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ENGINE MOTORING
Dry motoring is accomplished by toggling the start switch from OFF to CRANK and hold for the duration of the cranking. Dry motoring may become necessary to cool the engine when restarting the engine immediately after shutdown.
Wet motoring is accomplished by setting the RUN/OFF switch to RUN, toggling the start switch from OFF to CRANK and holding the latter for the duration of cranking. In response, the ECU energizes the air turbine starter control valve, controls the run solenoid, and controls the fuel metering valve per the start sequence.
A dry motoring follows the wet motoring start. Dry motoring is used to clear any pools of fuels that may have collected in the engine during the wet motoring.
IGNITION SYSTEM
DESCRIPTION
The ignition system consists of an ignition exciter, two igniter plugs, and two sets of igniter leads. The ignition system for each engine is a dual independent and redundant system. The ECU will activate the ignition system during automatic starts and restarts. The ECU will also automatically turn the ignition system off when the engine is running. The pilot can man-ually activate the ignition system by turning on the IGNITION switch.
For automatic ground starts, the ECU uses one ignition channel, changing the channel used on each start. For all other starts, both ignition channels are used simultaneously. The system is capable of continuos operation by manual activation by the pilot, but is normally only energized during the starting sequence.
COMPONENTS AND OPERATION ENGINE STARTING
When the FADEC in-control channel is determined during N2 spool-up, the in-control channel closes the associated igni-tion relay. When the applicable L (R) ENGINE RUN switch is selected, the FADEC selected dc powered ignition exciter is energized. Ignition is de-energized by the FADEC at starter cutout.
AERODYNAMIC STALL
At an excessively high angle of attack (AOA), there is a possibility that turbulent airflow from the wing root could disrupt the flow of air into the engine intake. Disruption of airflow at the intake could lead to engine compressor stall. The FADEC and the stall protection computer provide two levels of compressor stall protection.
As the aircraft angle of attack reaches the stick shaker firing angle, the stall protection computer signals the FADEC to energize both ignition channels.
If the FADEC detects a compressor stall or surge, the FADEC will modulate engine thrust to clear the event.
FLAMEOUT PROTECTION
If the FADEC detects an engine flameout, it will automatically initiate a re-light. Both ignitions systems are energized.
An engine flameout is detected when the following occurs:
-The engine is subidle and either the ITT rate of change is negative, or the N2 rate of change is lower
than commanded
-A flameout is detected while the engine RUN/OFF switch is still in the RUN position
-The L (R) ENGINE FLAMEOUT (C) CAS message is illuminated
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