Pitch Trim; Pitch Trim Selector Switch - BOMBARDIER LEARJET 40 Pilot's Manual

PITCH TRIM

Pitch trim is provided by a moveable horizontal stabilizer. Operational
structural redundancy has been incorporated by using primary and
secondary sections that are independent. Primary and secondary each
have electrically and mechanically independent motors (separated for
rotor burst considerations), gear trains, and control inputs. Position
sensors in each section of the actuator, geared directly off of the main
drive screw, are monitored by both IC-600s. The computers compare
the primary position sensors to the secondary position sensors in the
actuator to annunciate to the pilot when the display position may not
be accurate. The secondary section structure, construction, and opera-
tion is the same as the primary and both sections drive a common
screwjack-type actuator to move the leading edge of the horizontal sta-
bilizer up or down. The primary motor is actuated by manual primary
pitch trim (control wheel trim switch), configuration trim, and Mach
trim systems. The secondary motor is provided as a backup for primary
trim and is operated by the secondary pitch trim and the autopilot.
The following CAS illuminations are specific to the pitch trim system:
CAS
PIT TRIM MISCMP
PIT TRIM MISCMP

PITCH TRIM SELECTOR SWITCH

This switch, as shown in Figure 5-4, is located on the trim switch panel
(pedestal) and is used to select which trim system will be used. The PRI
position enables the primary trim switches in the control wheels, while
the SEC position will enable the secondary trim switches in the panel.
Selecting OFF or SEC will disable all #1 IC-600 trim functions. When set
to OFF position, the power and ground circuits for the motor command
functions in the actuator control box are disconnected and a CAS is
posted.
The following CAS illumination is specific to the pitch trim system:
CAS
PITCH TRIM OFF
PM-132A
Color
Red Miscompare between the primary and sec-
ondary pitch trim on the ground and either
thrust lever is advanced to MCR or above.
White Miscompare between the primary and sec-
ondary pitch trim in flight.
Color
White Pitch trim is selected to OFF.
Pilot's Manual
Description
Description
5-15