3B QB Wing error - aileron bracket location

Ironflight · #1 08-24-2009, 08:33 AM

Just a note to all the RV-3B folks with QB wings - we have been scratching out heads on this one, and finally realized that the quick builders have put our inboard aileron bracket doubler (and pushrod hole) in the wrong place! Louise and I have been working on getting the ailerons and flaps mounted, and after attaching the aileron brackets, we discovered that the pushrod was rubbing on the inboard bracket. Measurements ensued, and it appears that the pre-drilled rivet holes and the pushrod hole are about 7/16" closer to the root than they should be, according to the drawings. There is a measurement on the drawing noting a distance from "the root rib", and it appears that they may have measured from the root end of the rib flange, rather than the rib web.

I have talked with Van's engineering department, and a fix appears to be to move the aileron bellcrank pivot point inboard by about 3/4" (by remaking the bellcrank mount brackets - a pretty easy fix with a little 4130 steel). They were also going to pass this on to the factory to make sure they are aware of the problem. I just thought I'd get the word out to anyone else that has recently-built -3B QB wings. I'm curious if anyone else has found an issue here, or if we just got a lucky set?

I am really enjoying the fact that I have to actually have to THINK while building the -3....this requires a bit more creativity than even my older -8 kit did. Much more satisfying to have some mental sweat in the game!

Measure carefully and take nothing for granted...

Paul

mvs163 · #2 08-24-2009, 07:35 PM

Mine wasn't displaced spanwise.
You will notice however that the supplied aileron bkt has the large/spanwise pushrod and the small/chordwise pushrod displaced vertically when the plans version has them in-plane.I believe this is an -8 part. The big pushrod will run close to one side of the lightening holes in the wing and I had to widen out the hole in the rear spar doubler...the differential travel is different also with the supplied bkt so you won't get the spec'd travels.
I have a pile of kit parts that were paid for but unusable...
Mike

Ironflight · #3 08-24-2009, 08:17 PM

Quote:

Originally Posted by mvs163

Mine wasn't displaced spanwise.
You will notice however that the supplied aileron bkt has the large/spanwise pushrod and the small/chordwise pushrod displaced vertically when the plans version has them in-plane.I believe this is an -8 part. The big pushrod will run close to one side of the lightening holes in the wing and I had to widen out the hole in the rear spar doubler...the differential travel is different also with the supplied bkt so you won't get the spec'd travels.
I have a pile of kit parts that were paid for but unusable...
Mike

It's definitley a "make fit" build, yes - of course, that's what I am finding fun....

Opening up the hole for the pushorod is no surprise - I even had to do that on my QB -8. The trick is figuring out what shape to make it so you remove minimal material....