THANKS LARRY - NEEDED THREAD
I have a lot of hours now ( over 200 ), and likely was one of the first to have this problem. When I first found it, like Larry said, I thought I had made a mistake, and added Loctite 'blue', and did all 4. ALL 4 were loose. I Dremeled out a large enough section of the airduct to give access. I 'glued' the piece back in place and went on. The SECOND mistake I made was to not go back and look at the instructions to see if Loctite was called for. I ASSUMED it was, and I just made a mistake. That mistake was almost worse than the first. After Tony T. sent us a note a few days ago, I realized I made the biggest mistake of all, not telling others of my problem originally. 2 or 3 wrongs does not make a right for sure ! Since I put Loctite on mine ( several months ago ), mine have not moved. I used a marker pen and 'marked' all 4 bolts so I could see if the bolts moved.
We now know at least 7 of us early builders who have had this problem. IT IS A PROBLEM !
THIS COULD BE A MAJOR PROBLEM. Check them and forward the info to Van's.