Sonex Wing Squaring/Skinning Instructions - Manual

Sonex Aircraft
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Squaring and Skinning the Wings
Instruction No. SNX-W07-02
Reference Drawing SNX-W07
05/16/06
Fitting the Aft Wing Skins
Before fitting the aft skins the wing structure MUST be
squared and levelled so no twist or wash-out is built into the
wing. One method for accomplishing this is shown here:
1. On saw horses or a workbench, shim the wing spars until
a carpenter's level placed across the spars at the root and
the tip show the spars are level with each other. The levels
at each end of the wing MUST agree with each other. If
they do not, add shims as necessary to eliminate the twist.
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3. Align the upper aft skin so the pilot holes for the ribs are
aligned directly above the rivets which hold the ribs to the
aft spar.
4. Clamp the trailing edge of the aft skin to the flange on the
rear spar, aligning the edge of the skin to the edge of the
rear spar as you go.
5. Pilot drill and cleco the wing skin to the aft spar.
6. Make sure the wing is still twist-free and begin to drill
and cleco the skin to the wing ribs, aligning the ribs as
needed and working forward toward the main spar.
7. Pilot drill and cleco the front edge of the upper aft skin to
the main spar.
8. Turn the wing over and re-level the assembly as described
in step 1. While the spars are now locked straight and in
the correct position, the structure can still twist. The struc-
ture MUST have any twist removed prior to installing the
lower aft skin.
The spars are shimmed off the workbench as needed to get
them level at both the tip and root.
While two levels speeds the job, a single level can be used,
checking each end of the wing structure for level.
2. Establish the proper location for the hole in the aft spar
attach plate relative to Wing Station 0.0. This dimension
is provided on the plans. See photo, next column.
A carpenter's square works well for setting the rear spar's
position relative to wing station 0.0. (See step 2)
The pilot holes in the up-
per and lower aft wing skins
MUST be in vertical align-
ment to get the leading edge
to fit properly.
10. Pilot drill and cleco the skin as described in steps 5
through 7.
9. Position the lower aft
skin so the pilot holes in
the aft edge of the skin
are DIRECTLY above
the holes in the upper aft
skin. This is important to
assure a proper fit of the
leading edge.
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