People,
Although there might be a few subtleties missed in regard to the stability comments above, the problem really is one of in-service stall character deterioration for whatever reason.
At certification, the stall character was shown to be reasonably benign, and the lateral control capability to be reasonably effective. Yet, here we are, with an in-service aircraft which now exhibits most undesirable characteristics - I can recall one PA31 mod program when, to my surprise, I ended up quite inverted during a very docile approach to the full flap stall - interesting. Subsequent testing demonstrated that the problem was not mod related and it was hand balled back to the local regulator - I have no idea what happened in regard to its resolution.
I suggest that a simplistic playing about with CL-alpha curves and thoughts of pressure derived forces moving nicely inboard is just that - far too simplistic ....
And .. when the talk gets around to consideration of each wing's operating to a different side of the stall alpha, then a consideration of Cd asymmetry results in that condition known as autorotation ... which is not nice in little trainers not designed for that sort of thing.
[This message has been edited by john_tullamarine (edited 25 May 2001).]