Section 8 - Horizontal Stabilizer

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	Section Hours: 112.2	Section Status: Complete

June 3, 2006 (8-9 step 8): And so starts the teardown process :-( Since I know there's a lot of countersinking after tearing down the horiz stab I decided to do it as we go. So after pulling off the rear spar I began countersinking the flange holes. As you can see, I've got a loooong way to go! Not to mention I get to do the other side as well!!

Next came the upper & lower stringers. I did each set while they were still clecoed together (the two uppers & the two lowers) and just clamped them in the bench vise. After those were done, then came the front spar… almost done with the countersinking!!

(8-9 step 6): Angela came out for a while to help disassemble, and also started on deburring some of the holes.

(8-3 step 2): After finishing up the countersinking the next step was some deburring. I deburred all the spar holes, and once that was done I tried out the new torque wrench by finally attaching the inboard hinge bracket assembly to the rear spar.

I finished up the day by deburing the nose rib holes. Only deburring left is one of the skins. After that we'll see about prepping & priming all these parts!

June 4, 2006 (8-9 step 7): Today was 'cleanup & dimple' day ;-) I started off the day early by deburring the holes in the remaining skin. Then it was off to church. Once back I took down the cradles and cleaned up the tables. I then layed out all the ribs to check them for any missed spots... only one! In keeping with our 'scuff & prime' the alclad pieces, I sanded on one of the inspar ribs until I realized it would be much quicker to just alodine it so I left the others as-is. So it was on to dimpling. Not too long after I got started on it Angela returned home from her soccer game & decided she wanted in on the fun! She helped finish up the remaining ribs.

After the ribs we scuffed up one of the skins prior to dimpling the holes. Angela then tried out the dimpling set up and did as many holes as she could on her own while I sanded down the stringers in preparation for priming. We then finished up the remainder of the holes on the skin.

(8-9 step 9): The last thing I did for the day was scuff up the other skin. I made a remark to Angela earlier in the day that I was starting to look like the 'Tin Man' from the Wizard of Oz from the Aluminum dust so I decided to get a shot of it.

June 5, 2006 (8-9 step 9): Tonight I just wanted to get the ribs prepped for alodining. Some of the ribs don't appear to be alclad (dull aluminum and no blue vinyl covering) and the part lable stickers were stuck directly to the aluminum. Well, the sticker gum proved to be slightly more difficult to remove than I expected. I learned that denatured alcohol doesn't do a very good job of taking it off, but acetone does very well! I don't know about MEK though (don't have any) Anyway, I originally thought I'd be hanging the ribs into my alodine buckets, so I cut, labeled, and rounded the ends of enough romex wire to handle every rib. Once done I remembered I had some plastic tubs that I bought just for pieces like these (doh!) I'll eventually get a system down, and things will go quicker... maybe if I keep telling myself that it'll actually happen!! So, the ribs are ready to be dunked & alodined... next time.

June 8, 2006 (8-9 step 9): Yesterday morning Angela & I took advantage of the cooler weather before work and alodined all the nose and inspar ribs. The tubs I had were just ever so slightly too small to fit the inspar ribs so we weren't able to use them, so we used our 5gal buckets that we store the alodine in. We wound up using the labelled romex I put together also... a benefit... we didn't have to keep track of which rib was which so we could dunk all the nose ribs at once. So, we were able to get everything done in just under an hour.

Today it was finally time to prime everything. While cleaning the dust off the skins we realized we still needed to dimple one of them. After that I was off to prime. The skins, as usual, took more primer than expected so I had to 'reload' and finish in the dark. Here's a shot of the results... the quality is definitly getting better, but I've still got some improving to do. One thing I think I'll make a point of is only priming during daylight hours. I don't like priming inside the garage (tried it, but don't like it) and there's a very limited amount of light even just outside the garage when its dark out. It's very hard to tell if you've got complete covereage.

June 11, 2006 (8-9 step 9): One last thing I wanted to do prior to assembling the horizontal stabilizer was so something with the countersink holes. I'm not too worried about the rivet holes because the rivets will expand to fill that space, but the area between the skin and spar seems a little vulnerable to water seepage right up to where the rivet is. So, I wanted to corrosion proof these countersunk holes at least a little. It seemed like a good job for the alodine pen so I just dabbed it in each of the countersunk holes of both spars.

(8-10 step 2): Now the assembly starts… 1st thing was the center section of the horiontal stabilizer. I attached the stringer web to the center two inspar ribs. After that the stringers are riveted together and onto the stringer web.

(8-11 step 3): After I got the center section all riveted together, the next step was to attach it to the front spar assembly. Since the center two inspar ribs share rivets with the center two nose ribs, they only get clecoed for now. Next I slid in the next 4 ribs on either side of the center ones. These 8 ribs did get riveted in place since they don't share rivets with nose ribs. Here's a shot of the ribs and the center section attached to the front spar assembly. There are still 4 ribs (2 on either end) that will be attached later.

(8-12 step 1): After the spar & rib assembly came the nose ribs. These were placed in the skins and were riveted in before anything else was put in place. We did the center two on each skin first. Angela & I played around with a few different techniques before finally deciding on laying the skin in the cradles on its side, and she shot while I bucked. This seems to be working good for us. I considered using the smallest bucking bar I had, when Angela suggested the 'special' RV-10 bucking bar (the long thin one). This turned out to be the one we went with. With the skin laying on its side I held the bar parallel to the leading edge of the skin. This allowed me to hold it with two hands and maintain excellent control of both the pressure, and the angle of the face on the rivet (I used the flat side opposite the beveled side). Here's a shot of one of the completed nose ribs... not too bad!

Once we completed the 2 nose ribs in the center of each skin it was time to call it a night. Angela wanted to stick around and attach a couple of the outter nose ribs though. So, she hooked up the squeezer & attached the end ribs to one of the skins. (the inboard and outboard ribs)

Heres an external shot of one of the nose rib rivets. We've got 2 more nose ribs to do, and then we're on to the spar/web assembly...

June 13, 2006 (8-12 step 2): Nothing special tonight... I finished riveting the two remaining nose ribs into their skin and then set the skins back up in the cradles. The next step was to reposition the spar assembly back onto the nose ribs in the skins. However, before I did that I checked to see how the epoxy we used to glue in the snap bushings turned out. Seems its quite brittle which isn't too good for high vibration environments like an airplane. Guess I won't be using that stuff anymore. Most guys I've seen use something like RTV silicone or something similar since it stays somewhat flexible. I didn't have any so I decided to dab a small bit of silicone caulk on each of them. (In case you're wondering, the snap bushings are inserted into holes in the front spar. The elevator trim cables pass through these holes and the snap bushings provide chafing protection for the cables.) So, once I was satisfied with the bushings, in went the spar assembly. Angela wasn't home yet so maneuvering everything to get all the holes to line back up was a little tedious (ok... so I'm whining a bit!) Once that was done it was time to cleco it all back together. Once the clecoes were in, next step was to pop rivet the 2 nose ribs in the middle portion of each skin to the front spar. There is no access on the nose rib side of the spar so a blind rivet is the only way to go on these 4 ribs. The nose ribs on the edge of each skin are accesible on both sides so these take solid rivets. I did the outboard ribs tonight, but the inboard ribs will be riveted to the spar later. Access to them while the horizontal stabilizer is in the cradles is somewhat limited. Here you can see the solid rivets on one of the outboard nose ribs (foreground) and the pop rivets used on the adjacent rib (the row of rivets just this side of the inspar rib).

June 19, 2006 (8-13 step 1): Angela & I were out of town this weekend... spent time with her family. I was having a hard time today at work trying not to think about getting back on the plane. It was made worse by the fact we got in late today so I was at work pretty late. Once home it was time to get back at it! First off, sorry, no pictures... nothing really to look at. The first step of the night was to put in the remaining four inspar ribs. The most inboard on each side were pop riveted to the front spar due to no access to the front side of the spar. The other two were the outboard pair so these took solid rivets.

(8-13 step 2): The next step was to rivet the skin to the front spar flanges. We knew we wouldn't be finishing this tonight so we picked a select set of them to do before calling it a night. We basically chose to do the 1/8 rivets on one side (1/8 due to the holes we mis-drilled in the spar flange). We stuck with our tried and true system... Angela shooting, me bucking, and the results were good. We're definitely getting more proficient! Can't wait to do a little more in a day or two! We'll have to order some more AN426AD4-6 rivets though. There aren't very many supplied in either the wing kit, nor the emp/tailcone kit, and we pretty much blew our supply tonight! Currently we don't even have enough to do the other side of the horizontal stabilizer.

June 20, 2006 (8-13 step 2): Tonight, more of the same. We continued on with riveting the skins to the front spar flanges. There are a bunch of rivets, but we're taking our time and the quality is definitely improving! We basically finished all of them except the 1/8" rivets on one side. We don't have enough of those so we'll be ordering some tomorrow (planned to today, but I got too busy... bummer) Not to worry though, we can continue on with the next steps on one half of the assembly while we wait. Tonight's activity was very repetitious but allowed us to get a groove down and I think we found a good rythm with each other. Timing is improving and consistency is picking up. Angela is getting much more consistent on the gun which is allowing me to feel differences in what I'm doing with the bucking bar. It's now easier to tell when I did something a bit different. We're 'fine tuning' things now, which is a good feeling. We're even seeing some rivets that are looking as good as squeezed ones (yeah baby!) We've basically been using Dan Checkoway's air line presure chart (see bottom of page) to know how to set the gun up. However, we've been noticing some slight dimples in the skin around the finished rivets. Nothing wrong with them, but I just felt they could be better... trying to shoot for that totally flush look! I've seen a few builders who have achieved this and its very impressive! So, we tried lowering the pressure on the gun about 3 or 4 pounds and worked with that. Once we got the timing of the bursts, and the pressure applied to the bucking bar down, the finished rivets have noticably less of a dimple around them! Niiiice... that's what I'm looking for!! We'll stick with that in the future, and hopefully improve on it a bit more. Anyway, here's a couple of shots of Angela & I 'in the act'. I basically had to stand on a stool to be able to reach down inside the thing to buck. Angela would place the gun on the head of the rivet, indicate she's "ready", and that was my cue to place the bucking bar up against the rivet shank and say "ok". Thats the 'go' sign so she shoots away! Once done, I check it and decide if its ok, or we need to hit it again. The second shot shows the bucking bar we used and how. By the way, we now tape ALL of our bucking bars wherever there is the potential for contact with metal. Compare the pic here with some of the ones from the vertical stabilizer and you'll see why! I basically tape any of our tools now that may come in contact with pieces on the airframe!

June 22, 2006: We placed our order for more AD4-6 rivets yesterday, and in fact went ahead and got a bit more of all the ones we have in our inventory to try and avoid waiting in the future. One thing we've learned is extra rivets are a good idea because even if Van's gives you the exact number they call for in the plans of every single rivet, there are quite a few times where the rivet called for isn't the best fit for the application and you wind up using a different size. This causes you to be short on some and have too many on others... so extra rivets on hand is a good thing!

(8-3 step 14): Annnnnyyyway... while we wait for the rivets to finish something like 30 holes on the spar flange, we decided to work just on the side of the horizontal stabilizer that we do have all the flange rivets driven. So, the first step was to install the rivets attaching the skins to the inspar ribs up to the stringers. Then we installed the rivets attaching the skins to the stringers. While doing this, there are 5 rivets that are completely hidded on the shank side because of the stringer itself. On the outside, its just another rivet but trying to buck those guys... well, it isn't really that difficult, you just can't see them... I call it 'bucking by braille' ;-) After shooting each one you have to insert a mirror in order to see it and determine if it's set correctly or not. Welp... on one of them, right after Angela pulled the trigger I let the bucking bar slip off... you definitely know when it happens... it suddenly vibrates a LOT less! As it made its way off the shank it beat the rivet down a bit... here's the results... definitely going to have to drill that one out... [sigh]

So mark it, and come back to it later...

Once we finished all the rivets we planned to buck (the entire bottom left surface of the horizontal stabilizer) I wen't back and drilled the offending rivet out. Last time I drilled through the entire rivet. I've since learned you're only supposed to drill into it just enough to be able to pop the head off, and then you use a punch to drive the shank out the other side. Here's the results of my attempt. The boogered up shank is on the left, its shaft that used to be attached to the head is facing the popped off head on the right. I think I did a pretty nice job, don't you think!

(8-13 step 5): Neither Angela nor I were feeling like we were in 'the groove' tonight with our bucking, so for the rivets attaching the lower left skin to the end ribs we used the squeezer.

We basically did all the rivets on the skin in the foreground above the spar flange rivets tonight... the clecoes are starting to disappear!!!

June 24, 2006 (8-13 step 2): We didn't expect our new stash of rivets to show up until at least Monday so I figured we'd only work on half the horizontal stabilizer until then. Well… tempted by the fact that we could get this thing done this weekend if we had the rivets I just decided to cut some longer rivets down to the right length and get'er done! So that's what we did!

While riveting the 28 1/8" rivets in the spar flange I get a little over-anxious with the bucking bar on one of them at the same time Angela was trying a lighter pressure on the gun. With hundreds of rivets this sort of stuff is bound to happen every once in a while. I basically pushed the rivet slightly out of the hole while it was being set resulting in the head protruding above the skin a 32nd or so... not much but if you ran your hand over the skin quickly it would definitely draw blood!

So I got to drill it out. Turns out this is the last one we had to drill out on the horizontal stabilizer… so 2 total!

(8-13 step 5): With the skins completely riveted to the front spar flanges now we moved on to the inspar ribs and stringers. There were a bunch of rivets but Angela & I stuck with it. We bucked just all the ribs and stringers that we had to and left anything that could be reached with the squeezer for later (basically the end ribs). Here is a shot Angela snuck of me checking our work.

By the end of the day we got'er done! Look ma, no clecoes!!

June 25, 2006 (8-13 step 6): After getting the elevator ribs squared away it was on to the main goal for the day… finishing up the horizontal stabilizer! The first thing I wanted to do was clean it out before closing it up. While bucking yesterday some of the tape from the bucking bar left some gum in places, plus there were a few scratches in the primer. So, I cleaned all the crud up, and then touched up the primer. Then it was time to close it up by putting the rear spar in place. It got pop riveted to most of the ribs due to access issues. The remainder got solid rivets.

(8-13 step 7): Once the rear spar was securely fastened to the ribs the last step was to attach the skins to its flanges. All of these were accessible with the squeezer.

Angela arrived home frome her soccer game just in time to check out the finished product. The parts just keep getting bigger… yeah baby!!!