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that was given, will turn the wheel counterclockwise, dropping the left wing and turning back to 270. Now, to keep holding that assigned heading while the instructor is still pressing the right pedal, the wings cannot be brought back to level. Instead, a slight left bank must be retained.
Has the light bulb illuminated? Has your brain grasped why the autopilot is not flying wings level? It is doing so in order to fly the heading it wants while compensating for an incorrectly adjusted rudder. Keep in mind that although the autopilot may be in GPSS, Nav or Approach mode, not Heading mode, it still must find and hold an exact heading to track the course. Sure, that heading may be changing often as conditions – especially crosswind components – change, but at any given time the autopilot has a heading target when holding a heading or tracking a course.
It is common to see a pilot attempt to raise the wing that the autopilot
is keeping low by turning the aileron trim wheel. If the bank angle changes due to this action, then no longer will the target heading be held, so the AP will not let that wing come up. Oh sure, there is a reaction time so the wing will probably rise before it returns to the position it needs. Eventually, enough aileron trim will likely overpower the strength of the roll servo and the wing will indeed come up ... and keep coming! Thus, it is incorrect and fruitless to adjust aileron trim to correct the wing-low condition. Instead, just adjust rudder trim to add rudder force on the low- wing side.
Back to our training scenario: If we are now banking 2 degrees left-wing- down to compensate for the right rudder force our instructor sneaked in, we could take the rudder trim wheel – assuming our trainer has one – and turn it left, toward the low wing. Eventually, the rudder trim would create just the right amount of left-rudder force to balance the right- rudder force that the instructor was
applying and we would have the wings level again as we held the assigned 270 heading.
“Patience is a virtue.” I am sure you’ve heard that adage. If we move the rudder trim wheel in our King Air rapidly, the nose will of course momentarily swing in the direction of the rudder force that has now been applied. The Yaw Damper, obediently doing its job, will apply opposite rudder to dampen that yaw. Go slow with the trim and then stop to give the airplane and autopilot time to stabilize. Truly, in a King Air, the initial motion of the rudder trim wheel toward the low wing may be no more than one-fourth of one index division on the trim indicator. Expressed another way, the geared knurled knob that you are moving with your hand probably rotated only 30 degrees or less. Wait 30 seconds or so and inspect the wings. Better, but not level? Turn the trim wheel another small amount and wait again. Eventually you’ll have it nailed in level flight. Doing this perfectly throughout an entire flight (without an engine failure!) I will state that the rudder trim index is never more than one unit from center. Be patient; go slow.
Rarely do two different airplanes fly identically and hence what is right for one may not apply to others, even others of the exact same model. But let me tell you, readers, every King Air needs rudder trim adjustment throughout a flight! Why it drives me nuts when I ride with pilots who treat rudder trim and aileron trim the same –rarely if ever touching either one – is because the result is uncoordinated flight. Please work at being more aware of coordination.
“But I am aware! I keep the ball pretty darn well centered!” Yes, I am sure the ball is “pretty darn well centered” most of the time, as it should be. Give yourself a pat on the back; you’re doing good thus far. However, the amount the ball is out of the center – or the slip-skid bar is not aligned with the bank index – in level cruise flight is so small as to be almost unnoticeable even though the wings are obviously not level. Holding
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28 • KING AIR MAGAZINE
JUNE 2024