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Thread: The Barn Find Build

  1. #11

    Join Date
    Jun 2020
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    Toledo, WA
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    44

    Default Re: The Barn Find Build

    Quote Originally Posted by PapuaPilot View Post
    As far as you rudder pedal issue I would search the forum on this subject. Look especially for the people who did a build log. This is a known problem and it usually takes us several days of work to align, trim, shim, and mount the rudder pedals and get them free from binding. There is a good chance this wasn't done properly at the original build. Now is the time to take care of it.
    When I discovered the problem I thought it must be a misalignment in the way the brackets were mounted to the fuselage, but the assembly is still very stiff even after it's removed. I need to look at the assembly and fitting procedure in the manual to understand how it's supposed to work, but it sure looks like the bolts/nuts that attach the torque tubes to the brackets are too tight.

    Like the flaperons, fixing this will wait awhile. Primary focus for now is getting the fuselage ready to go to the welder for tail reinforcement and additional mounting tabs for avionics and antennas. The disassembled rudder torque tubes will go as well, for gusseting.
    Eric Page
    Building Kitfox 5
    Member: EAA, AOPA, ALPA
    ATP: MEL / Comm: SEL, Glider / ATCS: CTO
    Map of Landings

  2. #12
    Senior Member Dave S's Avatar
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    Oct 2008
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    St Paul, MN
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    1,571

    Default Re: The Barn Find Build

    Eric,

    It is not that rare that people have some fitment issues with the torque tube mounting. If the original builder did not remove enough material from the hard plastic bearing that could be the issue.

    Your comments about encountering bolts that were over tightened may be an issue; but, realizing that the bearings are inserted after the bolts are tightened to the mounting part would seem to indicate that the bigger problem with them sticking may be the fit in the first place.

    If a person follows the procedure in the build manual for turning/filing/sanding the bearings down to fit that should alleviate the problem. I found that mounting the bearing on a bolt chucked into the drill press made it easy to turn them down. I also found that working the bearing into a slight barrel shape by taking a bit more off the ends of the bearing while keeping the fitment at the center very close helps a lot with whatever misalignment may be present.

    It is not beyond possibilities that if the assembly sat for a while there may be some light surface rust inside the torque tube at the bearing end that may be interfering.

    You'll get it figured out.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  3. #13

    Join Date
    Feb 2020
    Location
    Tacoma, WA
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    63

    Default Re: The Barn Find Build

    Yes, those outboard bearings with the hidden bolt heads should pull right out of the tubes. The bolt isn't some kind of chinese finger puzzle.

  4. #14

    Join Date
    Jun 2020
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    Toledo, WA
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    Default Re: The Barn Find Build

    Excellent, thanks for the tip, Alex. I'll give that a try tomorrow and see if the bearings will pull out of the torque tubes. And Dave, I appreciate the tip on fitting the bearings for smooth operation. I'll refer back to this when the time comes.

    -=-=-=-=-=-

    I finished disassembly of the fuselage today, after having the light bulb come on over my head with the idea that I didn't need cable cutters to get the control cables out -- I could use the Dremel! The cable made short work of the first cutting disc, so I switched to a 4-1/2" angle grinder, which did the trick. That freed the rudder pedal adjustment handles, which had bolts holding the cables in place that were stuck. I put them in the padded vise jaws, applied a little penetrating oil and gave them a few taps with The Persuader, which broke them loose.

    I also removed the flap handle and center console, which completed disassembly of the flight controls.

    Finally, I pulled off the brake calipers and found that they had significant surface corrosion, some of which appears to extend into the cylinders. If anyone has an idea how to get the pistons out of these things, I'd be thrilled to hear it. I want to check the cylinder bores and pistons, and at a minimum, replace the o-rings.
    Attached Images Attached Images
    Eric Page
    Building Kitfox 5
    Member: EAA, AOPA, ALPA
    ATP: MEL / Comm: SEL, Glider / ATCS: CTO
    Map of Landings

  5. #15
    Senior Member Dave S's Avatar
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    Default Re: The Barn Find Build

    Eric,

    The calipers are pretty expensive so it pays to go slow and get it right the first time.

    WORD OF CAUTION - FIRST

    The normal way of getting the pistons out carries with it a risk of creating a 40 millimeter cannon which you don't want to have any body parts in the way as well as some risk of damaging the parts if done incorrectly.

    So we do it carefully.

    Applying air pressure to the line going into the fluid chamber is how these things are normally removed. USE ONLY VERY LOW AIR PRESSURE APPLIED WITH AN AIR GUN - no more than 5 psi at first and only increase a little at a time as needed to get it to move.

    1) Have some type of retaining clamp (C clamps often used) to prevent the piston from getting away but you need some give in it so use some foam, rag or similar between the clamp and back side of the caliper - doesn't have to be tight but you need to assure the thing doesn't come flying out. The clamp is loosened as the piston comes out.

    2) Since there is some surface corrosion that may interfere with smooth extraction - its good to remove what corrosion you can first - then be prepared to alternately apply air pressure and press the piston in to work it loose. This may be your biggest test of patience.

    3) If the piston comes out part way and seems to stick - do not be tempted to grab it with a pliers! Just keep pushing it in and out with you fingers and air pressure to work the gunk out and allow the piston to come out.

    Normally the pistons come out with very little problem and just a little air pressure. The corrosion may make them a bit sticky.

    Good luck and be careful.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  6. #16

    Join Date
    Jun 2020
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    Toledo, WA
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    Default Re: The Barn Find Build

    Thanks again, Dave. I'll try your method next time I'm working on it. I'll be away for a few days, but should be back at it by the middle of next week.

    -=-=-=-=-=-

    I had a nice visit this morning from fellow Series 5 builder Alex (alexM of Project 5), who flew down with his son in his Citabria. He gave my project a good look-over and offered some valuable advice on a couple of things. He also generously gave me his eight leftover rudder torque tube gussets, so I won't have to fabricate those. Thanks, Alex!

    Today I re-built a couple of sawhorses from the remains I got with my kit, then put the fuselage on them and removed the landing gear and tailwheel. I found two of the four landing gear bolts missing cotter pins, and a third that was installed but not bent around the nut.

    I drilled out the rivets in one end of my dented elevator push-pull tube, which freed it from the fuselage. On Alex's advice, I used some heat to try to remove the reducer from the end of the tube. I kept increasing the temperature until I had the heat gun on maximum and the adhesive began to change color, but it wouldn't budge. When it got to the point that I was damaging the reducer in the attempt, I gave up. Alex mentioned that SkyStar used to use another (3M?) adhesive that doesn't soften with heat before later switching to Hysol, so maybe that's what I've got. Anyway, I'm sure Kitfox will be happy to sell me two new push-pull tube reducers. The rod end bearings look new, so I'll keep those.

    While Alex was here, he showed me how the bearings in the rudder torque tube come apart (we tried briefly to pull them out, but couldn't do it). I put them in the bench vise and tried to pull, then knock them out, but all I was doing was dragging the bench away from the wall! The original builder must have pressed them in (I did see a hydraulic press in the trailer with the plane). I had to resort to using a flat blade screwdriver and a rubber mallet. Three out of four came out cleanly, but one was damaged around the flanged end, and I found a Grade 5 hardware store bolt and nut holding one of them to its bracket. Have I mentioned how happy I am that I decided to disassemble this thing?

    Now for the bad news: I found that two of the lower fuselage tubes are bent. They're both at the same "station" in the plane, between 30" and 51" aft of the wing strut attach point. The bends are pretty gradual, over several inches and without any kinks, so I think they're fixable. It looks like the original builder must have let the plane sit (or drop!) on a sawhorse in the middle of the tubes' span. I'll have to build a straightening tool like what 109JB used, here. I also plan to go through the entire plane with a straight edge to be sure there aren't any more surprises!
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    Eric Page
    Building Kitfox 5
    Member: EAA, AOPA, ALPA
    ATP: MEL / Comm: SEL, Glider / ATCS: CTO
    Map of Landings

  7. #17
    Senior Member
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    Apr 2009
    Location
    Chisholm Mn
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    1,091

    Default Re: The Barn Find Build

    Earlier Kitfoxes used Scotch weld 2216 epoxy instead of the Hysol. It's a nice epoxy, it seems to last forever, but the mix is 5 parts to 7 by weight, so maybe not as convenient as the 1-1 mix of the Hysol. Not sure if it takes more heat to soften it up, but as the aluminum tube is shot anyway, you could carefully cut it off the steel end. Also, it should be real easy to straighten those longerons. JImChuk

  8. #18

    Join Date
    Feb 2020
    Location
    Tacoma, WA
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    63

    Default Re: The Barn Find Build

    Agree those tubes should be easy to straighten. At one point when I was looking over your fuselage something caught my eye that seemed not quite right (only because I've stared at my own enough), but I got distracted and couldn't find it again. It must have been those tubes and it is understandable why that didn't jump out when you first saw it.
    Let me know if you want an extra hand when you put them back in shape.

  9. #19

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    Jun 2020
    Location
    Toledo, WA
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    Default Re: The Barn Find Build

    Thanks, Alex. I'm mulling over in my head what I can build as a straightener with the lumber and other junk that's knocking around in my garage. Stay tuned.
    Eric Page
    Building Kitfox 5
    Member: EAA, AOPA, ALPA
    ATP: MEL / Comm: SEL, Glider / ATCS: CTO
    Map of Landings

  10. #20

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    Jun 2020
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    Default Re: The Barn Find Build

    Well, I guess either no one wants to fly yet, or my employer doesn't want me back. My entire 4-day trip was cancelled, so I went back to work on the Kitfox!

    With full credit to John Brannen (109JB) for the design, I made a blatant copy of his tube straightening tool. It's ugly, but it works.

    The wood parts are a leftover chunk of oak from some long forgotten wood butchery and the red steel part was something I found laying around (I think it's the locking bar from an old toolbox I don't have any more). Getting the steel bent required a vise, a hammer, a propane torch, and some very amateurish blacksmithing over the course of two hours, but it finally assumed the desired shape, more or less.

    The bottom of the steel "U" is drilled and tapped (at a funny angle; I don't have a drill press) for the 4-inch 1/4-20 bolt. The small section of steel cut off in the second photo got a centering dimple drilled in it that keeps the tip of the bolt from wandering and protects the wood spine. I use a socket wrench to tighten the bolt.

    The white guides holding the red steel "U" in the last photo were added on both sides to keep things in alignment during use. The non-perpendicularity of the bolt thread made it wander without reinforcement. The guides are short sections of steel cleat left over from hanging a closet system in my master bedroom walk-in. Never throw anything away!

    I got the right side longeron about 90% straight, but the tool doesn't quite have enough travel to get the last 10%. I was tired, hot and sweaty, so I called it quits. Tomorrow I'll make a shim to go under the wood spine that will give me another 1/2" of thread on the bolt.

    Oh, and I found two more lower longerons, aft of the first two, that are also bent. They're not as bad, but they're bent. I'm developing a fondness for this plane due to pity!
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    Eric Page
    Building Kitfox 5
    Member: EAA, AOPA, ALPA
    ATP: MEL / Comm: SEL, Glider / ATCS: CTO
    Map of Landings

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