Here at DOG Aviation there is a knack for turning the seemingly simple into a time sucking abyss. Installing the instrument sections was no exception due to the powder coating. As frequent viewers of the blog have seen, the left and right panels have been in place for quite a while waiting for the center panel section, but it was all for not … when attempting to attach the center panel section it quickly became apparent there was no way the center section was going to fit. At first it appeared as though the powder coating in the holes of the left panel was preventing the panels from fitting together, so all the holes in the left panel were cleaned out with a jewelers file and the panels were mated again. Better but still not enough.
The center section screws were barely able to be screwed in … after installing
a few screws to secure the center panel, it became quickly apparent that the screws
for the right section would not align.
Long story made short … spanning two work sessions the panels were
installed and removed at least four or five times before it became evident that
the clearances are such that the panels will tolerate absolutely no powder
coating along the edges that mate together … the screw holes just would not
align correctly. So the panels were removed yet again and all the powder coating
was removed along the mating edges with a long sanding block … this solved the issue of the screw holes not
aligning correctly. Once all three panels finally began playing nice together,
two #19 holes needed to be drilled into bottom of the map box for screws. The
instrument panel base has two predrilled holes which are used to match drill into
the bottom of the map box.
About to use an angle drill to match drill the bottom of the map box to the
instrument panel. The initial drilling was done with a #30 drill bit.
Once the bottom of the map box was drilled to #30 the right instrument
panel section was removed so the two holes could be enlarged to #19. Glad I did
it this way because both the #30 holes were very close to the forward edge of the map so a jeweler’s
file was used to open up the two holes working away from the edge of the map
box. The two holes in the instrument panel base were also opened up the same way
then a step drill was used to round up all the holes.
Installing the right instrument panel section (hopefully for the last
time) after drilling and deburring the mounting holes going into the bottom of
the map box.
With the right instrument panel section screwed in position, I was eager
to find out how bad the interference issue will be with the ADS-B module. Frequent
readers of the DOG Aviation blog may remember a few months ago a test fitting
was made and it appeared as though there may be an interference issue between
the backup airspeed indicator and the ADS-B module. Today my fears were
realized in that there is a clearance issue but fortunately it is not too bad …
as luck would have it, the ADS-B module just barely touches the fitting on the
airspeed indicator. Had the airspeed indicator been located just a little
higher, all would be good … but I wanted it centered on the AP & Knobs
Panel modules and knew there may be a clearance issue.
Photo of the ADS-B module hitting the metal portion of the fitting that
screws into the back of the airspeed indicator. Lowering the ADS-B module about
1/4" will solve the issue.
After spending a half hour or so analyzing the situation, think I have
figured out a simple solution to rectify the situation. Looking closely at the
above photo … if one looks at the bracket the ADS-B module is sitting on and
follows it to the left there is a nut there that secures the ADS-B mounting
bracket to the com stack bracket. The nut is a little hard to see because it is
in a shadow (should have used a flash) but my thought is to slot the screw hole
in the bracket upward which should drop the bracket enough to clear the fitting
on the backup airspeed indicator. There appears to be plenty of material to do
this without creating any weakness. A problem to resolve during the next work