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

Page: 630 / 2144

CSP − 900RMM − 2 MD Helicopters, Inc.
Rotorcraft Maintenance Manual
Page 2
Revision 17
25-60-10
The controller assembly incorporates the
following safety features:
Field loss detection circuit - The
controller with inhibit hoist operation if a
loss of motor field is detected.
Under voltage lockout - The controller
with inhibit hoist operation if the input DC
voltage is <17 VDC.
Automatic overload detection - The
controller will detect hoist system overloads
when high speed is selected by the hoist
operator. The controller will automatically
shift the hoist into the low speed mode. This
safety feature is recognized by the hoist
operator's motor warning light flashing. The
hoist system with stay in the low speed
mode and when the load is reduced to a safe
level the hoist operator can return to the
high speed mode.
Motor warning light - Provides the hoist
operator with a motor overheat indication
by a continuously illuminated motor
warning light. This condition will result
from operating the hoist system under
prolonged high temperature environments
that exceed the design limits of the system.
Pulse by pulse current limit - The
controller will detect excessive current
requirements from the DC power and limit
the amount of power consumed from the
aircraft power system.
Cable payout display lamp tests - The
controller upon initial power up will perform
a lamp test on both cable payout display.
This provides the hoist operator and the
pilot a visual means to verify all display
elements are operational.
The Control Pendant Assembly provides the
crewman with freedom of movement while
utilizing the following control features:
Direction/Speed Control - thumbwheel is
centrally located on the shrouded upper
portion of the hand grip. Except for the ICS
switch, all controls are partially guarded to
reduce the possibility of inadvertent
operation. A bracket is provided on the hand
grip to facilitate stowing the pendant in the
aircraft. The pendant is equipped with an
electrical connector for interfacing with the
Controller.
250 lb/600 lb control - two-position
(maintained) toggle switch used to signal
the System for either the 250-lb mode or
600-lb mode.
Direction/Speed control mechanism -
contains and actuats two switches and a
potentiometer. Two of the switches (one for
either direction) provide an on-off signal.
Potentiometer is rotated by the control
thumbwheel to provide a speed command
signal to the Controller Assembly.
ICS control - snap action switch provided
for connection to the aircraft intercom
system. Switch is operated by an auxiliary
actuator which protrudes from the back of
the hand grip
Cable payout display - provides the hoist
operator with a visual indication on the
pendant of how much cable is extended from
the hoist in feet. Display is sunlight
readable.
Over Temp/Over Load warning light -
Warning light provides the hoist operator
with a visual indication of two fault condi­
tions: 1) motor over temperature -steady
light; 2) 250 lb o/l - blinking light. Warning
light is sunlight readable.
B. Operation
The Pendant Control Assembly provides hoist
speed and direction signals to the controller.
The hoist is operated by displacing the
thumbwheel in the upward direction to lift a
load and the downward direction to lower a
load. The speed of the hoist is controlled by the
degree of displacement of this thumbwheel and
the thumbwheel is spring loaded to return to
neutral (off) position, hands off.
A load selection switch (toggle type) is located
on the right side of the speed/direction
thumbwheel. Positioning the toggle in the
downward direction selects operation with
loads up to 250 lbs. This minimum load (250
lbs.) may be lifted or lowered at speeds up to
225 feet per minute. The load selection switch
is clearly marked defining the 250 lb position
(down-ward direction) and the 600 lb in an
upward position. When the toggle switch is
placed upward in the 600 lb position. the hoist