Originally Posted by BoilerUP

If its a single-pilot jet (such as a Mustang, CJ or Premier), one can long SIC time provided you have been trained in accordance with 61.55, your logbook reflects as much, and the PIC is 61.58 current. This is because the TCDS for these aircraft shows Required Crew as "minimum one".

If its a King Air, then the TCDS shows Required Crew as "one" and you're pretty much out of luck.