Reassemble fuel tank end ribs

It was decided to redo the fuel tank fittings. Contributing to this decision was: 1) the first time around the sealant was way beyond the nominal 2 hour pot life (more like 4 hours) and had to be stirred a lot to get it to settle into position. This had the effect of aerating the sealant to a noticable degree. 2) I did not rough up the surfaces of the fittings - sealant adhesion was possibly suboptimal. 3) I found that it was an easy matter to strip down the fittings and clean up to perfection with the use of methylene chloride paint stripper. 4) I needed to upgrade the bracing of the fuel return fitting.

So I re-did the fittings. I also made use of the decision to use the open ended rivnuts, so was able to complete this as well. I elected to seal the backs of the rivnuts by forming a blob of sealant. I inserted to bolt to the required depth though the rivnut to serve as a keeper while the sealand set. At this stage I was confident that removal of these keeper bolts from the grip of the sealant would not be an issue.

I also re-torqued the AN6 copper flared fitting of the fuel inlet filters to 120 in-lbs, after verifying positively that these flares were in fact formed to the correct 37 degree give or take.

I did not bother to mask the ribs prior to applying sealant, as I found from the previous experience that this was not of much utility.

Postscript 3 March 22: I also did not use Loctite 577 on the threads of the fittings. Instead I smothered the threads and nuts with flameseal and wrenched the fittings into place wet, forcing the flameseal into every cavity within the the threads, the washers, and the body of the fittings. Actually I misinterpreted the directions, but here is my after-the-fact rationale! I feel this one-part sealing method is possibly better to the two step process more-or-less stated in the manual: first use 577 to seal the fitting, second cover the nuts and vicinity of the fitting washers. In this scheme all washer and fitting surfaces are interfacing with flameseal rather than an uncertain combination of the it and 577. I am also concerned with the passive nature of all the materials concerned, the all aluminium fittings will not do a good job of activating the 577, which may remain in a semi solid state. There is the option of using 7471 activator (a copper salt) to trigger the certain hardening of the 577, but then there is the possible interference of activator overspray with any overlaying flameseal. The final part of my rationale is that the hardened 577 has no "give" in the event of a slight movement of the fittings, at least the flameseal might have a bit of compliance. The fittings are certainly tight enough, in fact such tightening served only to deform the very soft aluminium washers. The flameseal itself is enough also to prevent any loosening of the nuts, I believe.

Postscript 3 March 22: Further I did not use 577 on the fuel filter flare joint thread, as these are supposed to work dry. Like all flared fittings they are open at the end, and the B-nut only serves a clamping function. I will do the same for the fuel overflow tubing, which are also all based on flared joints. I may put a little flameseal over such B-nuts to hinder unintended loosening.