Right Float Sender, Riveted Leading Edge to Spar

July 23, 2011

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Guess what? I worked on the airplane today, so the observant of you should realize that I am NOT on my way to OSH. Boo.

No use worrying about the spilled milk, though. More time for me to work on the airplane.

I need to leak test the right tank, but first, I have to finish sealing it up completely. Last post, I got everything sealed except for the float sender. Here’s the plans shot showing the sender, but it’s showing it mounted to the access plate. Mine will be the same dimensions, but entering from the rear of the tank in the second bay.

A couple 90° bends, and I'll be cooking with gas.

That was easy.

To install in the sender, you line up the plastic piece with the slot in the metal housing, and slide the float wire in.

Can't get any easier than that.

Now, let’s clean up and get this thing sealed in there.

Five #8 screws after swishing in some MEK.

After cleaning up a whole bunch, I put the rubber gasket in place with some sealant (couldn’t decide if I needed some or not), then put the float in, then more sealant around the edges, and some sealant for the screws.

Looks good to me.

I retested the sender and noticed 240 Ohms to 80 Ohms (I think I saw something lower before). That’s okay, my EFIS (Electronic Flight Information System) will calibrate the range of fuel levels based on resistance later.

Okay, that was about a half hour, and there are plenty of hours left in the day, so let’s move on. I think the next thing on the docket is to get the leading edge on the spar permanently. I have the leading edge landing light installed, and the tiendown bracket is good to go.

A changing of the plans picture…to the wing rivets and skins page.

Always fun to change plans.

After a few long minutes of getting the spar holes countersunk, I rubbed the scotchbrite pad over the length of the flange, cleaned up with MEK, then taped off to get some primer on there.

Ready for primer.

Sorry the light kind of precludes the primer from showing.

Okay, before I just start riveting the leading edge to the spar, I want to make sure everything lines up again. So, I want to put the tank on the spar, and the opposite skin from where I’m working.

Before I can get the tank on, I need to grab some nutplate for the inboard tank z-brackets.

Looks like AD3-4 and K1000-3 nutplates.

Here they are.

Done. I couldn't countersink very well along the spar bars, so I went a little light and used oops rivets on the very top and bottom (right and left here) holes.

Then I grabbed the outboard lower skin, and got it clecoed on.

Here's just the leading edge clecoed.

Then, I grabbed the tank and put screws in every 5th hole.

And a screw in every hole along the tank/leading edge joint. Everything lines up great and looks awesome.

I told you it looks awesome.

With the leading edge 50% clecoed, I decided it was finally time to show the FAA I’m really building this airplane. Sorry this awesome picture of a pre-squeezed rivet blocked the shot.

My visor says "Foxy's" on it. Anyone? Oh, and that rivet size looks appropriate, let's get to squeezing.

After 65 rivet squeezings, I had the upper leading edge skin riveted to the spar.

The leading edge looks so cool with no clecos in it.

After 65 more rivet squeezings, I had the lower leading edge skin riveted to the spar.

Oh man, I'm so excited.

GOOD DAY IN THE SHOP, high fives all around.

So….0.5 hours toward the tank. 2.5 hours toward the wings.

6 rivets for the spar nutplates, and 65 rivets each on the top and bottom of the leading edge. That makes 136.


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Right Leading Edge Joint Plate Nutplates

July 13, 2011

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Wuhoo! Got my latest Van’s order. Below, you can see my two T-411 tank access plates, two tiedown rings, a tenth of a pound of AN470AD6-10 rivets, and the left inboard leading edge rib.

I love getting orders in.

First thing, I ran over and screwed in the tiedown ring.

Uh Oh.

It was way loose. Hmm. I know I did the 1/2 turn in, 1/4 turn out with the tap.

After some thought (and a trip to work), some of the guys were convinced that 1) I didn’t ruin the part, especially since I had only tapped the 1″ shown on the plans (and the rings are like 1 1/2″ long), and 2) it must be the tap quality.

They lent me a really nice tap (as opposed to the $7.99 tap and die set from Harbor Freight.)

I screwed in the nice new tap, and once I got past the first inch, I immediately felt a difference. When I turned 1/2″ in, the tap felt like it was cutting, instead of just pushing material out of the way. There was significant resistance at the end of the 1/2″ turn. Once you start the 1/4″ back out, there is some more resistance, then a “release.” I could tell immediately that the release was the cutting of little chips from the material.

It was like I heard angels. This is what tapping is supposed to feel like.

(The old one was just steady increase in resistance in, then decreasing resistance out.)

Just one more reason why I should have bought the $80 tap and die set, instead of the $8 tap and die set.

Lesson learned.

From the following picture, you should be able to tell that the thread cutters on the left are nice and sharp, and the apex of each blade comes to a point. The one on the right is not sharp, and the apex is kind of rounded.

The nice tap on the left, the crappy one on the right.

So now, I have about 1″ of loose threads, and 1/2″ of perfect threads. I am okay with at least four threads perfectly engaged, and 16 threads mostly engaged. If I’m worried about 10,000 lbs of holding power versus 5,000 lbs of holding power, I have more to worry about than my tiedowns pulling out.

Let’s build on.

Here's the tiedown installed.

It was subsequently removed, and will be stored in my storage box until, I don’t know, a few years from now.

Next up, I needed a nice little project.

How does the leading edge joint plate nutplates sound. Good?

Good. I’ll work on those.  A quick check on the plans showed some hardware needs.

Some #8 screws and nutplates.

First, let’s cleco some nutplates to the previously dimpled holes. This worked great, and perfectly centered the dimpled nutplates over the dimples.

#30 clecoes worked great.

I drilled one ear of each nutplate, then clecoed.

After drilling both ears, I deburred, then started countersinking for NAS flush rivets.


Here’s one of the oops rivets, just holding it in place.

This will work.

Oh man, I'm making a mess.

Then, some riveting.

All done.

1 hour,  including the tiedown re-tapping, and 28 rivets in the leading edge joint plate.

Not much more in the way of sealing up that right tank.

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Right Tank Plumbing

June 30, 2011

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Okay, so a little of my work this evening was actually done AT WORK today. (Don’t tell my boss.)

Since I don’t have a Parker Rolo-Flair (shouldn’t it be “flare”?), but we have a few at work, I asked one of my RV buddies from work to show me how he does it. So, I brought my prebent -4 tube into him, and he, well, showed me how to do it.

(I was going to buy a rolo-flair tool, but at $80, I don’t want to buy one until I really need one. I need this flare (see?) now, the one for the left tank in a month or so (more like 3 or 4), and then I won’t need one until working on the fuse and running fuel, brake, and vent lines. I don’t want an $80 tool gathering dust until then.)

Anyway, he showed me how to do it, with a little cutting oil on the flaring (see!?) cone.

Back home, this is what I ended up with.

(He also showed me how to roll the straight portion of the vent line, which I was having a heck of a time getting perfectly straight, on a countertop or flat piece of door. You roll it like a roller between your fingers and the countertop. I was inside doing it on the granite countertop while the girlfriend was making dinner. She said “Get your fuel line off my counter!”)

No, she didn’t. But it would have been funny if she did, right?


Next, I fed the vent line through all the snap bushings and slid the inboard rib with the -4 bulkhead fitting in place.

Looks good here.

How perfect were my measurements! Now I just have to bent the end up a little to get to the highest portion of the tank.

I copied Mike Bullock here, and used a wrench and another lever to bend it slowly upward.

Nice trick, Mike.

After repositioning the inboard rib, this sucker is at the very highest point.

Oh, I also did a little safety wiring. Then, thinking that I could unscrew the nut, and re-clock it to have a shorter, more sturdy safety wire run, I figured out that the nut only has one “entrance” for the threads, so the clocking is as shown only.

First try, which was perfectly acceptable.

Second try, after reciting the famous quote ‘perfect is the enemy of good enough.’

Alright, Andrew, stop messing with it.

0.5 hours. Time to start thinking about closing this bad boy up.

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Two More Right Tank Ribs Sealed

June 18, 2011

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Today was a busy day! Even though I’m logging all the time today as on the fuel tanks, I did spend just a couple minutes on the leading edge.

First thing, I deburred and dimpled the inboard leading edge rib, then fit it back in place on the leading edge, this time WITH the joint plate.

Looking good.

Oh, while I was in autozone today, I grabbed a tubing bender and mini tubing cutter.

These should work.

After much reading, deliberating, gnashing of teeth, and hand wringing, I decided to bite the bullet and add a fuel return line.

Not very many fuel injection systems require it, and if I got with the ECI injection (which is supposedly very nice), they say you can just add a bulkhead fitting to the inboard bay, but I think I’m going to run a -6 line to the second bay.

As of a week ago, I had decided I was not going to add any injection system that required return lines, so we’ll see how I feel in another week.

Anyway, I was milling about the parts under my workbench when I came accross the standard rigid pickup tube that Van’s provides. Since I’m using flop tubes, this is scrap, so I held it up against the tank, and figured out it would just make it over to the second bay. Wuhoo!

I guess with the normal pickup, they crimp the end and you make saw cuts in the side of the tube as the actual pickup.

First, let’s get this thing cut in half.

Not bad. Needs deburring, though.

Then, let’s uncrimp the other side so the thing will fit into the cutter (I want a fresh cut on both ends).


Of course, I made a fresh cut on this end too, then deburred both sides, and promptly put the tubes away before taking any more pictures. Sorry.

On to some tank ribs.

After the usual cleaning and preparations, I buttered up rib #5 and clecoed it in place. Here are some undriven rivets with tape on the heads, ready to be set.

Ready for riveting.

I went light on the pictures today, sorry. Here’s rib #5 and #6.

I still don't like the proseal on the outside of the skins, but I'm trying not to have any leaks. I hope the razor blade trick works.

Then, I repeated the whole process for rib #3.

...and my trusty rivet gun.

A picture of the top side.

Nice, except for the very last rivet I shot, which is on the lower right corner. Ding city.

Starting from the (invisible) rib all the way to the left, I did ribs 2 and 5 today.

Still need some rivet encapsulation, but overall, a really good day. 34 rivets times 2, none drilled out.

Oh, and 3 hours. (It really only took me one hour per rib, but I was messing around with the leading edge and the fuel tube stuff.

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Riveted Right Tank Stiffeners

June 8, 2011

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Well, tonight was the big night. I finally got started sealing up the right tank.

The general order is as follows:

  1. Backrivet stiffeners
  2. Rivet drain flange and fuel cap flange (don’t forget the vent clip!)
  3. Cleco all ribs into tank (to maintain assembly straightness)
  4. Starting with second-to outboardmost rib (the smallest area to work for bucking), seal and rivet each inboard rib. Assuming 7 ribs, from inboard to outboard, my order will be 6,3,5,2,4,7,1. That way, there’s always ribs on either side of the one I’m working on. This may be a waste of time, but it will make me feel better.
  5. Oh, before the inboardmost rib, I need to make sure I get the vent line in there, with the AN fitting, before bending and flaring the tubing to fit over the AN male fitting in the inboard rib.
  6. Install anti-hangup brackets, trap door, float sender (have to move this to 2nd bay) and flop tubes.
  7. Close tank.
  8. Have beer in celebration.

Oops, looks like number 8 will occur after each step (but only at the end of each night.)

Okay, let’s get to the pictures. I got out my new kitchen scale, the small and large popsicle sticks, rubber gloves (snap!), MEK, electrical tape, and paper towels out. Let’s see, what am I forgetting?

Oh YEAH, the Proseal. I guess it’s really called FlameMaster tank sealant, but I’m going to continue to call it proseal.

Also, I have 900 or so solo cups from my earlier partying days, and I thought those would be great for mixing proseal. (Caveat: when the directions tell you to swirl some rivets in MEK to remove the manufacturing oils, don’t use solo cups, the MEK burns through the white coating and the whole mixture becomes milky. Ask me how I know…at least I did a test before throwing in some rivets.)

First thing, I laid the stiffeners in place without rivets just to see where I needed to protect the rib lines with electrical tape.

Okay, let's start getting messy.

Anyway, I got some rivets soaked in MEK and then dumped them out on the paper towel.


I did a THOROUGH cleaning of both the skin and the stiffeners, then said a little prayer and got to proseal mixing.

I started with 2 oz. of white stuff and then added 0.2 oz of black stuff. (The picture reads 2.3 because I kept the popsicle stick.)

Oh, and I barely caught myself before using the white-stuff-soaked stick to scoop out some black stuff. That was close.

Anyway, I did my first batch in a solo cup, and I’ve decided to immediately switch to something wider and lower-lipped. In mixing the proseal, you basically push all the proseal up on the walls of the cup, and now you really only have an ounce or so to work with, because you’ve done a great job of sealing your cup. I feel like I wasted a whole bunch of proseal tonight having left most of it on the walls of the cup. Grrr.)

My first batch was the messiest because while stirring, all my gloved knuckles kept hitting the walls of the cup and gathering proseal.

Moving on, I grabbed a….CRAP…I don’t have anything to dab proseal into the dimples of the skin! Umm….Umm…

This cable tie will work! (It actually worked great, very similar to a toothpick that others use.)

Just to test out the process, I dabbed 4 holes of one of the outboard stiffeners, put some rivets in, spread sealant on the stiffener, laid it in place, and backriveted the heck out of it!

Looks okay, but why didn't you clean up the skin (you'll find out later).

Oh man, this stuff is MESSY. After reading a ton of build sites (Bullock’s, Oliver’s, Beaver’s), I was convinced I would make mine really neat compared to their’s.

By the end of the night, I felt like I was “arbitrarily slopped all over the place as a sort of voodoo talisman employed to ward off leak demons.” (Quote from Rick Galati.)

Anyway, I flipped the skin back over, put a dab of sealant in the rest of the dimples, taped over them all, flipped the skin back over, laid the stiffeners in place and got to backriveting.

Taped, ready to backrivet.

You can see how messy the outside of the skin is going to be.

It went well. The worst part is that by wet setting the rivets (sealant in dimple before inserting rivet), there is proseal all over the rivet on the other side. That means the proseal gets all over your rivet set, and therefore my hands as I steady the set during shooting (watch for my fingerprints later).

After getting all the rivets set, I grabbed more sealant and created fillets around each of the stiffeners.

Yikes, this is not very pretty.

Finally, I filled a little 20cc syringe I got from Target with sealant and encapsulated each rivet. This part worked REALLY well.

Tomorrow, the encapsulations look even better.

See my fingerprints?

As a final note, I followed Bill Repucci’s advice and resisted ALL TEMPTATION to wipe off the skin of the tank with MEK after backriveting. Apparently, some MEK might soak under the rivet head and work its way into a leak path. (No Leaks!). I’ll try the razor blade trick later, but just so you know, that’s why these skins don’t look as pretty as Bullock’s and Oliver’s.

Bill suggests using a razor blade to clean after a week or so.

In the end, it was about 2 hours and 78 rivets. not bad for a day’s work. It was wicked hot in the garage, and I was in desparate need of some refreshment once inside.

That'll do the trick.

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Matchdrilled Right Tank Ribs and Baffle

May 26, 2011

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Not many pictures tonight, but I did get the tank matchdrilled.

But first, I got some things ordered from Van’s today in preparation for the tank sealing process:

  • 60 x BUSHING SB375-4 Snap Bushings, 3/8 (1/4)
  • 1 x DUCT NT 5/8-25 Nylon Conduit
  • 30 x BUSHING SB437-4 Snap Bushings 7/16 (1/4)
  • 2 x IF-4/6 RV-4/6/6A/7/7A/8/8A Wing tank flop tube
  • 1 x MC-236-B2 Tank sealant with accelerator QUART KIT
  • 1 x FUEL TANK TEST KIT Fuel Tank Test Kit

Of course, once I placed the order, I remembered that I buggered up the inboardmost rib of the right leading edge and needed a new one. I need to remember to order that one, and BEG Van’s to send it in the same shipment.

I decided to go with 2 flop tubes. (Flop tubes allow the fuel pickups to flop around in the tank, and therefore sustained inverted flight.)

One school of thought is that if you have two flop tubes and they get stiff, you could increase your unusable fuel (they don’t flop good no more) in either the upright or inverted attitudes. People therefore put one flop tube in and one rigid pickup. This means you have to switch tanks to your “aerobatic” tank before doing negative-g aerobatics. (How often will I do sustained inverted flight? Probably not very much.)

Anyway, I weighed the pros and cons, and came to the conclusion that the aesthetics of not having a single tank for aerobatics, and therefore a checklist item or a special placard, outweighed the possibility that after 10 years, my tube wouldn’t flop as floppily as it did when it was young.

Every couple years, I’ll open up the tanks and verify adequate flopitude. They are only $38, so it’s probably worth replacing them every 5 years anyway.

So, now that I’ve settled on duel flopicity, let’s get back to building.

I decided while matchdirlling, it would be easiest for me to do it while it was on the spar, so up on the spar the tank went.

(Be careful though, Van’s notes to matchdrill off the spar to avoid damaging the spar. This is really only a concern with the baffle holes (about the 10 most inboard ones). Take the tank back off the spar do matchdrill those.)

No action shots today, but much cleco-moving.

Back off the spar for baffle drilling.

Next up is fuel tank stiffeners, then a lot of prep before assembly of the fuel tanks.

1 hour.

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Prepped and Clecoed Right Tank Ribs to Tank Skin

May 25, 2011

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Well, tonight was fairly interesting. I pulled the right tank skin off of the spar (where I had been storing it using a few screws) and set it in the cradle.

Then, I fished out the right tank ribs from under my workbench and started fluting and edge-straightening them. (Luckily, I had remembered to edge-finish them on the scotchbrite wheel with the others a long time ago.)

Anyway, after fluting ribs 1 and 2 (the two inboardmost ribs)…

Not too exciting. 5 more to go.

While I was working, I kept thinking, “I should stop to take a picture…no…they’ll be okay with only a final picture.”

All 7 ribs ready to be matchdrilled.

Another shot.

50% clecoed.

Tomorrow, I’ll try to get this thing matchdrilled.

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