The purpose of the cranking system is to motor the engine. This can be done with or without a fuel supply. Crank selections to motor the engine are usually done for maintenance purposes.

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By setting L CRANK or R CRANK on the ENGINE control panel, air goes to the air turbine starter from the starter air valve through air ducts. The primary difference with the cranking cycle is the isolation of the ignition system to prevent an engine start. A cranking cycle can be dry, with fuel also isolated, or wet when fuel is supplied for a specified time.
When L CRANK or R CRANK is set on the ENGINE control panel (in the flight compartment), the EEC causes the starter air valve to open. The EEC also prevents the automatic selection of ignition. The air turbine starter turns the engine and continues to operate until L CRANK or R CRANK is cancelled. But if the HP compressor speed increases to starter disengagement speed, the EEC will close the starter air valve. During engine cranking, the starter must operate in its limits.

Dry Crank

Engine operating mode when the engine is motored/cranked without fuel and without power to the ignition circuits.

Wet Crank

Engine operating mode when the engine is motored/cranked with fuel, but without power to the ignition circuits.

When the ENG START switch is in the L or R CRANK position with the airplane in flight or on the ground, and the ENGINE RUN switch is placed in the ON position, it will bypass the EEC, and directly command the HPSOV in the FMU to open, to provide a "wet crank". It must be noted that subsequent pushing and latching of the IGNITION PBA will be ignored on the ground, but will result in a manual engine start in the air.

Dry Cranking

Initial Switch/Control Knob Positions and Aircraft/Engine Status

Airplane is on the ground, (weight on wheels) and the applicable engine is not running.

ENG START Selector	AUTO
IGNITION Switch	NORMAL (not selected)
ENGINE RUN Switch	OFF
THROTTLE Lever	IDLE

Procedure

The procedure for dry cranking is as follows:

• Operator selects the ENG START switch to L or R CRANK
  
  
• The EEC initiates the command signals necessary to crank the engine without ignition. The SAV solenoid is energized as in the previous cases. A START icon will appear on the left/right side as applicable
  
  
• The engine begins to turn and accelerates somewhat slowly, with the N2 and N1 gauges reflecting the same. The EEC will be able to maintain the SAV solenoid energized for up to 3 minutes if not terminated by the operator
  
  
• It must be noted that the starter duty cycle permits the starter to be engaged during any single attempt for a maximum of 180 seconds only. To terminate the cranking operation at any time, the operator must move the ENG START switch back to AUTO

Wet Cranking

Initial Switch/Control Positions and Aircraft/Engine Status

Airplane is on the ground, (weight on wheels) and the applicable engine is not running.

ENG START Selector	AUTO
IGNITION Switch	NORMAL (not selected)
ENGINE RUN Switch	OFF
THROTTLE Lever	IDLE

Procedure

The procedure for wet cranking is as follows:

• Operator moves ENG START switch to L/R CRANK; engine will be motored, without ignition and fuel being supplied to it
  
  
• It must be noted that pushing in the IGNITION PBA after the ENG START switch has been moved to L/R CRANK has no effect on ignition, unless ignition was selected first. It becomes the responsibility of the operator to ensure that the IGNITION PBA is not selected prior to this operation, so as to preclude a potentially hazardous condition
  
  
• The operator moves the ENGINE RUN switch to ON. The HPSOV will open to allow fuel to the burners
  
  Caution:
  To avoid flooding (i.e. unacceptable accumulation of fuel in the exhaust nozzle and thrust reverser), limit the above procedure to a maximum of 20 seconds. a dry crank must be performed on the engine after a wet crank is carried out. The maximum pre wet crank ITT limit is 100°C.
  
  
• The operation may be terminated at any time by first moving the ENGINE RUN switch to OFF to turn off the flow of fuel into the engine, and thereafter selecting the ENG START switch to AUTO

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