Tail Rotor - GRAUPNER heim Bell 230 Instructions D'utilisation

Bell 230

1.7 Tail rotor

1.7.1 Installing the tail rotor
Glue together parts (A9) to form the tail rotor bulkhead. Trim the bulkhead to fit in the tail end of
the fuselage. Fix the tail rotor to the bulkhead using three 2.9 x 13 mm self-tapping screws, then
slide this assembly into the fuselage.
The end of the tail boom features an all-round recessed flange to accept the tail cap (B3). The
first step here is to cut a semi-circular opening in the recessed flange to clear the tail rotor
gearbox housing. The opening should be large enough to allow the tail rotor gearbox to be fitted
into the tail boom to a depth of about 16 mm. Trim the reinforcement for the vertical stabiliser
support A12 so that it fits flat on the inside, with the tail rotor bulkhead A9 engaged in its slots.
You will have to remove the tail rotor gearbox for access to these parts.
Glue parts A9 and A12 together and to the fuselage using slow-setting epoxy (UHU plus endfest
300). While the glue is still soft it is important to align the tail rotor bulkhead; this is the
procedure: locate the 50 cm length of spring steel rod which is used later for the tail skid, and
temporarily insert it in the tail rotor shaft coupling. The tail rotor gearbox can then be fitted in the
bulkhead and screwed in place. Set the (temporary) tail rotor shaft exactly horizontal.
If you now look down the tail boom from the front, you can check that the shaft is aligned
correctly as follows: the steel rod projecting from the tail rotor gearbox should be central,
horizontal, and point straight forward to the bottom edge of the tail boom at the point where it
joins the main fuselage. This ensures that the actual tail rotor drive shaft runs in a smooth curve
from the mechanics to the tail rotor. Tack the tail rotor bulkhead in this position with a few drops
of cyano, check alignment once more, then apply a fillet of UHU plus endfest 300 all round the
joint. Apply glue to the inside of the joint too (use a length of stripwood or similar).
1.7.2 Tail rotor drive system
Trim the bulkhead (A10) to fit in the tail end of the fuselage, and glue it in place using UHU plus
endfest 300. Note that the large hole for the tail rotor pushrod must be on the left as seen from
the tail looking forward.
1.7.2.1 Fitting the tail rotor drive shaft, cutting the shaft to length
Install the mechanics in the fuselage. Fit the quick-release coupling sleeve 4618.58 on the tail
rotor drive shaft (B9) with the pre-formed end located inside the sleeve. Fit the retaining collet
56.0 on the shaft, but don't tighten the screw yet. Fit the shaft and sleeve into the fuselage from
the tail end, and engage the pre-formed end of the shaft (B9) in the yoke 4618.57 of the quick-
release coupling. Slide the sleeve right forward to close the coupling. Push the shaft into the
yoke as far as it will go, and mark the point on the shaft where it crosses the tail rotor bulkhead.
The final length of the tail rotor shaft needs to be about 15 mm less than the marked length. At
the front end there must be about 1 mm axial clearance, and at the tail end the shaft needs to
be shortened by the installed length of the tail rotor gearbox (25.5 mm), measured from the
mounting flange, less the socket depth of about 11.5 mm in the coupling component 4618.40.
The exact length of the tail rotor drive shaft on the prototype model is 872 mm.
Remove the shaft from the fuselage and cut it to length, taking care not to bend the end as you
cut it, and remove any rough edges from the cut face.
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