WD-721 Gear Leg Weldment

[ShookieRV7A]

I am in the process of installing my gear legs and I am still scratching my head on this one. I have made the gear leg cutout in the F-772 skin and some of that cutout does go into the flange of the F-704 spar. All of this is on the left side so far.

However, there is still a sizeable gap between the lower portion of F-704 spar and WD-721, most notably where the NAS bolts will attach the wings to the fuselage. It appears from looking at rub marks on the WD-721 socket that I am still not close enough to the spar. There are rub marks right at the weld between the socket and the bracket.

Here is my question:

Just exactly how much material from the spar flange on F-704 is allowed to be removed?

I am really close to the double flush rivet now (probably 1/16" to 1/8").

 

[lostpilot28]

Man, it's been a long time since I've done that part, but I seem to recall that you put a washer between the weldement and the Center section on the lower holes. I don't think I removed that much of the center section flange.

 

[Rupester]

I got within 1/8" of the spar rivet on both sides.

 

[ShookieRV7A]

There is an AN-960-416 washer that goes in between the weldment and the spar but that is the inboard side where you are using the AN4-12A bolts.

I am talking about the outboard side where the NAS bolts join the spar/wing/weldment. Judging by some of the rub marks on the powder coat, I am pretty sure that I am still hitting the aft side of that cutout where the skin/spar flange are located. The wife is going to hold it up there while I climb underneath and look.

I am just concerned about taking any more of the F-704 flange off.

 

[roee]

As I recall, I had to cut out quite a bit of the spar carry-through flange, including cutting into one rivet, in order to clear the tube. Rather than leave an edge with half a rivet, a potential stress concentration, I reasoned that the structure will be left stronger by actually cutting a bit further and eliminating that rivet completely. So I'm left with a nice smooth cutout, one less rivet, and all remaining rivets have proper edge distance.

Don't remember if I talked to Van's about this one or not, but I do remember other builders encountering the same issue. Anyhow, that's what I did.

 

[swisseagle]

Hello!

I have done this shortly, so I can tell you how I have done it:

- really look that the weldment is laying flush on the spar, there should be no gap that you might pull tight when you installing them. There are missing cutouts (for the rivetheads) in the weldment, some of the cutouts are also missaligned compared to the rivethead.

- dont care about those single one rivet, the welding must lay flush, thats what count. It will be anyway difficult to install and rivet this rivet propperly.

- Install the weldment thogether with the spar, with all the screws once (maybe some of the powder coat must be removed), as long as these parts are not yet fully installed in the fuselage. So you can check and see where the fit is not ok. Otherwise it will complicate the process of installing the wings much much more and you dont see where ist does not fit!

Hope it helps,
regards, Dominik

RV7A, slowbuild
Switzerland

 

[ShookieRV7A]

Good news

I sent the same question to Vans and I got a reply from Ken and it looks like the rivet is history.

The reply was, "Almost all the flange will be removed."

When I asked about the rivet and clearance from the head, etc. the reply was, "Yes -- the rivet will be gone by the time enough flange is removed. If you haven't removed enough flange, you'll get exactly what you described."

So, it seems that the second rivet inboard is history.

It is intimidating for me to look at the spar flange and say, yes most of it is history.

Thank you everyone for your input.