We studied and picked brains from as many sources as we could about fuel tank cracking. First and foremost probably not a great idea to let tank dry out once fuel in it for a while. Old nonflorinated tanks probably worst?? This exercise is an attempt to make us feel better that we do not get tagged with a cracked tank, although we have procedure down "When" we have to replace it. Top of tank and forward we foamed with no release. Then we 3 BID center tunnel with CPM in place, baggage bay not yet installed though. Then we put mylar between tank and fuse and foamed it. No bulge at all. No picture after trim job, but in all it looks "Much More Better", to us anyway in ability to relieve stresses.
