I pressure tested both my right wing tanks this weekend, my right auxiliary tank is fine (after I took it in the house to eliminate the temperature swings in my unheated garage). My right main showed a rather large leak almost immediately after pressuring up, so I took it back to the workshop, pressurized it to about 30" of water column, and ran the soap bubble test. Sure enough, only one leak found - coming out of the central stem hole of one of the blind rivets used to fasten the Z-brackets to the rear baffle and internal rib flange. The air was most definitely leaking through the center hole - not around the edge of the rivet.
These blind rivets have a sealed head that is supposed to stay sealed when the rivet is installed, to prevent this exact scenario. I did twirl all my blind rivet heads in proseal prior to installation, but obviously I missed getting enough on this one, or it scraped some off during installation AND the head covering cracked when it was pulled. I did not cover the heads of the blind rivets with proseal, since they are supposed to be self-sealing heads - so that's what I get for assuming the product will perform as advertised. I will certainly cover all the rest of the blind rivet heads on my two left wing tanks, and be very careful to over-coat the blind rivets with proseal before installation.
Has anyone else seen this happen with the self-sealing blind rivets?
To fix it, I pulled about 25" water vacuum on the tank with an aspirator and applied a drop of loctite to the center hole of the offending rivet. It immediately drew the loctite in until the liquid hit the leak point, at which it stopped drawing it in and has not pulled any more. I'll leave it as is for a couple hours, then restart the pressure test this evening.
These blind rivets have a sealed head that is supposed to stay sealed when the rivet is installed, to prevent this exact scenario. I did twirl all my blind rivet heads in proseal prior to installation, but obviously I missed getting enough on this one, or it scraped some off during installation AND the head covering cracked when it was pulled. I did not cover the heads of the blind rivets with proseal, since they are supposed to be self-sealing heads - so that's what I get for assuming the product will perform as advertised. I will certainly cover all the rest of the blind rivet heads on my two left wing tanks, and be very careful to over-coat the blind rivets with proseal before installation.
Has anyone else seen this happen with the self-sealing blind rivets?
To fix it, I pulled about 25" water vacuum on the tank with an aspirator and applied a drop of loctite to the center hole of the offending rivet. It immediately drew the loctite in until the liquid hit the leak point, at which it stopped drawing it in and has not pulled any more. I'll leave it as is for a couple hours, then restart the pressure test this evening.
