Aft fuselage preparation: 10-02 to 10-10

Completing the elevators was a big milestone for me because it’s the last of the metal assembly to be done on the empennage. At this point, I’m following the Van’s instructions to the letter and the next steps is to assemble the aft fuselage, attach the stabilizers and control surfaces, and finally complete all the fiberglass fairing installation.

It’s a little refreshing to start a new section because it’s almost like you have a new slate to work with in addition to a lot more experience from the previous steps. As with past sections, the sequence is separate, match or final-dril, and deburr.

Page 10-03 and 10-04

After preparing the J-stiffeners and longerons, the horizontal stabilizer attach bars are straightened using the “WHANG” technique which involves placing the bar in a vice, preloading opposite the bend, hitting with a rubber mallet and repeating until the bar is straight to within 1/16”. No pictures of this process, but I think it worked okay and I was able to get any bend to less than 1/16”. Mostly the process takes careful iteration without overdoing it. I found that after a certain point, more tweaking just introduced more distortion.

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There are some angles which are used to fabricate the horizontal stabilizer attach angle and the rudder stoops. Since I don’t trust my $140 bandsaw to cut precisely, I used it to cut close to the line, then used files and scotch-brite to finish.

Horizontal stabilizer attach bar (F-01411D)

Rudder stops

The next steps focus on the F-01412A&B bulkheads. First, several holes are match drilled to the vertical stabilizer, then the flanges and dimpled. I opted for the flush mounted access port which is an option that requires you to dimple the #27 holes to accept the flush AN507 screws.

F-01411 Bulkhead

The F-01411 bulkhead is riveted together with the F-01411C attach bars and match drilled. The bottom two holes are drilled out to 1/4” for the tail dragger. I used my bench press and slowly worked up to about 0.246” using drills then reamed the final size with a 1/4” reamer. The bars are final drilled to #30 and I clecoed and I also checked the fluting with the F-01479 aft bottom skin. I didn’t find there was a need for very much fluting to get the tabs to fit nicely with the skin. After dimpling, the parts were dissembled and deburred.

F-0140 Bulkhead

The first step for the F-1410 bulkhead is to enlarge the systems hole a the bottom of the buikhead with a step drill. I find, good clamping is necessary to keep the part stead and ensure a well-formed hole. After drilling the system hole, I dimpled holes on the flanges to #40 and checked the fit with the aft-skin (F-01479) and made only minor adjustments. Then, I used the drill press to ream the top holes to a final size of 1/4”.