ugrade requirement is 3 years(36 months) and 5000h.(theoric)
Donīt known about this 42 months..?
But of course the bigger the company become,and the slower the expansion rate is, this may take more than 3 years before you may be selected...
Fleet "upgrade":...i would say around 2 years..variable..depends of the need, and depends as well of the number of people who doesnīt want to move to 330 or 340...