I marked and drilled holes to suit the port wing tip tank fuel drain, then ProSealed the insides of the aft bay in a neat fillet to encourage water to accumulate down in the receptacle. I taped off the opening and trimed a close-fitting hole through that to match the screw-in fuel drain so that it wouldn't end up bonded in place by any stray ProSeal. I applied a small bead of ProSeal to the lower edge of the receptacle, the rivets holes, the soft rivets and held it in place with the fuel drain, then bucked the rivets. Once that was done, I ProSealed over the top of the bracket and rivet shop heads inside the tank for good measure and double checked everything with the inpsection mirror.
Later I'll remove the drain and inspect all the drain holes in the receptacle to ensure they aren't blocked or obstructed by ProSeal.
