Vac pumps

Discussion in 'Maintenance Bay' started by airheadpenguin, Apr 10, 2016.

  1. airheadpenguin

    airheadpenguin Pre-takeoff checklist

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    It looks like the Sigmatek pump in my Comanche is finally dying for real. It was installed 5 years ago and we've been dealing with it reading low intermittently for the last 2 years by adjusting the regulator at annuals. In IMC this time it decided it wanted to put out 3.5" at 6kft and 23^2 which is way out of spec but its mostly OK on the ground. Oddly all of the instruments read well enough to continue the flight without being "nogyro"

    At 9k its down to 3" so clearly something is wrong. Now comes the education part, Aircrsftpruce has a variety of replacement pumps and it looks like there are 3 groups of dry pumps out there:

    *Rapco/Airpower which can be used as cores of one another and are really cheap
    *Tempest which doesn't deal in cores and nobody will accept as cores so I assume there's some internal difference. These aren't really cheap like the Rapco pumps but they are reasonable
    *Sigmatek which also doesn't deal in cores and nobody will take them as a core, these are double if not triple the cost of the prior 2

    My questions are:

    1) How do the 3 groups differ?
    2) Is the Sigmatek worth it?

    Longer term how do you help a vac pump last, since this one died much quicker than the one in the Warrior I flew.
     
  2. Dan Thomas

    Dan Thomas Final Approach

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    Tempest and Rapco have vane weay inspection ports to let you know to replace the pump before it fails.

    Tempest has a seal to keep engine washing stuff out of the pump drive. oil or solvents getting in there can end up in the pump cavity where it causes gumming up of the vanes and bore and shortens pump life.
     
  3. bnt83

    bnt83 Final Approach PoA Supporter

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    Is it really the vacuum pump or are the hoses in the system so old, hard and crappy that they leak or are fittings leaking?
     
  4. airheadpenguin

    airheadpenguin Pre-takeoff checklist

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    Consensus including our A&P seems to be that this looks the slow death of the pump but the tubing theory isn't out of the running
     
  5. neilw2

    neilw2 Line Up and Wait

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    Are you using Infinity at KASH? I just dropped off my plane there yesterday for it's annual...it's my first time using them for it...they seem like a good bunch of guys over there.
     
  6. airheadpenguin

    airheadpenguin Pre-takeoff checklist

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    Nope Leeland is our guy these days but the Inifinity line guys are great and always there to help the 100ll crowd
     
  7. Clark1961

    Clark1961 Touchdown! Greaser!

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    How many hours on the sigmatek? Aren't they supposed to be 1,000 hour service life?
     
  8. JohnAJohnson

    JohnAJohnson Cleared for Takeoff

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