CSP
−
902RFM207E
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1
ROTORCRAFT FLIGHT MANUAL
MD900 (902 Configuration with PW 207E)
Systems Description
Original
7
−
20
Reissue 2
7
−
7.
HYDRAULIC SYSTEMS
Flight Controls:
The helicopter is equipped with two hydraulic systems for operation of the flight
controls. Under certain conditions, the main rotor control loads are such that
they require at least one hydraulic system operating at all times; hence, the
dual system for safety. However, the aircraft can be flown in a minimally degraded
condition with the anti-torque actuator depressurized.
The system is powered by two variable displacement hydraulic pumps mounted
on and driven by the main transmission, has a reservoir/manifold for each system
placed on opposite sides of the upper fuselage deck, and has three tandem actua
tors, one for each cyclic pitch function and one for collective pitch of the main
rotor.
The #1 system operates only the main rotor controls while the #2 system operates
the main rotor controls and also the NOTAR
anti-torque control system.
The main rotor actuators are mounted forward of the main rotor while the anti-
torque actuator is mounted in the cabin ceiling just aft of the right hand cabin
door.
A hand pump option is installed for use in servicing the hydraulic systems in
the field.
The two systems normally operate at 500 psi each for a total system pressure
of 1000 psi. If pressure in one system should drop to less than 400 psi, the other
system automatically compensates by increasing its pressure to maintain a total
system pressure of 1000 psi nominal. A yellow caution annunciator,
``1 HYD'' or ``HYD 2'', illuminates on the IIDS caution/warning display and a
caution message is displayed on the alphanumeric display when the affected
system's pressure falls below 250 psi.
Summary of Contents for MD900 Explorer
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