actuates a gas-spring cartridge, providing between 110 to 150 pounds of
controlled force to fully extend the handle and separate the elevator control
systems.
NOTE:
If the red power assist trigger was used to actuate the
ELEV DISC handle, the system cannot be reset
without the use of special tools.
C. Pitch Trim System:
(See Figure 4 through Figure 6.)
(1) Elevator Trim Tabs:
A trim tab is installed on the trailing edge of each elevator. They are
mechanically operated through trim actuators located in each
elevator. The trim actuators can be operated manually or electrically
as described below. Elevator trim tab travel ranges from 22 degrees
trailing edge down to 8 degrees trailing edge up.
(2) Elevator Trim Tab Actuator Heater:
The elevator trim tab actuator heater generates heat to prevent the
actuators from freezing. These heaters generate heat until the
temperature rises to a threshold temperature, predetermined by the
manufacturer. The heaters are controlled by the L/R ELEV TRIM
HEAT circuit breakers, located on the Right Electronic Equipment
Rack (REER), and receives power from the Right Main AC bus.
(3) Manual Trim Control:
Manual control of pitch trim is accomplished by an interconnected
manual trim control wheel set. A control wheel is provided on each
side of the cockpit center pedestal. With electric pitch trim
disengaged, moving either manual trim control wheel adjusts pitch
trim to the desired setting. With electric pitch trim engaged, the
manual trim control wheels move automatically corresponding to the
amount of electric pitch trim movement.
(4) Electric Pitch Trim:
Located on the pilot’s flight panel, the PITCH TRIM ENG/DISENG
switch engages or disengages the electric pitch trim. Pitch trim is
automatically engaged when the autopilot is engaged. However,
pitch trim is not automatically disengaged when the autopilot is
disengaged. To disengage the pitch trim, the ENG/DISENG switch
must be depressed, causing the DISENG legend to illuminate in the
switch. Pitch trim can be engaged even if the autopilot is off by
depressing the ENG/DISENG switch. Should a failure occur
rendering the electric pitch trim inoperative, or pitch trim become
disengaged, messages are prompted for display on CAS. The type
of messages depend upon aircraft airspeed.
With electric pitch trim engaged, pitch trim can be adjusted through
use of a split-half pitch trim switch installed on each control wheel,
labeled NOSE DOWN / NOSE UP. Inadvertent actuation of pitch
trim, including runaway, is minimized through the split-half switch
design. In order for the pitch trim to be actuated, both halves of the
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS 2A-27-00
Page 7
May 22/01
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