Right Tank Miscellaneous Work

I managed to get down to the shop to do a little bit of work.  This was a short session, but I knocked out some needed things to get done.  I did manage to capture it on a timelapse, so heres that short video:

Now that the sealant was cured on the outboard capacitive sender plate, I wanted to get it mounted on its rib, and route the wiring around the vent tube.  So, I gathered up the three screws, washers, the delrin spacers and the piece of 15/32″ tubing I cut in the last build session, and mounted the outboard capacitive sender plate in its place.

     

Then I worked on spinning the wire around the vent tube per the instructions to keep it from dangling.  I got a few nice spirals on each of the bays, and then moved on to the rest of the work.  I wanted to test fit the access plate, and finish riveting it up.  So. I mounted the inboard rib and clecoed it in place, and finger tightened the vent tube connection.   Then I grabbed the access plate and installed the fuel pickup tube finger tight, and the float fuel level sender to make sure everything was in the proper orientation.

Notice that the fuel pickup is NOT resting over the tank drain hole.  This is per the recommendations so that the pickup tube doesn’t block the operation of the plunger on the tank sump when it gets installed.   You’ll notice in the photo above, there are not nutplates on the T-708 access cover plate for the float sender to be mounted with.  I wanted to DOUBLE check my oritentation before riveting it.  So, I marked the access plate and pulled out the K1000-8 nutplates and some AN426AD3-4 rivets.  I used my microstop countersink to do the countersink for these rivets, on the OUTSIDE of the cover.  This will assure that the fuel sender has a nice flat surface to mount against, when the sealant is applied.

 

Once I had the rivet holes countersunk, I clecoed on the K1000-8 nutplates, and used my squeezer to set them nicely, making sure that outside surface was completely flush.

 

And that wrapped up this build session.  I went ahead and ordered another quart of fuel tank sealant. I am going to need it for the other tank.  It should ship out by the end of this week.  I am also still waiting on my other Van’s order to arrive, which has the fittings for the fuel return line.  Hopefully it will be here this week and I can get that inboard rib sealed and riveted on!  I also placed an order with McMaster Carr for some hex head screws instead of the phillips head AN515-8r8 screws that Vans supplies.  These are used to attach the T-708 access cover plate as well as the float style fuel sender.  The hex heads make them MUCH easier to remove in the future, and they are completely stainless.  These came recommended by other builders, and they were cheap.  I got two boxes of 25 for around $8 shipped!  Here is the link to McMaster Carr if anyone is interested in buying the same:  https://www.mcmaster.com/92185A194/

Google Photos Link:  https://photos.app.goo.gl/hDGAhnwJ57dsdMMq7

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Hours Worked: 1.25

Sealing the Outboard Rib and Installing the Capacitive Sender – Right Tank

Its time to get the outboard rib sealed in place and start working on the capacitive sender for the right tank.  This was a pretty long work session, but it went pretty easy.  I started out by pulling out the plans and instruction for the capacitive sender.  I picked up where I left off, and this time I needed to trim a 48″ piece of 18 gauge wire and crimp a ring terminal on it.  All the parts were supplied in the capacitive sender kit, so this went pretty easy.  I captured another time lapse of this work session, but it actually stopped and missed the last 30 minutes or so.  I was just dolloping on the sealant on the shop heads so it didn’t miss much.  Heres that video:

So, I started out by cutting the wire and crimping the end.  I did this for both the left and right tank to save time.

Next up, I gathered up my hardware, and screwed on the terminal connector to the right tank outboard sender plate, orienting like the plans tells us.

After that I put the plate in the tank and ran the wire through the plastic bushing, making sure the wire went into the notch I had cut in the bushings several work sessions prior.  Then I inserted the vent tube into the bushings so I can make my last trim so it would fit in the tanks.  I also made sure everything was lining up and looking right. I twist the wire around the vent tube once I get the plates mounted and ready for final crimping.  I still need to install the inboard plate and crimp the wire from the BNC connector into this 48″ wire and and a terminal ring together.

With the outboard sender plate ready to go, I needed to mix up some sealant to blob onto the terminal connector and its screw and nut to act as locktite and strain relief.  Since I am mixing sealant, why not go ahead and install the outboard rib as well, since this is a good time to do it as well.  But first, I needed to scuff the outboard  T-703-L rib, and the T-410 reinforcement plate and get them clean, which I did, and cleaned them well with MEK.

I made sure to do the flanges on the rib as well.  Next I needed to find a rivet to use on the T-410 plate and T-703-L rib, so I used my rivet sizer and found that an AN470AD4-5 was a perfect fit.  I grabbed 4 of them and cleaned them in MEK. I mixed up 70 grams of sealant and smeared a decent amount on the nose of the rib where the T-410 plate would attach.

Then I clecoed on the T-410 and used a squeezer to set the rivets nicely.  I used a popsicle stick to make a nice filet around the edges of the T-410. The photo below shows the rivets before and after I dabbed on a dollop of sealant and did the filet.

 

Next it was time to dollop on some sealant on the sender plate’s terminal and screw to act as a loctite for it. I probably over-did this a little bit.  But it ain’t going anywhere!

With that done, Its time to butter up the rib flanges, and get it clecoed into place for riveting.  I used a popsicle stick to spread a layer of sealant on the flanges of the rib, making sure I had enough to cover the flutes in the flanges.  I also but a good bit on the nose of the rib, since this seems to be where most people end up with leaks.  My gloves got pretty messy on this part so I didn’t get any photos.  Once I had it buttered up, I gently dropped it into place on the outboard of the tank, and clecoed every other hole.  I am going to wet set these since I can use a squeezer and they are really easy to get to.  In the other holes, I stuck a rivet in place and then used the squeezer to set them.  There was a decent amount of ooze-out on both sides, which leaves me confident these wont leak :-). Heres what it looks like after the first round of squeezing.  I only had to wipe my squeezer set off about every 8 rivets.  Worked out nicely!

Then I removed the last of the clecos and riveted those last few holes up. After it was riveted, I used a filet spoon to make a very nice filet from the squeeze out sealant, only having to add a touch more here and there on the inside.  I did however, glob on a pretty good amount around the nose of the rib, just to be cautious and give it a bit more change of not leaking.  Once I had the filet on the inside, I moved to the outside and did the same with the filet spoon.  Again, only having to add a tiny amount of sealant here and there.

All that was left was to dollop on some sealant on the rivet’s shop heads, and then cover up the bolt and nut I am using to close off the tooling hole.  I had to mix up another 30 grams of sealant to have enough for the rivet shop heads, but then I used a popsicle stick to dollop it on all the rivet heads, and smearing another big amount for a thick filet around the nose.  I also dobbed on some sealant to the shop heads of those AN470 rivets that were holding the T-410 plate on as well.

Lastly, I smothered the little bolt thats closing up the tooling hole with a generous amount of sealant.  I went ahead and did the left tanks tooling hole bolt as well, because I had some extra left over.  Why waste it right?

      

And that wrapped up the session for tonight! This tank is darn near ready for its baffle!  I am still waiting on the parts from Van’s for my return lines, so I can’t seal up the inboard rib just yet.  But, I can go ahead and start on the left tank getting it up to this point while I wait on those parts I guess.  I will also need to order some more sealant, this quart is almost empty and I know it wont be enough to finish. I’ll go ahead and get another quart on its way so it will be here by the time this one runs dry.

Google Photos Link:  https://photos.app.goo.gl/csVbPFtH2QgoTtZ1A

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Hours Worked: 3.5

Sealing the Right Tank Ribs – Part 2

With a much fresher mind and body, it’s time to finish up where I left off.  In the last session, I managed to rivet 4 out of 5 ribs, and dollop the shop head on two of them.  I also left two bad rivets I needed to fix.  After letting the sealant cure, it was much easier to drill them out and clean the holes for a new rivet.  I’m glad I didn’t dollop on the sealant on those shop heads now!  So, after getting those two rivets drilled out, I gathered up my tools, and then mixed up 50 grams of proseal to use on the dimples of that last rib, and leave enough to get a good dollop on all the shop heads on all the ribs.  I did get my Wyze camera setup in the shop to capture a Time-Lapse, which is below:

Notice I am wearing that respirator for almost the entire duration of this session! I got a little bit woozy last time by not wearing it, and wearing crummy gloves.  I have that corrected this time 🙂 I only had one rib left to rivet, so I cleaned out the dimples, and swabbed in some sealant using a q-tip in the dimples.  Then stuck in an AD426AD3-3.5 rivet and flush riveted it by bucking.  Just like last time pretty much.  I also did the same to the last few rivets that needed fixing, and then double checked all the rest to make sure I didn’t miss anymore.

Once I had the rib done, I moved on to dolloping some sealant onto the shop heads of all the rivets.  This was pretty easy work, albeit a little time consuming but eventually I had all the rivets nice and encapusalted.  It’s a pretty big mess in the tanks, but I’d much rather have too much messy sealant in a tight tank, than not enough in a leaky tank.

After all the sealant work was done, I grabbed a towel soaked in MEK and did a cleanup inside the tank, getting all the loose bits of goop and smears trying to clean it up the best I could.  I left the two end ribs off for now, as I’m waiting on the return line fittings to get delivered from Van’s.  I still have some work to do on this tank while I wait though.  I’ll get the outboard rib sealed and riveted, and then work on mounting the capacitive sender plates and the fuel pickup next.  Those will be nice and easy (and fun) jobs to do.  I’m REALLY hoping this thing doesn’t leak!

 

Google Photos Link:  https://photos.app.goo.gl/95H99UXVMUNBgfWy5

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Hours Worked: 2.5

Sealing the Right Tank Ribs Part 1

I’ve let the ribs cure from their sealant in the last session, and now its time to rivet them.  I didn’t get many photos from this session, as I was pretty focused on knocking these out.  I had planned to do all 5 of the interior ribs, but I only managed to get 4 done, and didn’t get the shop heads dolloped in sealant either, this was more work than I thought.  I should have quit earlier, because I wound up with some shoddy work at the end, that I’ll have to fix the next session.

First I removed every other cleco in the ribs, so I could rivet those holes first, then I mixed up 70 grams of sealant to be used to wet set the rivets and also dollop on the shop head after I was done.  My plan was to use up all 70 grams and then call it a night when it ran out, but it went a LOT further than I had thought!  Once I had it mixed up, I used a q-tip to smear a tiny amount into the dimples on a rib, and then stuck a rivet in the hole.  The rivets were soaking on MEK to be nice and clean, so I had them on a towel drying off, later putting them into a small metal tin for easier handling.  After that it was pretty standard flush riveting.  I used the jig to help hold the tank in a good position for riveting, and I’d clamp it to whichever side of the table gave me the best access to the interior to buck with.

Once I got the first set of rivets set, I’d remove the other clecos, and repeat the process of dabbing on some sealant into the dimples, putting in a rivet, and the bucking it nice and flush.  After getting two ribs done, I figured I’d start dolloping on the sealant onto the shop heads while it was still workable and not hardening.  After I got the first two ribs riveted and the shop heads dolloped, I was running a bit low on sealant, so I decided to use what I had left to smear into the dimples, and rivet the rest and then come back later to dollop on the sealant since there was no rush at this point.

I managed to get a total of 4 out of 5 ribs riveted, before I totally ran out of steam.  I was also feeling a bit woozy from the fumes, so I stopped after noticing two rivets were not set very good.  I marked them for repair later and called it a night.  I didn’t get the dollops on 2 of the ribs, so I’ll get them in the next session.

Google Photos Link: https://photos.app.goo.gl/61oUwzaN3RjRNjdJ6

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Hours Worked: 2.75

Sealing the Right Tank Ribs

Excellent day today! I took Acacia (my now 4 year old) up for her first flight today!  We took her up in our 1973 Cessna Cardinal RG and flew over Nana’s house, then over Lake Ocoee before heading back to KFGU.  She did great and looks like she’s going to love flying!  Tammy was in the back with her, and shot a video of her from taxi, takeoff and climbout for about the first 15 minutes of the flight.  Here’s that video:

Now, on to the build!  I decided to tackle the biggest sealing job so far: Sealing the interior ribs. I have decided to try the fay sealing method, on this tank and see how it does before doing the other tank.  Essentially, you butter up the flanges of the ribs with sealant, then cleco them in place with every hole getting a cleco, doing all of the interior ribs first.  Leaving the end ribs out for now makes it a bit easier to rivet.  Then Once the ribs are 100% clecoed, you can take your time and make really nice filets on the inside of the tank, around the flanges of the ribs.  Then you let the ribs sit at least overnight, longer if needed, before wet riveting them.  Supposedly, this is way less messy and promotes a better seal.  You can read about the method on the VAF thread here:  http://vansairforce.com/community/showthread.php?t=7602

So, I started the night by cleaning the tank skin and ribs with MEK.  They were already cleaned and scuffed in a prior build session, but I wanted to get them CLEAN before sealing. I opened my back door to let in some fresh air as MEK is pretty stinky, along with the Proseal!

Once I had my ribs and skin thoroughly cleaned, I mixed up my first batch of sealant.  I initially mixed up 70 grams, but that only got 3 ribs done.  So I wound up mixing two more batches, ultimately I ended up using about 250 grams of sealant to get a good buttering on the rib flanges, and leave enough to touch up on my filets.  I’ll go ahead and mix up 250 grams when I do the next tank, so figure about 50 grams of sealant per rib (there’s 5 internal ribs).   Pro-Tip:  Keep a glass jar of MEK ready to go for cleanup.  I kept a paper towel(s) and would routinely dip it in the MEK to wipe of any errant sealant from my gloves and tools.  That REALLY helped keep any mess down.

But, the biggest thing that made this go sooooo easily was a Semco Sealant gun. I had bought mine from Brown Tool a while back, along with the cartridges, nozzles and accessories for pretty cheap, and decided I’d use it this time.  Here’s what it looks like:

After I mixed up my sealant, I scooped it into the plastic tube for the Semco and screwed on a nozzle with a large opening.  Then assembled the Semco and started with my ribs.  This thing is freaking amazing!  It lays out a very nice bead of sealant with a gently squeeze of the valve.  What I found worked for me was this:  Grab a rib, and start by laying a nice thick bead of sealant along the BOTTOM flange first, using the semco.  I did go around the nose of the rib, and up an inch or so on the top flange with the bead.  Then, I used a popsicle stick to smooth that new bead across the entire flange, so I could get nice even coverage when I attached the rib.  After I had the sealant buttered on the flange, I clecoe’d it to the tank skin, bottom flange first.  Then moved on to the next rib and did the same process.  I ad my tank skin laying on its top surface, making it really easy to work on, and since I only had sealant on the BOTTOM flange, there was almost no mess.  See the photo below, those ribs only have sealant on the bottom flange where its clecoed.  You can sort of make out where the sealant has oozed out from the flange, leaving me a good amount to make a filet with.

Once I had all 5 of the interior ribs sealed and cleco’d to the bottom of the skin, I flipped the skin so it’d lay on its bottom surface, and I used the semco to lay another nice bead of sealant on the TOP flanges of the ribs.  Having the ribs clecoed in, made them super easy to work with and laying the bead with the semco was easy peasy.  Like before, I smeared the bead across the entire flange evenly using a popsicle stick, making sure there was enough to cover the fluted areas.  Then, I used my tank jig and slowly and gently inserted the tank into the jig, which helped wrap the skin around the ribs smooshing the sealant down nicely, without smearing it around.  I was honestly surprised at how well this worked!  Once I had the tank fully inserted into the tank jig, I grabbed my clecoes and started 100% clecoing every hole in the top of the skin, working from the leading edge back.

 

 

Once I had all the clecoes in every hole, I flipped my tank jig on its side, leaving the back of the tanks easier to access, and then used a filet spoon (also picked up from Brown Tool), to form my filets on the bottom of the skin, and then the top of the skin, making sure I took special attention on the ribs nose. Here are some photos of my filets:

 

Since there was no rush to rivet things before it dried, I was able to spend a good deal of time making sure I had nice filets around the flanges.  Where ever it needed, I would use the semco to squirt a little bead of sealant so I’d have enough for the filet, and then work with with the filet spoon into a nice smooth filet.  There was surprisingly very little mess so far, and very little waste of sealant.  I will say though, I am going to need to order another batch of this stuff.  I don’t think there will be enough left over to complete my other tank.  I’ll get an order in to Van’s when its close to empty as this stuff does have a shelf life.

Once I had my filets done, all that was left was the tiny bit of cleanup.  The plastic tube and nozzle on the semco are disposable, and make cleanup a breeze.  I highly recommend picking one of these things up to do your tanks!  I’ll leave these to cure at least overnight, or maybe 2 days, then I’ll wet rivet the ribs.  Wet riveting is where you dab some sealant into the dimple, and then rivet.  Then, you go back and dollop some sealant onto the shop head of the rivet to complete the encapsulation seal.  Take a look at the photo gallery below for more pictures of how the filets turned out. I think they’ll hold up just fine.  I am planning on doing a water test on these tanks before attaching the rear baffles.  Thats where you get everything sealed, except for the very rear baffle, then you leave the tanks in the jig (leading edge facing the ground of course), and fill them all way up to the baffle with water and leave them sitting for a few days to look for drips. That way I can easily touch up any areas with sealant before attaching the baffles.  Also, I am going to setup some cheap Wyze camera in the shop so I can record footage of me working and include in these blog posts.  Stay tuned 🙂

Google Photos Link: https://photos.app.goo.gl/qhYTeQ41dfknd2yX6

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Hours Worked: 2.25

Right Tank Return line and Preparing for Sealing

I’ve decided to go ahead and plumb in a return line for my fuel tanks, just in case I go with a fuel system that needs it my tanks will be ready for it.  This will save a lot of hassle if I do have to use a return system.  If not, i’ll just keep them capped off, and it will only add a few ounces of weight to the airplane. It’s also time to start getting the tanks and ribs prepped for sealing and riveting.  So, I started off by locating where I wanted to run the return line.  I’m going to run my return line almost to the very outboard fuel bay in the tank, actually one in from the outboard most fuel bay.  This way, the warm fuel can return into the tank and have time to cool off with the rest of the fuel, and to help reduce any foaming that may occur.  By not going all the way to the outermost fuel bay, it keeps the return from mixing with the fuel vent line, and keep the return safe from any fueling nozzles etc.  I will probably bend the return line upward aiming it towards the top leading edge of the skin so it can splash up against the skin further cooling it.

I found a good spot on the ribs that kept the line clear of the capacitive sender plates, and the vent line as well as left me plenty of clearance distance from the flanges and other holes.  I drilled a pilot hole in my first rib with a #30 bit where I wanted that return to go.  I’ll widen the hole with a step bit.  But first, I need to transfer this hole to the same spot on all my other ribs! To do this, I grabbed some scrap wood and clamped my rib onto the wood, and marked all the holes from my rib onto the piece of wood with a sharpie to use as indexes for the other ribs.  Then I backdrilled my new #30 hole for the return line all the way through the wood.  This will give me a drilling jig to transfer the hole to the exact location on all my other ribs.

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I’ll just need to clamp each rib onto the wood, lining it up with the sharpie marks, and use the #30 through hole I drilled in the wood as a drilling jig to drill the hole into the rib.  A simple and easy way to transfer a hole!  Now, my piece of wood is in the rough shape of the rib simply because it was the scrap I had left from making my leading edge jig, any piece of scrap would have worked.

Once I had the #30 holes drilled into all the ribs (I left out the inboard end rib for now, I’ll get it later when I decide where the plumbing will go) I chucked up my step bit, and opened the holes to 3/8″, just big enough for the plastic bushings to fit.  I am using -4 aluminum tube for my return line, its the same size as the vent line, so I’ll just the same size bushings for these return line holes.  I think they were SB-437-4 size.  Once I had the holes opened up to the right size, I deburred them and moved on.

This next part was where I spent the bulk of my time for the session:  Scuffing and cleaning the right tank parts!  I put the tank skin on the bench and then scuffed all the rivet lines throughly with some scotchbrite to give the sealant more surface area to cling to.  Once I had both the top and bottom side of the skin, as well as the rivet line on the skin for the tank baffle, I moved on to scuffing both sides of the flanges for all the ribs.  I turned on some music and got comfy in my shop chair while I was scuffing these things.  After I had them scuffed, I cleaned them very well with some acetone followed by MEK.  I did the same with the tank skin, but instead of focusing on JUST the rivet line, I went ahead and COMPLETELY cleaned the entire surface of the skin, since it will be closed up pretty soon.  I wanted to make sure I had ALL of the little bits of sealant and ink markings gone from the skin to prevent fuel contamination.  I’ll do one more wipe down before closing it up with the baffle of course.  Heres how clean everything came:

 

The MEK is pretty strong organic vapors, so I made sure to wear some PPE when working with it.  Gloves and a respirator.  Here’s a photo of my PPE and Me for proof I’m doing the work 🙂

Once I had the ribs and skin scuffed and cleaned, Van’s has us re-assemble the tank and ribs fully clecoing everything together to make sure its all in the right shape before we seal the ribs.  They want us to remove one rib at a time, seal it and rivet it before moving on to the next rib.  Makes sense, as it assures that the tank keeps the proper shape during riveting.  So, I re-assembled the right tank, putting a cleco in every hole to hold it tight. I left the inboard end rib undone for now, since I need to trim my return line to fit.

For the return line, I unspooled enough of the -4 aluminum tubing to reach the outboard most inner fuel bay, and gave myself a tiny bit extra for the bend to fit the fittings, making sure I’d have enough to do both tanks to the spot where I wanted it. You can see where the tube will end up at inside the fuel bay.

 

This photo shows the hole I will use for the return line, in all the ribs.

Once I had the return line cut, i deburred both ends of it, and set it aside for now.  Then I clecoed both the end ribs in place so I can start the work of sealing everything at a later build session.  I’ll need to order a few fittings for my return line, so I’ll get an order in to Spruce to get them on their way and be ready by the time I need to seal up the inboard end rib (where all the fittings will be going).  Here’s where the tank is as of right now:

Thats a good stopping point for tonight. Scuffing and cleaning took up a bunch of time, and I was pretty shot after this sort-of-long work session.  It’s a good place to start the sealing work, as all I’ll need to do is mix up a batch of proseal, and get after it.  I do plan on removing a rib, cleaning the rib and skin with a quick wipe of acetone to clean up any stray contaminants, and then sealing / riveting it into place, then repeat.  I’m hoping I can get all 5 of the interior ribs done in my next session.  That would leave me in good shape to let it cure, then move on to the end ribs in another session.  We’ll see.

Google Photos Link: https://photos.app.goo.gl/TRr7uDDGNKEAn2y59

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Hours Worked: 3.25

 

Sealing the Left Tank Drain and Fuel Cap

Tonight was pretty much a repeat of the right tank drain and fuel cap sealing. I also had my wife Tammy helping me since we were kidless for the night!  We made a trip down to our favorite restaurant “Boathouse Raw Bar and Rotisserie” and had a great meal, then I somehow managed to talk her into helping me on the tanks tonight since she is waaaaayyy less messy than me with working with goops.  This session started off like all sealing sessions:  Scuffing and cleaning the areas to be sealed.  We scuffed both sides nice and well, and then cleaned both sides with some MEK until the paper towels came up clean.  We did this for the drain flange and the tank filler neck.

 

Then Tammy mixed up 40 grams of sealant, while I applied some masking tape to the areas around the tank drain to create the little channels for water to drain safely into the sump. I did this last time and it worked great, so why not do it again this time?

Once Tammy had the sealant ready, she slathered some on the back side of the tank drain, and then put it in place on the tank skin while I clecoed it.  She’s much cleaner at working with this stuff than I am! We went ahead and clecoed all the holes in the tank drain to hold it secure while we worked on the tank filler flange.  This is where I didn’t get a chance to get any good photos, since we were gloved up and had sealant going everywhere.  But, Tammy slathered a nice layer onto the skin facing side of the filler neck flange and then we clecoed it in place, making sure to not forget the vent tube holder.

Now its time to set the rivets.  I pulled out the AN426AD3-4 rivets, cleaned them in a jar of MEK, and then dried them on a towel.  Then I inserted then into the tank drain flange, and squeezed them with my squeezer.  I was able to use my 4″ flush squeezer yoke to get all of these rivets very nicely, just be cautious as the set will slip and slide on the sealant so keep a steady hand and bring the set up to the work very gently.  I’m happy in how it turned out. All the rivets set very nicely, and flush in their dimples, with a tiny bit of sealant oozed around them to further help them seal.  Here is what they look like after they were cleaned off:

Tammy then dolloped on the sealant on the shop head side of the rivets on the tank drain, and then we pulled off the masking tape to clean up any little bits of sealant before it dried.  She did a good job on this, and made sure there was a clean path for the water to drain, as well as making sure the threads were all cleared of sealant.

While she was working on that, I used the squeezer to start setting the rivets on the fuel filler neck.  I was able to reach all but 4 of the inboard rivets with the squeezer.  However, like the right tank, the plans called for AN425AD3-4 rivets, but they seemed to short for the deluxe caps flange.  So I used the sizer and went with AN425AD3-5 rivets cleaned with MEK.  The 4 inboard rivets I set with a standard rivet gun and bucking bar, and they came out really nicely. here is what it looks like after riveting, and before applying sea

lant on the back side.

And heres the view of the outside of the filler neck flange, after being cleaned up with some MEK.  We also cleaned the oozed sealant from the inside of the flange but left enough for a small fillet, as you can see in the photo below.

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All that was left was to apply the dollops on the shop head side of the filler neck flange.  Just like I did on the right tank, I decided to completely cover this area with sealant since it’s an area that will get a lot of abuse from rampers and me filling the tanks with fuel.  Its a bit overkill, but better safe than sorry!

 

That finished up this build session.  I cleaned off all my tools with MEK and paper towels and also cleaned up some stray sealant from the tank skin as well.  I’ll let this cure for a few days and start working on sealing the ribs on the right tank.  These things are starting to come together!

Google Photos Link: https://photos.app.goo.gl/YmGi19CDqvoznqko8

Hours Worked: 1.25

Fitting the Left Tank Fuel Sender

Tonight I was able to accomplish a part of the fuel tanks that I’ve been worried about.  The left tank fuel sender.  My left tank is my “acro” tank, and as such has a flop tube installed in the inner most bay, and that forces us to move the float style fuel sender into one of the inner bays.  That brings its own problem:  You can’t use the end rib access plate to install the sender, leaving you to custom cut and mount the fuel sender in the baffle itself!  I’ve read up on this for a bit, and put a bunch of thought into it, and I decided a way to tackle it.  At this point, I am also out of rubber gloves so I can’t do any more sealant work, and with COVID-19 going on rubber gloves are sort of hard to find!  So, I figured I would work on this as its coming up REAL quick and this would be a good time to go ahead and get this done.

I started out by sticking the left tank into the leading edge jig, and fitting the ribs back in and clecoing them in place.  I left out the two inboard ribs, so that I could see the sender and be able to adjust the float wire accordingly.

Then I grabbed the baffle and started working out where I’d install my fuel sender.  Luckily, my kit came with a now unused access cover that was pre-drilled for a sender, so I used that as a jig to gauge where it needed to be installed, as well as my drill guide. I made sure everything was clocked correctly as the sender has a certain way it needs to be installed. The photos below show where I ultimately decided it should be installed.  I also used the right tank to measure the distance from the bottom of the tank to the bottom of the access plate to make sure I had this sender going in the right spot vertically on the baffle.  Then I clamped it down with some C-clamps and drilled.

   

I used the holes in the access plate as my drill guide to drill the #40 holes for the K1000-8 nutplates, and then the larger screw holes were drilled with a #19 drill bit to fit the screws.  I also outlined the hole for the sender with a sharpie. I’ll need to cut this out.

Then it was over to the drill press where I chucked up my fly-cutter and got everything centered up and the fly cutter adjusted to cut just to the outside of my sharpie outline.  GO SLOW!! Set your drill press to a slow speed and use light pressure when using a fly cutter.  That seemed to work really well for me, and gave me a nice round and smooth hole!

Now its time to bend the float sender wire.  The senders will ship with a float that has plenty of stiff straight wire attached to the float-bobber, and its up to the installer to get the bends set correctly to read full and empty.  So, I clecoed the baffle onto the tank making sure I got the skin nice and flush so I could get an accurate measure on these bends. I installed the sender and clecoed on the baffle!

This is where I spent A LOT of time.  It took a lot of trial and error, and testing and bending and fitting to finally come up with a shape that seemed to have worked.  I started off by doing the first bend at 2 3/4″ inches where vans normally recommends 3″.  Then I sort of eyeballed it, and trimmed off the excess, and made a few test bends.  There really wasn’t any sort of “system” or “tips” to make this easy.  Fit the float, and then use a sharpie to mark where you want to bend and see if it works.  Thankfully, the wire on the float is stiff and it seems to be fine being bent multiple times.  The three photos below show what I wound up with.

I wanted the float to land just in front of that stiffener, so it would sit JUST above the skin when reading fully empty.  I was able to find a series of bends that did just that, while also giving me a decently correct full position.  The float is maybe 1/8″ of an inch from touching the top skin at the FULL position, which is perfect.  I want these things to read more accurately close to empty than full anyways.  With this sender being outboard by another bay, and sitting a little more forward towards the leading edge, when they read EMPTY, there will probably be close to 3-ish gallons of fuel left in the tank, with about 1/2″ gallon being unusable.  This is a good enough safety margin for me, so when it reads empty, I’ll still have a small reserve.  Here is what I came up with as far as my bends.

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It’s not very helpful without measurements, but honestly, those measurements would vary a bit depending on where you wound up mounting the sender in the baffle anyways.  But, the shape itself is hopefully helpful to any future builders so they can see what worked for me.  Roughly, the float to the first bend is about 2 3/4″.  Then the little distance between the 45 degree bents is about an 1″ to 1.25″.  Then probably another 2.75″ before getting to the 90 degree bend that nests into the sender itself.  With all this hard work of getting the bends done, there wasn’t much left to do, but finish up the mounting holes.  So, I deburred the holes, as well as deburring the larger hole made by the fly-cutter, making sure it was very smooth on all edges.  Lastly, I decided to use some NAS1097 “oops” rivets for an AD426AD3-3.5 hole and do a very easy countersink on the outside rivet holes so that the sender sits perfectly flush and seals good.

I used my hand deburring tool to get the gentle countersink done just right for these “oops” rivets, since it doesn’t take very much at all.  I tested each hole to make sure it was perfect.  Then I clecoed on the K1000-8 nutplates, and  squeezed the rivets using my squeezer.  I’m pretty happy with the way this turned out!

It feels good to FINALLY get this part done.  I’ve been worried about it for a while, and put a bunch of thought into how I wanted to do it.  I contemplated making a doubler, but decided that wasn’t needed since the sender itself serves as a doubler.  I’m happy with the results! this was a good stopping point for tonight.

Google Photos Link: https://photos.app.goo.gl/j55S1A1HFjNzhipw5

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Hours Worked: 3.0

 

 

 

Sealing the Left Tank Stiffeners

Time to work with the black sticky goop again.  This time I decided to do a little more prep work, and forgo pitting sealant on the rivets, instead slather it onto the stiffeners first.  First things, first:  I need to scuff the mating areas, and clean them very well with acetone and MEK.  So, I grabbed a scotchbrite pad and scuffed up the rivet line where the stiffeners would go. It’s a little hard to tell in this photo, but the horizontal row of rivet holes were the ones I scuffed, with about a 1.5″ wide area.

Next step was to clean this scuffed area squeeky clean with some acetone and MEK until the cloth came up clean, and then mask off the areas where I don’t want sealant to go.  I used the stiffeners as my guides, and left a small area around them for the sealant fillet.  Plain old making tape worked fine here.  I also made sure to mask the area off where the ribs would go later on, I didn’t do this on the right tank, and it made a heck of a mess to clean up later.

You can see the difference of where I scuffed in this photo a little better, and the masking shows up a bit better.

This is where things went a little fast, and I didn’t have time to take all my gloves off and snap photos with my phone.  I pulled some AN426AD3-3.5 rivets from my the glass jar where they’d been soaking in MEK, dried them off on a terry cloth towel, and inserted them into the rivet holes.  Then I put masking tape over the rivet heads to serve as back riveting tape, and hold them in place.  Next, I mixed up 50 grams of the white part and 5 grams of the black part of the sealant, and donned all the necessary gloves and protections from the goop, and went to work.  Like I mentioned earlier, I decided to only put the sealant onto the bottom side of the stiffener, THEN place it down onto the rivets and skin.  This was SOOO much easier.  I smeared the entire bottom side of the stiffener with probably 1/8″ or so of sealant, enough so that I would get some squished out when I riveted them onto the skins, but not so much that it’d cause pillowing.  I did ALL my stiffeners like this, placing them into their marked positions on the skins.

Like I mentioned, I REALLY wish I had snapped some more photos, but I tend to get this sealant EVERYWHERE, and I knew it would be all over my phone if I tried to sneak a photo.  But, after I had all my stiffeners slathered in sealant, and placed onto their spot on the skins, I started back riveting them into place.  I slide my back rivet plate into position, and then back riveted the stiffeners starting in their center and working outwards to their edges.  A nice bead of sealant would gently squeeze out from under the stiffener as it went into place, making it really easy to do the fillets later.

Once I had all the stiffeners back riveted into place, I only had enough sealant left in my cup to complete the dollops on the rivet heads on a couple of stiffeners, so I mixed up another 50/5 grams and then applied the dollops of sealant onto the shop heads of all the remaining rivets.  I TRIED my best to not make a huge mess, but as you can see, I was only partly succesful:

But, I’d much rather have too much sealant and be messy than not have enough and deal with leaks.  After I’d dolloped my shop heads, it was time to work the filets around the stiffeners.  The sealant was starting to cure, but that made it a little easier to work with on the filets I think.  I used popcicle sticks to dip some sealant out where needed, and make my filets, making sure to get completely all around the stiffener.

Thank goodness for the masking tape, because I was making a helluva mess.  Once I had all the filets made, I double checked everything looked good, and the removed the masking tape so that the sealant would self level as it cured, and not have any tall ridges where the masking tape was.  The tape came off easy, and left some very clean looking lines!

As you can see above, there were a few spots where I went back and touched up a bit after pulling the masking tape.  I still managed to make a little bit of a mess, but this won’t be hard to clean up once its cured.  Lastly, I decided to check the manufactured heads on the rivets to make sure I had some sealant squeeze around the heads in the dimples from riveting to help seal them.  To my surprise, this process worked very nicely on getting sealant all the way back into the dimple! You can see the dark circles around the rivet in the masking tape in this photo:

 

 

And this photo is with the masking tape removed.  You can see where the sealant did a nice job of squishing down into the dimple from the other side! I didn’t wipe this away for now, as I want to cure a bit to make a good seal, it will get sanded away during the painting process anyways.  The rivets were all set perfectly and looked great!

Then it was clean up time.  I only had to clean off my back rivet set in some MEK, as nothing else got contaminated due to the masking job.  It’s well worth the time to mask this stuff off first, and save a ton of clean up time in the end.  I had learned that lesson on the right tank stiffeners 🙂 I’ll leave more photos in the gallery below to show some of the filets and dollops on all the other stiffeners.

Google Photos Link: https://photos.app.goo.gl/QpdfysyHz4afXB2m9

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Hours Worked: 2.75

 

Dimpling the Left Tank Skin

Local weather was pretty crappy, so I didn’t go flying in the Cardinal today, and didn’t have anything else on the docket to finish, so I decided to spend some time working on the RV-7.  Picking up where I left off, I needed to get the left tank skin dimpled so that I can start prosealing it and getting it up the point where the right tank is.  Simple process:  I used my DRDT-2 dimpler, to make quick and easy work of dimpling all these holes.  I made sure to NOT dimple the line of rivets that hold the tank baffle on, as they are machine countersunk instead. I also made sure to dimple the screw holes with a #8 dimple, as this is where the tanks skins screw onto the main spar.

And heres some photos of me doing the work, so I can prove to the FSDO that I am the guy building this thing.  I am hoping to get the repairman certificate for this aircraft, if and when it ever gets done! I was working by myself, so I hope a couple of selfies is OK.

       

I did complete the tank skin in a little over an hour.  I spent probably ten minutes catching up and reading where I left off, nearly a month ago! I have got to start making these a bit more frequent, or she’ll never get finished.

Hours Worked: 1.25