"Crew" is a collective noun, like committee, team, family, staff, choir, and faculty. It is singular. A crew is made up of individuals. In American English, this kind of collective noun (group of people) takes a singular verb, while in British English it usually takes a plural verb but may also take a singular one.
The camera crew has arrived to tape the interview (American English)
The camera crew have arrived to tape the interview (British English)
"Crews" refers to more than one crew. Contrast
"”Is the crew ready for the race? Yes, but the captain would like to recheck the equipment.
"”Are the crews ready for the race? "”All the crews are ready, but one of the boats has just sprung a leak