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Trim system parts in hor stabs

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  • Trim system parts in hor stabs

    Over the years we have seen some cases where the trim "arms" in the hor stabs get play in them where they are bolted to the 1/2" x .035 tube that runs inboard through the hor stabs to the trim horns in the fuselage tail.

    The plans show that arm welded to the 1/2" tube, but we have always sent the kits out calling for an AN3 bolt to connect the parts. If they are welded - the mechanism can never be removed from the hor stabs. That was our motivation for doing something different than the plans show. Bob was aware of this and did not have a problem with the different way of attaching those parts.

    The actual stress on the parts is not great. However, vibration in the tail surfaces causes problems as we have seen over the years in other areas.

    So there is a new recommendation from Bob on how to connect those parts together. Before the final assembly, clean the parts so they are not oily. Then as you insert the 1/2" tube into the 5/8" tube of the "arm" - apply red Loctite. Then go ahead and insert the AN3 bolt. The red Loctite should eliminate any chattering from vibration.

    Interestingly - the trim horns are attached to these same 1/2" x .035 tubes with AN3 bolts. There has never been a problem with those parts getting play in them. Just out in the hor stabs.

    Please check this area when you inspect your planes. If something needs to be done - you can install an inspection ring in the fabric there to permanently allow access. Mark

  • #2
    This is good advice, and matches with the operational experience we've had.