GRAUPNER Jet Ranger Handbuch Seite 35

Jet Ranger
yoke 4618.57. Viewed from the side, it should describe a slight, gentle curve. The shaft should
also run to the tail rotor mounting surface in an exactly vertical line when viewed from the tail.
Remove the tail rotor drive shaft assembly from the fuselage.
1.4.2.3 Final installation of the tail rotor drive shaft
In the two previous sections you temporarily assembled and installed the tail rotor drive system;
you can now be confident that the parts fit, and that their final position is known. Withdraw the
tail drive shaft from the tubular sleeve, oil it lightly where it runs inside the sleeve, and slide it
back into place.
Apply a few drops of UHU plus endfest 300 to both ends of the channeled rail, and at roughly
every 60 mm along its length. Rotate the tubular sleeve in the rail to distribute the epoxy inside
the channel.
When the glue has set hard, fit this assembly into the tail boom from the front as described in
stage 1.4.2.2, threading it past the mechanics, until the drive shaft projects at the rear to the
point where it can be screwed into the tail rotor gearbox coupling 4618.40. Carefully de-grease
the rear end of the tail rotor drive shaft and roughen it by rubbing with fine abrasive paper in the
axial direction. Slip it into the shaft coupling as far as it will go, and tighten the grubscrews in the
shaft coupling in this position. This is done by first removing the grubscrews from the coupling
and applying thread-lock fluid, Order No. 952, or bearing retainer fluid, Order No. 951, to the
threaded holes, then fitting the grubscrews again and tightening them fully. If possible we
recommend grinding a flat in one side of the shaft where the grubscrews engage, as this
improves the strength of the joint considerably.
The shaft and throat of the tail rotor gearbox can now be fitted into the tail end of the fuselage,
engaging the front end of the shaft in the quick-release coupling at the same time. Fix the tail
rotor gearbox in place using three 2.9 x 13 mm self-tapping screws. Check the length of the
shaft once more (clearance in the front coupling yoke).
Apply plenty of UHU plus endfest 300 to the underside of the support rail spacer blocks, so that
the rail is glued securely to the tail boom. Rotate the channeled rail so that the channel is on
top, and slide it back into the previously stated position.
Rotate the tail rotor several times while the glue is still soft, so that the tail rotor shaft and tubular
sleeve align themselves naturally in the position of least stress.
Leave the epoxy to cure completely.
Position the retaining collet 56.0 about 1-2 mm aft of the union sleeve, and tighten the
grubscrew.
1.4.3 Tail rotor control linkage
The tail rotor bowden cable outer must run in a straight line to the tail rotor servo. You will need
to drill a hole in the tail bulkhead through which the outer can be fitted into the fuselage from the
rear; the outer should end flush with the tail end of the fuselage. Before drilling the hole check
that the tail rotor pushrod can be moved from one end-point to the other when it is installed and
connected to the outermost hole in the tail rotor bellcrank. Cut off the outer at the front end
about 70 mm short of the tail rotor servo, and glue it to the inside of the fuselage side at a
minimum of three points, applying the epoxy on a length of wood strip or similar tool.
The actual tail rotor pushrod consists of a steel rod with a Z-bend at the tail end; at the front end
it needs to be cut to length and completed with a threaded coupler, M2 locknut and clevis
(supplied with the mechanics) for connection to the servo.
Check that the tail rotor servo is installed with the output shaft (rotational axis) at the top, and
the output arm pointing straight down.
Set the tail rotor servo output arm and the tail rotor gearbox bellcrank to centre (neutral). Screw
the locknut and clevis about half-way onto the threaded section of the threaded coupler, and
connect the clevis to the servo output arm. Slip the tail rotor pushrod (12) into the bowden cable
outer from the rear, and line up the Z-bend with the tail rotor crank - but without connecting it at
this stage. Determine the length of the pushrod, taking into account the socket depth of about
11 mm, and mark this point. Shorten the pushrod, roughen it thoroughly at the coupler end and
solder it carefully into the threaded coupler. Connect the pre-formed end of the pushrod to the
outermost hole in the tail rotor bellcrank, and check that the pushrod cannot possibly become
disengaged even under a severe load.
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