Propeller Pitch Drive Assembly
These indicators are provided at both the operator
control station and the engineer control station.
The propeller pitch drive works to position the
You have just read about the steering control system
propeller to the position ordered by the operator. When
and the propeller pitch control system. Now, let's take a
the operator moves the control levers, an electrical
look at another system that works with these two
signal range is produced and sent to the CSEP where it
systems to allow the operator to maneuver the craft.
is amplified. From the CSEP, the amplified signal is sent
to the propeller pitch drive mechanism. The propeller
LIFT FAN CONTROL SYSTEM
pitch drive mechanism turns the propeller, causing a
feedback potentiometer to send a signal to the CSEP.
When the feedback signal equals the command signal,
The lift fan control system allows the engineer to
the propeller is in the ordered position. The propeller
control the airflow to the cushion of the craft. An
pitch drive mechanism can also be triggered by the
emergency dump switch is provided at the operator
vernier pitch control circuit we will describe in the
control station to allow the operator to stop the craft in
an emergency by taking it off the air cushion.
The structure of the lift fans and associated vane
Vernier Pitch Control Switch
cushion assembly is shown in figure 7-10. The main
c o m p o n e n t s of this system are four double-entry
The function of the vernier pitch control switch is
centrifugal fans. A rectangular box structure containing
to allow the operator to select the control source, or
two lift fans is located on each side of the craft. The fans
combination of control sources, to control propeller
pitch. When the vernier pitch control switch is in the
OFF position, the operator can control propeller pitch
only by moving the control levers. When the vernier
pitch control switch is ON, the operator can control
in-and-out movement of the yoke. The operator uses the
control levers to set the midrange for the yoke propeller
pitch control range.
Propeller Pitch Selector Switch
The propeller pitch channel selector switch is
located on the C&C keyboard at the engineer station.
This switch, labeled PROP A/B, allows the operator to
choose between channels of the CSEP in case of an
emergency or system fault.
Propeller Pitch Control System Indicators
The function of the propeller pitch indicators is to
inform the operator of existing conditions. The operator
uses this information to move the craft as effectively and
safely as possible. This subsystem informs the operator
of the following conditions:
Propeller control failure
Port and starboard hydraulic reservoir low
Port and starboard hydraulic pressure low
Figure 7-10.--Lift fans and cushion vanes assembly.