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Fuel Flow sensor Install

in General Tech Discussion 7 years ago

  • Re: Fuel Flow sensor Install

    by » 7 years ago

    A couple of things:
    1- It was strongly recommended to me that the FT-60 not be mounted on the engine due to heat and vibrations. I mounted mine in the cockpit in the fuel supply line.
    2-Yes it measures total flow including bypass flow. I did not want the expense and complexity of using two flowmeters as was suggested, so it was a simple matter to recalibrate my pulses/gal "K" factor to give an accurate reading at cruise rpm. I manually measured my actual fuel used for a straight and level x-country trip and compared this with the FT-60 reading, which gave me a % to modify the "K" factor. Admittedly, this only gives an accurate reading when cruising at the rpm used for calibration, but that is all I really care about anyway.
    3- I did not use a fine filter ahead of the FT-60, just the coarse strainers in the wing tanks. My fine filter is ahead of the fuel pump. This system has been working fine for 600 hours. If you look thru the hole in the FT-60 and the little paddle wheel, you will see that there is actually quite a large area to pass particles of fairly large size.
      
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  • Re: Fuel Flow sensor Install

    by » 7 years ago

    I have heard that fuel filters with "paper" elements are inappropriate for use with gasoline containing ethanol.


    Water in Diesel fuel causes issues because there is no Ethanol to dissolve the water.
    Algae can grow in the water and clog the filters, Paper or otherwise.

    The alcohol in MoGas dissolves any water up to ~1/2% of the tank. (~6oz per 10 gal)
    This water harmlessly passes through the engine in the same manner as the water that is dissolved (evaporated) in the air used by the engine.

    250 million U.S. Automobiles use Paper Fuel Filters with Gasoline containing Ethanol every year without issues.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

      
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  • Re: Fuel Flow sensor Install

    by » 7 years ago

    Bill, I have learned that automobile comparisons are tricky. You do have to be more careful with aircraft as you dealing with altitude, longer storage times and aircraft are often built using a mixture of technology such as fuel components and materials, possibly un-tested in combination with each other. Autos are designed and tested as a complete package.
    So paper filters have been proven to be a problem in aviation and should be avoided.
    But can you even tell if it is paper? the Rotas 912iS fine filter is a composite material but it sure looks like paper....

    Roger, I would not recommend an inline 10 micron filter for the carby engines; this is much too fine and due to the very small surface area of an in-line filter it can can plug up almost immediately with crappy fuel use.
      
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  • Re: Fuel Flow sensor Install

    by » 7 years ago

    Hi Rob,
    "Roger, I would not recommend an inline 10 micron filter for the carby engines; this is much too fine and due to the very small surface area of an in-line filter it can can plug up almost immediately with crappy fuel use."

    You're probably right. I see some use 40-70 micron.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Fuel Flow sensor Install

    by » 7 years ago

    Yes your right. Downstream of the FT60. Like on a Flight Design. The fuel goes through a fine filter then the FT60, then through the gascolator and up to the pump. Then the
    re-circulation line goes back down to the top of the gascolator which is downstream of the FT60. So all the fuel only passes through the FT60 one time. The re-circulated is is only accounted for that one time.


    Hi Roger

    New guy here, with a 912ULS in a Magni M-16 gyro on its way here from Italy. I'm wanting to put in fuel flow, e.g. with an MGL Vega, and am trying to make sure I do this right.

    I THINK I understand your answer and want to make sure I don't do something stupid. To confirm, that means it is OK to put the return line directly into a tee between the FT60 and the electric and mechanical fuel pumps (and past/downstream of the fuel filter)? The return line doesn't need to be vented to atmospheric pressure or anything? Seems like if the return line had pressure while the primary line didn't, the fuel would be able to flow back through the transducer and filter into the tank, so that would seem to be OK.

    I know the FT60 install instructions referenced in one of your earlier posts specifically says the 912 should have a second FT60 for the return but my guess is it would be a bear trying to accurately calibrate K factors for two transducers like that. If plumbing the return basically into the fuel pickup line after the filter but before the pumps as I think you propose works, that would seem to be ideal. I just want to make sure it wouldn't result in flooding the carbs or some other unexpected outcome because the return line is now plumbed directly into the circuit, albeit on the negative/suction side.

    Also, you had said earlier they need to be mounted with 6" of HORIZONTAL run on either side of the FT60 - is that true? The install sheet says they need to be STRAIGHT for 6" but didn't specify orientation.

    Thanks!

    /Ed
      
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