Friday, June 5, 2015

Rear Seat Ribs - cont'd

A slow day at work today allowed for an extended lunch hour and some great progress on the fuselage for a weekday... awesome kickoff for a hopefully productive weekend! I was able to rivet the rear spar bulkhead to the center section/seat rib subassemblies, and then all 12 rear seat ribs to the rear spar bulkhead. The resulting assembly looked like this:

Holy cow... It's starting to look like a backseat!

R side view of the back seat ribs after riveting

L side view of the back seat ribs after riveting


Once those were done, I couldn't think of a single reason not to cleco the last bulkhead and baggage floor ribs onto this rapidly-budding fuselage!

Aft bulkhead and baggage floor ribs clecoed into place for match drilling

10 minutes of work yielded 33% increase in apparent size... wow!

Got some final-drilling done on these parts too, but then discovered an issue: one of the baggage floor ribs had a crack in its lightening hole flange. I assume that this comes from when the part is stamped out of raw material at the factory, and for whatever reason this piece split just a little bit. Here is a closeup of the affected area:

Spotted a crack in the aft-most hole of the F-1020-R baggage floor rib

I decided to call Van's builder support tonight (they have a morning window and then a 1-hr window from 5:30-6:30pm local time to call and talk directly with the 'mothership' builders) and report the issue and ask for guidance. I assumed that I could stop-drill this crack and be good to go, but wanted to make sure before doing anything. I got the good news I had hoped for; this apparently does happen from time to time during the manufacturing process, especially with the 2024-T3 aluminum material that this is made of, and it's no huge issue for concern. The builder I spoke with confirmed that sanding the area out (if it is small) or stop-drilling the crack (if it is larger) is the correct and perfectly acceptable repair for this kind of defect. So, a quick zap with a #40 bit and EZ-Burr yielded this repaired part:

Stop-drilled crack in flange

Other side of flange, it is apparent the crack was not square with the material but the stop-drill covered the area just fine.

It was a bit disconcerting to have a "defective" part (or at least "a part containing a defect") shipped as part of the kit... but after examining all the rest of the ribs and considering exactly the problem found and the solution implemented, we were put a bit more at ease. The only thing we really care about is that this crack does not propagate past the flange and into the rest of the rib. Thankfully, both the crack and the stop-drill are contained within the area of that flange, and therefore essentially no structural integrity is lost.

With that minor setback behind us, it's time for more priming and assembly.... tomorrow!