I'm on a mission to get people to quit using the term "14 hour duty day" when referring to 135 ops. There is no such thing.
The regs say (paraphrased) that you have to be done doing 135 flying by the end of 14 hours of continuous duty (and the actual wording talks about "rest", not "duty"). Since "duty" can include many things besides flying (basically any work or travel that is done for the company), it is perfectly legal to have a duty day that is over 14 hours. I could do a trip that has 135 flying during the first 10 hours, then get put on an airliner and travel for 6 hours, then do 2 hours of paperwork in the office - that's a perfectly legal 18 hour duty day right there.
Yeah, yeah, I understand what most people MEAN when they say "14 hour duty day", but words mean things.
Bottom line is that you cannot accept (and the company cannot assign) a FLIGHT (135 flight) unless, at the completion of the flight, the pilot can look back and find 10 hours of continuous rest within the past 24 hours. This is not the same thing as being limited to 14 hours of duty.
[/rant or PSA, depending upon the receiver]