Learjet 60 - Pitch Trim Indicator; Trim-In-Motion Audio Clicker

Learjet 60

Pilot's Manual
PITCH TRIM INDICATOR
Horizontal stabilizer trim position indication is provided by the
PITCH TRIM indicator located in the trim indicator panel on the cen-
ter instrument panel
.
The indicator face has
markings for
1° to
12°
of
horizontal stabilizer travel ; however, only the T .O . range markings
are labeled . N DN and N UP markings indicate the direction of trim
travel for airplane nose down and airplane nose up
respectively . The
T .O . (takeoff) segment is
marked from
5
.7° to 8 .75° . The margins of
the
T
.O . segment are marked
AFT and FWD, representing the trim
limits for the center-of-gravity extremes . An index mark at
the 6 .5°
position, separates the high and low
trim rate ranges . At pitch trim
settings on
the N
UP
side of the index, the trim speed controller
will
be in the high trim rate (low airspeed) mode . At pitch trim settings
on
the N DN side of the index, the trim speed controller
will be in the
low trim rate (high airspeed) mode . The
indicator receives horizontal
stabilizer
position inputs from a potentiometer installed
in the hori-
zontal stabilizer pitch trim actuator
. The indicator operates on 28
VDC supplied through
the 2-amp TRIM-FLAP-SPOILER
INDICA-
TOR
circuit breaker on the copilot's circuit
breaker panel . The pitch
trim
indicator is operative during EMER BUS
mode .
TRIM-IN-MOTION AUDIO
CLICKER
A
trim-in-motion audio clicker system
is installed to alert the
crew of
horizontal stabilizer movement . The
system will annunciate
continu-
ous
movement of the horizontal
stabilizer by producing a series
of
audible clicks through the headsets
and cockpit speakers .
The system
consists of a potentiometer in the
horizontal stabilizer pitch
trim actu-
ator,
a trim-in-motion detector box
and associated aircraft
wiring . As
the horizontal stabilizer actuator
drives the stabilizer,
the output sig-
nal from the potentiometer
is altered . The change
in potentiometer
signal is sensed by the detector
box . After
approximately 1/4 second
of continuous stabilizer
movement, the detector
box will produce
the
speaker and headset clicks .
The trim-in-motion
audio clicker system
is wired through the flap
position switches
and will not sound
if the
flaps are lowered beyond
3° . The trim-in-motion
audible clicker
may
or may not sound
during autopilot trim
due to the duration
of the
trim inputs .
Power for system operation
is 28 VDC supplied from
the
7 .5-amp
WARN LTS circuit breakers on
the pilot's and copilot's
cir-
cuit breaker panels
through the warning lights
control box .
These cir-
cuit breakers are
powered during EMER BUS
mode .
PM-123
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