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FAA Description of Airworthiness Concern: Main Landing gear tie strut

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  • FAA Description of Airworthiness Concern: Main Landing gear tie strut

    Extracted from cover letter from FAA:

    "You are probably aware of this recent incident
    involving a failure of a BC-12D MLG tie strut due to corrosion. An old
    1978 Taylorcraft Aviation Corporation Service Bulletin attempted to
    address this problem, but the FAA has decided to issue an ACS to remind owners and operators of the importance to check their structure for potential
    corrosion related problems. I know with on your involvement in the
    Taylorcraft community you of all people appreciate the need to keep on top
    of aging aircraft issues. If you will, please share this ACS as
    appropriate with your club members.

    At this time, the FAA has not made a determination on what type of
    corrective action (if any) should be taken. The resolution of this
    airworthiness concern could involve an Airworthiness Directive action, a
    Special Airworthiness Information Bulletin, or the FAA could determine
    that no action is needed at this time. The FAA’s final determination will
    depend in part on the information received in response to this ACS. As
    described in the ACS, we consider this airworthiness concern as “Information”. We are also sending this ACS to AOPA, the TC holder and
    other Taylorcraft type clubs.


    ACS Document attached (We converted to .pdf format)
    Attached Files
    Taylorcraft Foundation Forum Administrator (Bob Ollerton)
    tcraft@taylorcraft.org

  • #2
    We just discovered a crack all the way across the bottom of the left main tie strut on our BC- 12D in around same place as the FAA ACS. Took the right side off and after sanding off paint found holes rusted through in the same area . I just became an owner of this airplane so someone dropped the ball on this because there were not drain holes . Our A&P repaired it by sleeve on inside and out . kind of a dumb design . bolted on the bottom and welded in solid at the top. If anyone knows why it was done that way I'd like to know.

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    • #3
      I have heard stories from someone who spoke with the engineer that designed the gear, and he supposedly gave a very long and detailed explanation of why the tie strut is done that way.

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      • #4
        Would you mind posting photos, if you have any , it is a concern for most of us.

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        • #5
          Hope this Helps Click image for larger version

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          • #6
            Here's a couple more
            Attached Files

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            • #7
              Nice catch on the corrosion and repair. It's a credit to the A&P for actually repairing and not just demand a replacement gear. I have a similar repair from a dent on mine. In addition to internal and external corrosion that tubing can be subject to impact from gravel and excessive side loads. Any exposed metal should be promptly cleaned and primed/painted.

              My suggestion is to blow through the drain hole and confirm air without debris exiting the tubing cluster under the bungees. I DON'T know if all three gear tubes are open at the upper cluster. I'd then spray preservative oil into the diagonal drain hole and upper cluster and position the gear to let it coat the interiors. There's likely another hole under the brake stuff above the axle where the two outside clusters meet. If there coat the tubing with preservative.

              Edit: I believe the bottom bolt arrangement is for adding a support plate for wheel pants. The outboard end of the axle is threaded to accept a fastener for the pants.

              Gary
              Last edited by PA1195; 04-04-2020, 18:47.
              N36007 1941 BF12-65 STC'd as BC12D-4-85

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              • #8
                That looks like and excellent splice, would you know where your A&P got the tubing for the splice and what size it is ? Thanks for posting

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                • #9
                  I have repaired some by replacing the lower end with the next size larger streamlined tubing using 1/2 of the splice and locating it near the top cluster.

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                  • #10
                    My A&P got 2 pcs. of streamline 4130 tubing 2 ' long each , 1 slightly smaller than original tube ID and 1 slightly larger than out side from Aircraft Spruce for $85. it was enough to repair both sides . I spent quite a bit of time trying to find some streamline tube same size as original with out any luck. We replaced bungees with winter ones since we had it apart and they needed replaced . I uploaded a tool I made for installing bungees. It worked real well. Click image for larger version

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