Rear Spar Edge Distance, and Van's suggested fix

Veetail88 · #1 07-21-2010, 08:12 PM

Ok, so after all the reading, knowing full well that I should have checked and checked and checked all dimensions, I jazzed up the edge distance when I drilled the rear spar attach point.

I had to jack the left wing up almost 3/8" to get the wing incedence equal to the other side. I checked the edge distance of all parts and thought I had it covered, but when I took the wing back off, to my horror, I've drilled the hole 3/32" too close to the bottome edge on the wing rear spar.

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What do ya'all think?

I'll take a print of this picture with me to OSH next week and see if I can get a professional opinion from the guys at Vans, but thought I'd throw it out to you guys.

There are indeed some educated folks here!

Help!

Rick6a · #2 07-22-2010, 07:01 AM

Jesse,

Credible responses to your query are slow in coming. Unfortunately, the truth sometimes hurts. Please don't kill the messenger.

Based upon your photo, I am guesstimating the existing e.d. is only a slight bit more than .500. Vans incidence drilling document calls for maintaining at least 5/8" (.6250) as the minimum acceptable e.d in this application:

http://www.vansaircraft.com/pdf/Wing_%20Incidence.pdf

Assuming you did everything right and "pulled the hole" up to its full size of .312 all the while skillfully maintaining the existing .500 e.d., the minimum e.d. requirement as described in that aforementioned incidence drilling document would still come up short. Even if you did possess the necessary tooling and technique to move the hole, basically you are asking the designer to accept .500. I am not sure this is something Van's or you would be entirely comfortable with, but I have been surprised before. Besides, why wait for Oshkosh? E-mail your picture to Van's today and start consulting. The busy Van's staff does not normally like to take up valuable time addressing individual builder problems at a busy venue where they are trying to sell kits.

Whatever you do, be sure to keep us in the loop. Everything can be fixed. Good luck.

Brantel · #3 07-22-2010, 07:06 AM

Call Vans, this is not one for the peanut gallery....too important...

I understand that this happens occassionally and Van's knows how to deal with it. Call em for the fix...

Louavul · #4 07-22-2010, 08:36 AM

Jesse: My first attempt at drilling the rear spar to the fuse attach turned out the same way, on both sides! Sweep and incidence looked good and I had to jack one wing as well.

I wrote Van's but before they responded I decided to remove and replace the rear spar straps rether than live with questionable parts. Was able to accomplish this without removing any skins however I did end up with lightning hole scarring on my arms.

Steven Hild
Belen, NM
RV-7, FK

Veetail88 · #5 07-22-2010, 09:41 AM

for the input gentlemen.

I've sent the info over to Van's and will wait for their response.

I looked at replacing the rear spar straps as Steven has done. Looks like probably the best fix, but drilling the same part with the correct edge distance will likely leave me with an unequal wing incidence problem.

Does half a degree matter much? Would it trim out?

Maybe the best would be to make up my own straps out of blank stock, duplicating the originals but leaving more depth on the tab where the hole goes. That way I could still have correct alignment between the wings.

Steven, having jacked up the trailing edges of both wings, how did you make up for the gap under the wing at the joint to the fuselage?

Either way, I'll update this thread with whatever comes back from Van's and what the final fix is.

Ironflight · #6 07-22-2010, 10:01 AM

On the -3 we're building, we put in a wider rear spar center section during initial fabrication, just to help ensure that we didn't run in to a similar problem. The -3 is really a 'make it fit' build - I'm surprised you had this problem in a more modern -8.

Paul

Veetail88 · #7 07-23-2010, 12:25 PM

Scott at Van's sent me a fix for the edge distance problem I have.

He asked that if I post it here, that I make clear that this fix is accptable ONLY if you have an edge distance for this hole of .50 or greater!!!

He says that no matter what, if you have this problem, to contact them anyway!

I like this fix better than removing a wing skin, which would really have boogered up the bottom skin, as there's no way to get behind the new rivets that would be needed to replace it!

Mods, can you rename this thread so it is easier to search for those who have this problem in the future?

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