TM 1-1500-204-23-1
Figure 9-15. Rudder Actlon
(5) Trim tabs. Trim tabs trim the aircraft in
flight. To trim means to correct any tendency of the
aircraft to move toward an undesirable flight attitude.
Trim tabs control the balance of an aircraft so that it
maintain straight and level flight without pressure on the
control column, control wheel, or rudder pedals. Figure
9-17 shows a trim tab. Note that the tab has a variable
linkage which is adjustable from the cockpit. Movement
of the tab in one direction causes a deflection of the
control surface in the opposite direction. Most of the
trim tabs installed on aircraft are mechanically operated
from the cockpit through an individual cable system.
However, some aircraft have trim tabs that are operated
by an electrical actuator. Trim tabs are either controlled
from the cockpit or adjusted on the ground before taking
off. Trim tabs are installed on elevators, rudders, and
ailerons.
b. Inspection of Flight Controls. Inspect all flight
control surfaces in accordance with the applicable
aircraft maintenance manual.
c. Repair of Flight Controls. Make all repairs to
flight controls in accordance with the applicable aircraft
maintenance manual.
d. Flight Control Operation Systems. Three types
of control systems commonly used are the cable, push-
pull, and torque tube systems. The cable system is the
most widely used because deflection of the structure to
which it is attached do not affect its operation Many
aircraft
incorporate
control
systems
that
are
combinations of all three types. The systems which
operate the control surfaces, tabs, and flaps include
flight
control
system
hardware,
linkage,and
mechanisms. These items connect the control surfaces
to the cockpit controls. Included in these systems are
cable assemblies, cable guides, linkage, adjustable
stops, control surface snubber or locking devices,
surface control booster units, actuators operated by
electric motors, and actuators operated by hydraulic
motors.
9-14
