I was not near full deflection, the ball was barely outside of the line.... I think with all this information I'm starting to put together what is happening. I guess my expectation, wrongfully, was that when I return from a turn to straight and level, the plane will self coordinate.... My takeaway is always fly the plane, never expect it to fly for you.
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You may especially notice this when returning to straight & level flight from a steep turn. You must apply both aileron and rudder opposite the turn while returning to level flight, while keeping the controls balanced to each other & coordinated.
From the airplane's frame of reference, returning to straight & level flight from a L turn is much like entering a R turn. And vice versa.
Another aspect to consider with coordination is static vs. dynamic. By static I mean you are established in a constant rate turn - the bank angle, airspeed, pitch, are not changing. By dynamic I mean starting or ending the turn, everything is changing - bank angle, pitch, power, etc. The "ball" (turn & bank indicator) is sufficient for maintaining static coordination but not for dynamic coordination. The ball has a lag time in its response, so if you rely on it for dynamic coordination you will always be behind the airplane. And your eyes will be down in the panel instead out the window where they belong.
Two suggestions for this. First, the Mark VII butt-o-meter. If you learn what being coordinated feels like (or alternately, what not being coordinated feels like), you can maintain it without fixating on the ball. In a turn, any G forces you feel should be pushing you straight back into your seat. If it pushes you outside the turn (like a turn in car) you have too much rudder / not enough aileron. And vice versa.
Second, using distant horizon references. In straight & level flight, point the airplane at a prominent distant landmark like a mountain. As you bank into a turn, watch how the nose/cowling moves with respect to that landmark. This enables you to see the effect of adverse yaw. If you maintain dynamic coordination while rolling into the turn, the airplane will rotate and the nose will not shift left or right relative to the landmark, but remain in a fixed spot. If you are not coordinated, you will see the nose shift left or right as you enter the turn. For example if you enter the turn with aileron only, no rudder, the nose will shift opposite or away from the turn (adverse yaw). The idea is to enter the turn using the ailerons and use just enough rudder to prevent the nose from shifting relative to the distant landmark. This also has the benefit of keeping your eyes out the windshield where they belong.