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Thread: Repairs for oversize holes? Other ideas?

  1. #1

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    Default Repairs for oversize holes? Other ideas?

    Hello everyone,

    I have been a member for some time but this is my first post so wish me luck! I believe we are so fortunate to have this website available to us. What a wealth of information about our little birds.

    During the last annual of my aircraft I decided to undertake a recover project to include the wings, ailerons, flaps, and horizontal tail surfaces. Although the fabric itself was in excellent condition, the silver coats and top coats had become extremely brittle and apparently not stuck to the fabric very well. If you pushed on it hard enough with a finger the paint would crack and you could break off chips of paint that left the bare fabric exposed. To complicate things, someone had used enamel paint, applied with a roller to the top of the wings to make it look nice while it was for sale. I did look pretty good until you looked close. The bottom of the wings looked like they were done yesterday although the cover was put on about 35 years ago. The fuselage was recovered about 25 years ago when it was converted to a tail wheel and it still looks good.

    Removing the covering certainly makes it apparent that the airplane is approaching it's 65th birthday alright. We have found several items of interest and I will be posting pictures as I go so I can seek advice from all of the experts out there. I am fortunate to have an IA who is very knowledgeable about aircraft like ours, but many heads are always better than just a couple.

    The first item I'm posting pictures of is the attach points of the horizontal stabilizer. As many of you already know they are joined by sections of tubing that pass through the fuselage and there are bolts that hold it all together. The clever people who put it together the last time had trouble getting the bolts through the holes so they just drilled new ones! That makes for some pretty funny looking holes. Most of the holes could be drilled out for an oversize bolt, which would work but we'd rather not do that. We were thinking also that we could weld the correct size washers to the top an bottom of the stabilizer tubes to make the new holes of the correct size. Also, we talked about trying to weld the holes shut completely then re-drilling them. In any case we will have to replace the tubes that go through the fuselage since they are in the same condition. Does anyone know if those are just from stock 4130 tubing? Here are the pictures:



    I'd love to hear from you if you have input on the best way to proceed.

    Thanks for reading! (and helping if you can)

  2. #2
    Stephen's Avatar
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    Default Re: Repairs for oversize holes? Other ideas?

    Replacing the tube is a good idea. Univair sells new tube liners for about $100. As far a fixing the leading edge of the horizontal stabilizer goes. If you can't use the existing holes, I would weld them closed, file out the tube so the liner slides in easily, then redrill. But, don't redrill untill everything is done and aligned.
    "You can only tie the record for flying low."

  3. #3
    Administrator Steve Pierce's Avatar
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    Default Re: Repairs for oversize holes? Other ideas?

    The liner tubes normally need replacing at recover due to rust. The holes were hand drilled and no two are the same. I did not see any pictures so from your post I take it you have multiple holes. I would weld up one set of holes and back drill the holes in the liner tube at final assembly or dry fit and dry prior to cover but be sure and mark the tubes top, bottom, left and right since they will only fit one way. It is hard to drill where a hole has been welded up. One thing I have learned, prior to drilling I take a flat file and clean the paint, glue and fabric from the ends of the stabs where they meet the fuselage. This will allow a tight fit at assembly. If this is not done you get slop between the stabilizer and the fuselage when the paint, glue and fabric weat from the up and down action of the trim. I have fixed the gap on airplanes in the field by putting the appropriate size safety wire in the gap.

  4. #4
    Jim's Avatar
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    Default Re: Repairs for oversize holes? Other ideas?

    Hi,

    A welding professional friend of mine once showed me a technique they often use. A block of carbon on the back side of a weld site will allow you to weld, gas or electricly, and not make gobs of crap back there. Carbon files real easily so making a rod that slips into tubing will allow you to make the repair without needing interior dressing. I have several carbon hunks that once upon a time were brushes from a rather large electric motor.

  5. #5
    Wag-builder's Avatar
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    Default Re: Repairs for oversize holes? Other ideas?

    If you back up the weld with copper you will get a smooth surface. Find a piece of copper pipe/ tubing and slide it inside the stab and weld the holes, I think you will be happy with the results.

    Steve

  6. #6

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    Default Re: Repairs for oversize holes? Other ideas?

    Thanks to everyone for your replies! It sounds like welding the holes in the stabilizer shut & redrilling is the consensus. I'll get new liners as suggested and drill them to match.

    thanks for the welding tips. I have heard of using copper before but not carbon.

    I'll post some pictures when I get the repairs made.

    Thanks again.

  7. #7

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    Default Re: Repairs for oversize holes? Other ideas?

    Well, I've run into the next issue that I could use some advice on. It appears that someone who recovered this aircraft in the past did some PM on the steel fittings that are installed in the aileron and flaps for the hinges. They are prone to corrosion due to the lack of paint/primer between the steel and aluminum parts. All except one appear to be in satisfactory condition. The one that needs attention is the only one that looks like it's never been messed with. I'll try to post some pictures tomorrow but the steel fitting caused the aluminum spar (outboard aileron hinge) to corrode almost completely through. When we first looked at it we though we might be able to install a doubler onto the back of the spar but now that it's drilled apart it is definitely more serious. Now we are thinking about splicing in a new section of spar and/or ordering a new spar from Univair. I don't see it listed on their website as a separate item from the aileron though. We might be able to fabricate one but we would have to find a longer brake than what we have available.

    Has anyone out there had to make a similar repair? Ideas and advice are always welcome! Thanks.

  8. #8
    JPerkins's Avatar
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    Default Re: Repairs for oversize holes? Other ideas?

    Just replaced the spars in both flaps and ailerons on mine, posted under the Stewart wingtip wing overhaul thread. Peruse through that and see how I did it as well as a link that Steve Pierce posted on a javron build of a guy building the ailerons. I ordered spar blanks from Dakota cub. They shipped me spar blanks for super cub aileron and flaps even though I remember the guy reap eating PA-22 back to me.
    If you call Univair you can order them that way.

    Sent from my SM-G930V using ShortWingPipers.Org mobile app
    Jason Perkins

  9. #9

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    Default Re: Repairs for oversize holes? Other ideas?

    Jason,
    Thanks so much for the information. I'll look at those threads right away.

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