T & B,
Thanks, although I didn't know about the particular one to which you refer, my question was rhetorical. You know the Chinook as well as I do and my point, which Tuc answered as fully as he could, is that we don't know at which point certain faults become acceptable and make an ac airworthy, and others are not.
Is the FADEC perfect? Is the AFCS, the most common cause of UFCMs, perfect? How many are incidents are acceptable in a mechanical system that undergoes severe vibration and stress?
And it is a reasonable question to ask for the sake of those who have to depend upon it for their and their pax safety, when did the Mk II become airworthy - or not?