It is difficult to predict what kind of knowledge is transferable, whether in aviation or in any other realm. Sometimes it's obvious one way or the other: a Course Deviation Indicator reads the same in a helicopter as it does in an airplane, and you can't bring an airplane to a hover except in the most unusual circumstances.
But I have also written about using the no-rudder-pedal Ercoupe to teach some stick-and-rudder skills.
Yesterday was to be my first helicopter training flight in a month, and when we last left our hero he was wondering how to smooth out his approaches and noticing that his airplane approaches had become sloppy, too.
Was holding a constant glide path a transferable skill? If so, shouldn't I practice in a $75/hr airplane rather than a $300/hour helicopter? And isn't practice part of the reportoire of a craftsman?
So before my helicopter flight I took an airplane and spent nearly an hour flying extremely precise approaches. Let me rephrase that: I took an airplane and spent nearly an hour trying to fly extremely precise approaches. I was most concerned with the portion from 500AGL to 30AGL, because you can't hover an airplane.
I told my instructor what I had done, saying it was really smart or really stupid and we would have to see which.
After an hour in the helicopter he concluded that it had worked and my approaches were much better despite a month's worth of rust. A few more autorotations and it will soon be time to solo.