14-15
FOR TRAINING PURPOSES ONLY
LEARJET 20 SERIES PILOT TRAINING MANUAL
FlightSafety
international
The steering actuator, mounted on top of the
nose strut, steers the nosewheel through a gear-
box and an electrical clutch. The clutch engages
whenever DC power is applied to the airplane
electrical system, allowing the steering actuator
to function as a shimmy damper, even with
steering disengaged. If DC power is lost or the
DC NOSE STEER circuit breaker is out, the
nosewheel is free to swivel.
Prior to towing, electrical power must be
removed from the airplane, or the 28-VDC
NOSE STEER circuit breaker must be pulled to
prevent damage to the system. Since the wheel
can swivel 360°, the nose gear strut must be
inspected to ensure that the nose gear uplock
roller is pointing forward prior to taxiing.
OPERATION—WITHOUT
VARIABLE AUTHORITY (SNS
24-263 AND PRIOR AND 25-103
AND PRIOR)
On airplanes without variable authority, nose-
wheel steering can be operated by the primary,
wheel master, or steer lock switches.
Primary mode is engaged by depressing
and holding either PRI STEER switch
(Figure 14-13).
This provides steering capability of 40 to 50° in
either direction for low speed taxi up to
10 knots.
Engaging the wheel master or steer lock switch-
es permits steering capability up to 10° in either
direction. Steering should be disengaged above
45 knots.
The wheel master switch on either control wheel
permits nose steering while held depressed.
Steer lock mode is engaged by momentary actu-
ation of either STEER LOCK switch, and can be
disengaged by depressing either wheel master
switch or the PRI STEER switch.
With steering engaged in any mode, the green
STEER ON annunciator illuminates. Rudder
pedal movement provides the displacement and
directional signals to the computer-amplifier
which drives the steering actuator in the appro-
priate direction until it is stopped by a signal
from a followup located in the drive gearbox.
WHEEL MASTER SWITCH
Figure 14-13. Nosewheel Steering System (Airplanes without Variable Authority Steering)