The rostered week must be 55hrs or less and a crew member can go to 60hrs maximum taking into consderation delays etc. Crews cannot be rostered in excess of 55hrs however, and can't be given changes to their roster which would take them above 55hrs. The following week would not have to be reduced down.
Grabber has a very valid point, any good crewing officer would stop the 55hr limit being busted anyway.... hope this helps.