Horizontal stab SB failure, and a question about hole spacing
I've reached the point in my -8 build where it's about time to fit the tail feathers to the fuselage. This seemed like a good time to undertake the service bulletin, prior to making my h-stab and fuselage a matched set, so to speak.
Unfortunately, in the process of drilling the doublers to the spars, a wandering dull drill bit enlarged several holes in the spar channel, too large to even open up for a -5 rivets. So I've resigned myself to replacing the spar, splice angles, and other associated parts. Obviously not happy about it, but I knew this was a risk going into the SB, which is one reason I did it sooner rather than later.
The real question I have is pertaining to all the holes in the spar doublers. I've seen multiple discussions about edge distance issues with these holes - and I ran into issues with this too, but I can see in retrospect where I wasn't careful and caused those problems.
The less-clear concern involves the spacing between the rivet holes in the "main body" of the doubler. Minimum acceptable rivet pitch/spacing for 1/8" universal rivets is called out at .500" center-center, but in many spots the pacing between the prepunched holes in the doubler and the holes drilled using the spar/angles as a guide are far closer than that. There are many spots where it's under .350" and one where it's barely over .300".
The thing is, I don't see how it would be possible to position the doublers such that this spacing issue could be avoided. If I'd moved them further inboard, I think that would have helped, but then they'd interfere with the vertical stab splice plate.
Maybe the solution when I get to rebuilding this is to place the doublers such that the spacing is good as well, and then trim inboard to clear the splice plate? I have that plate on hand, so I can easily use it as a guide.
Mostly I'm just wondering if others have run into this hole spacing issue while doing the SB, since I haven't yet run across a reference to it.