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  • BC12-D-85 vent system

    A friend is trying to figure out what was the Factory Original
    Fuel Vent System for a BC12-D-85.
    Anyone have one that was not an STC'd upgrade?
    Is it the Upper Fuselage Vent similar to the Model 19 or STC'd versions?
    Thanks in advance.

  • #2
    Re: BC12-D-85 vent system

    I posted this about a month ago.

    Anyone with a BC12-D-85?

    Comment


    • #3
      Re: BC12-D-85 vent system

      I have been watching this post for a reply also. A few months ago I posted a question about the vent system used on the Model 19 STC and received a couple of good responses. But now I have figured out that if I put the vent in the center of the top of the windshield, I will have a hole in either the windshield or the skylight. I don't like either of those options. So, I too would be interested in the original factory location of the vent for the BC12-D-85, or any other model that has it somewhere besides at the top of the windshield.
      Richard Pearson
      N43381
      Fort Worth, Texas

      Comment


      • #4
        Re: BC12-D-85 vent system

        On the F22 the vent is at the left-hand wing root.

        Comment


        • #5
          Re: BC12-D-85 vent system

          The fuel system plumbing on 26658 was up graded when they added wing tanks to the airplane years ago but who ever did it ran 3/8 steel line and used shut offs in both wing roots then when i did the engine i replaced the gascalator and all hoses with 3/8 id hose from the tank to the carb my tanks have the vented caps and will drain in to the main in about 5 min at cruse also a side note the lines from the wing run along the bottom of the panel and if you touch the tube before you open the valve and during the transfer the line gets very cold and you can tell if the fuel is flowing to the main tank before it show on the float in the main This is my thoughts on this the vent on your family car is a very small hole in the cap diesel trucks with 800+ cubic in engine has 1/4 vent on 200 gl tank and feeds a engine gulping 5 mi to the gl why are not the 1/4 vents on the tcraft tank cap sufficient to feed our little engine also take a look at the supper cubs with the big hp engines 30 gl wing tanks they only use cap vents only and feed 180 hp
          Last edited by cvavon; 11-02-2012, 06:38.
          1940 BLT/BC65 N26658 SER#2000

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          • #6
            Re: BC12-D-85 vent system

            Thanks for the info guys. Nice picture Robert. But can you tell me if the caps on the wing tanks also have a vent on them, or do they do away with them when they put the extra vent tube on. I can't quite tell in the picture. Magman, sorry to hijack your thread.
            Richard Pearson
            N43381
            Fort Worth, Texas

            Comment


            • #7
              Re: BC12-D-85 vent system

              Originally posted by Pearson View Post
              ...But can you tell me if the caps on the wing tanks also have a vent on them, or do they do away with them when they put the extra vent tube on. <snip>
              The caps are sealed, no vents.

              There was either some poor design, or some poor certification requirements for vented systems, or perhaps Jack Gilberti took an easy route, but I can assure you that there is no engineering reason behind the STC fuel venting system and "unusable fuel". I would like any amendment to the STC to get rid of all of the above, and if the current STC holder would like some hours-based reasoning for its exclusion, I can offer the same.

              (There are other bits of the STC that need removing as well, but we'll leave Bill Berle to describe those!)

              Rob

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              • #8
                Re: BC12-D-85 vent system

                Forrest answered the second part of your issue a long while back.
                It seems that once the fuel quantity gets low enough, with 85 hp the T-craft can climb at a high enough deck angle to un-port the fuel inlet of a nose tank . Ergo, un-useable fuel is shown on the data sheet even though you can run the tank dry in level flight.

                As for the vent... maybe Jack Gilberti was friends with Rube Goldberg.
                Best Regards,
                Mark Julicher

                Comment


                • #9
                  Re: BC12-D-85 vent system

                  Well according to CAR4a, you only need 4.5 inches of head pressure to the carb, that is like .162 psi from what remember.
                  Originally posted by Mark Julicher View Post
                  Forrest answered the second part of your issue a long while back.
                  It seems that once the fuel quantity gets low enough, with 85 hp the T-craft can climb at a high enough deck angle to un-port the fuel inlet of a nose tank . Ergo, un-useable fuel is shown on the data sheet even though you can run the tank dry in level flight.

                  As for the vent... maybe Jack Gilberti was friends with Rube Goldberg.
                  N29787
                  '41 BC12-65

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