BCAR, please accept my apology. I have checked again the FAA MMEL preamble and you are correct. The aircraft cannot be dispatched onto a sector which will terminate after 2400hrs on the last day of the relief.
From FAA MMEL Definitions.
Category A. Items in this category shall be repaired within the time interval specified in the remarks column of the operator's approved MEL. For time intervals specified in “calendar days” or "flight days," the day the malfunction was recorded in the aircraft maintenance record/logbook is excluded. For all other time intervals (flights, flight legs, cycles, hours, etc), repair tracking begins at the point when the malfunction is deferred in accordance with the operator's approved MEL.
Category B. Items in this category shall be repaired within three (3) consecutive calendar days (72 hours), excluding the day the malfunction was recorded in the aircraft maintenance record/logbook. For example, if it were recorded at 10 a.m. on January 26th, the three day interval would begin at midnight the 26th and end at midnight the 29th.
I guess we require a MEL revision.
TC