Open that data inis for the aircraft, scroll down to the engine part...........
[Engine3]
SystemType=PROP_ENGINE
InputName=THROTTLE_CONTROL
EngineID=3
SLPowerDry=15001.1
ThrustAngles=0.0,0.0,0.0
ThrustPosition=0.0,0.0,0.0
ThrottleRate=0.5
AltitudeTableNumData=10
AltitudeTableDeltaX=7000
AltitudeTableStartX=0.0
AltitudeTableData=1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0
TSFCM0=0.90
TSFCM1=1.26
SpinnerNodeName=Shaft
;RotationAxis=Z-Axis
StaticPropNodeName=Rotors
SlowPropNodeName=SlowRotor
FastPropNodeName=FastRotor
SlowPropRPM=500
;600
FastPropRPM=1000
MaxPropRPM=1200
;3000
IdlePropRPM=300
;480
ExhaustEmitterName=CleanExhaustEmitter
ExhaustPosition=-0.3565,-3.0507,0.7110
FireSuppression=FALSE
; New entries
MinManifoldPressure=30
MaxManifoldPressure=100
AnimationID=
MaxPowerAnimationTime=5
MinPowerAnimationTime=1
PropRotationDirection=
ReversePropOrientation=FALSE
ConstantSpeed=FALSE
NumBlades=2
PropDiameter=25.245<<<<<<<Replace this, with 5.245, that will make them turn
MomentOfInertia=2.25
PropEfficiencyAdvanceRatioTableNumData=7
PropEfficiencyAdvanceRatioTableDeltaX=0.2
PropEfficiencyAdvanceRatioTableStartX=0.0
PropEfficiencyAdvanceRatioTableData=0.041,0.40,0.70,0.82,0.78,0.50,0.00