This log entry is just a cumulation of several shorter tank sessions.  I spent two separate nights sealing the inboard and outboard tank ribs and reinforcement plates.  Pretty straight forward, just really messy....

I ended up using the fuel pick-up tube that I fabricated a week ago or so.  It was long enough to clear the nutplates on the reinforcement ring.  It is not perfectly centered between the nutplate and stiffener.  What I was really demanding here is that the nothing touched and chaffed.  I tried twice to get a more centered fuel pick-up, but I wasn't any closer than this pick-up.  We are talking 1/16" difference here.  Precision tube bending....

Anyway, after I screwed on the inspection plate, I torqued the 6N fuel pick-up nut to 100 in-ibs.

I also torqued the vent line 4N fitting to 60 in-ibs. 

Notice that there are two wires on the inboard capacitive plate.  One connection goes to the outboard capacitive plate and the other connection goes to the BNC connector on the inboard tank rib.

Tank sealant for the inboard capacitive plate.

I applied sealant to the electrical hardware before I mounted the capacitive plate to the tank rib.  Made it a little easier to goop the tank sealant on and clean it up.

I fully encapsulated the outboard capacitive plate electrical hardware.

To attach the inspection plate, I used the cork gasket and "buttered" it with EZ-Turn lubricant and then placed it between the rib and the inspection plate.  I then attached the inspection plate with some 8-32 x 5/8" stainless steel socket head capscrews.  I wasn't able to torque them with a torque wrench, but I tried to tighten each screw equally by feel.

To finish off the fuel seal of the inspection plate, I topped the whole thing off with some tank sealant around the screws and the inspection plate.  Since I used EZ-Turn on the gasket, I removed all excessive lubricant as I doubt if the tank sealant would stick to it...   This is what I did with the right tank and I didn't have any sealing issues.

The only thing I have left on this tank is to get 1/2" of polypropylene tubing to insulate one of the capacitive plate mounting screws (long story), mount-solder-seal the BNC connector.  Then it is sealing the rear baffle plate and pressure testing.  Woo Hoo....

I was supposed to go flying this morning for some more solo pattern work.  My CFI (and me) wanted some more solo time since it has been 9 months since I last flew on a regular basis.  I am getting ready for my first dual cross country.  Long story short, the weather was cruddy this morning so out to the garage I went to do more tank sealing.

On the right tank, I used alumiprep and a scotchbrite to clean and etch the aluminum prior to sealing.  Although that works okay, you have to be really careful to get everything thoroughly rinsed off.  On this tank, I decided that I would just use MEK and a scotchbrite pad.  After I scrub the parts thoroughly, I wiped them dry with a clean rag before the MEK evaporated.

No in-process pictures here as it is to difficult when you are sticking to everything.  As with the right tank, I have installed and sealed the tank vent fitting, a vapor return line, and the sealed nutplates used to secure the inspection cover.  I go a little overboard with tank sealant, but it worked for me on the last fuel tank.  I fully encapsulate rivet shop head and around the perimeter of the sealed nutplates.  If I did a good job here, the only fuel leakage path is through that big hole in the center.

Just a close up of the tank vent and fuel vapor return AN fittings.  I torqued these -4D fittings to 65 in-ibs and then fully encapsulated the fitting around the nut and up the 2 (or so) threads.

Here are the vent fittings from the outboard side.

I couldn't get real motivated to do more work on the plane today.  Installing the components on this rib make for a messy day.  I am wearing tank sealant on my arms, clothes and legs.  How does that stuff get EVERYWHERE???

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, 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?

Between other home projects (and chores) this weekend, I was able to get a "6-hr RV-FIX" today.  I started by fabricating the anti-hang-up guide for the inspection plate.  To be honest, I cannot figure out what function this guide serves.  Checking other builder's web sites, it seems that they had the same question.  This guide didn't take long to fabricate, so I went with the flow...  However, I did turn this bracket into a Trigonometry problem (I knew all those math classes would come in handy for something).

I made the anti-hang-up guide out of .025" 2024-T3 scrap aluminum and cut it 3/4" wide (Van's calls out approximately 1/2" wide).  I tapered the ends that are clecoed to the reinforcement ring to the diameter of the large end of my sharpie marker cap.  (Can you see all the precision instruments that are involved here?)

Below is a simple drawing for my anti-hang-up guide for the inspection plate.  The diameter to the outside edge of the inspection hole reinforcement ring was 6.75".  I guesstimated that I wanted the anti-hang-up guide to be an inch high (just a measurement that was higher than the height of the sealed plate nuts on the reinforcement ring).  I was going to make the bend 60 degrees (just another number I pulled out of thin air).  From there, I used a little trig to figure out the hypotenuse of the triangle which turned out to be 1.15".  I marked the aluminum at those points and made my bends.  I used a protractor to obtain my 60 degrees and viola...  I have a symmetrical anti-hang-up guide.

After I fabricated the anti-hang-up guide, I made sure I could get my hand in through the inspection hole.  (I don't know why...  With the capacitive fuel senders, there is nothing in this first bay except the flop tube, back side of the fuel sender BNC, and the nut holding the tank vent AN fitting).  I set the anti-hang-up bracket aside as I will rivet the guide in when I make up my next batch of tank sealant.

I then put the fuel tank back together to finish some other miscellaneous activities.  The first of which was to look at interferences for the capacitive fuel sender plates.  The picture below is the outboard plate.  This plate needs to be notched to provide at least 3/16" clearance between the plate and the fuel tank stiffeners.  I more or less eyeball'd how much material needed to be removed.  To remove the material, I used a hand nibbler I bought a while back.  That thing worked GREAT!!!!  I was able to accurately control removal of material to within 1/16" and the nibbler does NOT distort the aluminum when it makes its cut. 

This picture is of the inboard capacitive sender plate.  It does not require any modifications to maintain the 3/16" between the plate and the other tank components.

Then to finish out the day, I countersunk all the tank skin to baffle holes.  With the tank assembled, cleco in the baffle plate so that the countersink cutter pilot has something to guide the cutter on.  Van's has you countersink the tank skin (T-701) AND NOT the baffle. 

The weather is supposed to turn HOT/HUMID and Jeff hasn't come out to the house to tie in my heat pump refrigerant lines and do the initial freon charge.  I am going to have to get on him about it.  Guess I can't push to hard when he is doing it for free.  If he doesn't come out tomorrow, I will probably be riveting/sealing the tank stiffeners.

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.

Tonight's goal was to put a couple of hours on the plane without having to think too much...  For my fuel tank cap, I went with Van's deluxe locking fuel cap.  These fuel caps are very nice (and spendy).  These use a different filler flange than Van's stock fuel caps that are shipped with the wing kit so these deluxe caps have to be installed at the time of tank construction.

Because they are lockable, the fuel cap is oriented in definite locations (it can be locked down every 90 degrees).  So the idea here was to get the cap centered in Van's pre-punched hole and to have it oriented so that the latch is pointing straight aft (or forward) and not at some screwball odd angle.  The filler flange is angled so that it follows the curvature of the tank.  So orienting the flange is not to difficult.  If you are rotated out of position a couple of degrees, you can tell as it doesn't feel like it fits correctly up against the skin.

It should be noted at this stage, my fuel tank is clecoed together, but I have removed the inboard rib (T-703) so that I could use some simple clamps to hold the flange in place until I got a couple of holes with clecoes in them.

Below, is a far off shot showing the alignment of the fuel cap position .  I even had Tami come out if do some quality control for alignment in case my eyes were on crooked today.  To double check our eyeballs, I took a straight edge and ran it centerline from the forward to aft rivet holes and verified that the straight edge intersected the center of the latch rod and the little finger lip on the latch.

I just took it slow, drilled a hole, clecoed it, and made sure the hole I drilled was in the center of the fuel filler flange.  Went to the next hole (180 degrees out) did the same thing.  As I added clecoes, I took off my other clamps.  So far so good.

If you look at the filler flange, you can see the notches in the flange every 90 degrees.

After I got all the all the holes drilled, I inserted the fuel cap to make sure that the tank skin didn't interfere with the cap.  In the picture, it looks like it is not perfectly centered.  It must be the angle I shot these pictures because when I was putzing with this, it was perfect (thank goodness).  In the picture, the fuel cap is unlatched and you can see the keyhole.  Van's has put a little forethought when shipping these locking caps as they sent me two that were keyed alike.  Yes, you have to buy them individually.

Pictured below, you see the cap is latched and the latch is bent down (in-flight mode>>>   SOMEDAY).

While I was at it, I decided to countersink the fuel filler flange holes.  I made a test coupon out of some scrap aluminum.  However, for this coupon, I used my tank dimple dies (Cleaveland Tool Part #: DIE4263T) as I wanted a slightly deeper countersink to account for use of tank sealant.  The tank dimple die is supposedly .001" or .002" deeper than the standard 3/32" dimple die.

I don't particularly like countersinking as I have a difficult time getting consistent results with micro-stops.  Tonight, all holes looked really good...  I couldn't be happier.

Just a little anatomy lesson on these locking fuel caps.

Do I really need to go into more detail here???

I had a little time left before I wanted to quit for the night so I decided to cut out the tank access plate.  The first thing I was challenged to do was to determine the center of the hole being cut.  I tried to apply a little Geometry 101 here.  What I did was take two measurements 90 degrees apart with a machinists ruler.  I fixed one end of the ruler (with my finger) and then pivoted the opposite end.  At the maximum diameter, the ruler would intersect the center of the circle.  Do that again displaced by 90 degrees and viola, you have the center of the circle.

Okay, the center of the cutout has been determined...  Next, I had to adjust the cutter radius to get the proper diameter cutout.  I measured the INTERNAL diameter of the T-407 reinforcement ring.  Van's gives you the external diameter of the ring and you could subtract to get the internal diameter, but my way was just as easy.

After about 30 seconds of shaking the table with a spinning circle cutter, the damage has been done.  I de-burred and took 400 grit wet/dry sandpaper to finish the edge of the hole.  It turned out GREAT....  WooHooo!!!!