viewed from the aft end of the engine). To remove
ROTOR BRAKE
the main drive shafts, both remountable power
The rotor brake system permits applying the
plants must be removed.
main rotor brake manually or automatically.
It uses a master brake cylinder, pressure
TAIL DRIVE SHAFT
gauge, panel package, rotor brake, rotor brake
accumulator, check valves, and pressure switches.
Operation of the system is in conjunction with the
The tail drive shaft runs from the rear cover
operation of the automatic blade folding system.
of the main gearbox to the disconnect coupling
The rotor brake at the rear of the main gearbox
at the intermediate gearbox. See figures 7-10 and
7-11. The shaft between the intermediate gearbox
is hydraulically actuated. Its purpose is to stop
and the tail gearbox is known as the pylon drive
the rotation of the rotary wing head and rotary
shaft.
rudder. See figure 7-14. Actuation is manual by
means of the rotor brake master cylinder in the
The primary purpose of the tail drive shaft is
cockpit. Operation is automatic during blade
to send engine power to drive the rotary rudder.
folding by the blade positioner control valve. The
rotor brake consists of a rotor brake disc and
On some installations it also provides a means to
drive the main transmission gearbox oil cooler and
housing.
blower fan. On the SH-60, there are five sections
of drive shafting from the main transmission to
the intermediate gearbox. There is one section of
POWER TRANSMISSION
tail drive shaft between the intermediate and tail
COMPONENT MAINTENANCE
gearbox--making a total of six sections. Each
section connects by a flexible steel coupling called
When performing inspections, removal,
a Thomas coupling, eliminating the need for
repairs, or installation maintenance functions on
universal joints. Each coupling has flexible
parts, you must follow procedures specified in the
stainless steel discs stacked together. Flats assure
appropriate MIMs.
that the stack is in correct alignment. The grain
MAIN TRANSMISSION INSPECTION
in one disc runs parallel to the flats, and the grain
in the other disc runs perpendicular to the flats.
The shaft sections are supported by viscous-
Besides inspecting for corrosion, and treating
the main transmission outer surface for corrosion,
damped bearings. Each viscous-damped bearing
there are some areas that require more attention.
support is a ball bearing enclosed by a thick
Visually inspect these areas for signs of overstress
rubber-type bag. Heavy silicone oil in the bag
or beyond torque limit capabilities. The main
dampens vibrations in the tail drive shaft
areas are the barrel nuts, the forward bell crank
assembly. The pulley and belts that drive the oil
support bridge mounting pad, and the main
cooler fan are attached to the oil cooler drive
module mounting feet.
shaft. These are found between sections I and II
of the tail drive shaft. See figure 7-11. The
Barrel Nut Inspection
section VI drive shaft is in the tail pylon. It sends
power from the intermediate gearbox to the tail
On the H-60 helicopter there are three
gearbox.
different part numbers for barrel nuts. The
procedure for checking each one of them is the
same. Install a mount bolt onto the barrel nut
OIL COOLER AND BLOWER
until there are two threads exposed beyond the
nut. Using a torque wrench, back out the bolt.
The main gearbox oil cooler and blower
If the breakaway torque is less than that specified
unit of the SH-3 helicopter is in the aft rotary
in the MIM for that specific part number nut,
wing fairing. It consists of a cooler (radiator),
discard the nut. Replace the nut with a new one,
blower, and duct. The cooler is belt-driven by
and repeat the procedure.
the tail drive shaft. If the temperature of the
oil is less than 70C, the oil is bypassed
Bell Crank Support Mounting Pad
to the return line by a thermostatic regulator.
Oil returning from the radiator or the bypass is
Following all safety procedures, clean all
forced through the lubricating jets located in the
traces of paint and sealing compound from the
gearbox.
7-18
