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Installing seat lock pins and compression springs

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  • Installing seat lock pins and compression springs

    I think we're all allowed a couple embarrassing questions when we're just getting started, right? I think these two items are related so I'll post them together. Besides, I don't want to use up both of my embarrassing questions in one day...

    I'm not sure why, but I'm struggling to figure out how the seat locking mechanism is installed. I just can't figure out how the pin is pulled down with the lever if the cap clamps on the tube like I'm assuming it does. There must be something obvious I'm missing here. Does someone have a picture showing how this works?

    And then how are you guys putting the spring on this pin and the door pins? Do you work it on like a keychain ring, or what's the best way.
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    Colby Osborn
    Mullen/Lincoln Nebraska
    Model 5 Quick Build Kit

  • #2
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    Attached Files

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    • #3
      The cap does clamp and does not move. Use a large washer under the nut.

      33F20C38-59E6-43F3-A0CA-6FE56A8D45F6.jpeg
      Scratch Built 4-place Bearhawk. Continental IO-360, 88” C203 McCauley prop.

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      • #4
        On the door pin I assume you’d work it on like a keychain. I made my own pins and welded the washer on after I put on the spring.
        Scratch Built 4-place Bearhawk. Continental IO-360, 88” C203 McCauley prop.

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        • #5
          Thanks for the pictures, guys! Appreciate it. I don’t see a welded washer on your cap, Jon. Or if there is, how did you get the pin with the small washer welded on it on the bottom side of the cap?
          Colby Osborn
          Mullen/Lincoln Nebraska
          Model 5 Quick Build Kit

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          • #6
            My cap is the same as yours.

            The set pin assembly goes together like this: Insert pin into the tube threaded end down, then spring, then cap, then large area washer, nut. The handle slips on so the fork is between the large washer and the weld bead nubs. When you lift up on the handle the fork pushes down on the washer which pull the pin down to disengage from the seat.
            Scratch Built 4-place Bearhawk. Continental IO-360, 88” C203 McCauley prop.

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            • coosbo
              coosbo commented
              Editing a comment
              Got it! Thanks!

          • #7
            Check out the bearhawktips entry below, that may help. I'll see if I can find the pics I posted if you can't see the tips post.

            https://bearhawk.tips/2945

            One thing I just noticed on mine. With the way I drilled the stops on the seats, the passenger seat interferes with the flap handle when the seat is full fwd. When the seat is in the fwd most hole I can't engage the last notch of flaps.

            WIsh I checked that, then I would have worked backward from there on that seat. Wouldn't matter to me if the pilot and copilot seats had slightly different stops.
            Dave B.

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            • coosbo
              coosbo commented
              Editing a comment
              Thanks, Dave! I'm not sure how I missed that article. It shows the process very well. Appreciate the heads up to check for interference before drilling the stops.

          • #8
            Did you have to adjust the length/height of the locking pin? If I snug the clamp on to the bottom of the locking tube, the pin sticks out about 1/4” too far. I used a small compression spring inside the lower 1/3 of the locking tube/pin? Thanks for all the posts! Randy

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            • #9
              Yes I adjusted the length of my seat locking pins by grinding them to the appropriate length after assembly.
              Nev Bailey
              Christchurch, NZ
              Builders-log
              YouTube

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              • svyolo
                svyolo commented
                Editing a comment
                I rounded the end of all the pins like that as it makes them work smoother. If you cut them off sharply, if they are not aligned perfectly, they won't penetrated the hole. The rounding (or a cone shape) makes slight missalignment less of a problem.

            • #10
              And then how are you guys putting the spring on this pin and the door pins? Do you work it on like a keychain ring, or what's the best way.
              They do work like fitting a key ring chain if the spring is a reasonably light one. However I decided to use a heavier spring to increase the force required to open the door. This is probably overkill, and my rear door now requires significantly more force to work the latch.

              Because of this I wasn’t able to wind the spring on, so I cut the washer off, slid the spring into place, and welded a new washer on. I probably wouldn’t go to this trouble again because when others try to open my rear door from the outside, they assume they’re doing it wrong (which is my point). I think that once I placard it, there shouldn’t be an issue and the chances of it being opened inadvertently in flight are pretty low.
              Nev Bailey
              Christchurch, NZ
              Builders-log
              YouTube

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              • #11
                Colby, thank you for asking this question! I am working on my seat latch mechanism and have run into the same issue. It seems like the pin is too long or the mounting tube on the fuselage is too short. Nev, Thank you for the suggestion of trimming the pin down, that is what I was thinking I should do. It's great to have a place like this to share ideas and progress.
                Model B quick build started 2021

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                • #12
                  I did mine a little bit different and added a bushing to the door latch plus I didn’t want a lever sticking through the door.
                  DFB0AFEB-BC86-4E3F-B81E-6DC2179F1A9B.jpeg

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                  • #13
                    Chris Werner , Below are a few blurry screen grabs of what I ended up doing. I'm pretty sure it's not the intended method, but it seems to function well.

                    One of the pictures in the BH tips article Dave linked above and Jon's photo showed a pin that looked a little different than mine. The lower washer on those pins appeared to be a smaller diameter than the top washer. Both the top and bottom washers welded on my pins were the same size. I ended up grinding the lower washer down so that it was small enough to pass through the inside of the springs I used.
                    Capture1.PNGCapture2.PNGCapture3.PNG
                    Attached Files
                    Colby Osborn
                    Mullen/Lincoln Nebraska
                    Model 5 Quick Build Kit

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