SB 14-01-31 Complete, Horizontal Stab Complete! Also rudder dissassembly & deburring

With the girls in Texas herding cattle, I got two long days in on the plane. First up: riveting the horizontal stabilizer.

I'm a slow learner, but after scuffing the front spar repeatedly I realized I could put some scrap cardboard & tape to good use (above, prior to re-taping). The cardboard also served to position the bucking bar centered on the shop head, lessening both my workload and mistakes.

All in all, I only drilled out about half a dozen rivets, and was able to do so without damaging the parts or enlarging any holes. After banging/bucking the forward spar & rib rivets by myself, squeezing the rivets along the edges was a piece of cake.

Soldiers all in a row...

I had to modify (with the consent of Van's Aircraft) the SB forward flange on the left rib, mounting inboard instead of the prescribed outboard placement. Previously it interfered with two of the rivets holding on the new doubler plate, but offsetting to the inboard side eliminated the clearance problem.

Here's a view of the forward side of the doubler plates & reinforcement angles in the middle of the HS. SB 14-01-31 is complete.

Fastest looking workbench I've ever seen...Feels good to see pieces take shape.

While waiting for HS & SB parts this spring I had started on the Rudder construction, proceeding as far as match-drilling all skin holes except the trailing edge. I overcame my nerves and used an angle template like we'd practiced in the SportAir Workshop, drilling half of the holes from each side. This will help the double-flush rivets set properly.

Next I trimmed, fitted & match-drilled the rudder horn brace.

As Van's tries to wean builders off the manual, forcing us to think (and read the prints) for ourselves, I noticed that match drilling the skin-to-horn brace wasn't mentioned. Boom.

Next I fabricated, deburred, clamped and match-drilled the rudder bottom attachment flanges.

One

And two. Time to disassemble & deburr!

On Sunday my buddy Brian from work stopped by to help, so he got stuck removing vinyl & stickers and deburring holes in the skeleton while I deburred the skins. If he comes back after this he must be hooked...

We finished the day by dimpling the 3/32" holes in the skins.

 

Empennage: 12 hrs

Rib flange angle modification approved

A note on Service Bulletins (SBs):

Several people with whom I've discussed my recent work adding new reinforcement pieces to the plane questioned my sanity for relying on a company selling an apparently "untested" or "unsafe" product, especially one that can hurl you at the ground from 20,000 ft in the air.

On the contrary, the SB process is proof of the kit maufacturer's ongoing commitment (42 years at this writing) to continue to improve their products and make them safer for pilots. When a defect is discovered, Van's does a thorough engineering review and voluntarily publishes information to mitigate the problem, followed by making repair materials available for existing kits and incorporating the changes into future production kits.

I called Van's regarding the rib flange angle dilemma I faced, describing my proposed solution and outlining the resulting edge-distance issue.

Sterling agreed with my analysis and opined that many RVs would face a similar issue. He said that moving the rib flange inboard was acceptable, and that the edge-distance from the 2 center holes to the flange bend would not affect the safety of the airplane, it was acceptable, and I should "build on."

This problem-solving aspect of the build is one of the most attractive parts for me, and one of the best educational tools of Experimental-Amatuer Built (EAB) aircraft; nerve-wracking and frustrating though it may be...

Empennage: 0.5 hrs

SB 14-01-31 Rib Flange Angles

After buying a couple 1" C-clamps from the local hardware store I proceeded with fitting and drilling the new rib flange angles as part of SB-14-01-31.

 The right side flange fit well, holes carefully match-drilled using my dremel dentist's drill extension.

Next I removed the rib & flange from the HS and match-drilled the assembly holes to #30.

Upon drilling the left side I ran into a snag. Due to the front spar bend location, the left side doubler plate was riveted close to the existing HS-404 to HS-405 rivet holes. This interfered with the new rib flange angle.

 After considering a few solutions, I discovered that if I moved the flange to the inboard side of the rib I could gain sufficient clearance and maintain edge distance on most of the holes. However the edge distance from the center 2 holes attaching main rib to nose rib are less than 2D (2x diameter) from the bend of the rib flange. I decided to call Van's and see if this is an acceptable fix. As far as I can tell the alternatives all involve replacing an awful lot of aluminum...

Empennage: 4 hrs