• Flap prep
    Flap Section 21 Wing
    May 10, 2021

    While the flaps seemed fairly straight forward, there were a few new and interesting tidbits in the plans that haven't come up in previous parts. First was the use of duck-bill pliers to eliminate "pucker" in the ribs. I didn't actually own any duck-bill pliers by that name, but had a small pair of flat (non-grooved) surface pliers that I put some tape over to not damage the aluminum and straightened out the bend as best I could. It was pretty subtle to start with, but it came out slightly more flush so I suppose mission accomplished.

    And "pucker removed"!

    Next were the inboard leading edges that required doublers and a large nutplate. Pics still need to be deburred, but everything went together nicely.


  • Rib flange dimples
    Section 14
    Dec 24, 2020

    The plans were not particularly clear on this, and I only discovered exactly which flanges should be dimpled in the top wing skin section. In short, do not dimple upper flange of the inboard 4 ribs! The doublers for the skin to reinforce the section that can be walked on are too think to dimple and will be machine countersunk instead.


  • Rear wing spar
    Section 15
    Dec 14, 2020

    Riveting the rear spar to the wing ribs was accomplished mostly with a squeezer. There were a few places where it was really challenging to fit a yoke without interfering with another rivet shop head or a flange. I found that I ended up cutting a small groove into a few shop heads, caused by the yoke dragging a corner against it. These didn't seem too deep, however, so I simply smoothed them out with a file.

    The hardest part of the spar for me was the new inboard aileron bracket from the service bulletin. The rivets along the outboard flange of the bracket couldn't be squeezed because my squeezer would interfere with the bracket itself and couldn't be square. For these rivets I had to use the gun and bucking bar. For the inboard flange of the bracket, the neighboring shop heads interfered with even on offset rivet set. For these, I had to flip the rivets around so that the manufactured heads were on the inside of the spar. I couldn't quite square these up, and the shop heads ended up being


  • Riveting flanges
    Section 15 Techniques
    Dec 14, 2020

    One challenge I've had is riveting flanges against a webbing or similar cases where the outer surface wants to lift up to create a gap between the two pieces of material. I made a few observations here and have found an approach that seems to work pretty well in a variety of circumstances.

    Back-riveting

    When able to back-rivet, I've found this to be the easiest as the back-riveting tool has a strong spring that compresses the pieces together before riveting.

    Conventional riveting

    When using the rivet gun and bucking bar, unless you press the sheets together with your bucking bar hand a gap will often form between the sheets. This has caused me a lot of early frustration, as once this happens the sheets become slightly deformed and even after drilling out the rivet it becomes even harder to get them compressed flush without a gap.

    The technique that I've found easiest is to get a piece of rubber that has a hole punched in it just large enough to hang on the end of an unset rivet. You have to be careful on the thickness of the rubber; if it's too thick the bucking bar may not make contact with the rivet shop end. If the rivet is just slightly set with the rubber to compress the pieces, they will hold together. Then the rubber can be removed and the rivet fully set normally.

    Squeezing

    When rivets can be squeezed, I've found having the rubber insert works well here as well, but doesn't need to be removed to fully set the rivet. I've also found that the rubber pad tends to square up the squeezer to be orthogonal with the surface.


  • Inboard aileron hinge brackets
    Section 15 Service Bulletin
    Dec 12, 2020

    While not immediately obvious when starting the aileron hinge brackets I found that the parts were missing from my inventory for the inboard brackets. After digging a bit, I found that my kit included the service bulletin 16-03-28 subkit that address potential cracking problems with the original brackets. The new brackets are considerably heavier with a piece of angle aluminum instead of a folded flange, as well as two doublers with their own flanges on the backside.