Originally posted by Jim_McIntyre
For example, just this weekend I was told by an ex student of mine about an ARF seaplane they bought. The engine pylon wasn't glued in! It was tight enough to fool them during assembly but, on maiden, full throttle pulled it out! Luckily no one was hurt! 
Hi Jim,
Yeah - I've seen some ARFS that are not as well built as I would like - but unfortunately the same goes for kit builds. Regardless of who built it, there may be errors that need to be addressed.
Note that just because someone chose an ARF for their trainer, that doesn't mean that you consider it ready to fly when he drags it out to the field. Typically when a beginner brings an ARF trainer to our field, and asks for help flying it, the first thing I do is tell them that we need to
thoroughly check their airplane over, and that there is a very good chance that some things will need to be redone. If we can redo it at the field, great - but don't be surprised if you don't get to fly your new plane today. Then I systematically check every part of the airplane that I can -
while explaining to the new guy what I am looking for, why, and how to fix any defects that I find.
He learns from this process (some quicker than others!), plus I get a level of confidence about the integrity of the airplane I am about to fly. I yank and twist on the engine to see whether the firewall or engine mount moves, I try to pull the control surfaces off of the airplane, check how well the fin & elevator are attached (typically suggesting that tri-stock be added at the tail surface to fuz joints), check whether he loctited various parts, examine the quality of the joints between fuz sides & bulkheads, etc., etc. Then I try to I drum it into the guy that because vibration, flight loads etc may cause issues to show up later, we will redo these checks after the very first flight, and then they should be redone periodically thereafter.
In addition to letting me have some confidence in the aircraft, this process teaches him about the things that are important to check. When he gets his next plane, we'll do the same - and so he is schooled in checking for the aircraft's integrity, and should spot issues like an unglued engine pylon on his next plane... unless he's been totally ignoring everything I told him ;-)
Now, granted - there are some things that I can not
fully check - e.g. the inside of the wing because of it being covered. However, by twisting the wing slightly and watching how the covering moves I have been able to detect ribs that were not glued to the spars in one case - and that was actually a kit built aircraft (CG Eaglet), not an ARF - so any building issues that are hard or impossible to detect during your inspection apply to a completed kit as well as to an ARF.
Later,
Gordon