Tank attach bolts

I attached the fuel tanks last night. Several (1-2) of the bolts were very difficult to thread into the nutplates on the z-brackets - the hole was offset just enough to make threading the bolt tough and to really increase the drag on the bolt. I don't know why / how this happened - it was one bolt out of three on the z-brackets it happened on - the other two fit fine.
After much head scratching, I decided to take a small round file and open the edge of the hole in the spar to align the holes and make the bolt go in without drag. We're talking a few thousandths at one edge of the hole. I called Van's tech support and this is OK.

Anyone else have a similar problem? I can't remember what I drilled the holes to (i.e. if I used a numbered drill bit or a fractional ... perhaps the bigger would have been best). I can't figure out why a couple holes were out of alignment when everything else fit so well...

T.

Procedure/hole size?

There are a lot of opportunities for slight misalignments to occur. For #8 (8-32) platenut applications I drill every screw location hole with a #30 or 1/8" drill and cleco every mating hole as I am completing the hole pattern between pieces to assure that that kind of panel to panel hole misalignment doesn't occur. Then I cleco the platenut itself to the most accessable surface with a bronze cleco and drill one mounting hole with a #40 drill and cleco it in place with a silver cleco (with the bronze clecoe left in place). Next I drill the second mounting hole. Then I remove the clecoes and platenut and debur and countersink the mounting holes (yes, according to my school at Vans Aircraft this is OK on thin stock for platenut applications). Finally I drill the screw hole in both pieces to 3/16", debur them and install the platenuts using a hand squeezer. I never had an alignment problem in the building or modifying of my RV-6A.

Bob Axsom

tank bolts

Bob, we had the same problem on my brothers 7-A. Even after I had test fit the tanks and put every bold in place prior to final assemby. It may be that some tweeking is going on and causing the final missfit. I simply played around with the sequence of bold installation till I got them in.