The KingAir has the "Reverse Not Ready" master caution annunciator light to tell you the props aren't full forward. No physical stop to reverse selection, but my understanding is that it probably won't be beneficial for all the linkages when reversing whilst the prop levers are not in the full forward position.
There are, of course, gates or other mechanisms (twisty-grips in the Twotter etc) to help prevent inadvertent reverse selection.
Last edited by MyNameIsIs; 19th Jun 2013 at 12:33.