-tion, -sion, -cion trisyllabic lightening

Since the underlying form of -tion, -sion,and -cion is dissyllabic, i.e. at the time the rule or principle operates, even though the surface output is monosyllabic, the second "i" of division is light.

divide, divIsion
divisive, divIsibility
ignite, ignItion

I in IPA