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Sparrowhawk rotorhead

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  • Sparrowhawk rotorhead

    The slider on my SparrowHawk rotor head has a metal plate on each side that keeps the slider pin centered and one of them broke. Does anyone know if these metal plates are spring steel or just aircraft steel that I can buy at Wick's aircraft supply.
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    Gerry Loeser - Belleville, Illinois - PRA Chapter 35, SparrowHawk 1

  • #2
    Any steel with carbon content of 0.3% or above that can be hardened will work fine.

    “Aircraft” steel, 4130 has 0.3% carbon content.

    Heat cherry red, quench in water and draw until a polished area turns to a straw color.


    • #3
      It seems you were very lucky that the pivot did not come out
      My question would be rather: "Why and how the elastic limit is exceeded on this plate?"
      Last edited by Jean - Claude; 10-01-2017, 06:44 AM.


      • #4
        What do you mean by"draw"?

        I suppose it was a fatigue failure rather than a simple ultimate tensile strength failure. Probably due to a nick or scratch that was a stress raiser (amorce de rupture ??) and/or incorrect or lack of heat treatment.
        he was also lucky the broken part didn't go through the prop.

        You could try some of your town's washers 😂 Sorry couldn't resist it.




        • #5
          From the photos, it appears that it cracked off right at one of the holes where the bolts go through that plate...


          • #6
            I replaced both slider pin centering spring plates that I made from a sheet of 4130 Chromoly from Wicks aircraft supply. I had them heat treated and tempered to a hardness range of 34 to 38. $11.00 for the sheet of 4130 and $109.00 to have them heat treated. I flew yesterday and they are doing what they are supposed to do. I want to share this with all and thanks for replying and pointing me in the right direction. I hope this helps the next guy in need of replacement parts.
            Gerry Loeser - Belleville, Illinois - PRA Chapter 35, SparrowHawk 1


            • #7
              Looks like some good, thoughtful work Gerry. Thank you for sharing the fun.
              Regards, Vance Breese Gyroplane CFI


              • #8
                what type of steel rod is the slider made from and the hardness.what type bushing for the slider