TM 1-1510-224-10
(except the right aileron tab, which is of the fixed,
bendable type). Elevator and aileron trim tabs
incorporate neutral, non-servo action, i.e., as the
elevators or ailerons are displaced from the neutral
position, the trim tab maintains an as-adjusted position.
The rudder trim tab incorporates anti-servo action, i.e.,
as the rudder is displaced from the neutral position the
trim tab moves in the same direction as the control
surface. This action increases control pressure as the
rudder is deflected from the neutral position.
a. Elevator Trim Tab Control. The elevator trim
tab control wheel, placarded PITCH TRIM, DN - UP, is
located on the left side of the control pedestal and
controls a trim tab on each elevator (fig. 2-14). The
amount of elevator tab deflection, in units from a neutral
setting, is indicated by a position arrow.
b. Electric Elevator Trim. The electric elevator
trim system is controlled by an
ELEV TRIM -
OFF/RESET switch located on the pedestal extension
(fig. 2-14), dual element thumb switches on the control
wheels (fig. 2-24), a trim disconnect switch on each
control wheel, and a 5 ampere circuit breaker placarded
ELEC TRIM, located on the overhead circuit breaker
panel (fig. 2-9). The ELEV TRIM - OFF/RESET switch
must be in the ELEV TRIM (on) position to operate the
system. The dual element thumb switch is moved
forward for trimming nose down and aft for nose up.
When released, and the switch returns to the center (off)
position. Any activation of the trim system through the
copilot's trim switch can be overridden by activation of
the pilot's switch. Simultaneously operating the pilot's
and copilot's switches in opposing directions results in
the pilot having priority. An annunciator placarded ELEC
TRIM OFF on the caution/advisory annunciator panel
indicates failure or disconnect of the electric trim system.
A preflight check of the switches should be
accomplished before flight by moving the switches
individually on both control wheels. No one switch alone
should operate the system; operation of elevator trim
should occur only by movement of pairs of switches on
each control wheel. The trim system disconnect is a bi-
level pushbutton momentary-type switch, located on the
outboard grip of each control wheel. Depressing the
switch to the first of two levels disconnects the autopilot
and
yaw
damp
system,
and
the
second
level
disconnects the electric trim system. The system can be
reset by moving the ELEV TRIM switch toggle on the
pedestal (fig. 2-14) to OFF/RESET position, then back to
ELEV TRIM.
c. Aileron Trim Tab Control. The aileron trim
tab control, placarded AILERON TRIM - LEFT, RIGHT.
located on the control pedestal, adjusts the aileron trim
tab
Figure 2-25. Control Locks
2-52
