Aug 21, 2022     Section 18 - Fuel Tank 30 - (7.7 hours)       Category: Sec 18 Fue T

The right Tank leak test concluded successfully. The only leak, again, was on the sender screw that should ground the unit electrically.

In this work session, I worked on installing the OAT probe, Roll servo, tie-down bolts, and concluded the wing tank installations. The new fuel caps arrived, the keyed ones. They are identical to the stock caps but with a key.

After installing the right tank, I screwed the skin screws and got a perfect match between the skins. minimal to zero gaps and no overlap. then, I moved to torque the spar bolts. Torquing the right tank after setting the screws caused a larger variance on bolt torques. On the left wing, the range was between 10-15 of drag + 25 of spec torque resulting in 35-40 torque. On the right tank, I had some bolts with residual torque of up to 30in-lbs. (this was the Z bracket I had to install nut plates after the fact). My conclusion is that in some cases bolts ended up not perfectly aligned, despite the fact nothing was jamming... I believe another factor could be the fact that I installed this tank over the workbench instead of hanging in the cradle.

Another task I finished, which was pending for a while, was to swap the landing light lens screws from 8 to 6 length. Now the screws are less visible inside the light bay.

With that, I concluded the wing tank section 18. Section 19 is also concluded, per stock plans, but I still have to work on my specific changes like installing a pitot tube heat controller, running antenna wires, and AOA line. As I do that, I will start working on Section 20, bottom Skin. I will have all bottom skins ready to go as I install the guts of the wing.

https://youtu.be/qJOhyM6zFlk

  Aug 18, 2022     Section 18 - Fuel Tank 29 - (1.2 hours)       Category: Sec 18 Fue T

Finished attaching Right Tank, torquing bolts, and fastening skin screws. fit like a glove. Removed blue vinyl and skins are perfectly matching and spaced. Very happy with the results.

https://youtu.be/wYC70dQ9EcE

  Aug 17, 2022     Section 18 - Fuel Tank 28 - (2 hours)       Category: Sec 18 Fue T

Attachment of right wing fuel tank. The tank snapped into place with no issues. The bolts were all aligned and the residual torque was very consistent among them all. All bolts are now torqued on the right wing.

Going to the left tank, I found a leak on the fuel sender bolt that needed to be clean for grounding purposes. Again, trying to avoid issues with grounding I may have been a little lean on the sealant on this bolt. So I removed the bolt, injected a little bit of sealant, reinserted the bolt, and covered it around the edges with sealant. That means my ground connection is under the sealant. I tested for conductivity and it seems fine. I hope it will remain like so.

https://youtu.be/ECNbK6BOjBM

  Aug 16, 2022     Section 18 - Fuel Tank 27 - (1.5 hours)       Category: Sec 18 Fue T

In this work session, I completed the tanks by countersinking the remaining holes that attach to the baffle and moved forward with the tank leak test. Filled up the tank with air and found a leak on the balloon itself.

With the new balloon in place, the tank is pressurized for 20 hours now. The balloon is as inflated as it was yesterday afternoon. I think we can call the tank build a SUCCESS! No leaks whatsoever!

https://youtu.be/p869caP-_rM

  Aug 15, 2022     Section 18 - Fuel Tank 26 - (.5 hour)       Category: Sec 18 Fue T

Quick session installing fittings on the fuel tank and doing an internal inspection with the snake camera.

Also had an issue with the fuel cap... dropped it on the floor and it was enough to ruin it...

https://youtu.be/Ct0IlEiRMOY

  Aug 14, 2022     Section 18 - Fuel Tank 25 - (5.6 hours)       Category: Sec 18 Fue T

Today I installed the tank baffle. With all parts and tools ready to go I mixes 200gr of sealant and planned on using a ziplock to squeeze out the sealant. Everything worked perfectly. So smooth that I was able to do all Z brackets in the same work session. I did commit a mistake though... I installed the Z bracket with no nutplates in the wrong location...! (picture 132.6, 3rd bracket. it should have nutplates) Seconds of despair, followed by the correction plan. I would never try and drill out these rivets. First, because I would have spare rivets. Secondly, more importantly, how would I ever recover the rivet heads from inside the tank!? never... So I decided to go ahead and finish the installation and, given that the Z brackets are all identical, except for the nutplates, I would install the nutplates on the Z bracket that was missing the nutplate and remove the nutplates from the one that shouldn't have it in the first place.

The plan seems to work fine. I left the tank drying, baffle down, and I will install the nutplates a week from now.

On the right tank, I did the water leak test and it passed with flying colors. no leak whatsoever. The plan to encapsulate the nutplates of the fuel sender worked.

Right tank was easier after having done the left tank. I consumed a bit more of sealant and had some hiccups with the pop rivet tool. One of the rivets stem broke before fully puling the rivet in tis half. I was able to complete the pool using the pneumatic rivet puller without the tip, so the puller could catch the shorter stem.

Other than that, uneventful.

Now both tanks are resting until sealant cures. tomorrow I will install the drainer and fuel pickup finger. I believer I will be able to pressure test the tanks in a few days. I kept sample of sealant of both tanks to know when it is cured.

After closing and cleaning everything, I tried to take some pictures of the inside of the tank, picking through the filling hole and drain hole. What I was able to see looks good. Tomorrow I will try to make some videos with the micro "snake" camera.

https://youtu.be/I2pOIjnUKbo

  Aug 14, 2022     Section 18 - Fuel Tank 24 - (3.9 hours)       Category: Sec 18 Fue T

In this work session, I submitted the left tank to a water leak test. With that, I was able to check almost all sealing baffle forward. The successful test, almost flawless, wasn't perfect only because of the "ground screw" from the fuel sender. I guess I interpreted the instructions wrongly. When installing the nutplates for the fuel sender, the plans do not call for a sealant. But now I think what they mean is that there is no need for sealant between the nutplate and tank rib because, after that, we should encapsulate the whole nutplate with sealant. Picture 131.16 shows the screw where I found the leak.

What I end up doing is shown in picture 131.27. Nutplates are fully encapsulated.

Filling the tank up with water is interesting to see the fluid dynamics. the transfer of fluid between bays is not as "active" as one would think. it took a while for the colored water to get even. Very interesting.

After the test, it was time to countersink some holes in the attachment bracket and prepare the tank for final closure.

https://youtu.be/_oHr5wKInNA

  Aug 12, 2022     Section 18 - Fuel Tank 23 - (4.6 hours)       Category: Sec 18 Fue T

Finished installing all ribs, J stiffener, inboard rib, and fuel tank sender.

https://youtu.be/VqcVOr2F7UQ

  Aug 11, 2022     Section 18 - Fuel Tank 22 - (6 hours)       Category: Sec 18 Fue T

Finished installing tank ribs on right tank.

https://youtu.be/35ukfQrGJwY

  Aug 10, 2022     Section 18 - Fuel Tank 21 - (3.9 hours)       Category: Sec 18 Fue T

Installation of first 3 ribs on right wing tank.

https://youtu.be/vGEfwSbTPJU

  Aug 09, 2022     Section 18 - Fuel Tank 20 - (2.2 hours)       Category: Sec 18 Fue T

Installed fuel cap and fuel sender. To install the fuel sender first it is necessary to fabricate the wire that will hold the floater inside the tank. Followed all steps from manual with no hiccups. I left by tank drying on its side hoping that the sender will rest on a position that will allow the creation of the sealant bed of .7mm while providing good grounding to sensor.

https://youtu.be/BeezK07Yekk

  Aug 08, 2022     Section 18 - Fuel Tank 19 - (4.8 hours)       Category: Sec 18 Fue T

In this session, I installed the j stiffener, the vent line, and the last inboard rib.

J-stiffener was very easy to rivet but tricky to slide in without too much mess and even trickier to make sure sealant was well set behind the stiffener. I tried to pick using phone photos and it looks fine. hopefully no leaks.

The next step was fabricating the vent line out of the flexible aluminum tube. Straight forward. Simply use your hand to bend it to shape, cut, deburr, and slide it in through the bushings. But before that, there is a flared end that needs to be created. This was my first time and looks like I did it well... visually looks great.

When attaching the vent line to the AN fitting, it is necessary to make sure it is aligned and proper torque is set. According to Vans, it should be between 100 and 140 in-lbs. I aimed for 120.

Moving on, I used the same torque to attach the AN union through the inboard rib. applied sealant on both sides and a smear of sealant on the vent line nut just to check for loosening.

When torqueing the AN fitting of the vent line, the vent line turned a bit and I had to readjust the end of it to stay within the minimum clearance of 1/4in on the outboard side.

The last step was to rivet the inboard rib and seal it. riveting was hard on the flange that meets the bracket. thick rivet, offset, and no space for a squeezer.

60grams of sealant for j-stiffener and 50gr for inboard rib.

https://youtu.be/mnkN-4CjRtM

  Aug 07, 2022     Section 18 - Fuel Tank 18 - (1.3 hours)       Category: Sec 18 Fue T

Back to fuel tank assembly. I had this very short work session in which I attached the tank bracket. Some hard to reach corners to seal but I think it will pass the test. I used my phone to take pictures and inspect the work and, visually, looks like it is all sealed.

For the bracket I mixed 70gr of sealant but 50 would have been enough.

https://youtu.be/CAkG7sEFFfg

  Jul 28, 2022     Section 18 - Fuel Tank 17 - (2.7 hours)       Category: Sec 18 Fue T

On this work session I concluded installing all ribs on left tank, except for the most inboard river.

Tank sealant is almost over. I used 70g on the outboard rib doing a thick bead inside the tank and leaving the outside very clean. I just added more sealant outside at the nose of the rib as an additional barrier to avoid fuel leakage.

Looking at the amount of sealant I used so far, I believe 2 quarts will be my total. Probably a bit more then necessary.

https://youtu.be/dortjtsDlCE

  Jul 26, 2022     Section 18 - Fuel Tank 16 - (2.9 hours)       Category: Sec 18 Fue T

Installed another rib. Two to go. As it gets closer to the outboard it gets tighter so I made a wood stick with two slots to keep the skin open and have an easier access to insert the last ribs.

https://youtu.be/x1KCMMQUrAU

  Jul 25, 2022     Section 18 - Fuel Tank 15 - (3.6 hours)       Category: Sec 18 Fue T

Continued working on installing the tank ribs. Now this time I took a different approach and I am glad I did. The different approach was caring a little less about cleaning, using less sealant, and not masking everything up with masking tape. This resulted in an easier, faster process allowing me to finish 1 rib in 1h30min.

So doing this I was able to work on encapsulating rivets with the sealant still very workable. The last step was cleaning tools and clecos.

https://youtu.be/2vqXLAby-rw

  Jul 24, 2022     Section 18 - Fuel Tank 14 - (3.9 hours)       Category: Sec 18 Fue T

Installing the first two inboard ribs on the left fuel tank. I am using 60g of sealant on a rib, which is probably a little too generous. I will definitely need another quart of sealant.

This process is the worst, so far in the construction. The sealant is very sticky and requires constant cleaning of the tools. Next rib I will try to a little less sealant.

https://youtu.be/tRjisLJ04tQ

  Jul 22, 2022     Section 18 - Fuel Tank 13 - (4.5 hours)       Category: Sec 18 Fue T

Installation of tank stiffeners.

With all pasts ready to be installed, I did another pass on cleaning them and got sealant prepared for the first batch. I decided to try 4 stiffeners at a time. The work time was perfect but I thought I could do it quicker if I didn't have to spend so much time doing the perimeter sealant shaping on each part. So, for the next round, I decided to put masking tape on the tank skin.

Using masking tape on the skin helped to keep the mess under control and made it easier to build the sealant joints around the partas. But it still gave room to mess on the stiffer web itself. So I decided to cover the stiffer with tape on the right tank skin.

With both skin and stiffeners protected with tape, the work on the right tank was faster and cleaner. with two batches of mixed sealant, I was able to complete the stiffeners installation. I used approximately 120grams of sealant to do all stiffeners in 1 tank.

Picture 117.2 shows the first installation. Picture 117.12 shows the results with the masking tape.

https://youtu.be/Sb92zetDmjY

  Jul 20, 2022     Section 18 - Fuel Tank 12 - (.5 hour)       Category: Sec 18 Fue T

Quick session loading rivets on fuel tank skin.

https://youtu.be/dgo83QTszDo

  Jul 19, 2022     Section 18 - Fuel Tank 11 - (3.5 hours)       Category: Sec 18 Fue T

Session started with adaptation of squeeze yoke to fit inside the fuel cap hole in order to squeeze the rivets. See picture 115.10. Took some time to grind this thick material but way worth it. Bucking bar and rivet gun on this scenario would be very difficult.

As I started with the first fuel cap, I used a wrong rivet size. So with sealant all over, I had to drill out the rivet and replace for the correct size. A lot of cleaning all the time. Especially tools.

Following the fuel caps I installed the fuel drain. The work is looking nicer as I gain some practice with sealant. As per photo 115.1, I wanted to leave a path for water to get to the drain. And it turned out great. Used a small tube to encapsulate the rivets with sealant.

https://youtu.be/_uQ9q6MsBAI

  Jul 16, 2022     Section 18 - Fuel Tank 10 - (5.4 hours)       Category: Sec 18 Fue T

With the priming of tank parts done I started the first round of sealing. Before starting it though, I realized that I had pained one of the Z brakes wrongly. I painted the part that will be sealed instead of the part where nut plates are attached. So I had to redo that and clean the part again for sealing. The end ribs have a hole that needs to be closed with a 470AD6 rivet and a few accessories that need to be installed.

Working with tank sealant definitely has a learning curve. I finished the end ribs and it is messier than expected but not as bad as it could be.

https://youtu.be/vGRa-a9d3CY

  Jul 15, 2022     Section 18 - Fuel Tank 9 - (3.8 hours)       Category: Sec 18 Fue T

Preparation of tank bracket and fuel cap flanges. In this session, I am preparing the tank brackets by machine countersinking the #40 holes that mate with tank skin and scuffing it. Same process with the fuel tank cap. After having all parts prepared I washed and primed the parts only on the outside of the tank. I will have to give another pass of primer after the tank is fully assembled and leak tested.

100ml of Primer used

https://youtu.be/swZMYh6aenc

  Jul 14, 2022     Section 18 - Fuel Tank 8 - (5.6 hours)       Category: Sec 18 Fue T

During this work session, I scuffed the inside of tank skins and finish dimpling the whole skin, left and right.

https://youtu.be/gSdyJnVo4io

  Jul 13, 2022     Section 18 - Fuel Tank 7 - Radio Interview - (.3 hour)       Category: Sec 18 Fue T

I had the most unexpected and pleasant visit to my shot this day. The shop became an internet radio station studio when Pablo from "conectados radio" came to my place to interview me. He is an aviation enthusiast and has a great show that talks about community creation and how people get together for different reasons. In the show, he shared with the radio community a bit more about our Experimental Aircraft building craft. This all happened thanks to my new neighbor, who happened to know the show and pointed me out as a prospect interviewee. Very nice to meet new people with shared interests.

Now back to the build.

I was able to match-drill and sand the fuel drain, and that was it for this day.

https://youtu.be/dNuB3EewBUw

  Jul 12, 2022     Section 18 - Fuel Tank 6 - (3 hours)       Category: Sec 18 Fue T

Countersinking and final drilling the right fuel tank. Test fitting parts and adjusting flanges.

https://youtu.be/VB8Y3_oq9zE

  Jul 11, 2022     Section 18 - Fuel Tank 5 - (4.8 hours)       Category: Sec 18 Fue T

In this session, I concluded the machine countersinking of the tank skin. In order to do that I had to assemble the tank baffle. Instead of installing only the tank baffle, I decide to make a full assembly just to see how parts are fitting. Found out that the ribs need more work on fluting and squaring the flanges. Unless you have this shaping very well done, the ribs will not fit easily. I can only imagine that with the sealant on them would be probably a huge mess.

I marked all mating points so now I can scuff the tank skin inside. Lastly, I final drilled the screw holes #19 and demurred them.

This was done on left tank. On to the right tank. One last comment: I like using riveting tape on the face of countersinking cage. it avoids markings on the work surface.

https://youtu.be/2_kohLD6G0U

  Jul 10, 2022     Section 18 - Fuel Tank 4 - (8.3 hours)       Category: Sec 18 Fue T

With the rib flanges ready I concluded step 1 of the Fuel tank assembly. Most time-consuming step ever. Moving on with the build, the next step is to prepare some attachments for fuel lines. I accidentally increased the hole diameter of an existing connection instead of drilling a new hole, as instructions oriented. Thus, I had to spend a couple of hours coming up with a solution. (108.4 - 108.14). My solution was to fabricate a doubler that will go on the outside of the inner rib to cover and support the drain connection while properly sealing the hole. I tried to make sure this won't impact any future parts added to this section and I think it will work perfectly.

Apart from this fix, I also finished scuffing deburring, and dimpling all stiffeners, including the J-Channel.

https://youtu.be/mlrQcoBuRdU

  Jul 08, 2022     Section 18 - Fuel Tank 3 - (5.7 hours)       Category: Sec 18 Fue T

Two work sessions preparing skins and ribs. Before flange squaring and fluting I spent quite some time scuffing the matting surfaces with 150 grit aluminum oxide sandpaper in order to properly seal the assembly. The material of the tank ribs seems to be different. less shiny, thicker, and harder to conform to a certain shape. even after fluting and squaring the flanges the rib seems to warp a bit. There is no priming on these parts so I hope the scuffing will not open spots for corrosion.

https://youtu.be/0D4N7dFd43Y

  Jul 07, 2022     Section 18 - Fuel Tank 2 - (4.8 hours)       Category: Sec 18 Fue T

Deburring and parts preparation.

https://youtu.be/-Bg6qOjnkL0

  Jul 04, 2022     Section 18 - Fuel Tank 1 - (4 hours)       Category: Sec 18 Fue T

I started section 18 by preparing the parts for the fuel tank. I decided to cut all Z brackets and stiffeners and only after I realized that the vent clip has a hole that needs to be enlarged. It would be easier to do it before it has been cut out of the stiffener bar... but no big deal.

As far as parts preparations go, I am deburring all parts and I plan to scuff all mating parts before adding dimples and fluting. I am trying to follow as much as I can the recommendations from Van's on the fuel tank assembly video. (https://youtu.be/gTl827JWz68)

In this session, I finished demurring the T-00005 and T-00004 tank stiffeners.

On a side project, I've installed a fan in the garage ceiling to try and beat Florida heat...

https://youtu.be/sWaduLuhW4E