GREAT PLANES Piper J-3 Cub Instruction Manual page 20

wing. The holes in the wing ends of the struts should be
positioned so they will align with the hardwood blocks in the
wing. Do not drill into the wing or fuselage at this time.
❏ ❏ 3. Position the strut on the fuselage and wing. Drill a 3/32"
[2.4mm] hole at the fuselage and the front strut mount only.
Do not drill the hole for the rear strut mount at this time.
❏ ❏ 4. Thread a #4 x 1/2" sheet metal screw into the fuselage
and front wing strut mount block. Remove the screws and
place three drops of thin CA into the holes to harden the
threads. Wait until the CA has cured before you continue.
❏ ❏ 5. Attach the strut using two #4 x 1/2" sheet metal
screws and two #4 washers.
The following steps are necessary to install the struts so
they do not twist the wing. Work slowly and carefully,
checking the alignment until you are confident the strut will
not twist the wing when attached.
IMPORTANT: The struts are necessary to safely fly
your Cub. It must not be flown without them installed
under any circumstance.
❏ ❏ 6. Place your Cub upside-down in an aircraft stand.
Place a level (or incidence meter) on the wing near the
fuselage. Adjust the position of the airplane until the root of
the wing is perfectly level.
❏ ❏ 7. Move the level (or incidence meter) out to the tip of
the wing without allowing the position of the main aircraft to
change. Use the level to check the wing to make sure it is
not twisted. If so, carefully twist the wing until it is level.
❏ ❏ 8. Once level, mark the location of the rear strut
attachment through the hole in the strut. Remove the strut and
drill the marked location using a 3/32" [2.4mm] drill bit. Follow
the procedure in step 4 to harden the hole for the screw.
❏ 9. Repeat steps 2 through 8 to install the remaining strut.
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