(with shear pins)
(LDS only)
Np servo which affects metering valve
position via the collective fuel schedule)
inear ariable iferential ransducer
Torque Motor inputs actuate the Npservo.
LVD T
3
Increase load on Nr/Np andLVDT transmits Np servo position to ECUincreasefuel flowtoincrease to stabilizeECUto HMUinputs.
Ng output. Np servo is positioned by the torque motor.If there is no signal applied to the torque motor
E
fuel pressure within the Np servo saturates to
PCL advance
C
maximum& opens the metering valve
Np servo
(default to high-side failure).
U
8
Collective
increase
DecreaseloadonNr/Np and Camthat latches in an override detent when PCL decrease fuel flowto reduce Ng output.
is advanced to 130 deg. (lockout position). When in the override detent torque motor inputs are reset tomax COLLECTIVE MOVEMENT
6
andlockedthere. PCListhenfreetosetenginepower Collectivepitchcompensitoryfuelmetering
manuallyviatheNgcam. PCLtoidelresetsoverride. adjustmentsareproactivethroughLDS, override detent
IGV & Variable Vanes
attempting to offset main rotor droop, or reduce
close open
Ng camto PCL positions:
0=off,PCLstopcocked
VARIABLE GEOMETRY ACTUATOR
0
overshoot.
Collective fuel schedule:
variable geometry
26 = idle detent
LO Ng speed HI actuator piston FUEL
26 The Np governer (in ECU) is reactive to actual power turbine speed, it makes a fine fuel metering
Positioned by collective &
Ng 120 = fly detent
PRESS
130 = lockout
open
trimed by torque motor.
cam adjustmentviathetorquemotortotrimNgto VALVE
close PILOT
(Trq motor can be locked out.)
maintain Np/Nr constant at 100%.
130
anti-ice & start / bleed valve
Maximumpower setting camfollower: 120
normaly a fixed pivot point when PCL is in Ng OVERSPEED
theflydetent(120deg), thisallowsECU VALVE
trimmed collective schedule to control position and/or recalibrate various
2 & 3 dimensional cams:
metering valve position.
5
ACCELERATIONFUEL
Ng LIMITING:
mechanical linkages that contact the cams
FLOWLIMITING
limits max Ngspeed IAWT2&Ng.
Vapor Vent: valve is open when PCL is advanced
via their camfollowers.
Less Ng allowed in cold climates,
PREVENTS RICH BLOW-OUT DURING
tolockoutwithenginenotrunning. VentsHMU
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