Learjet 60 - MACH TRIM Light; Pitch Trim Selector Switch-Mach Trim Function

Learjet60

Pilot's Manual
Mach trim
computer
. Stabilizer
trim
motion will
cease as the followup
stabilizer position
signal
cancels
the
pitch
trim signal from the Mach
trim computer . Monitors are installed to disengage Mach trim in the
event of a malfunction . If a monitor disengages Mach him and Mach is
above 0 .77
Mr,
the overspeed warning horn will sound . The Mach trim
system is resynKhronized whenever either pilot manually trims the air-
craft and a synchronous standby mode is maintained if the autopilot is
engaged . In flight, Mach trim monitor may also be reset through the
SYSTEM TEST switch on the center instrument panel .
PITCH TRIM SELECTOR SWITCH-MACH TRIM FUNCTION
The Mach trim system utilizes the primary motor of the horizontal sta-
bilizer pitch
trim
actuator to increase
longitudinal stability
.
If the
PITCH TRIM selector switch on the pedestal 5 in the PRI position,
Mach trim will automatically engage at approximately 0 .70 ML if the au-
topilot is disengaged or inoperative . Mach trim
will not engage or will
disengage when the PITCH TRIM selector switch is moved to the OFF
or SEC position . If the PITCH TRIM selector switch is in OFF or SEC,
the Mach trim monitor will remain active and will illuminate the
MACH
TRIM
light
and
cause the overspeed warning horn to sound at
or above 0 .77 MT if the monitor detects a sufficient Mach/horizontal
stabilizer position error .
MACH TRIM LIGHT
The amber
MACH TRIM annunciator light, located on the glareshield
annunciator
panel, will
illuminate whenever
the
Mach
trim monitor or
Mach monitor has disengaged the Mach trim system . Whenever the
Mach trim system is disengaged and Mach is above 0 .77 MI, the over-
speed warning horn will sound 9 the autopilot is inoperative or not en-
gaged . The Mach trim monitor continuously monitors input signals
and
power
to the Mach trim computer . In the event of loss of power to
the Mach trim computer or primary pitch trim system, loss of input sig-
nals to the Mach trim computer,
or a Mach/horizontal stabilizer posi-
tion error, the Mach trim monitor will disengage Mach trim and
illuminate the MACH TRIM light .
PM-123
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