ENGINE-SYSTEM OPERATION
AUTOMATIC MODE
The normal automatic mode (AUTO) is the primary mode of operation
achieved with the ENG MODE switch on FLIGHT position and ENG GOV
switch on AUTO.
In automatic mode the EEC:
• provides automatic controls of the full operating envelope of the engine
without exceeding limiting parameters
• computes the desired fuel flow and through a torque motor sets the
position of the metering valve in the FMM to achieve a new NG
reference point in accordance with variation of pressure altitude, OAT
and collective position.
In AUTO mode the two EECs intercommunicate via a cross talking digital
bus so that they can match the engine setting either in ITT or torque (see
Engine Load share).
ENGINE START/STOP IN AUTOMATIC MODE
Engine starting and stopping is also automatically performed by acting on
the ENG MODE switch on the Engine Control Panel.
When the engine is started in AUTO mode, the EEC controls the FMM and
activates the starting command for the Engine Relay Box which:
• commands the GCU for starter operation
• activates the ignition system (consequently displaying the IGN legend
on side the ITT indicator)
• causes the START legend to be displayed on side the NG indicator
The starting phase is terminated by the EEC when NG ≥49%.
The engine is stopped by moving the corresponding ENG MODE switch to
OFF.