Tami and I finished sealing the rear baffle plate on Monday.  So today (Saturday), I decided to pressure test the fuel tank to see if my tank sealant days were over.  As I did with the right tank, I set up a tygon tubing manometer to monitor the tanks ability to hold a slight air pressure.

The idea here is that when you pressurize the fuel tank with low pressure air, the air will push on the water in the tygon tube and in this case, push the water up the 4" x 4".

I just secured the tygon tubing to the 4" x 4" and jammed a funnel at the top so that I could pour in the food colored water.

Using a manual bicycle air pump connected to a schraeder valve in the tank drain fitting, I pumped air into the fuel tank until I had approximately 20" in difference in the 2 column heights of water.  I marked the height of the water, the time, and the temperature.   A one degree change in room temperature was resulting in a change of approximately 1" in the height of the column of water.

After I initially placed pressure on the tank, level was very slowly lowering.  Ooh GREAT, my worst nightmare has come true, a leak that will be a pain to fix.  However, before I get to negative about the whole thing, I decided to check the fuel tank cap since it is a pretty big hole.  I have the more expensive locking fuel caps and the first tank gave me no problems.  Anyway, I see that their is a nyloc nut on the inside of the cap that controls the amount of pressure exerted on the cap and flattening a rubber washer.  I decided to tighten that up just a hair (I ended up turning it about "1-flat" on the nyloc nut).  I re-installed the cap, re-pressurized the tank and voila.....  The manometer was holding steady ...

I just sat a thermometer near the tank so that I could keep an eye on the temperature vs. water column height.

UPDATE:  I checked on the fuel tank the next morning (20 hours +) under pressure and the manometer level only varied a inch or so and this morning, it was higher than when I marked it yesterday.  I am going to call the tank good...

After I decided the tank was sealed, I removed all the manometer hardware and installed the tank fuel drain.  I torqued the fuel tank drain to 60 in-ibs.  As soon as I get some other miscellaneous wing stuff done, the tank will be ready to install on the wing.

I opted for the deluxe locking fuel cap when I ordered my wings.  I am extremely happy with the quality of these filler caps.

Now that my tanks are more or less done, I can work on a ton of other miscellaneous wing stuff I need to complete so I can get started on the fuselage.

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

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....

Well after a little sleep, work, and time to reflect on my vent line problem, I decided to see if I could rectify the vent clip problem today when I got home from work.  I fabricated a new vent line clip from aluminum sheeting that comes with the wing kit.  This is all pretty straight forward.  I liked how my last clip lined up with the vent line and held the vent line pretty high in the tank.  I strived to repeat that characteristic.

After repeated installing of the clip and some time on the scotchbrite wheel, I got a vent clip that sat pretty nice on the fuel filler flange.

My bigger problem was how was I going to set a solid rivet in this NARROW space.  Like I stated in earlier log entries, I used the rivet hammer and the back rivet attachment to form the shop head.  Well, that wasn't going to work here as I could no longer open the tank skin far enough to get the rivet hammer in there.  The only thing I could come up with was to remove my 3" yoke from my squeezer and use it for a bucking bar.  This worked pretty good (for doing 1 rivet).  I got a nicely formed shop head.  The vent clip and the filler flange looked good.  The hand holding the "bucking yoke" took a little hammering, but it was only one rivet.

It is a tight space and even as thin as the yoke is, it barely fit.

I mixed up a really small batch of tank sealant to encapsulate the filler flange, rivet, and vent clip.  I was pretty generous here as I certainly didn't want to have to try and fix a leak after the rear baffle was on.

While I was at it, I tried to push some tank sealant between the vent clip and the vent line to hold it in place and kind of work as an "anti-chafe" cushion.

It all looked good when I was done.  I decided to wait to rivet the outboard end rib until I am sure that this vent line is NOT BROKE, secured to the filler flange, and fully sealed.  I decided to call it an early night.

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.

Tonight I was going to fly to the local EAA Chapter 80 meeting in Omaha, but I got a wild hair to knock out another session with tank sealant.  Since when is sealing fuel tanks more fun that going flying and talking about airplanes????  I must be breathing to many MEK vapors.

Now that I have my fuel pick-up fitting and anti-rotation bracket mounted to the inspection cover, I installed my newly fabricated fuel pick-up tube.  It fit better than Van's original pick-up tube, BUT....  I still am not super happy with the clearance between the tubing and the nutplate.  They don't touch each other, but that can't be more than the thickness of a couple of sheets of paper between the two.

I think that I am going to fabricate yet another fuel pick-up tube.  As you can see there is plenty of clearance between the stiffener and the tubing, but I had to work hard to see that the tubing and the nutplate don't touch.

Otherwise, I am really happy with how the fuel pick-up sits in the fuel tank.

The fuel pick-up sits nicely along the end rib and clear of the tank drain.  I guess this is a good example of why it is a good idea to sump your tank before flight.  If there is any water in the tank, the fuel pick-up sits very near what would be the lowest point in the tank when on the ground.

Anyway, I had enough tubing to attempt two new fuel pick-up fabrications.  I had one absolutely perfect so that the fuel pick-up was nearly centered in the clearance between the fuel tank stiffener and the pesky nutplate.  However, YOU MUST REMEMBER that when working with tubing, you must put the AN sleeve on AFTER you make the bend in this tube and BEFORE you flare the end.  I made that same mistake X2!!!!!!! Dam-it....  It only cost me about 2 foot of tubing (a whole $1.38), but it was the last 3/8" tubing I had.  Okay, time to surf Wicks Aircraft Supply.

Okay, now that my fuel pick-up is not a done deal yet, I decided to move onto prepping and sealing the fuel tank filler flange and vent tubing clip.  I had everything ready on the fuel filler flange, so all I had to do before sealing was to finish fabricating the vent line clip.

I made this clip a fair amount shorter (less than 3/4", but noticeably shorter than the right tank).

When I clecoed the vent clip to the filler flange, I looked down the tank and it lined up almost perfectly with the tooling hole for the vent line.  In the background, you can see my vent and fuel return fittings on the inboard rib.

Where the vent clip butted up against the neck of the fuel filler flange, I radiused it slightly.  My thought here was to allow it to "hug" the neck of the filler flange which would keep it from twisting.  The vent clip is only held by one rivet and it doesn't take to much effort to twist it.  It is kind of a mute point after you put the vent line through it.  It becomes pretty immobilized after that.

Pretty happy how this is looking so far.  Alright, where's the tank sealant?

Let the sealing fun begin....  I am rather generous when I put on tank sealant.  I have seen builders who have really small fillets and sealant lines that look like a work of art (which is very difficult if you have ever worked with this messy, sticky stuff).  Then they go to leak test their tanks and sure enough, they leak.  My approach has been to fully encapsulate rivet heads and flanges.  What I work hard to stay away from is to have "stringy" messes all over the inside of the fuel tank.  Those little chunks of sealant that can become dislodged and make their way to the fuel pick-up.

I got the fuel filler neck riveted and sealed.  Then I spent about as much time again cleaning the area so I had none of those small, stingy, blobs of sealant I was talking about.

Nothing is fun about riveting this flange in.  Van's calls out AN426AD3-4 rivets for this fuel flange (when you are using the kits standard, non-locking flange).  The problem is that I upgraded my fuel cap to the locking style which has a different flange.  It is thicker on the sides and thinner on the forward and aft sides of the flange.  I reviewed my log entries for the right fuel tank and I didn't make any mention of trouble with rivet length.  It was clear that the rivets Van's called out were going to be to short in some of the areas around the flange (see my rivet call out below).

I saved the forward rivet that holds the vent clip until last.  This rivet gave me a hard time on the last tank and on this tank, I didn't have any problems.  As I detail in my right tank, the best solution I could come up with for riveting the forward rivet that holds the vent clip was to use the rivet hammer with the back rivet attachment on the shop head side of the rivet.  I used the bucking bar on the skin side of the rivet.  The reason I saved this rivet until last, was that in order to get the rivet hammer on the inside of the tank, you have remove the fuel tank from the cradle and set the skins on the table.  The tank skins open up enough to get the rivet hammer on the inside.

Here is my unofficial rivet call out I used for my fuel filler flange.  The 3-5 rivets were a little long, but the 3-4.5 rivets were a little short.  Why does it have to be so complicated?  I ended up bending over one of the 3-5 rivets, so I did have to drill one rivet out.  That was better than last time, when I drilled the same rivet out 3 or so times.

I should have went up to the EAA meeting.....  I feel pretty good about having the fuel filler flange riveted and sealed.  One more tank sealant session behind me...  WooHoo...

Tami is in Minnesota again as her mom is back in the hospital.  She had promised me to spend all day working on sealing the left fuel tank.  Family takes priority, so I just worked on tank things that I can work on without her help.

In the right fuel tank, I put in a flop tube.  in the left fuel tank, I decided to stay with the conventional fuel pick-up called out by Vans.  I am also using capacitance fuel senders which means I will be using the "blank" inspection cover.  Therefore, the first thing I needed to do if figure out where to drill the hole for the fuel pick-up AN ELL fitting.  I had also purchased the pre-fabricated fuel pick-up from Van's (see second picture below).  To see where I stood on fuel pick-up location, I used the standard inspection cover that you would use if you were installing float sensors.
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I then installed the pre-fabricated fuel pick-up and immediately noticed a slight problem with routing of the pick-up.

I modified my nutplates from the standard kit in that I ordered sealed nutplates to eliminate all these screws as a possible leakage path from the tank.  However, the pate nuts interfered with the location of the fuel pick-up line.  The tubing was just to short to go between the skin, stiffener, and nutplate.

This obviously is not going to work with the ELL fitting in the same location as on the standard inspection cover plate.  I figured that I had to come down about an 1/8" to route the tubing under the nutplate.  So I tried to drill out the ELL fitting hole lower, however, when I test fit the ELL and the pickup tube, I didn't move the hole down far enough and I still had an interference problem with the pick-up tube and the nutplate.  Therefore, I am going to have to fabricate a new pick-up tube.

Well, now that I was committed to the hole in the inspection plate, I began to fabricate the anti-rotation bracket.  I actually cut the angle at 1 1/4" instead of the 1" called out by the plans.  Van's only gives you 2" of this angle to make two anti-rotation brackets.  Since I didn't need this on my right tank, I had some extra angle to work with so I just made the bracket a little wider than called for.

In order to properly place the anti-rotation bracket, I drilled the 9/16" hole for the ELL per Van's dimensions and then did the following to ensure correct placement and orientation since the ELL will not be able to rotate once the bracket is drilled and riveted to the inspection plate. 

• I put the ELL back into the original inspection plate (for float senders) as it has the two holes pre-punched where you would rivet the anti-rotation bracket to the inspection plate. 
• Centered the ELL fitting between the two #40 holes for the rivets to secure the anti-rotation bracket.
• Drilled #40 holes in the anti-rotation bracket.
• Removed all the hardware from the original inspection plate and installed it on the blank inspection cover plate.
• Installed the inspection plate back on the fuel tank and inboard rib.
• Installed the fuel pick-up line and oriented the fuel pick-up so that it wouldn't chafe on the nutplate or the tank stiffener.
• Tightened the ELL fitting so that it would not rotate if I bumped it and verified alignment of the fuel pick-up.
• Removed the inspection plate from the tank and put in the vise.
• Installed and clamped the anti-rotation bracket to the inspection plate and drilled out the holes between the Inspection plate and anti-rotation bracket to #40.  Replace my clamps with clecoes.
• Once I checked it over and was happy with alignment, I drilled out the holes to their final size of #30 since Van's calls out using a AN470AD4-6 rivets to secure the anti-rotation bracket to the inspection plate.

Ooh NO!!!!  Getting ready to deal with nasty tank sealant again.  I will be glad when my tanks are DONE!!!

I planned on doing a lot of little tank sealing activities.  I.e.: tank drain, end rib hole plate, inspection plate fuel pick-up hardware and sealing the new fuel pick-up tube screen.

I started on the tank drain fitting.  Hopefully, I remember how to do all this.  I took a scotchbrite pad and MEK and cleaned / roughed up both surfaces to be sealed.

Ditto for the inside of the skin.  When sealing here, I made sure that each rivet was fully encapsulated and that there was space between each "blob" of sealant so any moisture would be sure to find its way to the tank drain.

I dipped each rivet in sealant and made sure that when I clecoed the tank drain flange to the skin, that I had sealant ooze out all the way around.  My theory was to make sure that I had enough sealant between the flange and skin so as to not have any leakage paths.  I had really good luck by having no leaks on the right tank.  I hope I can repeat that on the left tank.

This is a hole that has to be covered and sealed on the outer most rib on the fuel tank.  I fabricated a small plate, riveted it with two rivets and placed a big glob of tank sealant over the cover plate.

I also place sealant on the factory head side of the rib.

The fuel pick-up ELL and anti-rotation bracket.  Just make sure that you DON't rivet the anti-rotation bracket in place before you install the ELL.  It's a "cart and the horse" kind of thing. 

I placed spacer washer is on the OUTSIDE of the inspection plate.  I placed tank sealant between all the surfaces, torqued the ELL fitting and nut to 130 in-Ibs and then covered the whole assembly in tank sealant.  As with all my tank rivets, I fully encapsulated the factory head for the anti-rotation bracket (which is on the outside of the inspection plate).

This is my new fabricated fuel pick-up.  The tubing on the one Van's sent me was to short to make it around the inspection nutplates.  So I saved the AN fitting and the screen and fabricated a new length of tubing.

Underneath the tank sealant for the screen, I safety wired (.032" safety wire) the screen onto the end of the fuel pick-up tubing.  There is a #40 hole through the end of the tubing that the safety wire is run through and then twisted.  I "packed" tank sealant around the end to help secure the screen.  Looks just like the one Van's had originally sent me.

Arrrggg, this is only the beginning of sealing this tank.  Everything I touched for the next hour had sealant on it.  Hands, TV, tools, etc.  This is some messy stuff.

After I got done cleaning up my mess, I decided to get the Cherokee out and fly up to Plattsmouth (KPMV) to see how Kevin Faris is coming along on his RV-7.  He is a lot closer to being ready to fly than I am.  I am really envious of his current status.  I will get there someday.  Sorry, no pictures.

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???

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....

We are getting ready to head to Airventure for a couple of days this week so today's goal was to get all the miscellaneous tank prep work done so that when we come back, we could start sealing this darn thing up.  I will be so glad when I have the fuel tanks behind me.

This morning, I started by match drilling all the holes.  Using the sharpie marker to track which holes have been drilled has worked so well for my absent mind, I continued to use it when drilling the fuel tank.  You quickly forget how many holes are in this tank until you have to drill and debur them.

In the picture below, I placed a 2 x 4 scrap behind the screw attach holes and then drilled them out to size #19.  The 2 x 4 worked well to hold the skin and prevent it from chattering.

Next, I clecoed the stiffeners to the tank and labeled them with the same labeling convention I used on the right wing.  'A' = forwards, 'B' = aft and 1-6 from inboard to outboard.  Then I match drilled all the stiffeners.
Are you starting to see a recurring theme with this prep work????

On to the fuel drain.  When I had it positioned where I wanted it, I used a set of vise clamps to hold it in place.  I lined up the drain flange so that the forward and aft rivet holes were equally spaced from the edge of the skin.  It doesn't really matter, I just like a little symmetry and this is how I lined up the right tank drain.

Looks pretty good from this picture.

Next it was onto the fuel cap.  Since these are locking caps, the flange has a definite orientation (one because the filler neck is curved to line up with the skin and TWO, the locking cap has to be oriented in a specific location so the filler cap sits in the flange correctly.  See my right fuel tank log entries for more detail).

Drilling this flange kind of made me nervous as these fuel filler caps are not all that cheap.  $90 a piece.  All I need to do is mis-drill this filler flange to piss me off.  Everything has gone great since starting this right wing.  I didn't want to make my first mistake on the wing here.

Can't forget to machine countersink the filler neck flange.  I used my test coupon with the tank dimple die to set the countersink to the proper depth.

Then it was onto countersinking the tank skin where it is riveted to the rear baffle.  Just cleco the rear baffle in place to give the countersink pilot a guide point.

I countersunk the rivet holes a couple of thousandths of a inch here to allow for tank sealant between the tank skin and the factory rivet head.

Just a staged photograph what I worked on today.  I got so busy, I forgot to take pictures as I went along.  It is kind of boring anyway....  You know the routine: drill, debur, dimple, repeat....

Things yet to do before sealing:

1. Debur outside of skin
2. Dimple ribs
3. Dimple Skin
4. Dimple stiffeners
5. Drill ribs for capacitance senders
6. Fabricate vent clip (make 2 in case I screw up the first one while riveting)

After Tami and I got the leading edge riveted together, I decided that I would jump right into working on the fuel tank.  On the right wing, I started working on the landing light right after I riveted the leading edge together.  However, Tami and I are dreading the left (AND FINAL) fuel tank work.

Tank work tonight went really fast because I had already cut the inspection cover hole in the rib when I worked on the right fuel tank.  All I had to do is layout the reinforcement ring, clamp in place and drill for the nutplate holes.

#40 for the nutplate rivet holes
#19 for the nutplate screw hole.

As for orientation of the reinforcement ring, I decided to orient the ring exactly like I had for the right fuel tank.  As with the right fuel tank, my particular orientation places a nutplate in close proximity to the ribs aft tooling hole.  I had concluded on the right wing that the nutplate proximity to the tooling hole would not be a problem.

Here I have just completed drilling all of the nutplate holes in the rib and reinforcement ring.

One thing to note here that I did not discuss during the right wing was a minor "style point".  When I cut the hole in the rib for the inspection cover, I did not get it exactly matched with the diameter of the reinforcement ring.  IT WAS REALLY CLOSE, but not EXACT.  So I loaded up the die grinder with a rotary burr bit and "chased" the hole until I got the inspection cover hole on both the rib and reinforcement ring the exact diameter.  To polish the edge off, I switched the die grinder to a 1" unitized Scotchbrite wheel and put a nice finish on it.  I know....  you can't see it after the inspection cover is on, but I like to show some "craftsmanship" when things finally go together.

A picture below showing my progress so far tonight.  As with the right fuel tank, I have two 4D ELL's, one for the tank vent fitting, and the other for a fuel vapor return line (lower ELL fitting).  Last but not least, I cut the hole for the capacitance sender BNC fitting.

Since I didn't have to cut the fuel tank attach angle (that took almost 2 hrs to cut out during the right fuel tank), I could go right to drilling the attach angle to the rib and reinforcement plate.  The one thing I did on this fuel tank that I didn't do on the right fuel tank was to put the holes that run along the aft side of the angle farther away from the angle.  I am not installing a flop tube on this tank, so I don't have the added problem of needing to clear a 6D ELL fitting and nut.  This lets me put rivets wherever I want (more or less).

Just a picture of the reinforcement plate that will be riveted to the inside of the inboard rib.

I am almost ready to start sealing the inboard rib hardware in place.

Tomorrow, I should be able to fabricate all the outboard rib reinforcements and aft tooling hole cover plate.  My goal is to get the fuel tank ready to seal before we leave for Airventure next week.