When the PCL is set to IDLE a signal is given to the stick pusher computer to disable monitoring of the engine
torque and engine running signals. This prevents the amber PUSHER message on the CAS display from coming
on during a descent. The stick pusher and stick shaker operate as normal during this condition.
3.3
Stick Shaker
The AOA transmitter vanes turn to stay aligned with the airflow as the aircraft pitch changes and give pitch-angle
signals to the stick pusher computer. When the data supplied from the left or right AOA transmitter shows the
aircraft is near the stall angle, channel 1 or channel 2 of the stick pusher computer sends a signal to the stick
shaker actuator. The stick shaker actuator operates and vibrates the control wheels to give a warning to the pilot.
The stick pusher computer also gives a signal to disengage the autopilot, if it is engaged.
The AOA value at which the stick shaker actuator operates depends on several factors. These include the flap
position, engine torque and mode of operation (normal or ice). The AOA datums change by 8 degrees between
normal and ice mode operation. This is necessary because of the changes to the wing lift characteristics due to ice
formation.
3.4
Stick Pusher
The stick pusher computer disables the stick pusher servo operation when one or more of these conditions are
present:
−
The aircraft is on the ground
−
For five seconds after take-off
−
The aircraft vertical acceleration is less than 0.5 g
−
The PUSHER INTR switch is pressed.
When the data supplied to the stick pusher computer from the left and right AOA transmitters shows the aircraft is
very near the stall angle, channels 1 and 2 of the stick pusher computer send a signal to the stick pusher servo.
The stick pusher servo operates the elevator cable system to move the elevators and make the aircraft pitch go
nose-down. The stick shaker and stall warning tone stay on when the stick pusher servo operates.
The AOA value at which the stick pusher servo operates depends on several factors. These include the flap
position, engine torque and mode of operation (normal or ice). The AOA datums change by 8 degrees between
normal and ice mode operation. This is necessary because of the changes to the wing lift characteristics due to ice
formation.
When the AOA value is less than the set limits or the vertical acceleration is less than 0.5g the stick pusher servo
will stop.
Operation of the stick pusher servo also stops when the PUSHER INTR switch on the pilot’s or co-pilot's control
wheel is pushed and held. The aural stall warning tone and stick shaker actuator stay operational. The PUSHER
caution message on the CAS comes on and an aural gong sounds three seconds after operation of the PUSHER
INTR switch. This is in case of accidental operation of the PUSHER INTR switch. If the PUSHER INTR switch is
released when the aircraft pitch is still out of the set limits, the stick pusher servo will operate immediately.
If a failure of the stick pusher servo or capstan occurs and the elevator system does not move freely, the
mechanical slip clutch operates when the torque given to the capstan from the elevator control cable is more
than the slip-clutch limit.
3.5
Ice Mode
When both the inertial separator de-ice system, refer to AMM 12-B-30-20-00-00A-040A-A and the propeller de-ice
system, refer to AMM 12-B-30-60-00-00A-040A-A or 12-B-30-60-00-00A-040B-A are ON, the MAU connects a
PC-12/47E AMM Doc No 02300, ISSUE 01 REVISION 26 MSN 545, 1001-1719,
1721-1999
12-B-AM-00-00-00-I
UNCLASSIFIED
Effectivity: All
12-B-22-20-00-00A-040A-A
UNCLASSIFIED
2021-12-04 Page 6
