Hi!
My longest duty day (2 pilot crew) was about 25 hours. It was fully legal/and or acceptable to the FAA...depends on who reads the regs, who interprets them, and what your local FAA Regional Office/FSCO/POI says.
Oh, and the above also applies for my 240 hours of continuous reserve...my longest "legal" reserve period so far.
That has GOT to change!
cliff
NBO