Learjet 20 Series Pilot Training Manual page 310

motor operation (but prior to pusher operation), a
push command is applied to the pitch servo with
approximately 1/4 the force of the pusher.
OPERATION—AIRPLANES
WITH STANDARD WING
The vane-operated transducer provides a voltage,
proportional to airplane angle of attack, to the
computer/amplifier. If angle of attack increases
until airspeed is 7% above stick pusher actuation
speed, one or both stick shakers are energized and
ANGLE-OF-ATTACK
INDICATOR
PUSHER ACTUATION
SHAKER ACTUATION
VANE
SHAKER
MOTOR
Figure 15-13. Stall Warning System—Airplanes with Standard Wing
LEARJET 20 SERIES PILOT TRAINING MANUAL
NORMAL ACCELEROMETER
(1/2 g LIMITER)
COMPUTER/
AMPLIFIER
STALL WARNING
L
L STALL
*
FLAP POSITION INPUT
FOR TRAINING PURPOSES ONLY
one or both red STALL lights begin to flash
(Figure 15-13). When both vanes simultaneously
increase to 5% above aerodynamic stall condition,
the computer/amplifier signals the autopilot to dis-
engage and the pitch servo to apply nosedown ele-
vator (stick pusher). When angle of attack decreas-
es below the stall point, the pusher releases.
Stick shaker actuation occurs as the pointer
sweeps 1/3 to 1/2 into the yellow segment of the
indicator. The stick pusher actuates as the indica-
tor moves into the red segment.
ACCELEROMETER
CUTOUT BOX
*
BIAS
BOX
R
R STALL
FlightSafety
international
TO LH
ANGLE-OF-ATTACK
INDICATOR
VANE
AUTOPILOT
PITCH SERVO
SHAKER
MOTOR
15-19