Sealing the Left Tank Access Cover

Another quick build session.  I first wanted to do a initial water leak test, but that proved to be a bad idea.  Well, using the cork gasket as a temporary seal instead of sealant on the access plate proved to be a bad idea.  I filled the tank up with water, and things were looking good……right to the point of the access cover.  The cork gasket leaked pretty dang bad.

So I scrapped the water test idea for now, and I’ll permanently seal the access plate with sealant, and THEN test with water.  I was hoping the gasket would hold so that I could do this test, then remove the access cover for the final baffle seal so I could check the inner bay before sealing it up for good.  Oh well.  So, I brought the tank back in, dried it up, and then mixed up 20 grams of sealant for this access plate.  Then I scuffed up the access plate, and the rib and then cleaned it with MEK.

Then I slathered on a decent covering of sealant around the edge of the access hole making sure I got it nice and covered for the cover plate.  After that, I gently slide the access plate into place, and threaded in the stainless steel hex cap screws.  Before I let the screws bottom out, I smeared on some sealant using a toothpick on the bottom of the screw head / shoulders that way it would get a decent seal around the plate and prevent any seepage while keeping the screw accessible for easy removal in the future.  Here’s how it turned out.  In some of these photos you can see the screws are not fully seated, thats where I dobbed on the sealant.

Once that was done, I used the remainder of the sealant I had to do some touch ups elsewhere on the tank.  I had probably 8 grams or so of excess, and I didn’t really use all of it doing the touch ups.  I’ll let this cure and then do my water leak test. One step closer at least. Heres the time lapse:

Google Photos Link: https://photos.app.goo.gl/kKCQfhRiRXU8nHSq5

Hours worked: 0.75

 

 

Left Tank Closing Prep Work

Just a quick prep work session tonight.  I had a few things to get done before I do the water leak test.  The time lapse didn’t catch much due to the angle, but here it is anyways.

I started off by pulling the masking tape off the fittings, and then threading the cap onto the fuel return line.

The next thing I needed to do was finishing installing the capacitive sender plate on the inboard side.  The sealant was dry enough to work with now, so I gathered up all the hardware for it, and got it secured in place. Once it was mounted up, I used my Fluke multimeter to check for continuity between the shield of the BNC and the tank skin (for the ground connection), then I probed the center pin on the BNC and checked each sender plate to make sure I had good continuity there as well.  As a safety check, I checked the sender plates against the skin to make sure there was NO conductivity there as well.  It looks like these are ready to go.

I did a quick check of the flop tube to make sure it would not get hung on any part of its motion, and to make sure the anti-hangup brackets were looking good.

After that I needed to bend the tank vent line as far up as possible in the tank.  I used a small wrench over the tube for leverage, and got a decent bend, pointing right up to the skin. You can sort of see how I used the wrench in these photos, it was a bit hard to snap the photo, and hold the wrench for demo purposes, but you get the point.

I did a little cleanup on the inside of the tank with a clean MEK soaked paper towel, and some clean popsicle sticks to act as phenolic scrapers, getting up any stray bits of sealant.  After this, I forgot to snap any more photos, thankfully the time-lapse video captured everything else I did though.  But, I moved on to getting prepped for the next sealing session.  I decided to temporarily screw on the tank access cover using the cork gasket and no sealant for now.  I just wanted to get a seal for the water test, I’ll remove the cork and use sealant when its time to fix it more permanently.

Then I got the rear baffle, and scuffed up all the areas where I would be applying sealant, including the flanges.  I also did a another scuff job on the rear flanges of all the ribs (where the baffle rivets too on them), and scuffed the line of rivets on the skin where the baffle interfaces.  I’ll clean these with MEK right before sealing.  After that, I decided to align the baffle one last time to the tank, and then verify the position of the tank attach Z-brackets.  I clecoed them on, and then finger tightened the bafffle down to the spar with the z-brackets making sure the holes all lined up.  Then I used a sharpie to mark the orientation so I could put them back on when its time to close up the tank.

Then I removed the Z-brackets to get the baffle ready for sealing.  I’ll let the sealant on the rib cure for one more day, then I’ll do the initial water leak test on it tomorrow like I did on the right tank.  I’ll leave it in the cradle, with the rear baffle out, and fill the tank with water and let it sit to look for leaks.  This way I can fix any leaks easily with the baffle off.  Then It’ll be time for the sealing!

Google Photos Link:  https://photos.app.goo.gl/Nx8QjhxsLnLsRXAG7

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Hours Worked: 1.75

Riveting Left Tank Inboard Outer Rib

LOTS of work done in this session!  I had to capture it in two time lapse videos, Here is the first video:

The second covers the last bits, found below.  I started the session by dry fitting the outer rib and then trimming the last little bits of excess on the tank vent lines and fuel returns. Then I flared the tubing with my Parker flair tool, and slid on the sleeve and nut, inserted the tubing back into place in the plastic bushings, and double checked the fit.  Now its time to get ready for sealing!

Like always, I collected up my parts, scuffed them and cleaned them with MEK (same for the skin too).  Heres the cast of parts for this session.  I also notched the mounting bracket just a tiny bit to make clearance for the rivet heads on the rib flange.  I’ll leave the masking tape on the flop tube to keep it protected during the build, and remove it right before final sealing.

I mixed up 50 grams of sealant, which was not enough.  I had to mix another 30 grams for dollops and other bits I’d need to cover.  But this worked out well, since I didn’t have to worry about the sealant curing while I was working with it.  I had decided on buttering up the flanges of the rib, then clecoing it into place.  Once 100% cleco’d I’d go ahead and squeeze the rivets around the nose / leading edge so they’d be good to go. This worked out, and I had plenty of clearance on the squeezed rivets for the T-410 and T-405 mounting brackets.  Here’s how that looked.  One thing to note, I did go ahead and apply a buttering of sealant on the inside of the nose rib where the T-410 would be clecoed on later.  Since it would be hard to reach after the rib was in place.

 

Then, I gently positioned the T-410 stiffener plate where the sealant was buttered and got it aligned.  After it was stuck on, I buttered up the T-405 tank attach angle brackets with some sealant, and clecoed it to the T-410 / rib assembly.  I cleaned some AN470AD4-8 rivets in MEK and then bucked the T-410 / Rib / T-405 tank attach angle together.  After I had the rivets bucked, I smeared on some sealant on the shop heads to help seal them. It’s messy down there with sealant, but should be good.

With that being done, it was time to get the flop tube installed.  I gently inserted the already built and torqued flop tube into its hole and screwed its nut down on the outside, immediately cleaning off the sealant from the threads, and covering the threads in masking tape.

I am not sure if completely covering the nut on the flop tube was a good idea or not, in case I ever need to service it.  But, for now, i am wanting to avoid leaks more than servicing a flop tube 15 years from now.   Then I smeared some sealant around the inside part of the flop tube, where the fitting exits the bulkhead.  Next step was to torque down the tank vent and fuel return lines to their fittings and cover them in sealant to prevent them loosening.  This was pretty simple, and used a decent amount of sealant.  I mixed up the other 30 grams to have enough for the dollops and other bits.

Once that was done, I used the filet spoon to create some nice filets on the inner and outer flanges, then squeezed all the rib to skin rivets using my squeezer.  This went pretty quick since I was using the squeezer, and all the rivets were perfectly done.  I love this tool!  After that, I dolloped on some sealant to the rivets shop heads and moved on. I still had some sealant left, so I decided to go ahead and get the inboard capacitive sender plate ready to go.  I ran the wire, wrapping it around the vent line as prescribed in the instructions, then stripped it, and crimped on the ring terminal for the inboard sender.  I screwed the terminal onto the plate, and double checked alignment, then gooped up some sealant on both sides of the terminals nut and bolt to act as thread locker.  Then gooped in a bit glob inside and around the terminal to seal it and act as a strain relief.  I used my remaining sealnt to glob on some dollops where the wire was wrapped around the vent tube to glue it down.

Following that was clean up time.  I used an MEK soaked paper towel to wipe down the skin and rivets, and all of my tools.  I am darn near done with these tanks!

Here is the second time lapse video.  It captures me struggling with routing the wire in the plastic bushings and crimping the terminals in the tight spaces. heh.

Google Photos Link: https://photos.app.goo.gl/pwbGUjLdXZbNhVsK6

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Hours Worked: 4.0

Left Tank Miscellaneous Sealing Work

Good progress tonight! I wrapped up a few miscellaneous things that needed to be done before riveting the inboard outer rib. Here is the time lapse:

The first thing I did was to test fit all the accessories and fittings on the inner rib to make sure I had everything I needed in the proper places.  I also wanted to think through how I’d best complete the sealing work since there is some complex parts with the flop tube.  Ultimately, I decided I’d go ahead. and seal the fittings for the vent and tank return lines, the BNC connector for the capacitive senders, the anti-rotation bracket for the flop tube, and the anti-hangup brackets thats on the access plate. That way I could most effeciently use my sealant, and leave the other items (all the stuff at the nose of the rib) for when I am ready to rivet them in place.

Next, I scuffed all the pieces that were getting sealant tonight, and cleaned everything nice and well with MEK.  Then got my parts and work area organized to start the sealant work. Once thing I needed to go ahead and do, was to torque the flop tube down to its elbow fitting, safety wire it and make sure the nut shoulders fit into the anti-rotation bracket.  This is my first time safety wiring, but I watched some videos and read a little.  I think it turned out pretty nice for a first timer…….if you don’t count all the scrap from the other dozen times it didn’t turn out nice!!! HA.

The failed attempts:

It’s orientation is such that the safety wire is actually pulling the nut tighter on its threads. You have to really be careful you don’t have the safety wire pulling on the nut and rotating it LOOSE.  Anyways, that was a fun experiment. Now its time to seal! I mixed up 20 grams for this session, which was about 5 grams too much.  Close enough I guess.  Here is the list of parts I will be sealing.  Notice I went ahead and screwed the wire terminal on the capacitive sender plate.  I need to cover it in sealant per the directions to keep it from vibrating loose.

I started out by fixing the anti-rotation bracket.  I smoothed on a small amount of sealant around the rivet holes, and then clecoed it in place, and squeezed the rivets for it.  I had to use my rivet gauge to find the rivets I needed, since this is sort of a “custom” part.  I also cleaned them in MEK to remove any manufacturing oils on them. After that was done, I grabbed the access plate and covered it in sealant, clecoed on the anti-hangup bracket and riveted it in place with the squeezer as well.  Then I smeared some sealant onto the shop and tails of the rivets, and put it on the shelf to cure.

Next up was to slather on the sealant into the terminal connector for the capacitive sender plate.  I covered both sides of the bolt and nut, and completely covered the terminal connection and squished sealant down inside the terminal boot and smeared it up the wire a bit to act as a strain relief.  I had already torqued this connection down in an earlier build session.

Next up was to torque down the fittings for the tank vent and fuel return lines.  I slathered one side of the washers in sealant, placed it on the rib, and then slide the fitting into place, clocking it to the position I wanted on the outside of the tank. Then torqued it down.  I did this for both fittings, and got a decent amount of squish-out of sealant for a nice filet.

Now I’m in the hose stretch with the sealing! I gooped up the inside poriton of the fittings with a nice coating of sealant (after cleaning and masking the threads of course), making sure to get a nice filet around all the mating surfaces, and covering all bits nicely.  I also completely covered the back side of the BNC connector and went up the wire a decent bit to act as a strain relief.  I also dolloped on a little bit of sealant on the heads of the rivets holding the anti-rotation bracket in place. After getting the inside done, I made nice filets on the outside of the fittings to completely (hopefully) seal them.  I set this rib on the shelf to cure.

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I still had a little more work to do.  I needed to rivet the anti-hangup bracket that goes from the stiffener up to the inside rib and install the little trap door.  Easy enough to do, and required no sealant.  I did use a rivet gun to buck these two little rivets holding the anti-hangup bracket.  I decided to re-drill the hole on the rib, as its a little to close to the hole for the screw that holds the capacitive sender on the other side of the rib.  You can see the unused hole directly below the now riveted bracket.

Lastly, I decided to go ahead and install the capacitive sender plate on the outboard side, yes the one I just slathered sealant on.  This was probably a bad idea, as I did get a little messy from the wet sealant. HA.  But its installed and ready to connect to the inboard sender when that time comes, probably next build session.

And that’s a good stopping place for tonight.  I am ready to seal and rivet the inboard outer rib once it cures from this work tonight.  From there its a water test for leaks and then final sealing of the baffle! Its getting very close to being done with these tanks! W00hoo!

Google Photos Link:  https://photos.app.goo.gl/ZAUyeq39Zvo9LymR9

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Hours Worked: 3.0

Riveting and Sealing Outboard Rib Left Tank

The goal for tonight was to get the outboard rib sealed and riveted.  I started out with a bit of miscellaneous work first though. I did capture another time lapse, and heres that video:

I fixed up the fuel return line, and cut it to the right length, and then measured, marked and drilled the hole in the inboard rib for the return line fitting.  A step bit made quick work of this!

Then I put those inboard parts back on the shelf and grabbed the inboard rib, and T-410 stiffener so I could get them scuffed up with some scotchbrite, along with the inboard edge of the skin.  Then I cleaned everything with some MEK, and started mixing up the sealant.  I went with 50 grams, which seemed to be about the right amount in the end.

   

After giving it a good mixing, I used an old butter knife to slather on a thin layer where the T-410 stiffener attaches to the nose of the rib.  A butter knife works really well for this, since its designed to….spread things.  Once I had a coating done, I used some AN570AD4-5 rivets that had been cleaned in some MEK.  the 4-5 size worked out about right, after checking them with my rivet length gauge to be sure.  I used my pneumatic squeezer to set them.

Now its time to slather up the flanges of the rib with sealant, and gently cleco it in place for riveting.  I clecoed every other hole, since I planned on setting these rivets immediately, and not leaving them overnight.  Since these are the outboard rib, I was able to use my squeezer to make very nice rivets with almost zero mess.  I riveted all the holes with the squeezer.

Next up all that was left to do was to make my filets around the flanges and dollop on sealant onto the rivets.  I still had plenty left in my cup of 50 grams I mixed up, and I used the filet spoon to create nice smooth filets on the inside and outside flanges.  I thankfully had enough sealant to dollop on the rivet shop heads and cover them nicely with the filet spoon.

I also made sure to get a nice thick covering around the nose area of the rib to prevent any leaks in this critical area, making sure to get a nice filet around the T-410 stiffener as well.  I then dolloped a covering of sealant on both sides of the AN470AD4-5 rivets that were used to attach the stiffener plate.  All that was left was to clean up the excess sealant with an MEK soaked paper towel, and then clean up my tools for the night.  In my next session I plan on some miscellaneous work on the capacitive senders and the inboard rib fittings since its a little more complex with the flop tube.

Google Photos Link: https://photos.app.goo.gl/kHz1dsxVXkXePVWT9

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Hours Worked: 1.75

Riveting the Left Tank Ribs – Part 2

Got a lot done tonight! I finished up the larger riveting job on these inner ribs.  I had three left from the last session, so I finished those last three up tonight. Heres the timelapse:

My tools were already ready to go from the last session, so I jumped right in by removing every other cleco from the ribs, and cleaning any dried sealant with a drill bit and deburring tool.  Then I mixed up 10 grams of sealant to use on the dimples for the rivets, and swirled a tiny bit of sealant in each dimple.

Then I stuck the rivets in the holes (these were soaking in MEK to clean them first of course).  The sealant holds the rivets in the holes really well which is a plus.

I did the bottom side first, in all three ribs, then bucked them, checking the shop heads to make sure they were set correctly.  Once I had the bottom done, I flipped the tank over and did the same for the top side.  Then I went back and removed the last clecos, and followed this same procedure to finish up all the holes.

After getting each set of rivets bucked, I’d go back and wipe what little sealant squished out with a paper towel and MEK to keep the mess down.  Once they were all set, I mixed up another 40 grams of sealant to use to make the dollops on the shop heads.  I grabbed my filet spoon and used it to make nice dollops on the tails of the rivets. This was enough to cover the ribs I left on the last session.  The left over sealant I had from getting all the dollops done, I used to touch up the filets and gooped up a nice batch in the nose of each rib to reinforce this section.  I had plenty left over so I had plenty to work with.  I eventually had everything nice and covered and touched up, and tossed about 5 grams or so of sealant.

I’m glad to get this milestone knocked out.  Its looking pretty good, and I am ready to finish these tanks.

After that, I cleaned up my tools, and work area and called it a night. I’ll let this cure overnight, then it’ll be time to start sealing the end ribs and accessories.  Those are decently fun work sessions.

Google Photos Link: https://photos.app.goo.gl/Pjcg6f1CTq4hzCpt9

Hours Worked: 2.5

Riveting the Left Tank Ribs – Part 1

This is a simple update.  I got two of the inner ribs riveted in place in this short session.  I am coming up on the end of a 48 hour fast, and was a bit tuckered out, but wanted to get a little work done, so I decided to get two ribs riveted.  Heres the timelapse of this short build.

I guessed that 10 grams of sealant should be enough to cover wet setting the rivets, and also dolloping on the tails of the rivets, but I was short a few grams and only got one rib dolloped.  No biggie, I’ll dollop the rivet tails later on.

Then I removed every other cleco from the two ribs I wanted to finish, and cleaned up any sealant that had squished into the area and dried.  I also used a hole deburring tool to clean out the countersinks and a drill bit to help with any stuck sealant.

Then, I used a toothpick to swirl a little bit of sealant into the countersink, and inserted a rivet.  Then bucked the rivets with the flush set, cleaning the little bit of fresh sealant from the flush set and bucking bar every now and then.  This went pretty straight forward and I was able to knock these two ribs out pretty quickly.

The photos above are after I had cleaned the areas with some MEK, because a little bit of sealant did squish out from the riveting process.  These things are nice and flush!  Next up I used what sealant I had left in my mixing cup to make dollops on the tails of the rivets.  I used the toothpick to sort of swirl on the sealant and it made decent little dollops on the tails.  However, I only had enough to do one complete rib, so I’ll have to mix extra next time and cover the tails of the other rib.

You can see in the photo above where I ran just short of enough sealant for dollops right at the leading edge.  Oh well,  I’ll get these guys in the next session, and I plan to mix enough to also goop the leading edge nose up really well too.  I cleaned up my tools, but left them sitting out for the next session maybe later tonight or tomorrow, depending on how I feel after I end this 48 hour fast!

Google Photos Link: https://photos.app.goo.gl/1Y4bqrYCFNeedmhP9

Hours Worked: 1.5

 

Sealing the Left Tank Inner Ribs

After a short break from the previous build session today, I came back down to get the inner ribs sealed and cleco’ed in the left tank.  This will set me pretty good to do some riveting on them tomorrow and Monday.  I would love to have this left tank ready for an initial leak test by this coming weekend!  I did capture a timelapse of this build, which is nice, because I couldn’t get many photos due to the sticky mess that is Proseal.  Heres the video:

I started out by mixing up 100 grams of sealant, and putting it into the semco sealant gun.  I love how this thing dispenses sealant.  Then I grabbed my inner ribs and squirted a bead of sealant from the semco on the flanges, and smoothed it out with a butter knife.  I am using the same procedure that I did on the right tank in this build log: https://theskunkwerx.com/rv7/sealing-the-right-tank-ribs/

I first slathered on sealant on the bottom flange, curling it around the leading edge and back a few inches onto the top flange.  I am cleco’ing the bottom in first and then once I have all the ribs clecoed to the bottom, I buttered up the top flanges .  Once the top flanges are buttered with sealant, I took the skin, and gently slid it down into the cradle cleco’ing the ribs in place.  This worked really nicely to getting the ribs clecoed without smearing the sealant off the flanges.  Check the video for a better picture of how I did this.

After I had all the ribs clecoed 100%, I used the semco to squirt a nice bead on the edge of the flanges that I used to make the filets with a filet spoon.  Around the second rib, I ran out, so I had to mix up another 50 grams of sealant which was just about right, leaving me with about 10 grams extra that I squirted into the leading edge of the ribs for extra reinforcement.  Here’s how the filets came out:

Then I clecoed on (without sealant for now) the end ribs just to help the skin hold its shape while the inner ribs sealed.  I also strapped some masking tape across the skin at the ribs to help squeeze the skin together to assure a good bond of sealant at the aft edge of the ribs.  After that, it was cleanup time! I’ll let these sit overnight, and then rivet them tomorrow and Monday.

Google Photos Link: https://photos.app.goo.gl/jUSa1nX14A2bcixf7

Hours Worked: 2.0

 

 

 

Prepping the Left Tank for Rib Sealing

The right tank was left pressurized for about 3 days, and the balloon stayed inflated! There is no loss of air so I’m proud to say its leak free.  Now its time to start working on the left tank.  I collected all my parts, and then scuffed all the surfaces where the inner ribs mount, and then scuffed up the flanges (both sides) of my inner ribs.  Then I cleaned everything with MEK to get them ready for sealing tonight.

After checking everything, I realized I needed to drill the holes for the return line in these ribs. So I made up a template from a scrap piece of wood.  I decided where I wanted the return line to run, drilled a #30 pilot hole, then laid the rib onto my scrap wood to mark out some alignment holes to transfer this location to all the other ribs.

All I had to do was line up the ribs with the markings, and then back drill using my hole in the wood into the rib to transfer the pilot hole to the proper location. I did all my inner ribs like this clamping them each time to hold them in place while I drilled.

Then I used a step drill to open the holes up to the proper size to fit the SB004-6 grommet and deburred the edges.  Now I am ready to put some sealant on these ribs!

Hours Worked: 1.75

Final Leak Testing the Right Tank

The right tank has had a solid 3-4 days to cure.  I took my little family on a short trip up to the mountains of Pigeon Forge for a min-vacation, and the right tank had plenty of time to sit and cure.  So, I decided to give it a final leak test!  This is a short update, but a milestone! I got a little creative with my spare parts (as all builders do!).  I’m not using the supplied pitot tube that Vans has you craft from 1/8″ aluminum tubing and a bulkhead fitting, so I figured I’d make a pressure testing rig out of it!

I grabbed one of my daughters balloons, and it seemed to fit perfectly over the nut of the bulkhead fitting for the pitot tube, and I was able to finger tighten the other jam nut up against the lip of the balloon to create a gasket and hold the balloon nicely onto the fitting.

Then I flared a piece of the 1/8″ aluminum tubing that was supposed to be used for the pitot line.  Since I am using a nice plastic tubing kit for pitot, static and angle of attack, I didn’t need this tubing.  I flared it, stuck the fitting on it and tighteened it down onto the bulkhead / balloon fitting, then attached the other end to the vent line fitting on the fuel tank.

Then, I capped off the fuel tank return lines and pickup fittings with the proper caps, and screwed in the schrader valve fitting that Van’s puts in their tank test kits.  I set my pressure regulator on my airline as low as it would go, and attached a tire air chuck to my hose, and used the schrader valve to slowly and gently fill the tank with air, watching the balloon slowly inflate.  I like this method as you are safe from over-pressurizing your tank since the balloon will burst long before the tank is damaged.  You can also use the balloon to hold pressure in the tank to check for leaks.

It’s quite festive!!!!  Then I used a mixture of Dawn dishwashing liquid and water in. spray bottle and sprayed all over the fittings to check for slow leaks there first.  None were found! Then I moved on to spraying the baffle to skin joints, and the Z-brackets and all the rivet holes, checking for any bubbles that may be rising from the soapy water.  NONE!  I am pretty stoked so far.  It doesn’t appear there are any gross or major leaks in the tanks….yet.  So I carried the tank outside and sprayed it gently with the garden hose to clean the soap off, brought it back on the bench and dried it off.  The balloon still holding air!

I’ll leave it sitting like this for a day or so.  I also have my camera focused on the tank and balloon and have it set for a 6 hour time lapse.  That will show me if the balloon is deflating, indicating a possible slow leak somewhere.  This was a short session at about 30 minutes, but very much needed!

Google Photos Link:  https://photos.app.goo.gl/MB4WG3V8gtbRPSHK7

Hours Worked: 0.5