User Guide

188
AUTOMATIC TRIM
In order to control the elevator without its servos constantly
holding excessive pressure, the autopilot system includes an elec-
tric motor to operate the trim wheel. In addition, when the autopi-
lot isn’t engaged, a switch on the control yoke allows you to
adjust the trim without letting go of the controls. If the autopilot is
engaged, pressing the trim switch will disengage it.
FLIGHT DIRECTOR
There are times when it would be nice to utilize the capabili-
ties of the autopilot’s computer for things like ILS guidance or inter-
ception of desired courses, but keeping the human pilot “in the
loop.” For this, there’s the flight director function. Engage it by press-
ing the FD switch and a pair of “command bars” appear in the arti-
ficial horizon (now called the Attitude Director Indicator, or ADI).
Now, selecting any of the autopilot’s guidance modes, but without
engaging it, will cause these bars to move.
As long as you, the human pilot, keep the miniature airplane
in the ADI “tucked in” to the bars, you’re satisfying the comput-
er’s commands. It’s the same computer that would otherwise run
the autopilot; the only difference is that its output signals are going
to the command bars, rather than the control servos, and you’re
providing the muscle to move the controls instead.
Even with the autopilot engaged, the command bars provide
a useful reference and confirmation that it’s doing what it’s sup-
posed to. Whether you or the servos are flying the airplane,
remember that satisfying the command bars doesn’t necessarily
mean that you’re on course - but if you’re not, you’re doing what
you’re supposed to in order to return there.
YAW DAMPER
While the autopilot doesn’t need to use the rudder to control
airplane direction (aileron control alone is more than sufficient), it
incorporates a third axis, called the yaw damper, simply to keep
things coordinated and the ball in the center. This provides a sig-
nificant increase in passenger comfort, particularly in long-body
airplanes. The yaw damper is typically turned on just after takeoff,
and off just before landing. This is particularly important if you’re
landing in a crosswind; otherwise the yaw damper will “fight” your
pedal inputs as you level the wings and “kick out the crab.” Turn it
off anytime you’re adjusting the rudder trim, especially in single-
engine situations in the Navajo Chieftain.
Flight Instruction
189
Piper Navajo Chieftain
MOVING UP TO A TWIN
Welcome to the world of multi-engine flying! In a sense,
you’re already getting a head start: most students start out either
in one of the very light (“lite?”) twins like the Beech Duchess or
Piper Seminole or, if they’re lucky, a slightly larger traditional light
twin like the Cessna 310 (remember Sky King’s “Songbird?”),
Beech Baron, or Piper Aztec.
Flight Instruction
Piper’s Navajo Chieftain