Horizontal Stab Front Spar Rivets

acpilot · #1 11-30-2022, 01:27 PM

I have been battling with a few of the rivets in step HS 8-10 where you rivet the ribs to the front spar. A couple of the top and bottom rivets I have had to drill out a few times. As a result of drilling out the small tabs on the ribs are bent up slightly. I have tried the "rubber tube" technique to press the tab against spar, however, I still can't get them to set correctly. I'm wondering if there is any reason why I can't reverse the direction of these few rivets so the manufactured head is on the inside if the spar. This will allow me to use my squeezer to pull on the manufactured head pulling the tab towards the inside of the spar and then, the ram squeezing the shop head on the front of the spar. I believe watching and controlling the ram will give a better result. I have checked clearances and the manufactured head on the inside of the spare is shorter than an ideal shop head. I can't see how this will effect the clearance riveting the skin on later.

georgemohr · #2 11-30-2022, 02:07 PM

Im not at all confident that reversing the rivet direction will get you what you are looking for. In my experience, the rubber tube trick is the best approach, unless you can clamp the flange with some kind of spring clamp. Your last option is to disassemble and fix the bend. Not great I know.

dwollen89 · #3 11-30-2022, 03:00 PM

I don't think it matters which way a universal head rivet goes in. The rule of thumb though is to put the manufactured head of the rivet on the side with the thinnest material. If you have a longeron yoke for your squeezer, you could probably reverse the rivet direction, then pull the flange tight to the spar while squeezing it like you described.

acpilot · #4 11-30-2022, 03:19 PM

Dustin

Thanks for your input. Interesting, the rib side is the thinner material so putting the manufactured head on that side should be okay. I'm just curious where it mentions which direction to place those rivets? I don't remember reading and was just going of pictures of others I have seen. Anyhow, thinking I may even get a second person to hold the tab tight with a straight screw diver at the same time as well. I just heard back from Vans and they say there is no problem changing the direction of the rivets.

George

Thanks for the input. Fingers crossed I don't have to disassemble,

georgemohr · #5 11-30-2022, 04:02 PM

When Vans prescribes a rivet direction, it usually conforms with the "shop head on the thicker material" principle. If it doesn't, then they are doing that for clearance reasons (manufactured heads are lower profile than shop heads, usually).

lipper03 · #6 12-01-2022, 06:04 AM

I think it's the rear spar for elevator clearance the head placement is more important, so front should be ok, I'll take a look at my HS later today and get back to you though.

robertahegy · #7 12-01-2022, 08:36 AM

Dittos on the Longeron Yoke. When I built my 7-A QB, I didn't need the yoke for the longerons, but it came in handy for many hard to access rivets. I would get it if you don't have it.

Roberta