I was beginning to think that I was never going to finish the left fuel tank.  I was waiting to make a Van's order to order some Polypropylene tubing to finish my capacitance fuel sender installation.  After some SLIGHT procrastination, I ordered the polypropylene tubing I needed along with some other airplane things since Van's charges a "$5 handling charge".

One of the tasks I still had outstanding on the tank internals was to solder my BNC fitting to the capacitance fuel sender wiring (wire).  Not a great looking solder job (remember, I come from the occupation of "bigger the blob, better the job").  After soldering the BNC connector, I used a Fluke digital multimeter to verify the following:

• That I had electrical continuity between the center pin on the BNC connector and each of the capacitance sender plates.
• The I had NO ELECTRICAL CONTINUITY between any of the fuel tank ribs and the capacitance fuel sender plates.

Everything checked out fine after my highly skilled solder job.....

A pict of the inboard fuel sender capacitance plate.

The outboard fuel sender capacitance plate.

I reviewed the log entry I made for sealing the rear baffle on the right fuel tank and started to assemble all the tools and equipment I was going to need conduct my last (hopefully) sealing session.

Before putting on the rear baffle plate, I finished sealing the BNC connector.  I have heard of a couple of builders who have had leaks around the BNC connector.  I used copious amounts of tank sealant to seal around the BNC connector.  I also encapsulated the wire back a couple of inches so that I didn't get any "wicking" of fuel up the fuel sender wire.  I did this on the right tank as well and didn't have any problems with leaks in this area.

I also put dabs of sealant securing the sender wire(s) to the tank vent tube.

Earlier, I had encapsulated the fuel sender capacitance plate wire that is attached to each fuel sender plate.  This is the inboard rib.

Ditto for the outboard rib.

After putzing with the miscellaneous fuel sender tasks, I coaxed Tami to come out and begin the task of sealing up the rear baffle plate.  Sealing the baffle plate is a BIG JOB.  I didn't get any "in-process" pictures.  If you have done any tank sealing, you know that you stay busy and are usually pretty messy.

One thing that made me really nervous sealing the rear tank baffle is when it came time to mount the 'z-brackets' to the rear baffle plate.  It is really easy to get disorientated and mount these 180 degrees out.  If that happened, I would really be cussing when trying to mount the tank to the spar.  Anyway, I took a few extra minutes to double, TRIPLE, verify that I had the correct orientation for my z-brackets

Just an end shot of the outboard tank rib.

There are a ton of rivets on the rear baffle plate.  It took a ton of time just to do "touch ups" on the rivets, the flanges, etc.

A shot of my inboard rib.

Everything looks okay from the end.

A little messy on the inboard rib, but by this time, I really didn't care.  I was just beat and ready to call it a night.

I am thrilled, if everything on pressure testing goes well, that I am done sealing fuel tanks.  I did make the mistake to seal the rear baffle on a "school night".  I started around 6 pm and didn't finish up until around 1 am.  I didn't even bother cleaning up my mess.  Tami had already cleaned up my clecoes and tools so I didn't have to worry about them.

Not a very detailed log entry.  Check my log entry I made for the right tank baffle plate.  I had much more detail.

Sealing The Baffle Plate Log Entry

I don't have a lot of pictures to show for my efforts this weekend.  I started installing and sealing tank ribs which is a MESSY operation.  I have been dreading sealing my second AND last fuel tank.

I have been prepping my wife for a month or two about sealing the fuel tank as she doesn't like working on tanks either.  So the weekend arrived and I asked (I mean told her) that is was time to work on sealing the tank.  After a little groveling on HER part, she came out to the garage and grabbed the bucking bar.

No in-process pictures for the log.  Everything you touch (i mean look at) during a sealing session gets tank sealant all over it.  We were well on our way to finishing our second rib and Tami broke the relative silence of the garage air conditioner;

"You know, I hate to admit it, but sealing the fuel tank is more enjoyable than riveting the ailerons"   I shit you not!!!  That is what she said straight faced an all.  It was a good thing I was already sitting down on the garage floor when she said that.  I thought I was delirious and like a fool I asked her what she said and she repeated the statement over.  Maybe she is delirious.

Anyway, over the course of the weekend, I got 5 of the 7 tank ribs riveted and sealed.  So far, so good.  Tanks are an incredible amount of tedious work considering the brevity of this log entry.

Before I riveted the outboard end rib on and sealed it, I wanted to get my vent tube fabricated and routed through the tank.

WARNING:  An abbreviated version of tubing bending for dummies (me)...
I had ran the vent line through the tank (before I bent the offset) and measured the distance between the rib hole for the vent and where I drilled the hole in the inboard rib for the vent line ELL.  That distance (as best I could tell) was approximately 1 18/32".  Okay, now I need to bend the tubing such that it will actually line up with the Inboard rib ELL.  How did I do that on the last tank???  Ooh yeah, a little trigonometry.  One of the few times I have had to use what little math knowledge I have.  I figured that I would bend my tubing to provide a 60 degree offset.  Basically the tubing angle forms the hypotenuse of a right triangle and this is where it turns into a math problem.

Needing a finished offset distance of 1 18/32" (1.562"), I just took the cosine of angle 30 and solved for the hypotenuse (or actual tubing) length.  I came up with 1 26/32" (approximate is close enough).  So before I made any bends in the tubing, I made my first mark at the end of the vent line far enough away so that I could get my AN fitting on and make my tubing flare (Approx 3").  I then measured down the tubing 1 26/32" and made my second mark on the tubing.  This represents where the two bends will be started in the tubing to create my offset.

The two lines that were measured out on the tubing are where I started my bends.  I put the first line under the "0" on the tubing bender, bent to approx. 60 degrees.  Then move the tubing down to the second mark and place it under the "0".  It is important to properly orient the tubing here or end up with a shape that starts to approximate that of a STOP SIGN.

When I got done with my two bends for my offset, this is how it lined up.  Pretty darn good.....  If its not perfect, there is a little room to bend the tubing by hand over the width of the inboard bay.  By measuring out the bend, I didn't have to do any additional "tweaking".

I am really happy with my offset.  I couldn't have gotten it any closer if actually knew how to bend tubing.   Now I just need to put my AN fitting on the end and flare it.

Okay, what the heck is this?!?!??!?!?  Damn It !!!   I was routing my vent tube through the tank and as I fed the vent tube through the vent clip, I noticed that it moved fairly easy.  It isn't supposed to do that...  Uh oohh.  I briefly pondered whether or not to move the clip and just see how bad this was going to get.  Of course, I couldn't let something like this go.  It is easier to fix now than it will be to fix later.  I removed the vent tube and gave the clip a little tug.  It was clear that the only thing holding the vent clip in place was the tank sealant I gooped over it.  It was actually pretty tough to remove just being held in place by sealant.

I wonder how hard this will be to fix?

I used an x-acto knife to cut and remove tank sealant around the vent clip, drilled out the rivet and cleaned the area of tank sealant with the x-acto knife and a small rag soaked in MEK.  The clip area looks pretty good.  I should be able to re-apply tank sealant to the affected area, install a new vent clip, and have no problem getting a good seal.

The real trick, which I haven't figured out yet will be how to set a solid rivet in here.  My back rivet method isn't going to work as I can't open the tank skin enough to get the rivet hammer in here.  I am thinking that I may be able to use a 426 Cherrymax rivet here as they sit and look very close to the aesthetics of the solid rivet and the Cherrymax rivet is way overkill for this application.

To much to think about tonight.  I am going to take the rest of the night off, give this some thought, and fix it tomorrow.

We came back from vacation a couple of days early to just relax and do things we wanted to around the house.  For me that was to work on the LAST fuel tank.  Well, when we got home, the Falls City FBO left a message on the answering machine stating that they had a Cessna 152 available for instruction.  So, instead of working on the fuel tank the last couple of days, I have been flying.

I figured that it would take me several hours to get proficient again.  This 152 has a few minor differences than the 150 they rented last year, but within 2 hours of aerial maneuvers and pattern work, I was landing very consistently.  LANDINGS are my "achilles heel".  I was pretty happy to be shooting good landings so quickly after such a long flying dormancy.

Between flying, I was able to get the tank ribs and stiffeners dimpled.  Again, I used the tank dimple dies I bought from Cleaveland Tool.  They worked really well on the last tank.  My rivets came out really good (at least as good as those planes I saw flying at Osh).

Just a shot of the inside of the tank skin after dimpling with the c-frame.  I know.... real exciting stuff here.

The tank skin dimpling is complete.  Let the sealing begin.

My arm got fairly fatigued dimpling the skin with this 16 oz dead blow hammer.  It is not that the hammer is really heavy, but you swing this thing like 10,000 times (thats what it feels like anyway).  It is amazing how warm the head on the hammer gets after doing half of the tank skin.  I alternated heads every couple of dozen rivets, but after doing the right wing, I think that this hammer is ready to retire.  Time for another trip to Harbor Freight for another hammer.

I just couldn't wait to get started sealing the fuel tank.  Are you kidding me???

Sealing seemed to progress a little faster the second time around.  I must be getting proficient with this tank sealant stuff.

Just a shot of the outside.  I am pretty happy with my riveting results on the stiffeners.  They all sit nice and flush.  Back riveting is the easy part....

All I have left before I pressure test the tank is to seal the inspection cover.  To secure the inspection plate to the rib, I ordered some 18-8 stainless steel 8-32 x 5/8" hex head screws.  The hex head screws will be easier to remove when the tank is installed on the airplane.  I have seen other builders do this and it is also recommended by Van's 21 years of the RVator.  I thought is sounded like a great idea.

I decided to use the cork gasket AND tank sealant.  By using the cork gasket, it should make the inspection cover easier to remove and using the tank sealant only on the edges, should act as a redundant sealant barrier.  Before I installed the cork gasket, I lubed up both sides of the gasket with ez-turn lubricant I got from Aircraft Spruce last week (5 oz tube).

I installed all of the inspection plate screws and washers and secured them alternating from side to side.  I couldn't find any way to use my torque wrench on these so I just tried to provide a consistent torque "by feel".  I removed all excess ez-turn lubricant from the edges of the inspection plate.

I mixed some more tank sealant and made a fillet around the edges of the inspection cover and the hex head screws and washers.  Since I am taking credit for the cork gasket to seal the fuel tank here, it isn't imperative to have a perfect seal so I didn't get to crazy with tank sealant here.  We'll see how it goes after the leak testing.

With all of the effort I have put in around the inspection cover, I HIGHLY doubt that this will leak.  My order of additional AN caps and fittings from Aircraft Spruce is supposed to be here on Tuesday.  Hopefully, I can start testing the tank Tuesday or Wednesday.  Leak testing the tank is the last thing I need to do before mounting it to the wing.

Today was the big day for the finishing the first fuel tank.  All that was left for the right fuel tank was to seal and rivet the rear baffle plate.  This will only take an hour or two at the max...  WRONG!!!

After some contemplation, I decided to prime the z-brackets with the exception of the flange that gets sealed and riveted to the fuel tank.  To keep the primer off of the z-bracket flange, I masked the z-bracket with some Scotch 35 vinyl electrical tape.

Prior to mixing up tank sealant, I decided that it was finally time to subject my $5 Harbor Freight blind rivet puller to the ferocity of the scotchbrite wheels on the bench grinder.  My rivet holes for the z-brackets are pretty close to the "web" of the z-bracket so pulling those blind rivets was going to be a challenge.

This is a cheap rivet gun and it shows when going to pull rivets with it.

Here is another picture of the down right tool abuse at the hands of the bench grinder.  This thing only has to pull a handful of rivets on the tanks and leading edge.  I hope it survives long enough to get the job done.

I wished that I had the time to take some pictures of the tank sealing process just to better show how messy this job can be.  Anyway, we are down to crunch time.  This is where it all comes together.  After sealing the rear baffle plate, if I have forgotten anything inside the tank, I will no longer be able to correct the problem (easily anyway).  Therefore, I gave the tank one more last look over and inspected all the ribs, shop heads, etc.  I made sure that the vent line sat securely in the vent clip by the fuel filler neck.  I checked the capacitance sender connections and that the wires were secured to the vent line with sealant.  I checked all fittings for tightness...  You get the idea.

I spent probably an hour getting everything ready.  Kind of kept a checklist of things to do in my head:

• Read other builders web pages on sealing the tank baffle to get everything straight
• Cranked the air conditioner in the garage down to 65 to start cooling the garage down. 
• There has been some discussion on the Yahoo group about how quickly tank sealant starts to set-up.  One builder claimed to have as little as 45 minutes working time with the cartridge tank sealant at 80 degrees.  However, lowering the temperature of the room to 70 degrees and I have gotten nearly 1.5 hours of working time.
• Clean the blind rivets and solid rivets in MEK.

• • AN427AD3-3.5
• • 41-H (tank baffle skin to rib)
• • 42-H (z-bracket, tank baffle skin, to rib)
• • AN470AD4-4 (outboard z-brackets: baffle skin to rib)
• • AN470AD4-5 (outboard z-brackets: z-bracket, skin, to rib)

• Cleco pliers and cleco's
• Rags
• Last quart of MEK.
• Sealant gun and air hose.
• Sealant spatulas
• ONE ENTHUSIASTIC HELPER or WIFE (Which ever is easier to obtain).
• One chilled 6 oz cartridge of tank sealant.
• FORGOTTEN / MISSED ITEMS

• • Rivet hammer with universal rivet set.
• • Bucking bar

I used the sealant gun to place a bead of sealant along the rivet lines on the tank skin and rib flanges.  I used a spatula to smooth the bead of sealant out and make a nice smooth line of sealant.  Then the race was on.  Okay TAMI, put in cleco's.  I put cleco's in every hole on the rear baffle.  My thought process was that when the tank sealant is fresh, it flows pretty well around all the irregularities and cleco's pull the two components together.  I figured that clecoing every hole (like Van's tells you to do), that it would hopefully allow that tank sealant to flow better along the baffle plate flange.  THERE ARE A TON OF CLECO'S IN THIS THING.  Even with a helper, it took us a good 10+ minutes to get it all clecoed up.

Then came the use of the pneumatic squeezer.  I'm off squeezing at a frantic pace.  After about 10 rivets, I realize that this is going to take more than the 20 minutes it takes to rivet a rib.  I squeezed like crazy and it still took me just a hair over an hour to squeeze the tank skin to baffle rivets.  Tami cleaned cleco's as we went as that was a huge job cleaning up the mess.  It was good she did this early on as I needed her help at the end dabbing sealant over the rivet shop heads.

You are still not done by a long shot. 

I then started on the blind rivets for the z-brackets.  I stopped and did a double>>   No, I mean triple check on the orientation of the z-brackets.  If you you rivet them on backwards>>>  forget about ever getting this thing mounted to the main spar.  It would be a huge mess to fix.  When I was happy with orientation, I swirled the head of the blind rivet in sealant and put it in the hole.  I must have done something right as I didn't appear to have any alignment problems here.  After the 3rd z-bracket, my cheap-ass $5, ground-down rivet puller jammed and wouldn't release the pull shaft.  I ended up having to disassemble the rivet gun and retrieve the shaft.  Okay that KILLED 10 VALUABLE MINUTES>> CRAP...

Then came the outboard z-brackets.  They are NOT installed with blind rivets.  They use solid 470 rivets.  Okay, I will use the longeron yoke and the pneumatic squeezer>>>  NOT !!!!  TAMI> Stop cleaning cleco's?!?!?!?  Where is my rivet hammer and bucking bars?!?!?!?  Another 15 minutes and VOILA>>>>  The tank is riveted together.

I did not put a lot of excessive tank sealant on the rear baffle flange (not like I did with the rest of the tank anyway).  I just made sure I had a uniform bead of sealant about 1/2" wide or so.

All we had left to do is dab sealant on all the shop rivet heads and a little touch up work.  Use your helper here work on the opposite side of the tank you are on.  I had Tami make up another batch of sealant from the quart can (approx. 40 grams) to finish up.  Tami ran down one side of the tank with a spatula and I ran down the other.  It still took us another hour to finish this up. 

At the top and bottom of the outboard ribs, you have a notch that needs to get sealed up.  This is a relatively big opening.  I went kind of crazy with sealant here.  Looking at the tank the next morning, I think I am in pretty good shape here.

In my usual tank sealing fashion, I fully encapsulated the shop heads of the rivets.  Notice, my fillet is fairly small on the rear baffle.  I didn't want sealant to interfere with installation on the main spar.  I may beef this us a little, but I am going to wait until I see how the tank does on the pressure test.

I then did a visual inspection of all the rivets that were set tonight.  I noticed that the rivets on the top side of the tank were all flush and looked great.  The rivets on the bottom of the tank were not quit as flush.  The tank skin was countersunk at the same time with the same countersink cutter, but why the difference???  The only thing that I could think of is that I did set the rivets on the top side of the tank first.  This allowed the sealant under the factory head to flow better as it had not started setting up yet.  By the time I got to the bottom side rivets, the sealant was starting to setup and was holding the rivet heads up slightly.  The difference is ever so slight, but you can see it if you look really close or run your finger over it.  I will be happy IF IT DOESN"T LEAK !!!!!!!

Parting comments on tanks:

• TANKS SUCK!!!  Sealant gets everywhere.  If you touch sealant, everything you touch after that will have sealant on it.  I found sealant making it all the way into the house on the computer.  We toasted 4shirts, 2 pairs of shorts, and 1 pair of sweats during our sealing endeavors.  I ended up using almost 1 gallon of MEK to do the right tank alone.  MEK is not something I would voluntarily expose myself to if it wasn't for this project.  MEK is nasty...  Works great for cleaning up sealant, BUT.....
• If you are as lucky as I am to have your wife help you on the plane, don't expect her to be to happy (or willing) to work on sealing the fuel tank.  I had to darn near beg/grovel to get Tami out in the garage to help.  As soon as the last rivet was set, she was like the road runner sprinting out of the garage and into the house.  I would turn around and she would be GONE!!!  All I could see was the smoke from the soles of her tennis shoes!!!!!  Tonight, I told her we were done with tank sealing and she actually offered to come out and rivet skins on the wing (no groveling required)...  THAT's MORE LIKE IT.
• If you plan on using a sealant gun, do yourself a favor and order the quart can too.  Even when I used the sealant gun, I still always seemed to need to make up "just a little more " sealant.  On the right tank alone, I used two sealant cartridges and around 2/3's of a can of sealant.
• Work in a cool space.  10 degrees can make a big difference with the working time of the tank sealant.
• Van's claims you can seal a tank in 2 to 3 work sessions.  Whatever....  I probably have 6+ work sessions to get everything sealed.  Anyway you slice it, tanks are a ton of work.  I haven't pressure tested yet and I have almost 100 hours on this fuel tank.  I have seen some builders logs claiming to get their tank done in the neighborhood of 30 hours.  I don't know how they do it.  It probably wasn't their first tank.

This was a relatively short night dealing with tank sealant.  My plan tonight was to finish the two outboard ribs, but I didn't quite make it.  The stick you see below has been one of the most useful of the tank sealant tools I have.  This stick is nothing more than a homemade plastic stick with 45 degree bevels at each end.  This stick is about the width of the tank rib flange.  I put a glob of sealant on the end of the stick and spread the tank sealant over all the rivet holes.  I ensure 360 degree coverage around each rivet hole in the skin and a relatively uniform amount sealant along the bead.  Very simple, yet works great.

Below, I installed the tank vent AN fitting (ELL) and torqued the nut to 55 in-ibs with a crows foot attachment to my torque wrench.  Between the rib and the fitting nut, there is a spacer washer so that the nut can be tightened down to the fittings threads.  As with all my tank sealing activities, I fully encapsulated the spacer washer and AN fitting nut.  I also (not intentionally) had tank sealant on the threads under the nut.  This made the nut turn fairly hard.  One thing is for sure, this will not loosen up under vibration.  I just hope that it doesn't leak.  To protect the rear threads, I did have vinyl electrical tape over the threads and the opening.  It sure makes easy work of sealing as you don't have to take toothpicks and clean sealant out of the threads. 

Don't make me explain how I know a toothpick will get in between the threads....

What is wrong with this picture????  Give up???  There are actually two extra holes in the rib (one on each side of the larger tooling hole).  Before realizing that there was a T-410 reinforcement plate that is riveted to the forward part of the outboard rib, I started fabricating a smaller plate to cover the tooling hole.  Oops, didn't need it.

I seemed to use alot more sealant on this rib than I did on the other tank ribs.  I believe that is was in the neighborhood of 60 grams.  I believe on the other ribs, I averaged right around 35 to 40 grams of sealant.  Of course, the reinforcement plate did take a little extra and I also heavily placed that gooey stuff on the leading edge of the tank.

Just another picture of the results of my tank sealant torture ritual done tonight.

Below, you can see the inside of the tank on that outer most bay.  Everything looks pretty good.  I kind of wish that the vent line sat a little higher in the tank that it appears here.

Tomorrow, I will see if I can talk my wife into helping one more night sealing the tank.  She is losing her interest in helping on the tank in a hurry.  She did tell me tonight that she would take the financial reimbursement equal to the cost of a new BMW convertible so that she could go on a spending spree for her quilting hobby.  Thanks Dave P. for giving her the idea on the BMW and $$$$ thingy.

My log entries have been kind of slow this week.  Working with tank sealant is not very conducive to taking photographs.  Earlier in the week, Tami and I were able to install 3 tank ribs in one session.  So if you are keeping count, that means I have 5 of the 7 tank ribs riveted and sealed.  That leaves the two outboard ribs.  Therefore, I started working on the vent line and capacitance senders so I could rivet the LAST TWO ribs.
With capacitance fuel senders, you run the wire wrapped along the vent line so the instructions tell you to notch the snap bushing in order to make room for the 18 AWG wire.  It doesn't take much of a notch to fit the wire through the snap bushing.  I just used the Dremel tool and a small cutter bit to remove the small amount of material.

For my vent line, I measured the offset between the root rib and the next outboard rib.  Based on my vent fitting location, I needed to make a approximately a 2" off-set between the vent fitting and the hole in the next rib.  I decided to make this a 60 degree, 2" off-set.  This involved a new skill as I haven't had to use the tubing tools I bought for the project up to this point.  Again, I kind of made the off-set a math (trigonometry) problem to see where I needed to make my bends.  Three tries later, I had my 2" off-set.

After I checked my fit in the tank, I used the flare tool to put a flare in the vent tubing (don't forget to put on the AN sleeve and nut on the tubing before making your flare.)

Here is a picture of the outboard end of the fuel tank, the vent, and the fuel filler flange.  When making the T-714 clip, make sure that it will hold the vent line about where the bottom of the filler flange is (the vent line needs to be at the high point of the tank).  That way, you won't have to do any exotic tubing bends in the tight space to keep your vent fitting secure AND high in the tank.  As you can see, the vent line comes right out of the snap bushing and right into the T-714 clip.  I had to modify the vent clip as it was originally to long (low).  I cut it off, de-burred the end, and re-bent it to hold the vent line.  (If you remember, the rivet that holds the skin, fuel filler flange and vent clip gave me some trouble during installation so I had to hurry and make another clip before the tank sealant cured>>  ARGHH).

This is a picture of where I am trying to correct a tubing length issue.  I did not allow enough room for the AN ELL fitting on the in-board rib.  I had to trim about a 1/2" off, debur, and re-flare.  This flaring tool works GREAT!!!  I had no problem getting it into this somewhat confined space.

I could have just moved the tubing over in the tank, but I had all of my capacitance sender wires wrapped around the vent line and it was just easier to cut and re-flare.

Everything looks good.  When I re-installed the in-board rib, I had near perfect alignment.  WooHooo!!!

This picture kind of back tracks in the actual sequence of how things were actually worked today.  These are the insulating washers that you put between the rib and the capacitance sender plates.  When they were manufactured, the washers were not cleaned up with the excess molding material (in the Navy, we called this "Irish Pennants">>  Don't grade me on my spelling).  I didn't want this stuff to eventually flake off and get into the fuel line.  It is some pretty tough stuff, but I am not taking chances.  Besides, it looks better after the washers were cleaned up.

To clean the edges up, I took an X-acto knife and scraped the edges of the washers.  The bottom two are what they looked like after I was done.  It is all about "piece-of-mind" by trying to ensure some quality of construction.  For goodness sake, it is just an airplane.

Attaching the wire to the outboard sender was a piece of cake.  You have plenty of wire you can pull out to move the plate around to get on the screw and nut to tighten everything up.  When I got the wire/lug attached to the outboard sender plate, I mounted it to the rib so that I could final measure the wire to the inboard sender.
Okay, now the trick...   When you attach your inboard sender plate, the wire from the outboard sender is cut to length.  That doesn't give you a whole lot of room to move the plate around so that you can get on the screw and nut to tighten it up.  Additionally, the inboard sender has two lugs that are attached to the plate.  One from the outboard sender and one from the BNC coax connector on the inboard rib.  What I did to obtain enough room to attach the lugs to the inboard sender plate was remove the outboard plate from the rib so that I could pull a little wire through to the inboard sender plate.  You can get about 4-5" of extra wire on the inboard side to attach everything together.

This is a picture of the inboard side.  As you can see, there are several extra inches of wire that will allow me to attach the inboard plate.

This shows the inboard tank bay.  As you can see, the last thing that I will connect for the capacitance senders is to solder the lead to the BNC connector.  Sequence was important here.  If you soldered the BNC first, then you would not be able to pull any extra through to land the lugs on the inboard sender plate.

Once the inboard plate lugs were screwed on and tightened, the instructions have you put tank sealant over the screw, nut, lugs and wire to kind of seal everything up.  It also has you put a dab of sealant on the head of this screw.  I fully encapsulated everything and made sure the tank sealant was not touching anything on the tank creating a ground path circuit.  These senders will not work if one of the plates is grounded (connected electrically) to the tank.

With the inboard rib hardware almost in place, one last thing I wanted to check before riveting and sealing the inboard rib was the range of the flop tube.   I wanted to make sure there was not any possible orientation(s) that would result in a hang-up of the flop tube.

Normal flight, the flop tube rests in the bottom corner.  It physically cannot get lodged under and between the sealed plate nuts and stiffener.  No problem.

This orientation represents "knife-edge" flight with right wing down.  Flop tube does not rub or hit anything.  No hang-up concerns.

This picture is inverted flight.  The inspection hole strap prevents the flop tube from banging up against the plate nuts as it re-orients to the top of the tank.  I couldn't physically push, pull, or otherwise tug on the the flop tube to put it in a position of getting hung up on any of the plate nuts.  No concern in this orientation...

Just a close up of the flop tube near the inspection hole plate nuts (inverted).  As you can see, there is no possible way that the flop tube can get hung up on the plate nuts.

This orientation is knife edge flight with right wing up.  This was coming from being previously inverted.  The flop tube has not re-oriented itself as of yet.  Again, even if the flop tube moved to the the other side of the tank, the anti-hang-up strap on the inspection hole would prevent it from chafing up against the plate nuts.  When I continued rotation to normal flight, the flop tube immediately repositioned itself to the bottom of the tank.  No concerns here either...

Physically pushing the flop tube over, I could not get it to reach the trap door.  Additionally, it can not get lodged between the end of the stiffener and the rib.  Van's instructions (as vague as they are here) have you put a anti-hang up bracket that is angled down from the rib web to the aft stiffener (where the flop tube is at in the picture below.  I didn't put that anti-hang-up bracket in as it does not seem to serve any real purpose here that I can see.

So far, so good...  No concerns.

Again physically pushing the flop tube over, I also could not get it to reach the rib hole I covered with scrap aluminum. 

I didn't take the next two pictures showing the flop tube anti-rotation device, however, a discussion came up on this in the Yahoo group after I had finished my tank.  One builder was having a hard time keeping the ell fitting from rotating when the flop tube would reposition.  Supposedly, Van's had recommended to other builders with the same problem, to install a anti-rotation device for the flop tube.  I didn't find anything on the prints or instructions that told me to install an anti rotation device, so this must be something that Van's has been recently recommending.

I can't remember who had posted these, but he did a nice job, so I added hid pics to my log entry.  Looks simple enough as long as you don't already have your tank sealed.

I imagine that if the flop tube ell started rotating (if not restrained) that it could result in a tank leak at that fitting.

I borrowed a multimeter from work (I ordered a Fluke 177 from rhinotoolshop.com and it is supposed to be here next week.  They had the cheapest prices on Fluke DMM's I could find on the net).  Before getting to far on the tank, I wanted to make sure that the capacitance plates were isolated from the rest of the tank.  The "OL" is good.  That means there is a high resistance between the tank skin and the capacitance plates.

Next, I wanted to ensure that the two plates were electrically connected together and had a LOW RESISTANCE.  The meter reads 0.5 ohms which is low.  When I checked the resistance of the test leads, they read 0.5 ohms.  So if I subtract the resistance of the test leads from the indicated value, the resistance between the plates is 0 ohms.  THAT IS GOOD.

Today, was enjoyable.  I just took my time thinking things through and enjoying the "building process".  The weather was COOL.

After a whole lot of procrastination, I have finally got to the point of riveting the ribs into the fuel tank.  I wasn't sure what to expect with sealing the ribs.  I didn't know how long it was going to take to get each rib riveted and how much tank sealant I was going to need.

I have both the quart can of tank sealant and the 6 oz tubes for use in a sealant gun.  For the first session with tank sealant, I decided to try the sealant gun method.

Below, I am trying to get my ducks in a row prior to mixing the tank sealant up.  I have found that I have between 1 to 1.5 hours before the tank sealant starts setting up and getting to hard to work with (your mileage may vary .  Therefore, I want to have everything prepared ahead of time so I don't waste so much tank sealant.

I started with the second most outboard rib.  I had scuffed the skin and ribs up earlier, but I gave everything a quick wipe down with MEK before spreading sealant.

Because of the time constraints (AND MESS) of working with the tank sealant, there are not many (any) in-process photos.  I had Tami mix up the sealant and then laid a bead of sealant where the rib would be installed.  I spread the sealant with a spatula of sorts to the approximate width of the rib.  Push the rib in and cleco into position.  The thing I have noticed with tank sealant is that it tends to "flow" slightly and somewhat even itself out after a minute or two.

After Tami and I were done riveting the rib in place, I removed the outboard rib to make the rib fillets and encapsulate each of the rivet shop heads.  You might as well on this rib, because you don't get that luxury on the rest of the interior ribs.

Tami and I were able to get two ribs done during this session.  I found it took us about 20 minutes to rivet each rib and another 30-40 minutes to make the rib to skin fillets and encapsulate the rivet shop heads.  When we started, it took about 40 psi to the sealant gun to spread sealant.  On the second rib, it took about 90 psi to push out the tank sealant.

Next time I expend a 6 oz tube of tank sealant, I am going to lay a bead of sealant, rivet the rib in and form my rib to tank skin fillets and then move on to the next rib.  When I run out of or the tank sealant gets hard, I will go back and encapsulate the rivet shop heads.

SIDE-BAR NOTE:  I don't think that it is reasonable to build a tank with the 6 oz sealant tubes and a sealant gun alone.  You are going to need to purchase a quart can of sealant.  There are just to many things to seal where you just need "a little more" sealant.

Once, I had made the fillets and encapsulated each shop head, I had "stray" tank sealant all over the rib and the tank skin.  It took in the neighborhood of another 1/2 hour for each rib to clean up the tank.  You don't think that the building community calls this "black death" for no reason do ya???

One area that I was particularly careful with is the rear of the rib.  In Van's instructions, it states that the notch in the back of the rib is to provide a pathway through the tank to allow water to propagate toward the tank drain.  I am pretty generous with the amount of tank sealant I use on the ribs and rivets.  I don't want any tank leaks.  This is one area, that I have been real careful to limit the amount of excessive tank sealant.

All that work tonight and only two ribs completed to show for it.  I was pretty happy with how the rivets sit on the tank.  I used Cleaveland's tank dimple dies and they seemed to work pretty well.

Just picture of the top side.

Am I done with this tank yet?  Not by a long shot...

Today, I set out to get more tank sealing done so that I could knock out sealing tank ribs next week.  I didn't think today's sealing efforts would take but a couple of hours and then I could get some work around the house done.  WRONG!!!  Tami and I riveted the leading edge together in about 2 hours.  Tank sealing is turning out to take me a WHOLE LOT of time.  Over 20 hrs of riveting and sealing and I haven't started on the ribs yet.

Below, I riveted in the anti-hangup bracket for the root rib inspection hole.  I fully encapsulated the bracket and rivets.  Most builders do not do any sealing on this inspection hole as it is sealed by either the inspection cover gasket (if you use it) or the inspection cover plate is sealed with tank sealant to the outside of the root rib.  I have opted to use some after market sealed (floating) plate nuts.  I am hoping that sealing this reinforcement ring and other hardware, that I am able to use the gasket that is supplied with the kit.  If I need access to the tank or the gasket ever needs changing, no problem as my leakage paths here at the root rib are only through the "Big Hole" and not around every plate nut rivet and plate nut screw....

The next component sealed was the drain flange.  The drain flange was machine countersunk at the factory and the factory rivet heads are almost perfectly flush.  I frosted up the back side of the drain flange and slapped it on the skin and threw a couple of cleco's to hold it in place.  I was able to squeeze all of these rivets with the pneumatic squeezer.

Just another angle of the drain flange.

This is the back side of the drain flange.  As with all of my sealing to date, I fully encapsulate my rivet shop heads.  I tried to keep the skin between the rivets clear of tank sealant.  I didn't want any condensation in the tank from being impeded in its flow toward this drain flange.

This is a picture of my outboard rib tooling hole.  I cut a triangular shaped piece of aluminum and riveted it over the tooling hole.  The only trouble with this I had is that I didn't have any solid rivets short enough.  I did have some CherryMax universal blind rivets that were short enough.  The CherryMax universal rivet had a larger shop end.  The CherryMax rivet is really a pretty sophisticated rivet when you read through Textron's technical bulletin.  Link To:  CherryMax Rivets Info

I just placed copious amounts of tank sealant over everything.  This sucka is not going to leak.

This is the outboard side of the rib.  Again, plenty of tank sealant over the hole and the factory heads of the CherryMax universal rivet.

The last three sealing operations were not to bad.  Okay, now it is on to the problem child of today's efforts.  The fuel filler flange....  What a pain in the arse.  I started by clecoing the ribs in on both sides of the filler flange to hole the tank skin in its basic arc.  Then with all tank sealing efforts, I frosted up the filler flange to skin surface and cleco'd in place.  I got Tami to help me with this as I was not going to be able to reach every rivet with the pneumatic squeezer so I decided to buck these rivets.  They were all fairly straight forward with the exception of one rivet (read on).

After Tami and I got about 3/4 of the rivets set, we removed the ribs to gain access to the remaining rivets, including the difficult one...

Okay, can you guess which rivet on the filler flange is the problem child???  Hint:  It holds the vent line clip (T-714).  How am I going to set that rivet?

• Grind down end of bucking bar to get in between the filler flange and the clip.  NOPE>>>  Didn't work.  The end of the bucking bar that was flattened with the grinder does not allow enough surface area to properly form the shop head.  DRILL OUT RIVET start over.

• Use pneumatic squeezer.  NOPE>>>  Yokes are not long enough.
• Back rivet against bench back rivet plate.  NOPE>>>  Didn't work.  Factory rivet head set high, couldn't get skin to set up against back rivet plate.  DRILL OUT RIVET start over.
• Hold bucking bar on factory head and form shop head with rivet hammer and back rivet attachment.  YEP, GETTING CLOSE.  However, flattened out rivet shop head.  *&$%*%*$#@!*.   DRILL OUT RIVET AGAIN, Inspect T-714 clip find out clip mounting point is distorted....  Fabricate new vent line clip and start over.

On the 4th try, I did get a properly set rivet.  However, I will do this rivet slightly different on the next tank.

As you can sort of see in the picture, the factory head is not completely flush on all sides.  This is in part due to the fact that this is where the skin has the most curvature.

One the next tank here is what I am going to do for this troublesome rivet:

• Use the bucking bar on the factory head side.
• Use the rivet hammer back rivet attachment to get in between the filler flange and the vent line clip.
• Use a short burst (2-3 hammers at a lower pressure (approx 35 psi with my Sioux 2x rivet hammer).
• Rotate (rock) the bucking bar a couple of degrees forward to attempt to keep the factory head flush with the curvature of the skin.
• Use a short burst (2-3 more hammers).
• Check shop head for proper dimensions.

After all of this, I was sticking to everything.  I spent the rest of the night cleaning up.  WooHoo....  Am I done with this tank yet?

What does the photo below have to do with sealing the fuel tank???  This is my new Ductless, split type heat pump (air conditioner) AND IT IS FINALLY UP AND RUNNING !!!!!!  It is friggin' awesome !!!!  The last couple of days have been in the upper 80's with dew points in the upper 60's to lower 70's.  More or less miserable for working in the garage.  With the heat pump, I set the temperature on its remote to 70 degrees and within a couple of hours, I was actually cold in the garage.

Let the summer building season BEGIN !!!!!  (In Comfort, I Might Add)

Okay, I have my air conditioner running in the garage, lets get back to building this plane!!!!

I bought some heavyweight painters paper (?) at Home Depot a while back so I decided to use this to cover the bench top while working with this gooey tank sealant.  I made a cutout around my back rivet plate so that I could find it.

To mix the tank sealant, I used some plastic cups I had laying around the garage.   (Do not use these to mix AKZO Epoxy Primer.  The hardener disintegrates/melts this type of cup)

I cut the cup down so that I just had about the lower 1/3 of the cup.  For working with the stiffeners, I found that if I mix 20 grams of sealant with 2 grams of hardener (10:1 ratio) that I had about the right amount of tank sealant.  You only have about an hour of working time with the sealant and for me, the tank sealant process was fairly slow.  By the time I got to the bottom of the 22 grams of tank sealant, it was already getting hard to work with.

To keep the tank sealant off of the areas where the ribs go, I used yellow vinyl electrical tape (Scotch 35).  This worked great !!!  It comes up easily, leaves no tape adhesive residue and it doesn't "splinter" like masking tape has done for me in the past.

My basic process for sealing the stiffeners went like this:

• Clean and etch surfaces to be sealed with a scotchbrite pad and Alumiprep.
• Rinsed surfaces and went over area with MEK.
• Soaked rivets in MEK.
• Staged a TON of RAGS!!!
• Smeared a light coating of tank sealant over skin of fuel tank where stiffener will sit.
• Flipped skin up and inserted rivets and secured with rivet tape.
• Placed stiffener into position and made sure the rivets were not "cocked".
• Back riveted stiffeners into place verifying shop head dimensions as I went.  (YES, I still check most of the rivets I set.  It is just the habit I got myself into early on.)
• Frosted up the edges of the tank stiffener to skin surface area.  I used a narrow spatula (equivalent to a small popsicle stick) to make a nice, relatively smooth fillet on all four sides of the stiffener.  (I didn't skimp with the tank sealant.)
• Totally encapsulated the rivet shop head in tank sealant.  (This is above and beyond, but I want to ensure NO LEAKS.)
• Cleaned up the surrounding area and removed excess tank sealant with MEK.
• Flipped the skin over, removed the rivet tape and cleaned up the factory head and tank skin surfaces.

Just a sampling of two completed stiffeners.  It is really hard to get in and clean up the stiffener between the rivet holes as you can see on the left.  I tried cleaning a couple of these up, but ended up making it look worse.  Did I mention this is like taffy that has been on the dash of your car on 100 degree sunny day?  It is stringy, gooey stuff.

I went through a ton of rags, rivet tape, latex gloves, and I polished off my first pint of MEK.

Just a snapshot after I was done with sealing the stiffeners and had everything more or less cleaned up.  Everything looked really good.  It was just time consuming for me.  I definitely will not be setting any speed records on the tank.  It took me a good 8 hrs to just rivet the stiffeners on and seal them.

Today, the weather was absolutely beautiful.  The hot temps and high humidities we have had over the last week were gone.  This made a great day for working in the garage on the plane.

First thing I did today was figure out where I was going to place the rivet holes for the T-410 reinforcement plate ( T-405, tank attach angle).  Van's does not give you any real information on where to put these rivet holes.  They just say "fabricate it".  I just tried to come up with the same number of holes they show on the print.

The key here is that if you are installing a flop tube, placement of these rivet holes more restrictive as you have to drill a 9/16" hole to accommodate the flop tube AN fitting.

Here are the rivet locations match drilled to the attach angle.  Everything looks pretty good here, however, the three holes in a line by the angle are a little close to the bend.  If I put the factory heads on the reinforcement plate side (T-410), I will have plenty for the shop head on the T-405 attach angle.  The big question is:  Will I be able to orient those rivets that way when it comes time to shoot them?

The other thing worth mentioning here is that the T-405 attach angle does NOT go all the way up to the flange of the rib.  The reason being is that there are rivet holes along the T-405 that sits on the flange of the rib.  I left room for the shop heads of the tank skin-to-rib rivets.  Van's instructions do not make any mention of this and if you are not thinking ahead (my typical problem), you could be inventing new cuss words later on.  I guess they figure that if you are this far on the plane, you should just know those things.  Okay, but I am going to miss something sooner or later.

I decided that I would install a flop tube in the right wing.  Therefore, I needed to drill a 9/16" hole into the T-405 attach angle, the rib, and the T-410 reinforcement plate.  Don't ask me why I drilled the attach angle in this orientation...  Ooohh yea, I remember why....  The drill chuck was going to rub on the attach angle when I went to drill from the other side.  I just used a couple of quick clamps and C-clamps to hold the angle to some scrap wood.  Worked great. 

Just another close up picture of the measures I had to take in order to drill this hole.

Hey, what do you know...  The flop tube fits.  I looked at my rivet hole placement to make sure that the rivets would not interfere with the flop tube AN fittings.

I left my holes as close to the edges as I could and I probably do not have any more than 1/16" from any rivet to the nut that secures the flop tube AN fitting.  Builder beware...

Next, I moved on to drilling the reinforcement ring for the inspection cover.  Nothing really high tech here.  To figure out how / where I was going to orient the plate nut holes, I used the aft flange of the rib and measured to the edge of two screw holes and rotated the plate until two screw holes measured equally.  Now ask me if it matters....  I don't think so.....

I then proceeded on to dimple the plate nut RIVET HOLES in the rib and countersunk the plate nut rivet holes on the reinforcement ring.  Note the location of one of the aft plate nuts highlighted with the arrow.  It sets right next to the tooling hole in the rib.  You cannot see this when the reinforcement ring is placed on the rib.  I would consider re-orienting the plate nut locations to give me more distance between the plate nuts and the tooling hole.

I had bought these floating, sealed plate nuts a while back with intentions to use them for the inspection hole plate nuts.  The idea here is that the inspection plate screws are sealed off from the tank eliminating them as a source of leakage.  If you need to open your tank up, it is no big deal as you shouldn't have to take any extraordinary measures to seal it back up.

I got these from Wicks Aircraft Supply.  (Floating Plate Nuts:  NAS1473A08)

Okay, I got all the plate nuts installed and was admiring my work.  These look pretty good.

The one trick here is that the rivet holes are so close to the screw cavity, it was difficult to rivet these on.  I could barely get the squeezer square.

Then I realized I had somewhat of a problem.  I held the rib up to the light and I could see light between the rib and the reinforcement ring.  Okay, why did I spend money on the fancy plate nuts if I am not going to have a fuel tight seal between the rib and the reinforcement ring?  There are four major locations where a leak can occur in the inspection plate area:

1. Gasket between the rib and the cover plate
2. Plate nut rivets
3. Cover plate screws
4. Small tooling hole that sits under the reinforcement ring.  It would be covered by the cover's cork gasket, but not by much.

Considering my options here, I decided tooooo.....  drill out all of the plate nuts and prepare for my first session playing with tank sealant.  I decided that this would be a good practice session.  Since it is really not required to be sealed, I didn't have anything to lose if the tank sealant kicked my butt.  I got prepped up for the NEW experience I was about to under take. 

1. I soaked the rivets in MEK
2. Scrubbed all my parts down with a scotchbrite pad and Alumiprep. 
3. Wiped down all my parts with a clean rag and MEK (not required if you cleaned/etched with Alumiprep).
4. Measured out and mixed up a batch of tank sealant.  (10 to 1) ratio using a digital cooking scale I got from Wal-Mart (Worked GREAT).
5. Organized my tools and equipment so I wouldn't have to go searching for them with messy gloves.
6. Recruited Tami to help clean parts as I finished.

I didn't get a lot of pictures while doing this as Tami doesn't usually want to run the camera.  However, today she thought that was a better deal that using the little spatula's to spread sealant.

Here I am only a little over half way done installing the 12 plate nuts for inspection hole.  Dealing with tank sealant was definitely a new experience.  Once the sealant gets on your gloves, you stick to EVERYTHING.  I tried to pick up a rivet and 10 rivets would stick to my glove. 

I frosted up the mating surfaces of the rib and reinforcement ring, clecoed them together.  I then frosted the plate nut flanges then clecoed them to the reinforcement ring.  Last but not least, I put a little sealant in the dimples for the flush rivet factory heads.

With sealant all over (by this time), I had a hard time finding my rivet holes and the rivets I put in them.  As sticky and gooey as this stuff is, try and put your squeezer on it.  It was like trying to hold a GREASED PIG.  The squeezer dies slid all over the place.  I couldn't believe it !!!

In the picture below, you can sort of see how messy this was getting.  I had to wipe some of the sealant off the shop heads after setting them as I wanted to see if I got the rivet set properly.  I gave up trying to keep this looking neat until after I got done setting all of the plate nuts...

I had Tami cut my painters rags up into little "swatches".  As soon as you get sealant on the rags, it was just better to toss them.  When dirty, they just smear sealant around.  A lot of trash for such a small sealant effort.

Here is what the inspection hole looked like after I got everything frosted up and cleaned all the excess sealant off.  Can you figure out what I forgot in the picture below?

Yep, you guessed it...  I need to install an anti-hang up bracket over the inspection hole since I am using a flop tube in this tank.  I will wait until the sealant sets, otherwise I would never get all the aluminum shavings out of that new sealant.  I couldn't even imagine....

If all goes well here, I have eliminated 3 of the 4 leakage paths I discussed above.  All I have to worry about is the large hole.  Van's has you seal the cover plate with a cork gasket.  I know some builders who use tank sealant to seal the cover plate and throw the cork gasket away.  I am not sure what I will be doing yet.