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Thread: 'over reamed'

  1. #1
    wadeg's Avatar
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    Default 'over reamed'

    Appears I might have a reamed hole that is giving a bolt some play. Now first, get your mind out of the gutter.

    Atop one of my horz stab struts is the bolt that runs through the rod end bearing and through the stab's tube. The forward facing hole on the stabilizer's rear tube is the focus of the problem. This hole appears to be very slightly over size causing the bolt to be a tad loose and able to "rock". It is manifested in a +/- 1/16" vertical play at the tip of the horizontal stabilizer.
    Even though it is a very minute amount of movement and appears to not be enlarging, it would be nice to eliminate.
    The question is "how".
    Here are a few ideas I have pondered.
    1. Enlarge the whole and put in a hard to find oversized "oops" bolt. (the problem is getting a custom reamer and worse, finding a way to ream the rod end bearing.)
    2. Wrap the bolt with something very thin to fill the space and eliminate slop. (problem is it would have to be VERY thin.)
    3. Ignore it because I am probably rattling it more during preflight than it gets rattled in the air.
    4. Leave it and keep a record of movement at the end of the stab to determine over time if any wear is occurring.

    I have inspected the bolt periodically as well as the rod end bearing. Nether show any evidence of wear from this.

    Any ideas or opinions appreciated in advance!

  2. #2
    Senior Member jtpitkin06's Avatar
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    Default Re: 'over reamed'

    Ideally you would like to replace the welded tube, but that option is a huge undertaking and may not be necessary. So let’s address your ideas.

    1. The oversize bolt is not an option because it would not fit through the rod end.

    2. Wrapping the bolt with shim stock would mean reaming the hole larger to get it round and there may not be enough material to ream.

    3. Ignoring it is probably impossible at this point as you have already put it in your “concerned” part of your brain; and, it probably rattles infinite number of cycles in flight.

    4. Leaving it is the same as #3. You will not sleep well.

    Here’s my thought on the repair.

    The load on the bolt is carried over a large area in the welded tube.
    The movement at the stab tip is small. You state up and down 1/16”
    This means the movement at the bolt is probably half that of the tip.

    I believe you can fill the tube with JB Weld (or other metalized epoxy) then redrill and ream it for a tight fit. The loads are compressive and the layer of epoxy will be thin. There is no permanent change to the structure with the epoxy repair and if necessary it can be reamed out at a later date. No harm, no foul.

    To do the repair I would coat the inside of the tube with the JB Weld and also coat a small plastic soda straw on the outside. The purpose of the straw is to create a pilot hole and ease the task of redrilling. The type of straw attached to small fruit juice boxed drinks is about right. Lacking that, you can make a small tube out of paper and tape. Push the coated straw inside the tube and let everything cure overnight.

    When the epoxy has cured, drill out the straw with an undersize bit. Then use progressively larger bits and finally a reamer for a tight fit of the bolt.

    I think you will find this repair will do the job and last a long time.

    JP

  3. #3
    Senior Member DanB's Avatar
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    Default Re: 'over reamed'

    Great idea JP...I think we need to give you a new call sign...MacGyver
    Dan B
    Mesa, AZ

  4. #4

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    Default Re: 'over reamed'

    Why ream the hole after JB ?? put a very thin layer of grease on the bolt, put the JB weld in the tube and put the bolt in and let it set up. After it is set up you can pull the bolt out and have a perfect fit. Your right about the loads on the bolt and I would not hesitate for one second to just use JB weld or hysol for a fix on this.

  5. #5
    Senior Member HighWing's Avatar
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    Default Re: 'over reamed'

    I like John's idea. Before I read it my thought was to use a bit of the low strength Loctite or similar. I use it to bed the indexible carbide tooling on my lathe cutters.

    Then again. If your airplane is flying and this has developed or even if it has been there from the get go. I might suggest that it is play in the rod end especially if the play is evident after torquing the bolt. There has been discussion in the past regarding rod end bearings in that area developing some play. It happened to me. The conventional wisdom then was to replace the rod end. I did that and the new one had the same slop as the old one - out of the box. I just ignored it after that. Don't forget the oversized washer.

    Lowell

  6. #6
    wadeg's Avatar
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    Default Re: 'over reamed'

    Great discussion. I was concerned about the jb not holding up in the past but with the coated bolt idea, I could get as close tolerance of a fit as possible. The strain on the jb would indeed be very light as it is compression only. I had investigated the 'rod end bearing' theory as a cause but this is not the case. New bearings didn't resolve this and it is isolated to the left side only. When putting a slight pre-tension on the strut, I found that didn't help either. It turned my focus to the bolt hole and here we are.
    Thanks for the discussion and I shall report back on the results.
    Wade

  7. #7
    wadeg's Avatar
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    Default Re: 'over reamed'

    Oh and Lowell, say 'hi' to John and Karen Agee there at C.A. For me.
    Wade

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