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Potential First Mistake

E

ethand

Well Known Member
New builder here working on the VS of the -10.

Step #8, page 6-3 (got through one whole page before I had the first issue)

The directions say to machine countersink holes common to the Rear spar (1003), skin (1001) and the rear spar caps (1014-L and R).

My issue is I also countersunk the holes below the skin (about 16 holes) on one side of the rear spar flange. Is this piece now scrap or can I adjust what rivets I use where ever these holes are filled later in the build?

Thanks in advance for the feedback.

E
 
I,d have to double check, but I think you,re okay there. Pretty sure those are universal heads because nothing lays over them.
 
Page 6-6, Step 9 has you rivet the spar caps to spar using universal head rivets. If you countersunk those, just use AN426 flush rivets instead of universal in those locations.
 
If you countersunk them for the skin, then the countersinks may be too deep for AD3 rivets. Check with Van's, but I'd ream the holes out to #30 and countersink them for AN426AD4-4 rivets.
 
Thanks for the replies. I looked at figure 1 on page 6-6 but did not see rivets used in step 9. I will check with Vans but looks like the part can be salvaged.

Thanks again.

E
 
I did exactly what you did and I put in AN426 4-4 instead. I talked to an A/P and tech advisor, they said it was ok.
 
It is a good learning experience

You will learn to stop and think ahead to understand why you are doing everything. This is one of the things that you should learn in a class on building sheet metal airplanes. Also you will learn that in most situations there is a salvage method for mistakes and the process of finding them is educational (seriously). You should search out repair methods when mistakes are made because it reinforces you understanding of the cause and will set off mental alarms when you are faced with a similar potential mistake in the future. Thinking is good - I guess I should try it sometime.

Bob Axsom
 
Andy's reply got me to thinking about another question. I used a flush head rivet as a gauge for my CS holes. I now see this does not look like it is enough to accept the skin dimple and allow the two to mate properly.

Questions #2: When countersinking to accept a dimpled skin (or other mating part) is the countersink much larger than it would be just for a rivet head? (logic would tell me so as you need to account for the head and the displaced metal from the mating part. Looking for confirmation here.

Thanks for the tip Bob in reading ahead. I did a page or two but have learned the lesson that is not enough. Even this early in the build I can see where there is method to the madness of specific directions and order of steps.
 
ethand said:
...Questions #2: When countersinking to accept a dimpled skin (or other mating part) is the countersink much larger than it would be just for a rivet head? (logic would tell me so as you need to account for the head and the displaced metal from the mating part. Looking for confirmation here...
Click to expand...

Your logic is sound; the countersink does have to be a little bit larger; it's not a lot but it is noticable.

What I do, and what I think most builders do, is to dimple a piece of scrap aluminum of the appropriate thickness, and use that as a gauge to test machine countersinks. You press them together with your fingers and look for a snug fit where the dimpled piece does have freedom to move side to side, nor does it stand proud.

Thanks, Bob K.
 
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