The problem, which can be quite frightening, relates to asymmetric lift distributions, however caused. Some of the light aircraft LE VG mod kits cause considerable problems in this respect. I guess that most of us have seen the world substantially upside down due to this phenomenon.
It does not necessarily follow that flap extension will cause the inboard sections to stall before the outer in the ordered manner which you describe, although that is usually desirable to meet the aileron requirements in the stall regime. There are many detail design matters involved here. I suspect that you might be forgetting that the CL-alpha curves vary quite a bit as LE or TE devices are employed.
I have always suspected that much of the realworld problem relates to
(a) manufacturing tolerances
(b) small rigging variations
(c) in-service surface deterioration, contamination, and damage
- one doesn't need too much of a lateral lift asymmetry to generate significant rolling moments.
[This message has been edited by john_tullamarine (edited 24 May 2001).]