09/11/2018
RANS S-21 OUTBOUND
TEXT MANUAL
66
17.
Use a 120° countersink (preferably a micro stop countersink) to machine
countersink the holes in the Forward Spar to accept the dimples in the skin.
18.
Lightly lift the leading edge of the skin and debur the holes in the Forward Spar.
19.
Insert (4) tank supports and cleco them to the top skin.
20.
Rivet the top skin to the wing. Start with the leading edge and work your way
rearward one row of rivets at a time. Leave the holes open for the inner root rib
(#1). Push the skin to the ribs between the rivet to be pulled and the cleco in the
next row to prevent as much pillowing as possible.
21.
Stop riveting about 4 rows from the rear spar.
22.
Remove end Tabs from Gap Seals. Refer to
FIGURE 06-05A
.
23.
Fit the gap seals to the rear spar and slide the top edge underneath the trailing
edge of the top skin.
24.
Check for proper alignment to Wing airfoil profile with a straight edge on top of
the wing. Refer to
FIGURE 06-05
.
Double check that the wing is square and still
has 0° of twist.
25.
Once the gap seal conforms to the airfoil, transfer drill #30 through the skin into
the gap seal and spar.
Start at the middle and work your way out.
26.
Temporarily install the flap and aileron to check for clearance through the range
of motion. If any rivet heads contact the aileron or flap, the bottom surface of the
gap seal may be formed to clear by using a round object, such as the ball end of
a ball peen hammer. Press the ball of the hammer up and into the bottom of the
gap seal and drag along the length to push the metal surface up for more
clearance.
27.
Remove clecos back to the rivets of top skin and lightly lift the trailing edge to
allow removal of any burrs or chips in between the skin, gap seal, and the rear
spar.
28.
After satisfied, use a pair of shears to remove the supports at push-pull tube exit
holes indicated in
FIGURE 06-05A
.
IMPORTANT:
Once the supports are removed, the gap seals will be very
fragile and prone to damage. Remove the supports only after the top row
of holes is clecoed to the rear spar. If it must be removed for some reason
before riveting, use extreme caution.
29.
The rest of the top skin can now be riveted using the appropriate rivets.
NOTE:
Do NOT rivet the Inside Root Rib at this time.
30.
On the outboard side of the outboard gap seal, three holes in the gap seal do not
have matching holes in the spar and need to be transfer drilled using a #30 drill.
31.
Rivet the gap seals to the rear spar using the appropriate rivets.
NOTE:
Longer rivets must be used near the truss due to the rear spar
truss doubler thickness on the inside of the spar.