riveting fuel tank stiffener ring

[pilot2512]

I'm building my first fuel tank on a -9. I got the stiffener ring drilled to the rib. The instructions say to dimple the rib and countersink the stiffener ring. Now for my question. Has anyone used 1097 rivets for this and just countersunk the rib just enough for the rivets? Anything wrong with doing it this way?

Thanks

[KayS]

Hi Jay,

it should work but be aware that, because of the removed material, countersunk rivet spots are not as strong as dimpled ones. to dimple the rib and to countersink the ring for standard rivets, like the manual is telling you, is an easy and straightforward way to attach the two pieces together. i don't see any reason to deviate from the plans here, so i'd like to recommend to stick to the manual.

Kay Stecklum
RV-7 wrap-up/Electrical

[RV Jerry]

When you dimple metal it's like puting a funnel inside of another it helps the pieces stay in alingment I would not get in the habit of c/s especialy on wings, once airbourne the wings flex, dimpling will help keep thjngs from moving
c/s where you described is ok but poor building practice you don't want to remove metal where it's not neccessary.