Learjet 20 Series Pilot Training Manual page 312

two-speed trim system), the stick pusher actu-
ates, then releases as the pointer recedes into the
yellow segment. Repeat the test, positioning the
switch to the L TEST position. The test switch is
disabled in flight by its respective squat switch.
OPERATION—AIRPLANES
WITH MKII WING
As angle of attack increases, vane-operated
transducers feed a voltage signal proportional to
airplane angle of attack to the computer/amplifi-
er. If angle of attack increases until speed is
approximately 7% above airplane stall speed, the
computer/amplifier causes the stick shakers to
energize and the L and R STALL lights to flash
(Figure 15-15).
18
16
14
12
MK II
ANGLE
10
OF
8
ATTACK
6
4
2
0
VANE
SHAKER
MOTOR
Figure 15-15. Stall Warning System—Airplanes with MKII Wing
LEARJET 20 SERIES PILOT TRAINING MANUAL
PUSHER ACTUATION
SHAKER ACTUATION
NORMAL ACCELEROMETER
(1/2 g LIMITER)
COMPUTER/
AMPLIFIER
STALL WARNING
L
L STALL
* FLAP POSITION INPUT
FOR TRAINING PURPOSES ONLY
When both vane-operated transducers simultane-
ously detect an angle of attack beyond stall con-
ditions, the computer/amplifier disengages the
autopilot and signals the pitch servo to apply
nosedown elevator (stick pusher). When angle of
attack decreases below the stall point, the stick
pusher releases.
Stick shaker actuation occurs when the pointer
of the indicator is in the yellow segment. The
stick pusher actuates when the pointer is in the
red segment, and, except for model 23 airplanes,
the STALL lights are on steady.
ACCELEROMETER
CUTOUT BOX
*
BIAS
BOX
R
R STALL
FlightSafety
international
18
16
14
12
MK II
ANGLE
10
OF
8
ATTACK
6
4
2
0
VANE
AUTOPILOT
PITCH SERVO
SHAKER
MOTOR
15-21