MD Helicopters CSP-900RMM-2, Servicing And Maintenance

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CSP − 900RMM − 2 MD Helicopters, Inc.
Rotorcraft Maintenance Manual
Page 8
Revision 20
63-00-00
A. Disk
The disk is mounted on the Anti-Torque fan
drive flange of the Anti-Torque Fan drive
quill. The disk is of one piece steel construc­
tion, with four equally spaced mounting holes
and is factory balanced.
B. Brake Head Assembly
The brake head assembly is mounted on the
main transmission housing. The brake head
assembly consists of a housing, calipers, steel
carriers, and linings. The housing is made of
cast aluminum and anodized to prevent
corrosion. Two caliper pistons are mounted in
the housing. The steel carriers, and linings are
seated in the housing and is moved by the
opposed caliper pistons.
The brake head assembly receives hydraulic
pressure and fluid flow from the hydraulic
control valve. When fluid pressure is in­
creased, the opposed caliper pistons in the
brake head housing extend outward toward
each other. Each piston contacts a steel carrier
and lining that presses against the disk. This
engagement causes friction between the disk
and linings, resulting in a braking action.
The braking action causes the disk, Anti-
Torque fan drive quill, Anti-Torque fan drive
shaft, Anti-Torque fan, main transmission,
main rotor drive shaft, and main rotor to stop
rotating. When fluid pressure is decreased, the
pistons retract into the brake head housing by
a return spring. The linings disengage the disk
and returns to the disk clearance dimension
maintained by a self adjusting mechanism.
Each lining has a wear indicator. When the
wear indicator on a lining becomes exposed,
that is a visual indication to replace the lining.
Bleeder assemblies are located on the brake
head housing. The bleeder assemblies provide
a means to bleed air from the hydraulic lines
and brake head housing internal ports.
C. Hydraulic Control Valve
The hydraulic control valve is located on the
main transmission deck. The control valve is a
reservoir for hydraulic fluid (C112) used to
operate the rotor brake subsystem. A remov­
able filler cap is located on top of the control
valve, for servicing.
When the rotor brake handle in the crew
station is pulled, the control valve internal
metering circuit pressurizes fluid to the brake
head assembly.
D. Control Linkage
The control linkage is located in the cockpit
ceiling above the pilot seat. The handle has a
lockout feature that prevents the handle from
being inadvertently operated. To apply the
rotor brake, the control handle is rotated and
pulled down. The control handle moves the
hydraulic control valve metering circuit control
rod to pressurize the system. The control valve
pressurizes the brake head assembly to a
maximum pressure of 500 psig.
When the control handle is pushed upward,
the control valve internal metering circuit
decreases pressure, while maintaining a back
pressure of 10 psig.
E. Hydraulic Tubing
The hydraulic tubing is stainless steel high
pressure tubing. The tubing routes hydraulic
fluid from the hydraulic control valve to the
break head assembly.
F. Proximity Switches
Two proximity switches are installed in the
brake head assembly. The switches indepen­
dently monitor the position of each brake
assembly piston.
The switches complete an electrical circuit to
the IIDS display. The electrical circuit illumi­
nates the Rotor Brake light on the IIDS
display during rotor brake subsystem applica­
tion. The Rotor Brake light is extinguished
when the rotor brake subsystem is released.