Fuel Tank Assembly Continues

 

This afternoon I continued with the assembly of the fuel tank.  I set up the work tables on the driveway and organized the tools, parts and supplies to continue work on the tank.  I started by using the Dremel tool with a cut-off blade to cut off the stems of the blind rivets that did not break off properly.  The Dremel tool made quick work of the project.

 

I then mixed about 1.5 oz of Pro-Seal.  Using the digital scale it is pretty easy to get the proportions correct.  After mixing the sealant I spread a thin layer on the side and bottom edges of the rear tank skin.  I used clecoes to hold the top corners of the rear tank skin in place.  I then installed rivets along the bottom and then the edges of the rear of the tank.

 

After riveting the bottom and sides of the rear tank skin I spread a thin layer of sealant on the aft tank mounting bracket and clecoed it in place.  I used the specified blind rivets to attach the lower portion of the mounting bracket.  I then put sealant over the holes and installed the 7-each aluminum rivets in the top of the aft mounting bracket.  I used the rivet squeezer to set the aluminum rivets.  Of course with the sealant it got pretty much all over the place.  After squeezing the rivets I put sealant over the inside of the aluminum rivets and in the aft lower corners of the tank.  I also applied some sealant on the exterior corners seams to make sure they are fuel tight.  I drilled new #30 holes near the top of the 2-baffles and installed new blind rivets with washers as called out in the drawings.  I missed doing this when I installed the baffles.  I think they we be OK now.  

I set the tank upside down on top of the fuselage so the sealant can cure.

 

I went into the shop and prepped the fuel sender attachment ring for installation on the forward end of the tank.  I deburred the edges and countersunk the holes for nutplates.  I then installed the nut plates.

The final assembly today was the  Res Sending Unit float and attachment to the fuel sender attachment ring.  I used the bench vise to bend the float wire to the shape shown on the drawings.  I then  cut off the end, leaving ¾" as shown and snapped the wire in place on the sending unit.  I then used the correct screws to attach the sending unit to the attachment ring.  After the Pro-Seal cures for a couple of days I will attach the ring to the tank and make sure the float on the sending unit is adjusted properly. 

Fuel Tank Assembly

 

This afternoon I started to assemble the fuel tank components.  I started by setting up the work tables in the garage.  I gathered the parts previously prepped for assembly and placed them on the table.  I also gathered the supplies and equipment necessary to mix and spread the Pro-Seal fuel tank sealant.  I set up the digital scale, MEK, paper towels, putty knife, tongue depressors, popsicle sticks, nitrate gloves, etc.  I used the scale to measure out the Pro-Seal in a 10:1 ratio.  The stuff is not extremely smelly, but it does have a bit of an odor.  I mixed about 3 oz of material.  I have used Pro-Seal before so I know how to work around it.  The key is to keep things as clean as possible.  During the afternoon assembly session I used 5 pairs of gloves.  The main reason for disposing of and changing gloves is because they somehow get a hole or tear in them and then fall apart pretty quickly after that.  I have found by using paper towels and MEK to clean-up any smears or smudges of Pro-Seal it really makes a huge difference in how clean the work progresses.  

 

I spread Pro-Seal on the fuel flange and the edges of the forward tank bulkhead and clecoed them in place.  I then used the hand rivet puller to set the rivets on the bottom of the tank.

 

Next I riveted the left side.  I turned the tank upside down to see how things looked in the interior.

I observed a sealant bead at all of the seam and all of the rivets.  I can only assume the pieces are being sealed properly. 

 

I installed the forward mounting bracket and started to work on the baffles.  I became  a little frustrated with the rivets used to attach the forward mounting bracket.  There are 19 AK-42 rivets attaching the forward bracket.  As I pulled them, 11 of the rivets broke off about ½" above the head.  After the Pro-Seal has cured for several days I will use my Dremel tool with a cut off wheel to cut them off at the heads of the rivets.  I have heard of other builders having a similar experience pulling rivets.  I guess these must be part of a bad batch.  I'm sure I am not alone in this frustration.  

 

The next step was to install the bulkhead fitting in the bottom of the tank.  This is the fitting the return line will attach to under the tank and then a ¼" line will be run up to the underside of the tank top and up the filler tube.  That will be done in a future work session. 

 

Next came the baffles.  After riveting the baffles in place I place I filled the indicated corners with Pro-Seal.  This stuff is really messy.

 

I finished this work session by removing the blue film from the aft tank bulkhead and aft mounting bracket and prepped them for assembly.

I set the partially assembled tank aside to cure for a couple of days.  I realized at this point that I have inadvertently left 2-washers out of the assembly of the baffles.  They were to be installed inside of the tank at the top of the baffle attached to the forward skin and the left skin.  I have decided I will drill an additional hole and install an additional rivet with a washer in each of these baffles during my next tank assembly and sealing session.

Fuel Tank

 

This evening I started work on the fuel tank.  I spent some considerable time rounding up the parts for the tank assembly.  They were scattered about in the shop and out in the garage.  I located everything and began working on prepping the parts for assembly.  I started by countersinking the holes in the T-407 attachment ring.  I also used a Scotch Brite pad to prep the ring and the front wall of the fuel tank.

 

I then clecoed the front wall of the tank, the attachment ring and the required nutplates together.  I used the rivet squeezer to set the rivets in the holes.  It is good to be building again.

 

Next I deburred and prepped the fuel flange which will be attached to the bottom of the tank.  I also prepped the forward tank mounting bracket.  I countersunk the rivet holes in the ends of the mounting bracket for the nutplate rivets.  I then used the #30 countersink to prep the row of holes at the lower edge of the forward tank mounting bracket.  I riveted the nutplates to the ends of the bracket and deburred all of the edges.  I then stripped the blue vinyl film from the main tank part which includes the bottom and 2-sides all in one.  I prepped the mounting surfaces of the main tank part with a Scotch Brite pad.

 

 

After setting up the small work tables in the garage I put the parts on the tables.  I clecoed the parts together to be sure everything fits properly.  I am now ready to start mixing the Pro-Seal and rivet the parts together.  

 

After reading ahead I pulled out the tank baffles.  They will be attached to the bottom and front wall of the tank.  I then took everything apart and set the pieces aside.  I will start the tank assembly tomorrow evening.