Now that's being a good friend!
I recently completed the repair for a crack in the left horizontal stabilizer rear spar on mt RV-8 as detailed in SB-00036 Rev3. I devised a tool for holding the repair doubler on the front side of the spar while all pieces were Clecoed in place.
This was the easiest part of the whole repair. Removing three rivets from the outer rib, and seven rivets from the rear spar will permit installation of the repair doubler. After removing the 10 rivets from the top skin and the rivets from the hinge brackets, and stop drilling the cracks, the nested spar doubler and hinge brackets were positioned.
A single Cleco was placed through each bracket, nested spar doubler, and spar. The skin was then flexed up and the repair doubler (attached to the doubler positioning tool) was slid over the top of the spar and rotated down into position. It is important that the wire holder clearance between the top of the repair doubler and the handle portion of the tool permits vertical alignment of the rivet holes in the doubler with the Clecos. This can easily be adjusted to get the right clearance.
Once the doubler rivet holes are aligned with the Clecos the tool handle can be pulled aft to hold the doubler in place while the Clecos are squeezed to permit them to engage the doubler. It should be possible to verify that the Clecos have engaged the doubler by viewing the repair doubler from the space between the flexed skin and the end rib. Once the Clecos have engaged the doubler you can contine Clecoing the rest of the rivet holes and proceed with riveting.
The 10 rivets can be removed from either the top or the bottom of the horizontal stabilizer. I believe from the top is easier, the positioning tool can be reversed to work from the underside. The only difference is the side which is opened up and flexed will have four addional rivets removed.
CF86301, I hope I'm not stepping on your toes here by reporting a little analysis of the data in your Google spreadsheet.
Total responses posted: 255 -- Taildraggers 156, Nosedraggers 99
Total with cracks 38, without cracks 217
Of the 38 with cracks: 33 taildraggers, 5 nosedraggers
RV-3: 2, RV-3B 1, RV-4: 3, RV-6: 4, RV-6A: 1, RV-7: 7, RV-7A: 2, RV-8: 16, RV-8A: 2
Total time reported: minimum 270, max. 3382, avg 1257, median 1000
Factory rivet heads: FWD 2, AFT 23, not reported 13
Tailwheel without cracks: 123. Factory heads FWD 30, AFT 50 (remainder not reported)
Nosewheel without cracks: 94. Factory heads FWD 17, AFT 41 (remainder not reported)
2004 RV-8 TD
1000 hours
Counterbalanced IO360
Balanced Whirlwind prop
Minimal aerobatics and rough field opns
No cracks
...
If you have the option, shop heads on the thicker or stronger material, factory heads on the thinner and weaker material.
Sounds reasonable. I built my tail kit at a build center in Griffin, GA, with a very talented young man guiding me - and a few other guys on the forum - and I recall him giving advice on this exact thing, but honestly can't recall the details. In the end my shop head is towards the rear, which is where the steel bracket is.
Not sure if this was discussed and I may have missed it, but I found a borescope with a head diameter small enough to insert through the tooling hole in the outboard rib without enlarging it.
I know enlarging the hole isn't a big deal, but if this helps anyone I thought I'd pass it along.. 3.9mm head easily passed through on my H-Stab. Found on that big behemoth online retailer
Best part- No cracks!
Can you share what borescope you used?
I used this one, you've got to do a little manipulation to get the camera aimed just right, but at $50 I think time/effort saved vs opening up the tooling hole was worth it for me.
https://www.amazon.com/gp/product/B08R9V32VY/ref=ox_sc_act_title_1?smid=A3ILCX3MAOSUNM&psc=1
I don't know but would guess that the HS designs are similar enough between the older and newer models that Vans has reason to believe it could occur in the newer model fleet as it ages.Just like every other RV-9, -10, and -14 ever made….no cracks.
Why list a plane with no known issues on a SB ? Caution is appreciated but zero dot zero is not caution, it’s paranoia.
I don't know but would guess that the HS designs are similar enough between the older and newer models that Vans has reason to believe it could occur in the newer model fleet as it ages.