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Thread: Repairing flaperons

  1. #21
    Senior Member jrevens's Avatar
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    Default Re: Repairing flaperons

    Those are all good points, Fred. The fact that it has been done by others, and also proven to be OK by you for so many years up to now is a good testimonial to the change probably being safe. The flying and testing is the only way to know for sure. I tend to be, perhaps, over cautious about changes to a design like that, having been privy to an ugly lawsuit where a relatively minor change was made to a homebuilt involved in a fatal crash, and the lawyer(s) jumped all over it even though it had nothing to do with the accident. Flutter is also a complicated issue. It's amazing how a tiny, relatively minor change can make a surface more vulnerable. It's sometimes impossible to predict what will happen if, for instance, someone were to inadvertently dive the aircraft beyond the red line speed and "excite" the surface with a sudden movement of the controls. You might be surprised to see the very simple and tiny change that made the most difference in preventing a flutter issue with the Thorp T-18 stabilator. A very small amount of additional stiffness was created where the anti-servo tab end rib is connected to its hinge by adding a thin (.015") strip of stainless steel between the rib and the hinge. It was stated in print by the designer, after extensive instrumented testing, that the assembly was most probably flutter-proof up to the speed of sound after that. Stiffness between interconnected components can be a huge factor for flutter, and tiny changes can make a world of difference. This is all just an interesting conversation/subject to me, and I don't want you to think that I was trying to make you worry unnecessarily about what you did.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  2. #22
    Senior Member PapuaPilot's Avatar
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    Default Re: Repairing flaperons

    Quote Originally Posted by Eric Page View Post
    Thanks for the clarification, Phil. I was hoping one of you A&P guys would chime in. I'll do as you described. Most of my damaged slots are dented/cut at the forward end, so I don't have enough room for the row of three rivets. With that in mind, would you recommend wrapping the patch around the leading edge and putting those three rivets on the bottom side?
    Wrapping it around the LE would be fine. It will make it more challenging to bend it right, but .016" is easy for bend and form.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  3. #23
    Senior Member Eric Page's Avatar
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    Default Re: Repairing flaperons

    Thanks, Phil. I've requested some quotes to have a batch of these laser cut.

    Flaperon Patch.jpg

    Assuming they're not ruinously expensive, I'll order some and make any leftovers available to others in the same unenviable position.
    Eric Page
    Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
    Member: EAA Lifetime, AOPA, ALPA
    ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
    Map of Landings

  4. #24
    Senior Member Eric Page's Avatar
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    Default Re: Repairing flaperons

    The order is in and the material is on its way to the laser cutter. It looks like I'll get ~45 parts out of a 12" x 12" piece of 0.016" 2024-T3. I should have them in about 10 days, and I'll be happy to share extras with anyone who needs them.
    Eric Page
    Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
    Member: EAA Lifetime, AOPA, ALPA
    ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
    Map of Landings

  5. #25

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    Default Re: Repairing flaperons

    I could put a set to use.
    Mike
    Building the JaMFox N677JM
    Kitfox 5 Vixen
    KRNM

  6. #26
    Senior Member Eric Page's Avatar
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    Default Re: Repairing flaperons

    The flaperon hinge slot repair plates have arrived. I got 45 of them out of a 12"x12" piece of 0.016" 2024-T3.

    FlaperonSlotPlates.jpg

    Here's the cost breakdown: Material (incl. postage): $15.45. Postage (mat'l to cutter): $7.70. Cutting (incl. postage): $103.89. Total: $127.04, or $2.82 ea.

    I need 8 of them for my flaperons. The remaining 37 are available for $2.82 ea., plus $0.50 for a padded envelope, plus postage and PayPal fee. If you want some, please send me a private message with your mailing address, your email address and how many you need. I'll send you a PayPal invoice for the total. Please buy only what you need, so these can help as many builders as possible.

    If you want to see what you're getting, or if you're reading this well into the future and you need to make your own, here are the design files:

    Flaperon Hinge Slot Repair Plate.ZIP

    This .ZIP archive contains the Solidworks .SLDPRT file, as well as .SLDDRW, .DXF and .PDF drawings. The .DXF is the file that should be sent to a laser or water jet cutter for production. The .PDF drawing includes some rudimentary instructions for installation, and for adapting the plates to the trailing end of a hinge slot.
    Eric Page
    Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
    Member: EAA Lifetime, AOPA, ALPA
    ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
    Map of Landings

  7. #27
    Senior Member Eric Page's Avatar
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    Default Re: Repairing flaperons

    Two takers so far. 21 plates remaining. I'll update this thread as they're depleted.
    Eric Page
    Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
    Member: EAA Lifetime, AOPA, ALPA
    ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
    Map of Landings

  8. #28
    Senior Member ken nougaret's Avatar
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    Default Re: Repairing flaperons

    Eric, pieces arrived today in good condition.
    Thanks again
    SS7 O-200 Whirlwind

  9. #29
    Senior Member
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    Default Re: Repairing flaperons

    Same problem with mine (both)
    i just cut the slut more far on each slot,maybe 1/2 inch..
    on kitfox 4

  10. #30
    Senior Member Eric Page's Avatar
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    Default Re: Repairing flaperons

    I fooled around for awhile figuring out the best way to install my hinge slot repair plates and ruined one in the process, so I thought I'd post what I came up with to ease their use for others.

    I started by making a wooden buck for shaping the plates. I traced the flaperon's profile, cut away most of the excess wood and finished it by sanding to the line on a belt sander. I ended up with a nicely bent plate that didn't fit the leading edge very well. Don't waste your time with the wood buck; it doesn't help and just makes the job harder.

    IMG_1335.jpg

    Here's the easy way. Locate the plate so the sides and end of the slots match up, then tape the plate to the flaperon. Use another piece of tape to seal the slot so drill swarf doesn't fall inside, then match drill one of the holes nearest to the leading edge to #40 (be careful; drill punch-through can easily damage the opposite side skin) and install a silver cleco. Double check part alignment, match drill the hole on the other side of the slot and install another cleco.

    IMG_1337.jpg

    Caution: The following procedure requires flipping the flaperon onto its top side. Be careful not to press the hinge arms into the skins, doing further damage. Hanging them off the edge of the table worked for me.

    Using your thumbs, bend the plate around the leading edge to the bottom side, being careful to keep it in contact with the flaperon throughout the bend. Holding it down with your thumb as close to a hole as you're comfortable with, match drill a hole. A cleco won't hold the plate down tight enough to drill a second hole, so just repeat the thumb-clamp procedure to drill the opposite hole. Now install two clecos, extend the drill bit as far out in the chuck as you dare and drill the center hole.

    IMG_1338.jpg IMG_1339.jpg

    IMG_1341.jpg

    Flip the flaperon over, cover the slot with tape again, hold the plate's arms down tight with a finger and match drill the remaining four holes.

    IMG_1342.jpg IMG_1343.jpg

    Trace around the plate with a Sharpie to identify the bonding area, then remove the clecos, lightly deburr the holes and bond-prep the surfaces.

    IMG_1346.jpg IMG_1344.jpg

    Mix up a tiny amount of Hysol and butter the mating surface of the plate with it.

    IMG_1347.jpg IMG_1348.jpg

    Carefully place the plate on the flaperon and install six 3/32" x 1/8" dome-head pop rivets.

    IMG_1349.jpg

    Flip the flaperon over again, install the three bottom-side rivets, then wipe away any Hysol squeeze-out with acetone or alcohol.

    IMG_1351.jpg

    Done!

    IMG_1350.jpg
    Eric Page
    Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
    Member: EAA Lifetime, AOPA, ALPA
    ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
    Map of Landings

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