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Upper Mast, upper bolt bushing

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  • Upper Mast, upper bolt bushing

    I am about to replace the upper mast with a SC unit. The lower attach bolt bushing has two holes in the blue anodized aluminum bushing. Understood.

    However the upper mast attachment bolt went through a soft (degraded?) off-white plastic(?) bushing. The plastic was sticky and could be deformed/penetrated with a standard screwdriver. About the consistency of a wax candle but stickier, not as brittle. What is this stuff?? This bushing appeared to be one piece with extruded ends on both sides. How as could this ever be inserted? Is this "factory stock" or what should be used here? I destructively removed this for the photos. It just did not seem "right".

    There are also two 1/8" thick nylon(?) or propylene(?) plastic shims on either side of the lower mast. This would seem to cause deformation of the upper mast plates. The uppers are built with spacers to have a 2" width, as is the lower mast. But adding these two 1/8" thick spacers would cause a 1/4" deformation of the upper mast side plates. Is this correct parts/assembly procedure?
    Attached Files
    Last edited by dunc; 05-24-2018, 05:55 PM.
    CFI-ASMEL-IA, A&P
    @ 6450' MSL in W. Colo.

  • #2
    I think this is the "Magic" bushing that has been discussed for years on the forum. "Magic" as in the original RAF manufacturer in Canada claimed it is the reason their gyroplanes flew so well (smoothly).

    I believe Chuck Beaty and others had suggested replacement material for when the original "Magic" was gone from age/use.

    Rumor has it that the original factory is the one still making parts for the current owners: RAF-South Africa, and then ships these parts to the current company in SA.

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    • #3
      Paul Patterson (Paulp) at one time had polyeurthane bushings made and were for sale as replacements,it looks like that

      bushing was an original one.The Teflon plates on the side are so the uppermast will move back an forth,it elimantes the

      2/rev shake,I would suggest that you contact paul or perhaps use shock absorber bushings as replacement parts.

      to me this is important for a smooth running rotor system,the bolt that go's through the bushing should be very slightly

      tightened so the mast can move.Its important that the uppermast be allow to move,bolting it solid will make you vibirate

      like crazy.
      Best Regards,
      Eddie Sigman,Polvadera,nm
      (575) 835-4921

      Comment


      • #4
        Thanks! Can somebody PM me with Chuck's email address or phone? His account here does not accept private messages. I have reached out to Paul.
        CFI-ASMEL-IA, A&P
        @ 6450' MSL in W. Colo.

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        • #5
          Also Rob I checked the inside measurement of the upper mast and its 2 1/4" wide ,if I knew the shore hadrness I might try to start making

          those my self.
          Best Regards,
          Eddie Sigman,Polvadera,nm
          (575) 835-4921

          Comment


          • #6
            I made a mold for vulcanizing RAF mast bushings from real rubber, -”cushion gum” from the tire retreaders and gave replacement bushings to several individuals. I eventually gave the mold to someone that wanted to supply these things but I have no idea of what ever became of it. This was a very long time ago.
            Polyurethane potting compound as used by RAF Canada is the worst possible choice of material.

            Someone in Australia found an automobile rubber bushing that worked perfectly for this application but I don’t remember which car it came from.

            PS; My recollection as to the last location of the magic rubber bushing mold was that it was in the possession of an RAF owner in Louisiana whose first name was Rudy.
            It wasn'’t any big deal; the housing was machined from a length of water pipe with aluminum end plugs.
            During vulcanization, rubber must be kept compressed, otherwise, the end product will be a sponge.
            Last edited by C. Beaty; 05-25-2018, 11:48 AM.

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            • #7
              That is the whole story ...Dunc !
              Happy Flying, Chris S.

              Comment


              • #8
                I have sent an E-mail to Paul Patterson about his bushings if I don't hear back from him I have decided to

                make a mold and start producing them my self,so Rob just hang on and lets see how this plays out with Paul P.
                Best Regards,
                Eddie Sigman,Polvadera,nm
                (575) 835-4921

                Comment


                • #9
                  Paul talked with me yesterday and he said he still has a few bushing left for sale.
                  Best Regards,
                  Eddie Sigman,Polvadera,nm
                  (575) 835-4921

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