Step to vertical bulkhead rivet holes

The row of rivet holes in the steps that the plans say should go through the F-724 vertical bulkhead... Are those rivet holes to be drilled supposed to match the existing side skin and vertical bulkhead rivet holes, thus replacing the flush the side skin rivets? Or are they in addition? If they're in addition, do I have to worry about placement modification from the step's plans to not interfere or chop any of the flush rivets, etc? Just double checking. Thanks!

Hi Scott,

I just used the existing holes. I figured 16 rivets was enough. I also put some bird shot inside the step to hopefully dampen the vibrations that may cause step cracking down the road.

Hi Tom, thanks. Did all kinds of measuring over the weekend, and match-drilled that row once everything else was drilled and cleco'd to the skin. On the center step rivet hole interferes with an existing skin rivet, and only at the edge of the factory head. The shop head is fine. I'll live with that.

I'm considering birdshot also. Is the idea that the step is hollow, and the birdshot absorbs the vibration? My ignorant mind is wondering whether some spray-in expanding foam from Lowes Aviation would help similarly, without adding the weight of birdshot?

Step

I just called Vans about the side skins and asked about the rivet holes. The answer was uze the existing if you want or drill new but watch edge distances to the existing holes.

On the step cracks, some have cracked before first flight. I plan to have a gusset added on mine.

A vibration damper needs to move counter to the vibration of the step in order to do its job. Filling with foam won't help that much. I couldn't find loose shot so I emptied and added about 10, 20 gauge shotgun shells worth of shot to each step.

Ah k Tom. And then did you have to spot-weld the fill hole closed or something I'm guessing?

Larry, like I mentioned, the center of the 5 rivets does interfere with a skin to bulkhead rivet, if the bulkhead is already riveted (which it probably is, like me, since that step is like 2 sections prior in the manual!). Basically makes a figure-8 hole. So I plan on drilling out that skin rivet and putting a small doubler on the interior side, catching the next step rivets above and below.

I moved the holes around to line up with the ones underneath or have adequate edge distance to rivets left in place underneath.

Yep

Exactly Scott. Drilled a hole as shown:



Then I had my auto mechanic weld the whole closed - no charge.



Some people plug the whole with RTV or similar