Primary Pitch Trim; Trim Switch Panel (Figure 5-4) - BOMBARDIER LEARJET 40 Pilot's Manual

Pilot's Manual

PRIMARY PITCH TRIM

Each control wheel has a control wheel trim switch located on the out-
board horn of each control wheel (Figure 5-1). Each switch is a four po-
sition (LWD, RWD, NOSEDOWN and NOSEUP) barrel switch with a
momentary-action push button switch in the center of the barrel. This
switch is used to input trim commands for pitch and roll and autopilot
functions. Normally, the pitch trim control switch (Figure 5-4) is posi-
tioned to PRI. This position enables the control wheel trim switches and
causes commands from either of these switches to be processed by the
#1 IC. To complete the trim command circuit, the arming switch (but-
ton) on the top of the barrel must be depressed simultaneously with
movement of the barrel. Trim commands from the pilot's control wheel
trim switch will override commands from the copilot's. Primary trim
speed is variable and is automatically controlled by the #1 IC based on
indicated airspeed. The IC uses airspeed information from both ADCs
to schedule trim speed and Mach trim. The #1 IC sends the primary
trim commands to the primary trim actuator. The trim actuator and the
IC both monitor the trim operation. The primary trim actuator per-
forms a power-up circuit check. If the actuator detects a fault during the
power-up check, a fault is posted on the CAS. Primary trim will still be
available with the fault displayed; however, operation may be at a low
trim rate and configuration trim and Mach trim may be inoperative de-
pending on the malfunction. The primary trim actuator and #1 IC both
monitor primary trim operations for a number of possible malfunctions
including uncommanded trim and trim in the wrong direction. If either
of these malfunctions is detected by the trim actuator, a fail is displayed
on the CAS and primary trim is disabled.
5-16
PITCH TRIM
SEC
PRI
NDN
NUP
SEC
TRIM SWITCH PANEL
Figure 5-4
RUDDER TRIM
OFF
NOSE
LEFT
O
F
F
NOSE
RIGHT
PM-132A