Jastram ENGINEERING DSC 100 - Analog FFU #1; Analog FFU #2

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SYSTEM OPERATION – Steering Modes

Page 46 of 80

NFU mode for the main control station can be arranged to engage the

backup NFU steering system. This setting is selected through the DSC

setup program. In this arrangement selecting NFU mode at the main

station will disconnect the DSC’s directional valve outputs and connect the

backup NFU system in its place. The backup NFU system will not provide

acceleration and deceleration of a proportional rudder control system.

See also: 2.3.2

NFU Command Device

1.3.6

Backup NFU System

3.3.3 Analog FFU #1

FFU steering control is a closed loop system that compares a commanded

rudder position with an actual rudder position and moves the rudder

accordingly to cause the rudder to follow up to the commanded position.

FFU steering control allows the operator to dial in a desired rudder

position and then let the steering control system take care of placing the

rudder at the desired position.

An analog FFU input devices such as a lever controller, joystick or electric

wheel use a resistive potentiometer to provide the rudder position

command signal. The signal generated by this potentiometer is called a

Rudder Order Signal. The rudder order signal is connected to the MCP.

Certain FFU input devices such as an electric wheel do not provide a

physical representation of the rudder order signal. The MCP is capable of

outputting a signal to drive a Rudder Order Indicator (ROI) which will

continuously display the position of the potentiometer and therefore the

commanded rudder position of the analog FFU input #1.

When ANALOG FFU #1 mode is selected, the rudder will immediately

move to the position commanded by the analog FFU #1 input. The ROI is

useful in order to modify the Rudder Order Signal prior to selecting analog

FFU #1 as the active mode of steering control.