Elevator Trim Torque Tube Ends on Factory Kits

Source: 2022 Q2 Beartracks, Mark Goldberg
Over the years we have seen some cases where the trim "arms" in the horizontal stabs get play in them where they are bolted to the 1/2" x .035 tube that runs inboard through the horizontal 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 horizontal 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 horizontal 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.

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Service Notification for Patrol and LSA Kit Tail Struts

Bearhawk Aircraft Service Notification June 16, 2020 – For questions call Mark Goldberg, 512-626-7886 The horizontal stab strut for the Patrol and LSA share a common design feature on the top – how they are attached to the leading edge tube of the horizontal stab. An AN5 bolt has its head removed, and it is heated and forged flat with the 3/16” hole drilled for attaching to the horizontal stab with an AN3 bolt. The factory also cuts some more threads to add additional adjustment length. Some of these parts have left the factory improperly forged. The forged part (where the 3/16” hole is) needs to be flat so it fits flat against the bottom of the horizontal stab tube and also have the nut on the bottom fit flat. The parts not forged properly have an angle to them and are not flat on both sides. This can put stress on the AN3 bolt. There are two ways to fix this part if you have one or two that are not forged flat. One side can be ground down flat on a bench grinder if the remaining material is at least 1/8” thick. Of course any roughness or marks from the grinding would need to be polished/sanded out. Bob Barrows does a different fix for a situation like this that requires welding. A washer is tack welded to the “fatter” side of this part where the attach hole is. Then the other side of this washer is adjusted so it is flat compared to the other side. Then finish welded in place. Please inspect these parts that came with your Patrol or LSA kit. If they have this problem you should try to make the “repair” as detailed above. If you are unhappy with the result for any reason, let us know and we will replace these for you.

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