Leading edge ribs.

can someone who has been there before please help with explaining how the leading edge rib W-408-1L/R are attached to the main spar? (imediatly outboard of the fuel tank. the W423 splice plate attaches to it.)
The depiction given on drawing 12 and 9 seem to contradict each other, As do the measurements on drawing 12.
Is there supposed to be a reinforcing angle on both the in and out board side of the rib, and what is the position of the rib web?
Any photoes would be greatly appriciated.
Thanks
Bill.

Hi Bill,

Not sure if I can help, but I'll give it a shot.

I looked at the drawings you listed, and I would agree that they leave a little to be desired in this area. Looks like the W-408-L & R ribs are slightly undersized to allow for the W-423 splice plate that wraps around the leading edge for the outboard end of the tank to attach to. From what I can tell, the rib flanges point outboard, and the web is located at rib station 55.75. There does appear to be an angle re-inforcement just inboard of the rib's web, and is riveted to the web, and bolted to the spar through the cap strips (or flange strips). I looked at some old photos I had (not digital unfortunately) and one of them seemed to verify this re-inforcement angle was on the INBD side of the web, but unfortunately, I don't have a close-up photo of exactly what we need to see.

In DWG 12, there's also another angle shown (just outboard of the W-408 rib) on the forward face of the spar between the upper and lower cap strips, it's riveted to the spar web with some AN470AD4-5 rivets, but it's not clear to me if it gets riveted to the W-408 rib. I don't think it does because it is located 1/2 inch too far OUTBD for the vertical leg of the angle to attach to the web of the rib on the OUTBD side. I also think it would not line up well with the angle on the INBD side since one sits on the spar WEB (OUTBD angle), and the other sits on the cap strips (INBD angle), so they couldn't both attach to the web from either side and at the same time, share common rivet holes. I'm not sure what the angle on the forward face at rib station 56.25 is there for unless it just provides spacing between the upper & lower cap strips.

That area of my wings has been closed-up for a while or I'd try to look at the way I built it to see exactly how it went together. Unfortunately, my rememberer is broken. Good luck, I hope I helped some.

Les
RV-4
S/N 4030

Thanks

Yes ,you are right on the money. That is exactly what I am talking about.
In relation to the measurements, Vans gives three different referance points for the stations. 1 the C/L of the a/C, 2 the C/L of the first hole to attach a reinforceing angle, 3 the inboard edge of the fuel tank spar. methinketh that I may set up the other L/E ribs and put the PP skin on to confirm the placement of the I/B rib. (I sometimes wonder if Vans is not somehow related to Mr Cessna)( Puts tin hat on and dives for cover!!!)
Cheers,
Bill.

Hmmm, I think you may have sparked something in my rememberer. I think I may have done the exact same thing you're talking about, that is, set up the rest of the leading edge, then used the pre-punch holes to locate this rib. Sounds like the best idea to me. In fact, I if I recall correctly, I may have had to trim down the flange on the W-408 where it sits against the spar web, because the flanges are 5/8 inch wide, buth there was only 1/2 inch of space available before the flange hit the angle riveted to the FWD face of the spar web on the OUTBD side. I got my spar pre-assembled from the Phlogiston folks, so I think this angle was already installed.