Rolls-Royce Helicon X3, User Manual

Page: 25 / 140

System Description
3
Page 11 of 16 Doc. No.: 13S000411
Revision: A Copyright © 2010 Rolls-Royce plc
4.1.1 Normal Control
The output from the pitch controller is computed on the basis of the input signals from
pitch lever and the actuator position feedback.
Lever and feedback signals are scaled and checked against adjustable limits, with
corresponding alarm for exceeding the normal range. The levers have one set of
adjustments (minimum, zero and maximum) for each manoeuvre station. Multiple sets
of feedback adjustments (minimum, zero and maximum) are available for various
engine power take-outs.
In combined mode the lever signal is modified in a Combinator program, see chapter
Pitch and RPM Combinatory (combined Control) .
4.1.2 Backup Control
The Backup Control system consists of closed loop control identical to the Normal
Control system. The Backup Control is a separate system, and is independent of the
Normal Control system. A system failure in the Normal Control system will
automatically switch to and engage the Backup Control.
Lever order signals and feedback are monitored and verified against adjustable alarm
limits. If the signals exceed the limits this will release an alarm to the alarm plant and
both visual and audible system failure alarm will be actuated at the manoeuvre stations.
4.1.3 Backup Control Operation
If a failure occurs on important parts of the Normal Control for the Pitch, Azimuth or
RPM Control function, the control will automatically be switched over to the Backup
Control system. A system failure audible and visible alarm will be activated on each of
the control panels.
The thruster control will continue to follow the lever in command and transfer is done
by using the common in command buttons. The command can be transferred between
all bridge position and the bridge control levers will continue to work as in normal
control.
A failure that occurs on important parts of the Backup Control for the Pitch, Azimuth or
RPM Control function will not affect the Normal Control system. If a system failure
occurs on the Backup Control an audible and visible alarm will be activated on each of
the control panels.
4.1.4 Backup Control Limitations
The Backup Control system has only interface to the control levers. The Backup Control
system does not have interface to External Control systems like Dynamic positioning
systems, Joysticks or Autopilots.
Note: No pitch reduction or load function are included in the Backup system.
When operating using the backup system, the operator must be careful not to overload
the engine or the propeller system.
4.1.5 Local Control
If both the Remote Control system and the Backup Control should fail it is possible to