First D'oh moment, or not? - 7-A emp

Ray Williams · #1 12-18-2008, 12:57 AM

Guys, I still have my L plates on. I've been happily working through the "Drilling the HS" section, today clecoed the Left HS-601PP skin to skeleton. All good. The build notes call for drilling to final size or match-drilling all the remaining holes. Notes are silent on drill size. I used #30 bit to drill out top flange of HS-405, then drilled top flange of HS-702 as far as main rib HS-702: then realised that the rivet call is AN426AD3-3.5.

So I think the holes I have drilled to date are oversize and I should have used #40 drill bit. I would appreciate your opinion as to what to do. Get new parts including L skin, OR keep drilling every hole using #30 and use appropriate rivets, OR drill the remainder at #40 and match the resultant rivet pattern on the R HS. I'll also email Vans for an opinion.

Hope I've made the situation clear enough.

Thanks and regards, Ray Williams
Mittagong, NSW, Australia

sprucemoose · #2 12-18-2008, 01:11 AM

Welcome aboard Ray, and welcome to the Aw @#$% club.

Without the plans in front of me it is hard to visualize, but I believe that what you've described is the main spar, between the inboard and middle ribs, where you've drilled the holes oversize. Of course, you did this on the top side. You always should put your mistakes on the top side where everyone can see them, not the bottom side where they are hidden from view!

Opinions wil vary, but if it were me, I would leave it as is. Dimple the oversize hole with the correct dimple die, acquire some -4 rivets of the appropriate length and rivet away. Of course, this assumes that you have proper edge distance on the spar flange for the now oversized hole. This is as good a time as any to become familiar with the Mil-spec on riveting, which details, amongst other things, the proper minimum edge distance:

http://www.vansaircraft.com/public/Specs.htm

And, when some smart a$$ down the road asks you why those rivets are larger than the rest, just tell them that the P-factor requires that side to be built slightly stronger. Ask them if they made the same mod to their own horizontal stab.

skyyking56 · #3 12-18-2008, 04:01 AM

Hi Ray,
I dont have the plans in front of me but keep in mind that there are oops rivets that have the body of the #4's and the manufactured head as a #3.
I've used them in certain areas where I had to drill out a rivet and enlarged the hole.
I think aircraft spruce or avery's sells a kit with different sizes in it. I suggest that you get one of these.
Good luck,
Jim

7A 90% done with wings

Just got laid off...so stopping production for a while

mototopo · #4 12-18-2008, 04:48 AM

Hi Ray,

while oops rivets are a good solution for a misdrilled hole here and there, remember they are not structural rivets. I would contact Van's to be sure which is the best way to go. Probably, using AN426AD4 rivets is fine, but check for edge distance.

Mel · #5 12-18-2008, 06:16 AM

Quote:

Originally Posted by Ray Williams

So I think the holes I have drilled to date are oversize and I should have used #40 drill bit. I would appreciate your opinion as to what to do. Get new parts including L skin, OR keep drilling every hole using #30 and use appropriate rivets, OR drill the remainder at #40 and match the resultant rivet pattern on the R HS. I'll also email Vans for an opinion.

Ray,
Not a big deal. Go with 1/8" rivets where you have drilled.
Later if someone asks why you did it this way, give them a questioned look and say, "Well, if you didn't get yours right it's probably no big deal."
BTW, Claudio is right. Don't use "oops" rivets for something like this.

Ray Williams · #6 12-18-2008, 02:40 PM

Yes, lesson learnt and thanks for the advice. My local TC is visiting today to check flanges etc. FYI Gus at Vans said "leave it as is, use AD4 rivets in the existing #30 holes, and do the rest the correct size. The larger rivets will be harder to set without damaging the skin, so DO NOT drill the rest out #30 or match the RH side. On the finished airplane, no-one but you will notice the odd size rivets (only the ones on the HS-702 spar will be visible), especially once it is painted; and you'll probably forget them after you've been flying a while".

Best regards from Oz. Ray