14 CFR § 121.483

No certificate holder conducting flag operations may schedule a pilot to fly, in an airplane that has a crew of two pilots and at least one additional flight crewmember, for a total of more than 12 hours during any 24 consecutive hours.

If a pilot has flown 20 or more hours during any 48 consecutive hours or 24 or more hours during any 72 consecutive hours, he must be given at least 18 hours of rest before being assigned to any duty with the air carrier. In any case, he must be given at least 24 consecutive hours of rest during any seven consecutive days.

No pilot may fly as a flight crewmember more than—

120 hours during any 30 consecutive days;

300 hours during any 90 consecutive days; or

1,000 hours during any 12-calendar-month period.