Section 18 - Fuel Tank (riveting stiffeners, et al.; next two Prosealing sessions)

Slowly, but surely, the left tank is coming together ... and the gooey Proseal is getting a little easier to manipulate. During these sessions, I first back-riveted the stiffeners and fuel filler flange to the skin, riveted the drain plug, and riveted various fuel and vent ports on the inboard aft rib. The second Proseal session included encapsulating rivet shop heads, while the third Proseal session involved sealing 7 ribs to the skin.  The latter took a lot of planning and testing to ensure that the ribs would hang without smearing Proseal all over the skin.  Details of that process are provided, below.

Riveted and Proseal-encapsulated the vents/ports on the inboard aft rib:

Back-riveted the fuel filler flange ... all except for one rivet, since I forgot to Proseal the bracket for the vent line during the first Proseal session.  It was sealed here:

Inside view, showing rivet shop head encapsulation as well:

Proseal-encapsulation of all rivet shop heads on the stiffeners:

Proseal encapsulation of all rivet shop heads on the fuel drain plug:

Another view of the stiffeners:

During the 3rd sealing event (7 ribs to skin), I didn't get a chance to take pictures during the process since I was elbow-deep in Proseal.  Here is the top of the tank, after sealing and fully clecoing.  For this task, I applied Proseal to the flanges on each rib (one at a time) and then started the "fay-seal" by clecoing each rib in the following order:  top forward hole (permits rib to "hang" from top skin), bottom forward hole, bottom second hole from front, top hole second from front.  Clecoing those 4 holes enabled each rib to hang essentially straight and makes all subsequent clecos easy to install.  Once all 7 ribs were installed with those 4 clecos, I moved aft on the top skin one row at a time (i.e. on all 7 ribs).  Once ~5 holes were clecoed, I then skipped every other hole.  Once the top skin was fully clecoed, I turned the tank over (making sure to keep the bottom skin away from the ribs), and then proceeded forward to aft clecoing one row at a time.  Then I transferred the structure to the leading edge stands, and finished clecoing every hole.  Finally, the inside of the flange-tips of outboard and inboard ribs were Prosealed with a thick fillet to make sure fuel cannot leak through the gaps between the flanges. For good measure, I also added more Proseal on the outside tips of those two ribs.  Here is top of the fully clecoed structure:

Inboard-most forward (tip) rib, clecoed and Prosealed:

The bottom of the tank:

Inside, showing the vent line bracked riveted and prosealed, as well as the fillet seal on the inner portion of the outboard rib tip:

Fillet seal on the inner portion of the inboard rib tip:

Belt-and-suspenders sealing of the outside of the outboard rib tip:

Workspace (butcher paper) with leftover Proseal from two sealing sessions ... looks like there might have been just enough to seal the j-channel stiffener (but I still may not chance it on the right tank, since I'd hate to run out midway through the process):