Wing Bottom Skin
Pitot Mount Installation (Gretz Mount)
Access-Reinforcement for Stall Warning Access
Pull Stall-Warning Wires
Deburr/Dimple Left Wing Bottom Skin
Replace Autopilot Mounting Bolts
Added
2/6/2005 - 479.8 Me Hours, 519.9 Total Hours
During this section I did mainly small and old jobs that I'd
ignored previously. First, I replaced the 3 mounting bolts holding the
Autopilot Servo as listed on the last page
with NAS1801-3-20, which are fully threaded. This allows the bolts to
go all the way through the servo and bracket and have locknuts put on
the other side. Probably not a big deal, but likely more secure.
I then set about fixing an "oil canning" problem around my stall
warning access door. If you don't know what "oil canning" is, it's when
the sheet metal is stressed as such that moving it in will make it
"pop" in, and flexing it out makes it "pop" out. It's not stable that
way, and from bumps and airmovement the skin could pop in and out
rapidly in that area, which might not be a major problem, but at
minimum it's an annoyance. I don't know why my access hatch got this
way. I'm sure just small hole alignment problems or many things could
be a cause. For me the fix was to fashion a sort of "T" shaped bracket
that I would rivet behind a couple of the edges...reinstalling the
nutplates on top of the new angle aluminum reinforcement. I see no
issues with this. The leading edge has a curve to it the closer you get
to the tip, so I didn't extend the reinforcement too far. I did use
Proseal to secure the angle, in addition to rivets. It was clear that
even during clecoing that this was going to be much stronger. After
putting in the fore-aft reinforcement for a test fit, I determined that
it would still need reinforcement side-to-side. I also decided after
fashioning a separate bracket that if I didn't connect the 2 brackets,
there would still be a lot of flexing which would now be confined to a
tiny area between the brackets. So the safest thing would be to join
the brackets to prevent movement between parts. You can see the shapes
of the parts here, and see how they go together here. This really fixed the problem.
I then started out trying to place the Gretz Pitot Mount. You can see from these pictures here and here
(also below) that during the placing of the wing bottom skins, I had
set the bracket in a couple areas to test the looks of it. I wanted to
move it outboard of the outer access bay, but going only 1 bay outboard
still interefered with the tiedown bracket area...with a possible
conflict of a rope being close to my pitot tube. I decided to move it
to the inside of the 2nd rib from the tip. Almost to the outer bay. Here is my location.
The mounting works and looks great there. Note: I did have to buy a
longer roll of pitot tubing from Van's. I could have spliced in a piece
but decided to just buy 14' (lots of extra) and make it all continuous.
As for the instructions, you can see I put an angle attachment on the
rib, and then put the backing plate in place, and drilled it to match
the 4 spar holes. I then drew outlines around the backing plate from
the inside with the skin on and the plate clecoed in place. Now I knew
where to cut the skin and drill the 4 large holes. After drilling and
cutting these, I reinstalled the plate and the skin and then match
drilled the backing plate to skin rivets. The Gretz directions are not
organized very well and are very hard to read, but if you look at the
pictures, and think it through, it's not too bad. You can see the
results in my pics below. I won't rivet anything until the skin gets
rieted.
I spent a second and cut a small hole in the conduit to allow me to
fish out the stall warning wires and pull the through the conduit. No
brains required.
I then set out to deburr and dimple the bottom skins. No brains required here either.