SR3500 UPGRADES - FIN SPAR
Posted: Fri Feb 17, 2012 9:38 pm
Here's another piece of information for the upgrade process. Just going to
"cut and past" what I sent Brian for manual update, so I don't have to type
it all again!!!
Regards,
Wayne G. O'Shea
www.irishfield.on.ca
Maybe I'm a little bit handicapped getting into this SR second hand but
after some quick deductive reasoning I figured out that the 3rd ST-403 that
was supplied in the upgrade package is to be cut in half to become two
FIN-502's. Also no mention in the instructions but I figured out that the
FIN-500 and FIN-501's are for the new larger spar caps. Maybe should be some
mention in the instructions to avoid this confusion. The instructions also
say you will need a .040" packer between the top hinge bracket and the spar.
This should be .080" and I would suggest to just supply a third ST-405 in
the package! Also creating some confusion is the fact that the spar cap
drawing does not match the rivet pitch on the spar of the actual fin, or the
proper location of the fin rib that is referenced (unless this rib has been
moved in newer production runs!). This drawing also refers to the spar caps
in the opposite aspect as the manual. It switches the reference of
"external" for the "internal" spar caps and visa versa.
As for the instructions I offer the following as you can't pull the rear
spar just by drilling out the rivets on the spar.
Note: All hardware removed from the hinge brackets and FUS-436 L & R should
be able to be reused, and have acceptable grip, by substituting the AN960-10
washers for thin AN960-10L washers!
1/ Drill out all rivets holding the fin spar in place as well as one side
skins rivets back to the first stringer away from the spar. This will allow
you to lift the skin, so you can access the hinge bracket nuts at the top
and middle brackets to unbolt them from the ribs. Unbolt the 4 nuts and
remove the spar assembly from the fin.
2/ Mark a line on the spar at the location of the upper edge of the flange,
on the upper hinge bracket of the middle pair. Then unbolt the hinges and
the upper 8 bolts only, out of 10, that hold the FUS-436L & R.
3/ Cut an ST-403 in half to become two (2) FIN-502 doublers. These L shaped
pieces..................similar to the stabilizer main spar doublers. Clamp
firmly in position so the doublers covers from the line drawn in step #2, to
just below the holes from the lowest set of bolts removed from the
FUS-436's.
4/ ............
5/............... The top hinge will need a small piece of .080 packer
(ST-405) between it and the spar. Place, clamp, back drill the 4 holes,
remove, debur, chromate and bolt in place between the hinge bracket and
spar.
Hope this will clear things up some for others coming along this route.
Wayne
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"cut and past" what I sent Brian for manual update, so I don't have to type
it all again!!!
Regards,
Wayne G. O'Shea
www.irishfield.on.ca
Maybe I'm a little bit handicapped getting into this SR second hand but
after some quick deductive reasoning I figured out that the 3rd ST-403 that
was supplied in the upgrade package is to be cut in half to become two
FIN-502's. Also no mention in the instructions but I figured out that the
FIN-500 and FIN-501's are for the new larger spar caps. Maybe should be some
mention in the instructions to avoid this confusion. The instructions also
say you will need a .040" packer between the top hinge bracket and the spar.
This should be .080" and I would suggest to just supply a third ST-405 in
the package! Also creating some confusion is the fact that the spar cap
drawing does not match the rivet pitch on the spar of the actual fin, or the
proper location of the fin rib that is referenced (unless this rib has been
moved in newer production runs!). This drawing also refers to the spar caps
in the opposite aspect as the manual. It switches the reference of
"external" for the "internal" spar caps and visa versa.
As for the instructions I offer the following as you can't pull the rear
spar just by drilling out the rivets on the spar.
Note: All hardware removed from the hinge brackets and FUS-436 L & R should
be able to be reused, and have acceptable grip, by substituting the AN960-10
washers for thin AN960-10L washers!
1/ Drill out all rivets holding the fin spar in place as well as one side
skins rivets back to the first stringer away from the spar. This will allow
you to lift the skin, so you can access the hinge bracket nuts at the top
and middle brackets to unbolt them from the ribs. Unbolt the 4 nuts and
remove the spar assembly from the fin.
2/ Mark a line on the spar at the location of the upper edge of the flange,
on the upper hinge bracket of the middle pair. Then unbolt the hinges and
the upper 8 bolts only, out of 10, that hold the FUS-436L & R.
3/ Cut an ST-403 in half to become two (2) FIN-502 doublers. These L shaped
pieces..................similar to the stabilizer main spar doublers. Clamp
firmly in position so the doublers covers from the line drawn in step #2, to
just below the holes from the lowest set of bolts removed from the
FUS-436's.
4/ ............
5/............... The top hinge will need a small piece of .080 packer
(ST-405) between it and the spar. Place, clamp, back drill the 4 holes,
remove, debur, chromate and bolt in place between the hinge bracket and
spar.
Hope this will clear things up some for others coming along this route.
Wayne
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username "rebel" password "builder"
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