I also thought the author was probably mistaken however I dont know anything about Chinooks so I have not presumed to be correct.
Without getting stuck on words there was a problem and the pilots shut down. The phrase "its either a fuel blockage or its the hydraulics." is the bit that had my focus.
I have had vapour in the fuel lines on start and that can be quite noisy and also have vibrations. It is not hard to diagnose though.
With the hydralics/AFCS I understand how vibrations could occur and need ground inspection to work out where the problem is coming from.
Personally though the issues I have had, it has been apparent which system is playing up.
My question for Chinook drivers is, can you have a problem where you would be unsure as to the origin,either from the fuel or the hydralics?
Cheers