I was lucky enough to get the SB before paint so changing to #8 screws wasn't that big a deal. Even if I had been in paint I would have done it. First, that is the most vulnerable area in the ES design. Second, almost all SBs are the result of people experience in the field. Do what you can to save the paint, but implement the bulletin. If you carefully enlarge the countersink you may be able to do it without chipping the paint.
This thread was called "oxygen tank location", but perhaps this is enough of a change of subject to justify changing the title.
I have an ES and the access panel was already installed as part of the "fast build," so I left it alone. During the building process I received a bulletin that recommended changing the #6 screws to #8 in order to increase the strength and stiffness of the access port. I didn't do it, but I wonder if I should have. Of course, now there is a paint issue, but maybe the structural integrity issue would make it worthwhile changing. I could also add the large stainless washers to it and that should further increase the strength - and hurt the styling. Should I change these out? Note that the ES has a much larger horizontal stab and therefore might be
more sensitive to fuselage structure than the IV.
Gary Casey
We have a classic example in the IV-P world where some builders decided it would be nice to have the aft fuselage inspection panel hinged and latched for easier access. Turns out this panel is a part of the fuselage structure, and not mounting it with multiple screws, as specified in the plans, weakens the rear fuselage. At least two IV-P’s have developed structural cracks from the opening back to the horizontal
tail. As far as I know, we’ve not lost an airplane due to this, but on the other hand, we’ve probably been lucky… To the casual observer, this seems such a trivial mod—the opening is only about 8” x 12” or so—but the cover is designed to be a part of the fuselage structure…an important part. It can’t work that way if not secured all the way around it’s perimeter.
Hope this helps!
Bob