Lots ‘o riveting going on in the last few days…and drilling out some rivets too. 
I had to re-learn all those rivet bucking skills I had forgotten since the SportAir workshop. Ellen caught me in the midst of a hard-to-hit rivet. But the HS front spar is finally finished…
Here are the front and rear spars covered with spiffy yellow Super Koropon primer.
…and here’s everything clecoed together. Next task – practice flush riveting, then start putting the skins on.
HS parts are all alodined and primed. If you’re desperately interested in the whole process, go here.
Finally…some rivets squeezed! Constructed the horizontal stab rear spar and attached its elevator brackets. I had to drill out a few rivets, but didn’t make too much of a mess.
Here’s one rivet drilled out, and another ready for the punch. Once the rear spar was done, I started re-assembling the front spar in preparation for riveting.
Over the last few days I washed, prep-sol’d, etched, alodined and primed all the horizontal and vertical stab parts. I must say that this whole process was a tremendous pain in the…uh, butt.
Here are the parts after washing with liquid dishwashing detergent, a wipe down with PrepAll (same stuff as PrepSol), and a scrubdown with DuPont 225S aluminum metal cleaner (same stuff as Alumiprep). Not too big a deal to do all this stuff, and a box of Scotchbrite pads came in handy. If you plan to do this process but haven’t yet, make sure you put a little extra effort into scrubbing the alclad parts. Swapping Scotchbrite pads frequently helps.
Next step was application of alodine. This was not fun. Ribs and other parts aren’t too tough, but spars are awkward and skins are even worse.
Here are the results. Ribs – 
and a horizontal stab skin –
This step required a lot of cleanup. And the knowledge that chromate conversion processes like alodine use hexavalent chromium, a rather nasty carcinogen, is motivating me to consider a non-chromate conversion coating called PreKote. It’s non-toxic, non-hazardous, biodegradable, and can be applied with a hand sprayer and a fine (maroon) Scotchbrite pad. Unlike alodine, it doesn’t leave an anti-corrosive barrier and requires a chromated epoxy primer to provide corrosion protection. I’ve requested some information from the manufacturer, and we’ll see what happens.
And finally…priming. Because we live in metro Boston and are close to the Atlantic, I decided to use a fluid-resistant epoxy primer to provide an extra measure of corrosion protection. In particular, I’m using Super Koropon from PRC-DeSoto. It’s roughly equivalent to the Akzo Nobel epoxy primer that a lot of other builders seem to use. Here’s one horizontal stab skin – 
and other assorted ribs and spars – 
ike alodining, priming was a genuine pain and I’m glad it’s done for now.
My experience with applying this primer on the empennage is also causing me to consider how I’ll apply it in the future. Van’s rightly says that two-part epoxy primers are heavy. That’s true, but there is nothing better I’ve found for corrosion protection. On the wings and fuselage, I may choose only to apply it where it’s really needed – overlapping skins and skin-to-structure contact, anywhere that moisture can accumulate and promote corrosion. More to follow…
Now, it’s back to riveting the horizontal stab.
The new HS-710 and -714 arrived last week. Trimming and finishing went quickly, and the new parts fit very well with the existing holes match-drilled in the HS-702s. Pre-punched parts are freakin’ great!
Not much progress in the last week…family stuff took priority, and then work stuff got in the way. I did, however, get the remaining countersinking done on the VS spar doubler.
Following that, I finished all the parts prep work – deburring and edge polishing, then dimpling for the other VS parts. All that remains for the VS before assembly is cleaning, Alodining and priming.
While preparing to countersink the VS spar doubler, I re-read Vans’ instructions on how to countersink. Turns out I used the wrong method on the HS-710 and -714 reinforcement angles – using a male dimple to check countersink depth makes for too deep a cut.
For a hole that will accept a dimpled skin, the current instructions call for countersinking the hole just enough to make a rivet sit flush, then going another 0.005″ (two countersink sink ‘clicks’). Well, mine were a lot deeper than that. According to Gus at Van’s, there are no structural issues since the holes weren’t countersunk all the way through. Riveting the hole could be difficult since the rivet shank will expand in the area between the countersink and the dimple, but the suggestion was to rivet them anyway – four sub-par rivets wouldn’t make that much difference.
Just to be on the safe side, though, I’ve ordered a new -710 and -714. The challenge will be to make the match-drilled holes line up on the other parts drilled in assembly with these two. If I can do that, I’ll use the new parts. If not, I’ll fall back on Vans’ suggestions.
Lots of things happened in the last week. My primer finally arrived, after only a month’s wait. Super Koropon may be a great primer, but I don’t understand why it takes PRC a month to crate and ship a two-gallon kit.
One thing I didn’t mention in the last couple of weeks is that I messed up the VS spar reinforcement plate while trying to cut lightening holes with a fly-cutter. That’s probably a result of not taking shop classes in high school.
There were some newsgroup debates about whether to cut the holes at all. The argument that makes the most sense to me is that lighter is always better, at least in RVs, and that 8 ounces saved in the tail could mean not having to eventually add pounds of weight in the baggage compartment to fix a CG problem.
Anyway, the new VS spar reinforcement plate arrived on Tuesday, and after using the old part for fly cutter practice, I was able to cut acceptable holes in the new plate.
A side note about pre-punched parts – I was concerned that the new plate would have some minor alignment problems with the spar itself, since I had already match-drilled the two. Well, the new plate clecoed right into place on the spar. Pretty impressive manufacturing tolerances at Van’s, I think.
I didn’t waste any disk space on pictures of a match-drilled VS skin and all the individual parts after disassembly, so you’ll have to use your imagination.
Not much to report today. I match-drilled all the #30 VS frame holes, then clecoed the skin to the frame. Like I said before – this process is much easier after doing the HS.
It was a little tough to get back in the groove after a weekend on Cape Cod. The water was too cold to do any swimming, but Whits managed to log some beachcombing time.
We’re still waiting for PRC-DeSoto to deliver the primer we ordered almost a month ago. While horizontal stab construction is on hold, I started the vertical stab. First step is to cleco the rear spar doubler to the spar itself.
I also edge-finished, straightened and fluted all ribs. While doing this for the HS, I wound up with some scratches on the inside radius of some ribs – I think they were from my hand seamer. At any rate, they’re a pain in the butte to polish out, so this time around I covered the seamer faces with thick duct tape, and lined the inside of each rib with Scotch removable masking tape (the blue stuff you see on each rib). Worked great – no scratches.
Next step…clecoing the frame together. This whole process goes much quicker after doing it on the horizontal stabs!
DVD of the day…wait for it…classic Monty Python, including “Upper-Class Twit of the Year” and the Spanish Inquisition sketch.