have).

    The RPM settings set with parameter "AVERAGE CRUISE RPM."
     
    Last edited: Oct 16, 2018
  11. flyingron

    flyingron Touchdown! Greaser!

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    Not true.
     
  12. Unit74

    Unit74 En-Route

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    CFI says it’s true, so it must be.
     
  13. ybitz

    ybitz Pre-Flight

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    The tach reference rpm (default to 2400 rpm) looks like it has to be set within the first 10 hrs. On mine it doesn't let me change it. Does it have to be taken back to JPI to re-enable changing it?