Rotor Brake Assembly
thermal expansion and contraction of the fluid, and
aids in dampening pressure surges.
The rotor brake assembly is comparable to the
single disc wheel brake in its design and operation.
Rotor Brake Master Cylinder
Hydraulic actuation of the brake may be made
The master cylinder is gravity fed by hydraulic
manually by using the rotor brake master cylinder
fluid from the utility fluid tank. Move the brake handle
located in the cockpit. The brake applies automatically
down and forward to apply pressure to the system. A
during the blade folding operation by the blade
spring latch on the cylinder linkage automatically
positioner control valve. In manual operation, the
locks the handle in the ON or PARK position. To
brake is capable of stopping the rotary-wing head in 14
release the brake, pull the latch and place the handle in
seconds from 157 rpm. Replace the brake linings when
the DETENT position. The pressure gauge indicates
any of the adjusting pins recede into the adjusting nut
the amount of pressure produced by the master brake
1/8 inch. Replace lock screws and worn parts each
cylinder. The check valve provides a means to pressure
time linings are replaced.
bleed the system. A minimum pressure of 320 psi is
Rotor Brake Panel Package
required to effectively operate the rotor brake.
This package consists of an accumulator, relief
AUTOMATIC BLADE FOLDING SYSTEM
valve, pressure reducer, and a shuttle valve. The
An a u t o m a t i c b l a d e f o l d i n g s y s t e m o f a
package receives hydraulic pressure from the master
representative helicopter is shown in figure 17-12.
brake cylinder during manual operation. It receives
This system is capable of automatic blade folding of
pressure from the automatic blade folding system
one of the two rotary blades from cockpit controls.
during automatic operation. When the master brake
cylinder handle is in the OFF or DETENT position, the
Blade Folding Operations
master cylinder vents to the utility fluid tank.
Movement of the master brake cylinder handle blocks
The No. 1 blade does not fold, but it automatically
the vent and builds up brake pressure. When the
positions over the tail pylon. The only hydraulic
pressure increases beyond 200 psi, the shuttle valve in
actuation of the No. 1 blade is damper positioning. The
the panel package shifts. Pressure is sent to the rotor
hydraulic portion of the system positions the blades
brake and blocks pressure from the automatic blade
and folds the No. 2 blade. The electrical portion of the
folding system. The panel package accumulator
system provides the sequencing of operation of the
reduces minor pressure surges during manual and
various hydraulic components. It acts to prevent
automatic operation. The accumulator maintains a
accidental operation of the system. Warning and
steady pressure to the brake. The relief valve relieves
indicating lights show the status of the system at all
pressure surges in excess of 600 psi.
times. Safe operation is maintained by a series of
electrical interlocks.
Rotor Brake Accumulator
You should perform blade-folding operations with
The spring-loaded rotor brake accumulator
the pylon locked in the flight position and the engine
permits manual operation of the master cylinder
operating at 104 percent. The rotary-wing head must
handle during automatic blade folding operations.
not be operating. The accessory drive switch is placed
Applying the automatic brake unseats the accumulator
in ACCESS DRIVE. The safety valve switch is placed
sequence valve. The open valve permits actuation of
OPEN, and the master switch is placed ON. The blade
the master cylinder handle. The hydraulic fluid flows
switch is placed in the FOLD position.
through the sequence valve and compresses the
Hydraulic pressure from the utility hydraulic
accumulator spring. Releasing the automatic brake
system is 3,000 psi. The pressure flows through the
causes pressure to flow from the accumulator to the
motor-operated safety valve. This pressure flows to
panel package shuttle valve, and repositions it.
the blade positioner control valve, and is sent to the
Simultaneously, the panel package accumulator
blade positioner drive unit for engagement with the
maintains hydraulic pressure that was trapped from the
rotor brake disc. This action turns the rotary-wing
automatic application in the rotor brake. The rotor
shaft.
brake accumulator additionally compensates for
17-15
