SECONDARY FLIGHT CONTROLS - TRIM DEVICES
The secondary flight controls include electrically actuated pitch/roll/yaw systems and a rudder
trim aid device (TAD). The secondary flight controls are used for trimming and balancing the
aircraft in flight and to reduce the force required to actuate the primary flight control surfaces.
Trimming the aircraft is an essential skill for you to master and its importance is often
overlooked by fledging aviators. When an aircraft's flight conditions (attitude, power, airspeed,
loading and configuration) are changed, the control pressures required to maintain the desired
conditions are affected by the resulting changes in aerodynamic forces. The T-6A is equipped
with systems that allow you to trim the aircraft for balanced flight in all axes.
Trim System and Switches
The elevator and aileron trim are utilized by a thumb-actuated switch (Figure 2-4) at the top of
the control stick (fore/aft for elevator trim and laterally for aileron trim). The rudder trim switch
is located on the forward side of the power control lever (PCL). To trim, deflect the trim switch
in the opposite direction as the applied flight control force until that force is relieved. When
perfectly "trimmed," you can release flight control pressures (momentarily) and the aircraft will
remain in its current balanced state, then actuated, the Trim Interrupt button on the control stick
will remove electrical power from the trim devices and is used during certain trim malfunctions.
The general sequence for trimming the aircraft is: Rudder, Elevator, then Aileron. The rudder
trim is usually first because a correction for yaw precipitates a change in the trim setting for pitch
and roll. Consequently, not trimming the rudder first will generally cause you to go back and re-
trim the elevator and aileron after trimming the rudder.
Figure 2-4 Control Stick
THE FLIGHT CONTROLS