August 1, 2010
The kit comes from Avipro with the inspection holes cut into the wing bottom and also comes with the pre-cut inspection covers and rings.
The cover and ring are pre-drilled with one hole in each corner to help you
get the alignment correct.
Note: I didn't have the proper size cleco for the factory made alignment
holes, so I just used a couple of screws/nuts for alignment.
There are 3 sizes; a large one for the aileron bellcrank area, a small one
for the hole in front of the spar near where the wing strut attachment is,
and the rest are all medium size.
Start by drawing a line on the inspection cover ring connecting the four
holes. Figure out what screw spacing you want and lay out the hole locations
on the line. I put on hole in the center of each narrow end and two holes
along each long edge. Drill the holes with a #40 bit:
These will eventually be screws and anchor nuts.
Now lay out a rivet line exactly 1/4" in from the outside perimeter of the
inspection cover ring as shown here. Drill these holes with a #40 bit as
well:
I used 1 1/8" spacing for these holes.
Now to locate the inspection ring perfectly centered in the wing inspection
hole. Cleco the inspection cover on the bottom side of the inspection
ring. Then simply place the ring and cover in the hole making sure that the
cover is centered in the wing inspection hole. Note: you may need to file
the edges of the cover and/or the hole in the wing for a proper fit:
Double check that the cover is in the wing inspection hole, drill and
cleco the inspection ring to the hole. Note:
Be careful to not push down too hard while drilling these holes. There is
no support rib underneath and in pushing down you might deform the wing skin
downward while drilling. This may cause the inspection hole area to be a
low spot in the wing instead of level with the surrounding skin.
Just let the drill do the work and cut the
hole.
With all of the holes drilled, mark the ring, the cover, and wing skin so
you will be able to reinstall them later in the same orientation.
Now you can take it apart and put the inspection ring under the skin and
cleco it in place:
Now test fit the cover in the hole to make sure the holes line up properly:
I found that I had to lightly file the edges of the inspection cover and
the hole in the wing to make them fit together correctly.
Now we'll remove the ring and install the anchor nuts using the same techniques that we used on the fuel tank bay cover.
After installing the anchor nuts, the outside row of rivet holes were deburred
and dimpled:
The holes in the wing skin were also deburred and dimpled. The ring
was then clecoed and riveted in place using a squeezer:
Note: Don't push down too hard while squeezing these rivets. Since
there is no supporting rib and this skin is fairly thin at .020", if you
push down too hard while squeezing these rivets it will result in a dip (low
spot) in the wing skin at the inspection hole location. To get nice flat
inspection holes, press down just hard enough to keep the rivet seated in
the dimpled hole and squeeze the rivet.
One hint for you, make sure to mark each inspection ring and cover for location
and direction.
My coding indicates this is inspection cover #2 for the right wing and
the arrow always points toward the leading edge of the wing. When you
do your annual inspections and all of the inspection covers are sitting on
the work table in a big pile, you will need to know where each one goes and
its orientation.
For now, the inspection covers are just lightly screwed in place with 4
screws:
Now I'll do the rest of them.
