Simple question this time, cutting the piano hinge for the vertical stab. I suppose you’re supposed to take the hinge wire out first and cut that a bit longer so that you can curve it at the ends to lock it in?
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Sounds right to me.
As I recall, the plans call for cotter pins top and bottom to retain the hinge pin. That’s what I’ve done.
Art, Sonex taildragger #95, Jabiru 3300 #261
That’s the way mine is put together. Maintaining a Sonex built by someone else feels like an exercise in archeology. They are itsy bitsy cotter pins.
I am concerned about eventually losing a hinge wire while removing and reinstalling the cowl. Google believes the pins at Aircraft Spruce are the right diameter (0.089”).
Can you get a picture of how that’s done? Having a little trouble imagining how that looks in my mind.
The details will be in the plans. Different pins have different retentions. On my Waiex I have little cotter pins on the flaps & ailerons. The mini-rudder has a pin bent 90 on one side and it is safetied in. My ruddervators have a 90 degree bend on the top and a slight bend on the bottom, plus the tail tip keeps it from moving up.
Definitely make sure you find the detail on the plans page and follow the plans! For everything! Should be no guessing.
IIRC some of the hinge pins and holes for the cotter pins are on later drawings on my Sonex plans. I didn’t cut any of the hinge pins for the control surfaces until right before installing them. For test fitting it was lot easier to use a long piece so there’s something to grab on to when removing it.
I’ve been putting off drilling the holes for the cotter pins as I figure it’s one of those things where you practice the technique and do them all at once so you don’t have to relearn later on. Is there a good method or tool for drilling the cotter pin holes?
It’s not a hard task, or a critical hole. Drill them with the surfaces installed. If you can get the drill in and out, you can get the cotter pin in and out.
Thanks, but I’m looking at the plans now and they don’t seem all that clear on the specifics. All I’m getting from this drawing is that there is a cotter pin and it goes somewhere. Am I missing something reading this?
The pin is shorter than the hinge. On the loop near the edge, a hole is drilled. The cotter pin prevents the pin from migrating out. I’ll take a picture when I can, unless someone has one handy.
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This makes it much more clear, thanks for the help!
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Bryan, following this thread about the cotter pins and the piano hinge. I’ve had trouble with that…maybe what I missed is that the drill only goes through the hinge. I’ve been trying to drill the hinge and then through the piano pin also…and it’s not working. So if I understand, the piano PIN is cut short and the cotter pin only goes through the hinge - not the pin, is that correct?
Correct - no way to drill through the pin. The cotter just keeps it from sliding out the end. Plus there are no forces on the cotter pin. If you drilled through the pin by some amazing skill, the friction of the pin on the other half of the hinge would work the cotter pin.
The drawing isn’t showing a cotter pin; it’s showing the left-end view of the piano hinge. (Google third-angle projection for more on this.) I’m not sure why they felt it necessary to show that projection of the hinge but the drawing doesn’t call for a cotter pin, which they would label if it did call for one. That said, I don’t see the addition of a cotter pin doing any harm.
I agree with your interpretation of the drawing in FakeLouis’s post, but I’m pretty sure they tell you to put the cotter pin in on either end somewhere in the plans.
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Bryan, you are correct. It says end lug is drilled for safety: Drill 3/64" hole through hinge and hinge pin at a 45 degree angle and in the middle of the lug. Install MS24665-5 cotter pin. The wording including hinge pin makes people think it needs to go through the pin as well. I can see how this wording sounds like the pin would need to be drilled as well and would hang up people. Aint no way your drilling into that pin. Definitely dont omit the cotter pin in the lug though. It definitely tells you to install.
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Good to know!
I don’t see anything about a cotter pin on any the Onex hinge drawings, so perhaps this was changed when they drew it up.
On my legacy Sonex plans the cotter pin drill and installation detail is on the W02 and T01 assembly drawings so I’d check there. I see why they’d do it this ways since it’s easier to figure out the angles of the holes once it’s all together.
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