During T/E OUTB FLAP components inspection on B-737 3/4/500 you can find loose rivets on FLAP TRACK FAIRING FWD supports. It is not visible at first look, you can discover this irregularity by pressing upper plate opposite to the lower plate and check the gap between plate and web or you can find that the rivets have play. Some photos have been attached to explain this. Thanks to Josef, Czech Republic.